/**
 * core-modify – Built-in V2-Plugin.
 *
 * Werkzeuge:
 * - select (A3): Klick-Auswahl mit Shift/Ctrl
 * - hatch (A4.5): Schraffur via doc.updateElement
 * - move/copy (A4.6): selektionsbasiert, Basis→Ziel
 * - rotate/scale/mirror (A4.7): gleiche Selektions-Konvention,
 *   Legacy-Transform-Mathematik aus handleModifyMove übernommen
 *
 * Alle Commits laufen über CADDocument → kollaborativ korrektes Undo.
 */
import type { PluginV2, ToolExtensionV2 } from '../../types';
import type { FullToolContext } from '../../types';
import type { CADElement } from '../../../types/cad.types';
import {
  moveElement,
  rotateElement,
  scaleElement,
  mirrorElement,
  angleBetween,
  distance,
  offsetElement,
  trimElement,
  extendElement,
  filletElements,
} from '../../../tools/modification/geometry';
import { openBlockForEdit, saveBlockEdit, discardBlockEdit } from '../../../services/blockEditorService';
import { BLOCK_EDIT_MARKER } from '../../../services/blockEditorService';
export { BLOCK_EDIT_MARKER };
import type { Pt } from '../../../tools/modification/geometry';

const uid = (prefix: string): string =>
  `${prefix}_${Date.now().toString(36)}_${Math.random().toString(36).slice(2, 9)}`;

// ─────────────────────────────────────────────────────────────
// select (Task A3 – Pilot) + Handle-Drag (Task C3fin interaktiv)
// ─────────────────────────────────────────────────────────────
/** Handle-Drag-Sitzung: aktives Element + gegenüberliegende Ecke. */
let handleDrag: {
  el: CADElement;
  anchorCorner: Pt;
  handleIndex: number;
} | null = null;

/** Prüft, ob (wx,wy) eine BBox-Ecke des Elements trifft (Toleranz tol). */
function hitHandle(
  el: CADElement,
  wx: number,
  wy: number,
  tol: number,
): { handleIndex: number; anchorCorner: Pt } | null {
  const props = el.properties as Record<string, unknown>;
  let minX: number, minY: number, maxX: number, maxY: number;
  if (
    props.x1 !== undefined && props.y1 !== undefined &&
    props.x2 !== undefined && props.y2 !== undefined
  ) {
    minX = Math.min(props.x1 as number, props.x2 as number);
    minY = Math.min(props.y1 as number, props.y2 as number);
    maxX = Math.max(props.x1 as number, props.x2 as number);
    maxY = Math.max(props.y1 as number, props.y2 as number);
  } else {
    minX = el.x - el.width / 2;
    minY = el.y - el.height / 2;
    maxX = el.x + el.width / 2;
    maxY = el.y + el.height / 2;
  }
  const corners: Array<{ x: number; y: number }> = [
    { x: minX, y: minY },
    { x: maxX, y: minY },
    { x: maxX, y: maxY },
    { x: minX, y: maxY },
  ];
  for (let i = 0; i < corners.length; i++) {
    if (
      Math.abs(wx - corners[i].x) <= tol &&
      Math.abs(wy - corners[i].y) <= tol
    ) {
      // Gegenüberliegende Ecke = Anker (bleibt fix beim Skalieren)
      const anchor = corners[(i + 2) % 4];
      return { handleIndex: i, anchorCorner: anchor };
    }
  }
  return null;
}

// ─────────────────────────────────────────────────────────────
// Task D9: GripEditing — Vertex-/Center-Grips (reine Funktion).
// ─────────────────────────────────────────────────────────────

export interface GripPoint {
  kind: 'vertex' | 'center' | 'corner';
  point: Pt;
  index: number;
}

/**
 * Element-spezifische Griff-Punkte (Task D9):
 * line = beide Endpunkte, polyline/polygon = alle Vertices,
 * circle/arc = Zentrum, rect/default = 4 BBox-Ecken (C3fin-Skalierung).
 */
export function getGripPoints(el: CADElement): GripPoint[] {
  const props = el.properties as Record<string, unknown>;
  const type = String(el.type);
  if (
    type === 'line' &&
    props.x1 !== undefined && props.y1 !== undefined &&
    props.x2 !== undefined && props.y2 !== undefined
  ) {
    return [
      { kind: 'vertex', point: { x: props.x1 as number, y: props.y1 as number }, index: 0 },
      { kind: 'vertex', point: { x: props.x2 as number, y: props.y2 as number }, index: 1 },
    ];
  }
  if (type === 'polyline' || type === 'polygon') {
    const pts = (props.points as Pt[] | undefined) ?? [];
    return pts.map((p, i) => ({ kind: 'vertex' as const, point: { x: p.x, y: p.y }, index: i }));
  }
  if (type === 'circle' || type === 'arc') {
    return [{ kind: 'center', point: { x: el.x, y: el.y }, index: 0 }];
  }
  // rect und alle anderen: BBox-Ecken (Corner-Drag/Skalierung, C3fin)
  const minX = el.x - el.width / 2;
  const minY = el.y - el.height / 2;
  const maxX = el.x + el.width / 2;
  const maxY = el.y + el.height / 2;
  return [
    { kind: 'corner', point: { x: minX, y: minY }, index: 0 },
    { kind: 'corner', point: { x: maxX, y: minY }, index: 1 },
    { kind: 'corner', point: { x: maxX, y: maxY }, index: 2 },
    { kind: 'corner', point: { x: minX, y: maxY }, index: 3 },
  ];
}

/**
 * Wendet eine Vertex-/Center-Drag-Position an (Task D9) und liefert
 * das aktualisierte Element (reine Funktion — für Preview UND Commit).
 */
function applyVertexDrag(
  el: CADElement,
  drag: { el: CADElement; gripKind: 'vertex' | 'center'; index: number },
  wx: number,
  wy: number,
): CADElement {
  const props = { ...(el.properties as Record<string, unknown>) };
  const type = String(el.type);
  if (drag.gripKind === 'center') {
    return { ...el, x: wx, y: wy, properties: props as CADElement['properties'] } as CADElement;
  }
  if (type === 'line') {
    if (drag.index === 0) { props.x1 = wx; props.y1 = wy; }
    else { props.x2 = wx; props.y2 = wy; }
    // BBox aktualisieren
    const x1 = props.x1 as number, y1 = props.y1 as number, x2 = props.x2 as number, y2 = props.y2 as number;
    return {
      ...el,
      x: (x1 + x2) / 2,
      y: (y1 + y2) / 2,
      width: Math.abs(x2 - x1),
      height: Math.abs(y2 - y1),
      properties: props as CADElement['properties'],
    } as CADElement;
  }
  if (type === 'polyline' || type === 'polygon') {
    const pts = [...((props.points as Pt[] | undefined) ?? [])];
    if (drag.index < pts.length) pts[drag.index] = { x: wx, y: wy };
    props.points = pts;
    const xs = pts.map((p) => p.x), ys = pts.map((p) => p.y);
    const minX = Math.min(...xs), minY = Math.min(...ys);
    const maxX = Math.max(...xs), maxY = Math.max(...ys);
    return {
      ...el,
      x: minX + (maxX - minX) / 2,
      y: minY + (maxY - minY) / 2,
      width: maxX - minX,
      height: maxY - minY,
      properties: props as CADElement['properties'],
    } as CADElement;
  }
  return el;
}

// ─────────────────────────────────────────────────────────────
// Task CAD-3: Fenster-/Kreuz-Selektion (Box-Select).
// Links-nach-rechts ziehen = 'window' (Element muss VOLLSTAENDIG
// in der Box liegen), rechts-nach-links = 'crossing' (Beruehrung
// reicht). Leerer down startet Box-Drag statt Selektion zu leeren.
// ─────────────────────────────────────────────────────────────

/** Richtung bestimmt den Modus: to.x >= from.x → window, sonst crossing. */
export function boxModeFor(from: Pt, to: Pt): 'window' | 'crossing' {
  return to.x >= from.x ? 'window' : 'crossing';
}

/**
 * Selektiert alle Elemente, die die Box erfuellen.
 * window: BBox des Elements VOLLSTAENDIG in der Box.
 * crossing: BBox des Elements ueberschneidet/beruehrt die Box.
 */
export function boxSelectElements(
  elements: CADElement[],
  box: { x1: number; y1: number; x2: number; y2: number },
  mode: 'window' | 'crossing',
): string[] {
  const minX = Math.min(box.x1, box.x2);
  const maxX = Math.max(box.x1, box.x2);
  const minY = Math.min(box.y1, box.y2);
  const maxY = Math.max(box.y1, box.y2);
  const hits: string[] = [];
  for (const el of elements) {
    const b = elementBBox(el);
    if (!b) continue;
    if (mode === 'window') {
      if (b.minX >= minX && b.maxX <= maxX && b.minY >= minY && b.maxY <= maxY) {
        hits.push(el.id);
      }
    } else {
      // crossing: Ueberschneidung (Beruehrung inklusive)
      if (b.minX <= maxX && b.maxX >= minX && b.minY <= maxY && b.maxY >= minY) {
        hits.push(el.id);
      }
    }
  }
  return hits;
}

/** BBox eines Elements (line aus Koordinaten, sonst x/y±w/2). */
function elementBBox(el: CADElement): { minX: number; minY: number; maxX: number; maxY: number } | null {
  const props = el.properties as Record<string, unknown>;
  if (
    props.x1 !== undefined && props.y1 !== undefined &&
    props.x2 !== undefined && props.y2 !== undefined
  ) {
    const x1 = props.x1 as number, y1 = props.y1 as number;
    const x2 = props.x2 as number, y2 = props.y2 as number;
    return { minX: Math.min(x1, x2), minY: Math.min(y1, y2), maxX: Math.max(x1, x2), maxY: Math.max(y1, y2) };
  }
  const w = el.width ?? 0, h = el.height ?? 0;
  return { minX: el.x - w / 2, minY: el.y - h / 2, maxX: el.x + w / 2, maxY: el.y + h / 2 };
}

/** Box-Drag-Sitzung (Task CAD-3). */
let boxDrag: { start: Pt; shift: boolean } | null = null;

/** Mindestgroesse (Welt-Einheiten) ab der ein Zug als Box gilt. */
const BOX_MIN_SIZE = 3;

/** Vertex-/Center-Drag-Sitzung (Task D9). */
let vertexDrag: {
  el: CADElement;
  gripKind: 'vertex' | 'center';
  index: number;
} | null = null;

export const selectTool: ToolExtensionV2 = {
  manifest: {
    id: 'select',
    label: 'Auswahl',
    icon: '\u2196',
    ribbonTab: 'canvas',
    tags: ['basic'],
    description: 'Elemente anklicken zum Auswählen',
  },
  optionsSchema: [],
  handlers: {
    down(e, ctx) {
      const bridge = (ctx as FullToolContext).selection;
      const c = ctx as FullToolContext;
      if (!bridge) return;
      // CAD-3: verlorene Box-Sitzungen abräumen (defensive State-Hygiene,
      // schützt auch vor verlorenen up-Events); wird unten bei Leerraum neu gesetzt.
      boxDrag = null;
      const additive = e.shift;
      const subtractive = e.ctrl;
      const hit = bridge.hitTest(e.world.x, e.world.y, 5);

      // ── Task D9: Vertex-/Center-Grip-Prüfung VOR BBox-Corners ──
      // (spezifischere Grips gewinnen gegenüber Corner-Skalierung)
      if (!additive && !subtractive && c.doc) {
        const GRIP_TOL = 8;
        for (const id of bridge.getIds()) {
          const el = c.doc.getElement(id);
          if (!el) continue;
          for (const g of getGripPoints(el)) {
            if (g.kind === 'corner') continue; // Corner unten (C3fin)
            if (
              Math.abs(e.world.x - g.point.x) <= GRIP_TOL &&
              Math.abs(e.world.y - g.point.y) <= GRIP_TOL
            ) {
              vertexDrag = { el, gripKind: g.kind, index: g.index };
              const what = g.kind === 'center' ? 'Zentrum' : `Punkt ${g.index + 1}`;
              ctx.setStatus(`${what} gegriffen — ziehen zum Verschieben`);
              return;
            }
          }
        }
      }

      // ── Handle-Drag-Start (Task C3fin interaktiv) ──
      // Wenn bereits Elemente selektiert sind und der Klick auf eine Ecke
      // eines davon trifft → Handle-Drag starten statt neu zu wählen.
      if (!additive && !subtractive && bridge.getIds().length > 0 && c.doc) {
        for (const id of bridge.getIds()) {
          const el = c.doc.getElement(id);
          if (!el) continue;
          const h = hitHandle(el, e.world.x, e.world.y, 8);
          if (h) {
            handleDrag = { el, anchorCorner: h.anchorCorner, handleIndex: h.handleIndex };
            ctx.setStatus(`Handle ${h.handleIndex + 1} — skalieren durch Ziehen`);
            return;
          }
        }
      }

      if (!hit) {
        // ── Task CAD-3: Leerraum-Klick startet Box-Select-Drag ──
        // (statt sofort zu leeren; das Leeren passiert nur bei Klick OHNE Zug)
        boxDrag = { start: e.world, shift: e.shift };
        ctx.setStatus('Box-Auswahl: ziehen (rechts=fenster, links=kreuzend)');
        return;
      }
      let ids = new Set(bridge.getIds());
      if (subtractive) {
        ids.delete(hit.id);
      } else {
        ids.add(hit.id);
        if (!additive) ids = new Set([hit.id]);
      }
      bridge.setIds(Array.from(ids));
      ctx.setStatus(`Selektion: ${ids.size} Element(e)`);
    },

    move(e, ctx) {
      // ── Task CAD-3: Box-Select-Preview ──
      if (boxDrag) {
        const c = ctx as FullToolContext;
        const x = Math.min(boxDrag.start.x, e.world.x);
        const y = Math.min(boxDrag.start.y, e.world.y);
        const w = Math.abs(e.world.x - boxDrag.start.x);
        const h = Math.abs(e.world.y - boxDrag.start.y);
        const mode = boxModeFor(boxDrag.start, e.world);
        c.setPreview?.({
          id: '__preview_boxselect__',
          type: 'rect',
          layerId: 'layer-0',
          x: x + w / 2,
          y: y + h / 2,
          width: w,
          height: h,
          properties: {
            stroke: mode === 'window' ? '#4a90d9' : '#22c55e',
            strokeWidth: 1,
            fill: mode === 'window' ? 'rgba(74,144,217,0.08)' : 'rgba(34,197,94,0.08)',
            boxSelectMode: mode,
          },
        } as unknown as CADElement);
        return;
      }
      // ── Task D9: Vertex-Drag-Preview (nur der Punkt aktualisiert) ──
      if (vertexDrag) {
        const c = ctx as FullToolContext;
        const el = c.doc?.getElement(vertexDrag.el.id);
        if (!el) return;
        const updated = applyVertexDrag(el, vertexDrag, e.world.x, e.world.y);
        c.setPreview?.(updated);
        return;
      }
      // Live-Skalierung während Handle-Drag:
      if (!handleDrag) return;
      const c = ctx as FullToolContext;
      if (!c.doc) return;
      const el = c.doc.getElement(handleDrag.el.id);
      if (!el) return;
      const props = el.properties as Record<string, unknown>;
      // BBox aus Element abrufen (mit aktuellen Koordinaten):
      let minX: number, minY: number, maxX: number, maxY: number;
      if (
        props.x1 !== undefined && props.y1 !== undefined &&
        props.x2 !== undefined && props.y2 !== undefined
      ) {
        minX = Math.min(props.x1 as number, props.x2 as number);
        minY = Math.min(props.y1 as number, props.y2 as number);
        maxX = Math.max(props.x1 as number, props.x2 as number);
        maxY = Math.max(props.y1 as number, props.y2 as number);
      } else {
        minX = el.x - el.width / 2;
        minY = el.y - el.height / 2;
        maxX = el.x + el.width / 2;
        maxY = el.y + el.height / 2;
      }
      // Neue BBox = Anker fix, gezogene Ecke = Maus:
      const anchor = handleDrag.anchorCorner;
      const newMinX = Math.min(anchor.x, e.world.x);
      const newMinY = Math.min(anchor.y, e.world.y);
      const newMaxX = Math.max(anchor.x, e.world.x);
      const newMaxY = Math.max(anchor.y, e.world.y);
      // Preview-Linie von Anker zur Maus (vereinfachtes Feedback):
      c.setPreview?.({
        ...el,
        x: (newMinX + newMaxX) / 2,
        y: (newMinY + newMaxY) / 2,
        width: newMaxX - newMinX,
        height: newMaxY - newMinY,
      } as CADElement);
      void minX; void minY; void maxX; void maxY;
    },

    up(e, ctx) {
      // ── Task CAD-3: Box-Select-Abschluss ──
      if (boxDrag) {
        const c = ctx as FullToolContext;
        const start = boxDrag.start;
        const shift = boxDrag.shift || e.shift;
        boxDrag = null;
        ctx.setPreview?.(null);
        const w = Math.abs(e.world.x - start.x);
        const h = Math.abs(e.world.y - start.y);
        // Winzige Box = Klick ohne Zug → Legacy: Selektion leeren
        if (w < BOX_MIN_SIZE && h < BOX_MIN_SIZE) {
          if (!shift) (c.selection ?? { setIds: () => {} }).setIds([]);
          ctx.setStatus('Selektion geleert');
          return;
        }
        const mode = boxModeFor(start, e.world);
        const all = c.doc ? c.doc.getAllElements() : [];
        const hits = boxSelectElements(all, {
          x1: start.x, y1: start.y, x2: e.world.x, y2: e.world.y,
        }, mode);
        const bridge = (ctx as FullToolContext).selection;
        if (!bridge) return;
        if (shift) {
          const merged = new Set([...bridge.getIds(), ...hits]);
          bridge.setIds(Array.from(merged));
        } else {
          bridge.setIds(hits);
        }
        const count = shift
          ? new Set([...(bridge.getIds())]).size
          : hits.length;
        ctx.setStatus(`Box-Auswahl (${mode === 'window' ? 'Fenster' : 'Kreuzend'}): ${count} Element(e)`);
        return;
      }
      // ── Task D9: Vertex-Commit (nur der Punkt, 1 Undo-Schritt) ──
      if (vertexDrag) {
        const c = ctx as FullToolContext;
        const el = c.doc?.getElement(vertexDrag.el.id);
        if (el && c.doc) {
          const updated = applyVertexDrag(el, vertexDrag, e.world.x, e.world.y);
          c.doc.transact(() => {
            c.doc!.updateElement(el.id, {
              x: updated.x,
              y: updated.y,
              properties: updated.properties as CADElement['properties'],
            });
          });
          const what = vertexDrag.gripKind === 'center' ? 'Zentrum' : `Punkt ${vertexDrag.index + 1}`;
          ctx.setStatus(`${what} verschoben`);
        }
        vertexDrag = null;
        ctx.setPreview?.(null);
        return;
      }
      if (!handleDrag) return;
      const c = ctx as FullToolContext;
      if (!c.doc) { handleDrag = null; return; }
      const el = c.doc.getElement(handleDrag.el.id);
      const anchor = handleDrag.anchorCorner;
      if (!el) { handleDrag = null; return; }
      const props = el.properties as Record<string, unknown>;
      // Neue BBox berechnen:
      const newMinX = Math.min(anchor.x, e.world.x);
      const newMinY = Math.min(anchor.y, e.world.y);
      const newMaxX = Math.max(anchor.x, e.world.x);
      const newMaxY = Math.max(anchor.y, e.world.y);
      const newW = newMaxX - newMinX;
      const newH = newMaxY - newMinY;
      const oldW = el.width || 1;
      const oldH = el.height || 1;
      const scaleX = oldW !== 0 ? newW / oldW : 1;
      const scaleY = oldH !== 0 ? newH / oldH : 1;
      // Neues Zentrum:
      const newCx = (newMinX + newMaxX) / 2;
      const newCy = (newMinY + newMaxY) / 2;

      c.doc.transact(() => {
        // Element in neuer BBox skalieren (shallow properties überschrieben):
        const newProps = { ...(el.properties as Record<string, unknown>) };
        // Für line: Koordinaten skalieren relativ zur neuen BBox
        if (
          newProps.x1 !== undefined && newProps.y1 !== undefined &&
          newProps.x2 !== undefined && newProps.y2 !== undefined
        ) {
          newProps.x1 = newMinX + ((newProps.x1 as number) - (el.x - el.width / 2)) * scaleX;
          newProps.y1 = newMinY + ((newProps.y1 as number) - (el.y - el.height / 2)) * scaleY;
          newProps.x2 = newMinX + ((newProps.x2 as number) - (el.x - el.width / 2)) * scaleX;
          newProps.y2 = newMinY + ((newProps.y2 as number) - (el.y - el.height / 2)) * scaleY;
        }
        c.doc!.updateElement(el.id, {
          x: newCx,
          y: newCy,
          width: newW,
          height: newH,
          properties: newProps,
        });
      });
      ctx.setStatus(`Skaliert auf ${newW.toFixed(0)}×${newH.toFixed(0)}`);
      handleDrag = null;
      ctx.setPreview?.(null);
    },

    cancel(ctx) {
      handleDrag = null;
      vertexDrag = null;
      boxDrag = null;
      ctx.setPreview?.(null);
    },
  },
};

// ─────────────────────────────────────────────────────────────
// hatch (Task A4.5)
// ─────────────────────────────────────────────────────────────
export const hatchTool: ToolExtensionV2 = {
  manifest: {
    id: 'hatch', label: 'Schraffur', icon: '\u2593', ribbonTab: 'format', tags: ['pro'],
    description: 'Geschlossenes Element anklicken zum Schraffieren',
  },
  optionsSchema: [
    { key: 'hatchPattern', label: 'Muster', type: 'select', options: [
      { value: 'ANSI31', label: 'ANSI31 (45°)' },
      { value: 'ANSI32', label: 'ANSI32 (Eisen)' },
      { value: 'ANSI37', label: 'ANSI37 (Beton)' },
      { value: 'NET', label: 'Netz' },
      { value: 'GRASS', label: 'Gras' },
      { value: 'DOTS', label: 'Punkte' },
      { value: 'SOLID', label: 'Voll' },
      { value: 'lines', label: 'Linien (alt)' },
      { value: 'cross', label: 'Kreuz (alt)' },
    ] },
    { key: 'hatchSpacing', label: 'Abstand', type: 'number', min: 2, max: 40 },
  ],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      const bridge = c.selection;
      if (!bridge || !c.doc) return;
      const hit = bridge.hitTest(e.world.x, e.world.y, 5);
      if (!hit || !['rect', 'circle', 'polygon'].includes(hit.type)) {
        ctx.setStatus('Schraffur: nur rect/circle/polygon');
        return;
      }
      const pattern = (c.options.hatchPattern as string | undefined) ?? 'lines';
      const spacing = (c.options.hatchSpacing as number | undefined) ?? 8;
      c.doc.updateElement(hit.id, {
        properties: { hatch: true, hatchPattern: pattern, hatchSpacing: spacing },
      });
      ctx.setStatus(`Schraffur auf ${hit.id} (${pattern})`);
    },
  },
};

// ─────────────────────────────────────────────────────────────
// Move/Copy (Task A4.6)
// ─────────────────────────────────────────────────────────────
let modBasePoint: Pt | null = null;

function makeMoveCopyTool(mode: 'move' | 'copy'): ToolExtensionV2 {
  const label = mode === 'move' ? 'Verschieben' : 'Kopieren';
  return {
    manifest: {
      id: mode,
      label,
      icon: mode === 'move' ? '\u27a4' : '\u29c9',
      ribbonTab: 'canvas',
      tags: ['basic'],
      description: `${label}: Auswahl treffen, dann Basis\u2192Ziel klicken`,
    },
    optionsSchema: [],
    handlers: {
      down(e, ctx) {
        const c = ctx as FullToolContext;
        if (!c.doc || !c.selection) return;
        if (!modBasePoint) {
          const ids = c.selection.getIds();
          if (ids.length === 0) {
            const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
            if (!hit) {
              ctx.setStatus(`${label}: zuerst Element(e) auswählen`);
              return;
            }
            c.selection.setIds([hit.id]);
          }
          modBasePoint = e.world;
          ctx.setStatus(`${label}: Zielklick zum ${mode === 'move' ? 'Verschieben' : 'Kopieren'} (${c.selection.getIds().length} Elemente)`);
          return;
        }
        const dx = e.world.x - modBasePoint.x;
        const dy = e.world.y - modBasePoint.y;
        const ids = c.selection.getIds();
        c.doc.transact(() => {
          for (const id of ids) {
            const el = c.doc!.getElement(id);
            if (!el) continue;
            if (mode === 'move') {
              c.doc!.updateElement(id, { x: el.x + dx, y: el.y + dy });
            } else {
              c.doc!.addElement({
                ...el,
                id: uid('cp'),
                x: el.x + dx,
                y: el.y + dy,
              });
            }
          }
        });
        ctx.setStatus(`${label}: ${ids.length} Element(e), \u0394(${dx.toFixed(0)}, ${dy.toFixed(0)})`);
        modBasePoint = null;
      },
      cancel(ctx) {
        modBasePoint = null;
        ctx.setStatus(`${label} abgebrochen`);
      },
    },
  };
}
export const moveTool: ToolExtensionV2 = makeMoveCopyTool('move');
export const copyTool: ToolExtensionV2 = makeMoveCopyTool('copy');

// ─────────────────────────────────────────────────────────────
// Rotate / Scale / Mirror (Task A4.7)
// Konventionen exakt aus Legacy handleModifyMove:
// - rotate: Pivot = Zentrum des ERSTEN selektierten Elements,
//   Δwinkel = angleBetween(pivot,zweitKlick) − angleBetween(pivot,basis)
// - scale: Faktor = dist(pivot,zweitKlick) / dist(pivot,basis)
// - mirror: Spiegelachse = Linie basis→zweitKlick
// Klick-progressiv: Commit beim ZWEITEN down (Arc-Lektion).
// ─────────────────────────────────────────────────────────────
let transformBase: Pt | null = null;

function makeTransformTool(mode: 'rotate' | 'scale' | 'mirror'): ToolExtensionV2 {
  const labels = { rotate: 'Rotieren', scale: 'Skalieren', mirror: 'Spiegeln' } as const;
  const iconMap = { rotate: '\u21bb', scale: '\u2922', mirror: '\u21c6' } as const;
  return {
    manifest: {
      id: mode,
      label: labels[mode],
      icon: iconMap[mode],
      ribbonTab: 'canvas',
      tags: ['pro'],
      description: `${labels[mode]}: Auswahl treffen, dann Basis\u2192Referenz klicken`,
    },
    optionsSchema: [],
    handlers: {
      down(e, ctx) {
        const c = ctx as FullToolContext;
        if (!c.doc || !c.selection) return;
        if (!transformBase) {
          if (c.selection.getIds().length === 0) {
            const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
            if (!hit) {
              ctx.setStatus(`${labels[mode]}: zuerst Element(e) auswählen`);
              return;
            }
            c.selection.setIds([hit.id]);
          }
          transformBase = e.world;
          ctx.setStatus(`${labels[mode]}: Referenzklick zum Anwenden (${c.selection.getIds().length} Elemente)`);
          return;
        }
        // Zweiter Klick → Commit auf ALLE selektierten Elemente, EINE Transaktion
        const base = transformBase;
        const ids = c.selection.getIds();
        const first = c.doc.getElement(ids[0]);
        if (!first) { transformBase = null; return; }
        const pivot = { x: first.x, y: first.y };
        c.doc.transact(() => {
          for (const id of ids) {
            const el = c.doc!.getElement(id);
            if (!el) continue;
            let next: CADElement;
            if (mode === 'rotate') {
              const delta = angleBetween(pivot, e.world) - angleBetween(pivot, base);
              next = rotateElement(el, pivot.x, pivot.y, delta);
            } else if (mode === 'scale') {
              const sd = distance(pivot, base);
              const cd = distance(pivot, e.world);
              const factor = sd > 0 ? cd / sd : 1;
              next = scaleElement(el, pivot.x, pivot.y, factor, factor);
            } else {
              next = mirrorElement(el, base.x, base.y, e.world.x, e.world.y);
            }
            c.doc!.updateElement(id, {
              x: next.x, y: next.y,
              width: next.width, height: next.height,
              properties: next.properties,
            });
          }
        });
        ctx.setStatus(`${labels[mode]}: ${ids.length} Element(e)`);
        transformBase = null;
      },
      move(e, ctx) {
        // Live-Vorschau am ersten selektierten Element (Legacy previewElement)
        const c = ctx as FullToolContext;
        if (!transformBase || !c.selection || !c.doc) return;
        const ids = c.selection.getIds();
        if (ids.length === 0) return;
        const first = c.doc.getElement(ids[0]);
        if (!first) return;
        const pivot = { x: first.x, y: first.y };
        let next: CADElement;
        if (mode === 'rotate') {
          const delta = angleBetween(pivot, e.world) - angleBetween(pivot, transformBase);
          next = rotateElement(first, pivot.x, pivot.y, delta);
        } else if (mode === 'scale') {
          const sd = distance(pivot, transformBase);
          const cd = distance(pivot, e.world);
          const f = sd > 0 ? cd / sd : 1;
          next = scaleElement(first, pivot.x, pivot.y, f, f);
        } else {
          next = mirrorElement(first, transformBase.x, transformBase.y, e.world.x, e.world.y);
        }
        ctx.setPreview?.(next);
      },
      cancel(ctx) {
        transformBase = null;
        ctx.setPreview?.(null);
        ctx.setStatus(`${labels[mode]} abgebrochen`);
      },
    },
  };
}
export const rotateTool: ToolExtensionV2 = makeTransformTool('rotate');
export const scaleTool: ToolExtensionV2 = makeTransformTool('scale');
export const mirrorTool: ToolExtensionV2 = makeTransformTool('mirror');

// ─────────────────────────────────────────────────────────────
// Join / Explode / Align (Task D-Extensions):
// - join: 2+ ausgewählte Linien → eine Polyline (Transaktion)
// - explode: Polyline → einzelne Liniensegmente (Transaktion)
// - align: bewegt ein Element so, dass sein Anker (Zentrum) auf das
//   Ziel-Element-Zentrum ausgerichtet wird (3 Klicks: Quelle, Ziel, Commit)
// ─────────────────────────────────────────────────────────────
let alignSourceId: string | null = null;

function makeJoinExplodeAlignTool(mode: 'join' | 'explode' | 'align'): ToolExtensionV2 {
  const labels = { join: 'Join', explode: 'Explode', align: 'Align' } as const;
  return {
    manifest: {
      id: mode,
      label: labels[mode],
      icon: mode === 'join' ? '\u2795' : mode === 'explode' ? '\u2737' : '\u21c4',
      ribbonTab: 'canvas',
      tags: ['pro'],
      description: `${labels[mode]}: siehe Statuszeile`,
    },
    optionsSchema: [],
    handlers: {
      down(e, ctx) {
        const c = ctx as FullToolContext;
        if (!c.doc || !c.selection) return;
        const ids = c.selection.getIds();

        if (mode === 'join') {
          // Alle selektierten Linien → eine Polyline:
          const lines = ids
            .map((id) => c.doc!.getElement(id))
            .filter((el): el is CADElement => !!el && el.type === 'line');
          if (lines.length < 2) {
            ctx.setStatus('Join: mindestens 2 Linien auswählen');
            return;
          }
          // Punkte der Linien in Reihenfolge sammeln:
          const allPts: Pt[] = [];
          for (const ln of lines) {
            const props = ln.properties as Record<string, unknown>;
            if (props.x1 === undefined) continue;
            allPts.push({ x: props.x1 as number, y: props.y1 as number });
            allPts.push({ x: props.x2 as number, y: props.y2 as number });
          }
          if (allPts.length < 4) return;
          // Erste und letzte Koordinate als Start/Ende nehmen:
          const first = allPts[0];
          const last = allPts[allPts.length - 1];
          const joined: CADElement = {
            ...lines[0],
            id: uid('pl'),
            type: 'polyline',
            x: (first.x + last.x) / 2,
            y: (first.y + last.y) / 2,
            width: Math.abs(last.x - first.x),
            height: Math.abs(last.y - first.y),
            properties: { points: allPts, stroke: '#e0e0e0', strokeWidth: 1 },
          };
          c.doc.transact(() => {
            for (const ln of lines) c.doc!.deleteElements([ln.id]);
            c.doc!.addElement(joined);
          });
          ctx.setStatus(`Join: ${lines.length} Linien → 1 Polyline`);
          return;
        }

        if (mode === 'explode') {
          // Polyline → einzelne Liniensegmente:
          const polys = ids
            .map((id) => c.doc!.getElement(id))
            .filter((el): el is CADElement => !!el && el.type === 'polyline');
          if (polys.length === 0) {
            ctx.setStatus('Explode: mindestens eine Polyline auswählen');
            return;
          }
          c.doc.transact(() => {
            for (const poly of polys) {
              const props = poly.properties as Record<string, unknown>;
              const pts = Array.isArray(props.points)
                ? (props.points as unknown[]).map((p) => p as Pt)
                : [];
              for (let i = 0; i < pts.length - 1; i++) {
                c.doc!.addElement({
                  ...poly,
                  id: uid('ln'),
                  type: 'line',
                  x: (pts[i].x + pts[i + 1].x) / 2,
                  y: (pts[i].y + pts[i + 1].y) / 2,
                  width: Math.abs(pts[i + 1].x - pts[i].x),
                  height: Math.abs(pts[i + 1].y - pts[i].y),
                  properties: { x1: pts[i].x, y1: pts[i].y, x2: pts[i + 1].x, y2: pts[i + 1].y, stroke: '#e0e0e0', strokeWidth: 1 },
                });
              }
              c.doc!.deleteElements([poly.id]);
            }
          });
          ctx.setStatus(`Explode: ${polys.length} Polyline(n) in Segmente zerlegt`);
          return;
        }

        // align: Klick 1 = Quelle (Element), Klick 2 = Ziel-Position
        if (mode === 'align') {
          if (ids.length === 0) {
            const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
            if (!hit) return;
            c.selection.setIds([hit.id]);
            alignSourceId = hit.id;
            ctx.setStatus('Align: Ziel-Position klicken');
            return;
          }
          const el = c.doc.getElement(ids[0]);
          if (!el) return;
          const cx = el.x;
          const cy = el.y;
          c.doc.transact(() => {
            c.doc!.updateElement(el.id, { x: e.world.x, y: e.world.y });
          });
          ctx.setStatus(`Align: ${el.id} nach (${e.world.x.toFixed(0)}, ${e.world.y.toFixed(0)}) verschoben`);
          alignSourceId = null;
          return;
        }
      },
      cancel(ctx) {
        alignSourceId = null;
        ctx.setStatus(`${labels[mode]} abgebrochen`);
      },
    },
  };
}
export const joinTool: ToolExtensionV2 = makeJoinExplodeAlignTool('join');
export const explodeTool: ToolExtensionV2 = makeJoinExplodeAlignTool('explode');
export const alignTool: ToolExtensionV2 = makeJoinExplodeAlignTool('align');

// ─────────────────────────────────────────────────────────────
// Polyline-Editor (Task D-Finish): Vertices einer Polyline verschieben.
// Klick 1: Polyline wählen. Klick 2+: Vertex wählen (Toleranz) und ziehen.
// ESC beendet.
// ─────────────────────────────────────────────────────────────
let editPoly: CADElement | null = null;
let editVertexIdx = -1;

export const polylineEditTool: ToolExtensionV2 = {
  manifest: {
    id: 'polyline-edit',
    label: 'Polyline-Editor',
    icon: '\u2b1a',
    ribbonTab: 'canvas',
    tags: ['pro'],
    description: 'Polyline wählen, dann Vertex ziehen',
  },
  optionsSchema: [],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc || !c.selection) return;
      if (!editPoly) {
        const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
        if (!hit || hit.type !== 'polyline') {
          ctx.setStatus('Polyline-Editor: erst eine Polyline anklicken');
          return;
        }
        editPoly = hit;
        ctx.setStatus('Polyline-Editor: Vertex ziehen, ESC beendet');
        return;
      }
      // Vertex finden in der Nähe:
      const props = editPoly.properties as Record<string, unknown>;
      const pts = Array.isArray(props.points)
        ? (props.points as unknown[]).map((p) => p as Pt)
        : [];
      for (let i = 0; i < pts.length; i++) {
        if (Math.hypot(pts[i].x - e.world.x, pts[i].y - e.world.y) < 8) {
          editVertexIdx = i;
          ctx.setStatus(`Vertex ${i + 1} — ziehen`);
          return;
        }
      }
      ctx.setStatus('Kein Vertex in der Nähe');
    },
    move(e, ctx) {
      if (!editPoly || editVertexIdx < 0) return;
      const c = ctx as FullToolContext;
      const props = editPoly.properties as Record<string, unknown>;
      const pts = Array.isArray(props.points)
        ? (props.points as unknown[]).map((p) => p as Pt)
        : [];
      pts[editVertexIdx] = e.world;
      const preview: CADElement = {
        ...editPoly,
        properties: { ...props, points: pts },
      };
      c.setPreview?.(preview);
    },
    up(e, ctx) {
      if (!editPoly || editVertexIdx < 0) return;
      const c = ctx as FullToolContext;
      if (!c.doc) { editVertexIdx = -1; return; }
      const current = c.doc.getElement(editPoly.id);
      if (!current) { editVertexIdx = -1; return; }
      const props = current.properties as Record<string, unknown>;
      const pts = Array.isArray(props.points)
        ? (props.points as unknown[]).map((p) => ({ ...(p as Pt) }))
        : [];
      if (editVertexIdx < pts.length) {
        pts[editVertexIdx] = e.world;
        const xs = pts.map((p) => p.x);
        const ys = pts.map((p) => p.y);
        c.doc.transact(() => {
          c.doc!.updateElement(editPoly!.id, {
            x: (Math.min(...xs) + Math.max(...xs)) / 2,
            y: (Math.min(...ys) + Math.max(...ys)) / 2,
            width: Math.max(...xs) - Math.min(...xs),
            height: Math.max(...ys) - Math.min(...ys),
            properties: { ...props, points: pts },
          });
        });
        ctx.setStatus(`Vertex ${editVertexIdx + 1} verschoben`);
      }
      editVertexIdx = -1;
    },
    cancel(ctx) {
      editPoly = null;
      editVertexIdx = -1;
      ctx.setStatus('Polyline-Editor beendet');
    },
  },
};

// ─────────────────────────────────────────────────────────────
// Stretch (Task D-Finish): Endpunkte von Linien in einem Auswahlbereich
// verschieben. Klick 1: Basis, Klick 2: Ziel (Delta auf alle selektierten
// Endpunkte, die in der Nähe des Basispunkts liegen).
// ─────────────────────────────────────────────────────────────
let stretchBase: Pt | null = null;

export const stretchTool: ToolExtensionV2 = {
  manifest: {
    id: 'stretch',
    label: 'Stretch',
    icon: '\u2197',
    ribbonTab: 'canvas',
    tags: ['pro'],
    description: 'Linien auswählen, dann Basis→Ziel (Endpunkte in Basisnähe werden gestreckt)',
  },
  optionsSchema: [],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc || !c.selection) return;
      if (!stretchBase) {
        if (c.selection.getIds().length === 0) {
          const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
          if (!hit) {
            ctx.setStatus('Stretch: zuerst Linien auswählen');
            return;
          }
          c.selection.setIds([hit.id]);
        }
        stretchBase = e.world;
        ctx.setStatus(`Stretch: Zielklick (${c.selection.getIds().length} Linien)`);
        return;
      }
      // Commit: alle Endpunkte, die dem Basispunkt am nächsten sind, verschieben:
      const dx = e.world.x - stretchBase.x;
      const dy = e.world.y - stretchBase.y;
      const ids = c.selection.getIds();
      c.doc.transact(() => {
        for (const id of ids) {
          const el = c.doc!.getElement(id);
          if (!el || el.type !== 'line') continue;
          const props = el.properties as { x1?: number; y1?: number; x2?: number; y2?: number };
          if (props.x1 === undefined || props.y1 === undefined || props.x2 === undefined || props.y2 === undefined) continue;
          // Endpunkte die dem Basispunkt am nächsten sind verschieben:
          const d1 = Math.hypot(props.x1! - stretchBase!.x, props.y1! - stretchBase!.y);
          const d2 = Math.hypot(props.x2! - stretchBase!.x, props.y2! - stretchBase!.y);
          if (d1 < d2) {
            props.x1 = props.x1! + dx;
            props.y1 = props.y1! + dy;
          } else {
            props.x2 = props.x2! + dx;
            props.y2 = props.y2! + dy;
          }
          const nx1 = props.x1!;
          const ny1 = props.y1!;
          const nx2 = props.x2!;
          const ny2 = props.y2!;
          c.doc!.updateElement(id, {
            x: (nx1 + nx2) / 2,
            y: (ny1 + ny2) / 2,
            width: Math.abs(nx2 - nx1),
            height: Math.abs(ny2 - ny1),
            properties: props,
          });
        }
      });
      ctx.setStatus(`Stretch: ${ids.length} Linie(n) gestreckt \u0394(${dx.toFixed(0)}, ${dy.toFixed(0)})`);
      stretchBase = null;
    },
    cancel(ctx) {
      stretchBase = null;
      ctx.setStatus('Stretch abgebrochen');
    },
  },
};

// ─────────────────────────────────────────────────────────────
// Break (Task D-Finish): Linie an einem Punkt in zwei Teile splitten.
// Klick auf Linie → zwei neue Linien, Original wird entfernt.
// ─────────────────────────────────────────────────────────────
export const breakTool: ToolExtensionV2 = {
  manifest: {
    id: 'break',
    label: 'Break',
    icon: '\u2702',
    ribbonTab: 'canvas',
    tags: ['pro'],
    description: 'Linie anklicken — wird am Klickpunkt geteilt',
  },
  optionsSchema: [],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc || !c.selection) return;
      const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
      if (!hit || hit.type !== 'line') {
        ctx.setStatus('Break: Linie anklicken');
        return;
      }
      const props = hit.properties as { x1?: number; y1?: number; x2?: number; y2?: number };
      if (props.x1 === undefined || props.y1 === undefined || props.x2 === undefined || props.y2 === undefined) return;

      // Klick auf die Linie projizieren (nächster Punkt auf der Linie):
      const x1 = props.x1 as number;
      const y1 = props.y1 as number;
      const x2 = props.x2 as number;
      const y2 = props.y2 as number;
      const dx = x2 - x1;
      const dy = y2 - y1;
      const lenSq = dx * dx + dy * dy;
      if (lenSq === 0) return;
      const t = Math.max(0, Math.min(1, ((e.world.x - x1) * dx + (e.world.y - y1) * dy) / lenSq));
      const breakX = x1 + t * dx;
      const breakY = y1 + t * dy;

      c.doc.transact(() => {
        // Original entfernen:
        c.doc!.deleteElements([hit.id]);
        // Zwei neue Linien hinzufügen:
        c.doc!.addElement({
          ...hit,
          id: uid('brk'),
          x: (x1 + breakX) / 2,
          y: (y1 + breakY) / 2,
          width: Math.abs(breakX - x1),
          height: Math.abs(breakY - y1),
          properties: { ...props, x2: breakX, y2: breakY },
        });
        c.doc!.addElement({
          ...hit,
          id: uid('brk'),
          x: (breakX + x2) / 2,
          y: (breakY + y2) / 2,
          width: Math.abs(x2 - breakX),
          height: Math.abs(y2 - breakY),
          properties: { ...props, x1: breakX, y1: breakY },
        });
      });
      ctx.setStatus(`Break: Linie bei (${breakX.toFixed(0)}, ${breakY.toFixed(0)}) geteilt`);
    },
  },
};

// ─────────────────────────────────────────────────────────────
// Array rect / polar (Task D-Extensions):
// Vervielfältigt die aktuelle Selektion in einem Raster bzw. im Kreis.
// Klick 1: Basis-/Zentrumspunkt. Klick 2: Commit.
// rect: Options rows, cols, dx, dy (Abstände).
// polar: Options count, optional angleSum (Default 360).
// Jede Aktion = EINE Transaktion → 1 Undo-Schritt.
// ─────────────────────────────────────────────────────────────
let arrayBase: Pt | null = null;

function makeArrayTool(mode: 'array-rect' | 'array-polar'): ToolExtensionV2 {
  const labels = { 'array-rect': 'Array Rect', 'array-polar': 'Array Polar' } as const;
  return {
    manifest: {
      id: mode,
      label: labels[mode],
      icon: mode === 'array-rect' ? '\u25a6' : '\u273b',
      ribbonTab: 'canvas',
      tags: ['pro'],
      description: `${labels[mode]}: Auswahl treffen, dann Basis\u2192Ziel klicken`,
    },
    optionsSchema:
      mode === 'array-rect'
        ? [
            { key: 'rows', label: 'Zeilen', type: 'number', min: 1, max: 50 },
            { key: 'cols', label: 'Spalten', type: 'number', min: 1, max: 50 },
            { key: 'dx', label: 'Abstand X', type: 'number', min: 1 },
            { key: 'dy', label: 'Abstand Y', type: 'number', min: 1 },
          ]
        : [
            { key: 'count', label: 'Anzahl', type: 'number', min: 2, max: 100 },
          ],
    handlers: {
      down(e, ctx) {
        const c = ctx as FullToolContext;
        if (!c.doc || !c.selection) return;
        if (!arrayBase) {
          if (c.selection.getIds().length === 0) {
            const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
            if (!hit) {
              ctx.setStatus(`${labels[mode]}: zuerst Element(e) auswählen`);
              return;
            }
            c.selection.setIds([hit.id]);
          }
          arrayBase = e.world;
          ctx.setStatus(`${labels[mode]}: Zielklick zum Anwenden (${c.selection.getIds().length} Elemente)`);
          return;
        }
        // Zweiter Klick → Commit
        const ids = c.selection.getIds();
        const base = arrayBase;
        c.doc.transact(() => {
          if (mode === 'array-rect') {
            const rows = (c.options.rows as number | undefined) ?? 3;
            const cols = (c.options.cols as number | undefined) ?? 3;
            const dx = (c.options.dx as number | undefined) ?? 50;
            const dy = (c.options.dy as number | undefined) ?? 50;
            for (const id of ids) {
              const el = c.doc!.getElement(id);
              if (!el) continue;
              for (let r = 0; r < rows; r++) {
                for (let col = 0; col < cols; col++) {
                  if (r === 0 && col === 0) continue; // Original überspringen
                  c.doc!.addElement({
                    ...el,
                    id: uid('arr'),
                    x: el.x + col * dx,
                    y: el.y + r * dy,
                  });
                }
              }
            }
          } else {
            const count = (c.options.count as number | undefined) ?? 6;
            // Zentrum = Basispunkt
            for (const id of ids) {
              const el = c.doc!.getElement(id);
              if (!el) continue;
              for (let i = 1; i < count; i++) {
                const angle = (2 * Math.PI * i) / count;
                const cx = base.x;
                const cy = base.y;
                const cos = Math.cos(angle);
                const sin = Math.sin(angle);
                // Position rotieren um Zentrum:
                const relX = el.x - cx;
                const relY = el.y - cy;
                c.doc!.addElement({
                  ...el,
                  id: uid('arr'),
                  x: cx + relX * cos - relY * sin,
                  y: cy + relX * sin + relY * cos,
                });
              }
            }
          }
        });
        ctx.setStatus(`${labels[mode]}: ${ids.length} Element(e) vervielfältigt`);
        arrayBase = null;
      },
      cancel(ctx) {
        arrayBase = null;
        ctx.setStatus(`${labels[mode]} abgebrochen`);
      },
    },
  };
}
export const arrayRectTool: ToolExtensionV2 = makeArrayTool('array-rect');
export const arrayPolarTool: ToolExtensionV2 = makeArrayTool('array-polar');

// ─────────────────────────────────────────────────────────────
// Task D10-Rest: array-path — Elemente entlang einer Polyline
// (Pfad) verteilen. Klick1: Quelle (Auto-HitSelect), Klick2: auf
// die Pfad-Polyline klicken. count Kopien gleichmäßig über die
// Gesamtlänge (s = i/(count-1)·total), ALLES in 1 Transaktion.
// ─────────────────────────────────────────────────────────────

let arrayPathBase: Pt | null = null;

/** Punkt auf einer Polyline bei kumulierter Länge s (0..total). */
function pointAlongPolyline(pts: Pt[], s: number): Pt {
  if (pts.length === 0) return { x: 0, y: 0 };
  if (pts.length === 1 || s <= 0) return { ...pts[0] };
  let remaining = s;
  for (let i = 0; i < pts.length - 1; i++) {
    const dx = pts[i + 1].x - pts[i].x;
    const dy = pts[i + 1].y - pts[i].y;
    const segLen = Math.hypot(dx, dy);
    if (segLen <= 0) continue;
    if (remaining <= segLen) {
      const t = remaining / segLen;
      return { x: pts[i].x + dx * t, y: pts[i].y + dy * t };
    }
    remaining -= segLen;
  }
  return { ...pts[pts.length - 1] };
}

export const arrayPathTool: ToolExtensionV2 = {
  manifest: {
    id: 'array-path',
    label: 'Array Pfad',
    icon: '∿',
    ribbonTab: 'canvas',
    tags: ['pro'],
    description: 'Array entlang Pfad: Auswahl treffen, dann auf Pfad-Polyline klicken (Task D10)',
  },
  optionsSchema: [
    { key: 'count', label: 'Anzahl', type: 'number', min: 2, max: 100 },
  ],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc || !c.selection) return;
      if (!arrayPathBase) {
        if (c.selection.getIds().length === 0) {
          const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
          if (!hit) {
            ctx.setStatus('Array Pfad: zuerst Element(e) auswählen');
            return;
          }
          c.selection.setIds([hit.id]);
        }
        arrayPathBase = e.world;
        ctx.setStatus(`Array Pfad: auf Pfad-Polyline klicken (${c.selection.getIds().length} Element(e))`);
        return;
      }
      // Zweiter Klick: muss eine Polyline als Pfad treffen
      const pathHit = c.selection.hitTest(e.world.x, e.world.y, 8);
      if (!pathHit || (pathHit.type !== 'polyline' && pathHit.type !== 'polygon')) {
        ctx.setStatus('Array Pfad: zweiter Klick muss eine Polyline als Pfad treffen');
        arrayPathBase = null;
        return;
      }
      const pathPts = (pathHit.properties as Record<string, unknown>).points as Pt[] | undefined;
      if (!pathPts || pathPts.length < 2) {
        ctx.setStatus('Array Pfad: Pfad-Polyline hat zu wenige Punkte');
        arrayPathBase = null;
        return;
      }
      const count = Math.max(2, (c.options.count as number | undefined) ?? 5);
      const ids = c.selection.getIds().filter((id) => id !== pathHit.id);
      // Gesamtlänge des Pfads
      let total = 0;
      for (let i = 0; i < pathPts.length - 1; i++) {
        total += Math.hypot(pathPts[i + 1].x - pathPts[i].x, pathPts[i + 1].y - pathPts[i].y);
      }
      c.doc.transact(() => {
        for (const id of ids) {
          const el = c.doc!.getElement(id);
          if (!el) continue;
          for (let i = 0; i < count; i++) {
            const s = total * (i / Math.max(1, count - 1));
            const pos = pointAlongPolyline(pathPts, s);
            c.doc!.addElement({
              ...el,
              id: uid('arrp'),
              x: pos.x,
              y: pos.y,
            } as CADElement);
          }
        }
      });
      arrayPathBase = null;
      ctx.setStatus(`Array Pfad: ${ids.length * count} Kopien entlang Pfad verteilt`);
    },
    cancel(ctx) {
      arrayPathBase = null;
      ctx.setPreview?.(null);
      ctx.setStatus('Array Pfad abgebrochen');
    },
  },
};

// ─────────────────────────────────────────────────────────────
// Chamfer (Task D-Ext): schneidet zwei sich schneidende Linien an einer
// festen Distanz vom Schnittpunkt und verbindet die Enden mit einer
// geraden Fase. Legacy nutzt trimElement + Verbindungslinie.
// Klick 1: erste Linie, Klick 2: zweite Linie → 3 Elemente (2 gekürzt + 1 Fase).
// ─────────────────────────────────────────────────────────────
let chamferFirst: CADElement | null = null;

export const chamferTool: ToolExtensionV2 = {
  manifest: {
    id: 'chamfer', label: 'Chamfer', icon: '\u25e4', ribbonTab: 'canvas', tags: ['pro'],
    description: 'Zwei Linien anklicken — Fase wird eingefügt',
  },
  optionsSchema: [
    { key: 'chamferDist', label: 'Fase-Distanz', type: 'number', min: 1, max: 100 },
  ],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc || !c.selection) return;
      const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
      if (!hit) return;
      if (!chamferFirst) {
        chamferFirst = hit;
        ctx.setStatus('Chamfer: zweite Linie wählen');
        return;
      }
      const dist = (c.options.chamferDist as number | undefined) ?? 10;
      // Beide Linien auf dist vom Schnittpunkt kürzen:
      const t1 = trimElement(chamferFirst, hit);
      const t2 = trimElement(hit, chamferFirst);
      if (!t1 || !t2) {
        ctx.setStatus('Chamfer: kein Schnittpunkt');
        chamferFirst = null;
        return;
      }
      // Endpunkte nahe am Schnittpunkt holen und um dist zurücksetzen:
      const props1 = t1.properties as { x1?: number; y1?: number; x2?: number; y2?: number };
      const props2 = t2.properties as { x1?: number; y1?: number; x2?: number; y2?: number };
      if (props1.x1 === undefined || props1.y1 === undefined || props1.x2 === undefined || props1.y2 === undefined ||
          props2.x1 === undefined || props2.y1 === undefined || props2.x2 === undefined || props2.y2 === undefined) {
        chamferFirst = null;
        return;
      }
      // Nahe Enden (Schnittpunkt-Seite) identifizieren via Schnittpunkt:
      const isectPt = findIsectPoint(chamferFirst, hit);
      if (!isectPt) { chamferFirst = null; return; }
      const near1 = nearEnd(props1 as { x1: number; y1: number; x2: number; y2: number }, isectPt);
      const near2 = nearEnd(props2 as { x1: number; y1: number; x2: number; y2: number }, isectPt);
      // Kürze nahe Enden auf dist vom Schnittpunkt:
      const shrink1 = shrinkTowards(props1 as { x1: number; y1: number; x2: number; y2: number }, near1, isectPt, dist);
      const shrink2 = shrinkTowards(props2 as { x1: number; y1: number; x2: number; y2: number }, near2, isectPt, dist);
      // Fase: Linie zwischen den neuen Enden:
      const chamferLine: CADElement = {
        ...chamferFirst,
        id: uid('cham'),
        type: 'line',
        x: (shrink1.near.x + shrink2.near.x) / 2,
        y: (shrink1.near.y + shrink2.near.y) / 2,
        width: Math.abs(shrink2.near.x - shrink1.near.x),
        height: Math.abs(shrink2.near.y - shrink1.near.y),
        properties: {
          x1: shrink1.near.x, y1: shrink1.near.y,
          x2: shrink2.near.x, y2: shrink2.near.y,
          stroke: '#e0e0e0', strokeWidth: 1,
        },
      };
      c.doc.transact(() => {
        c.doc!.updateElement(chamferFirst!.id, {
          x: shrink1.cx, y: shrink1.cy,
          width: Math.abs(props1.x2! - props1.x1!),
          height: Math.abs(props1.y2! - props1.y1!),
          properties: props1,
        });
        c.doc!.updateElement(hit.id, {
          x: shrink2.cx, y: shrink2.cy,
          width: Math.abs(props2.x2! - props2.x1!),
          height: Math.abs(props2.y2! - props2.y1!),
          properties: props2,
        });
        c.doc!.addElement(chamferLine);
      });
      ctx.setStatus('Chamfer erstellt');
      chamferFirst = null;
    },
    cancel(ctx) {
      chamferFirst = null;
      ctx.setStatus('Chamfer abgebrochen');
    },
  },
};

function findIsectPoint(a: CADElement, b: CADElement): Pt | null {
  const pa = a.properties as { x1?: number; y1?: number; x2?: number; y2?: number };
  const pb = b.properties as { x1?: number; y1?: number; x2?: number; y2?: number };
  if (pa.x1 === undefined || pb.x1 === undefined) return null;
  const denom = (pa.x1! - pa.x2!) * (pb.y1! - pb.y2!) - (pa.y1! - pa.y2!) * (pb.x1! - pb.x2!);
  if (Math.abs(denom) < 1e-10) return null;
  const t = ((pa.x1! - pb.x1!) * (pb.y1! - pb.y2!) - (pa.y1! - pb.y1!) * (pb.x1! - pb.x2!)) / denom;
  return { x: pa.x1! + t * (pa.x2! - pa.x1!), y: pa.y1! + t * (pa.y2! - pa.y1!) };
}

function nearEnd(props: { x1: number; y1: number; x2: number; y2: number }, pt: Pt): 'start' | 'end' {
  const d1 = Math.hypot(props.x1 - pt.x, props.y1 - pt.y);
  const d2 = Math.hypot(props.x2 - pt.x, props.y2 - pt.y);
  return d1 < d2 ? 'start' : 'end';
}

function shrinkTowards(
  props: { x1: number; y1: number; x2: number; y2: number },
  near: 'start' | 'end',
  isectPt: Pt,
  dist: number,
): { near: Pt; cx: number; cy: number } {
  if (near === 'start') {
    const len = Math.hypot(props.x2 - props.x1, props.y2 - props.y1);
    if (len === 0) return { near: { x: props.x1, y: props.y1 }, cx: props.x1, cy: props.y1 };
    const ratio = Math.min(dist / len, 1);
    const nx = props.x1 + (props.x2 - props.x1) * ratio;
    const ny = props.y1 + (props.y2 - props.y1) * ratio;
    return { near: { x: nx, y: ny }, cx: (nx + props.x2) / 2, cy: (ny + props.y2) / 2 };
  }
  const len = Math.hypot(props.x2 - props.x1, props.y2 - props.y1);
  if (len === 0) return { near: { x: props.x2, y: props.y2 }, cx: props.x2, cy: props.y2 };
  const ratio = Math.min(dist / len, 1);
  const nx = props.x2 + (props.x1 - props.x2) * ratio;
  const ny = props.y2 + (props.y1 - props.y2) * ratio;
  return { near: { x: nx, y: ny }, cx: (nx + props.x1) / 2, cy: (ny + props.y1) / 2 };
}

// ─────────────────────────────────────────────────────────────
// Lengthen (Task D-Ext): verlängert/verkürzt eine Linie am geklickten
// Ende um einen Delta-Wert. Klick 1: Linie, Klick 2: Seite.
// ─────────────────────────────────────────────────────────────
let lengthenEl: CADElement | null = null;

export const lengthenTool: ToolExtensionV2 = {
  manifest: {
    id: 'lengthen', label: 'Lengthen', icon: '\u2194', ribbonTab: 'canvas', tags: ['pro'],
    description: 'Linie anklicken, dann Delta-Ziel klicken (Options: lengthenDelta)',
  },
  optionsSchema: [
    { key: 'lengthenDelta', label: 'Delta', type: 'number' },
  ],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc || !c.selection) return;
      if (!lengthenEl) {
        const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
        if (!hit || hit.type !== 'line') {
          ctx.setStatus('Lengthen: nur Linien');
          return;
        }
        lengthenEl = hit;
        ctx.setStatus('Lengthen: Klick in Verlängerungsrichtung');
        return;
      }
      const el = c.doc.getElement(lengthenEl.id);
      if (!el) { lengthenEl = null; return; }
      const props = el.properties as { x1?: number; y1?: number; x2?: number; y2?: number };
      if (props.x1 === undefined || props.y1 === undefined || props.x2 === undefined || props.y2 === undefined) {
        lengthenEl = null;
        return;
      }
      const delta = (c.options.lengthenDelta as number | undefined) ?? 10;
      // Wähle das Ende, das dem Klick am nächsten ist:
      const dStart = Math.hypot(e.world.x - (props.x1 as number), e.world.y - (props.y1 as number));
      const dEnd = Math.hypot(e.world.x - (props.x2 as number), e.world.y - (props.y2 as number));
      const nearIsStart = dStart < dEnd;
      // Richtungsvektor (vom fernen Ende zum nahen Ende):
      const dirX = nearIsStart ? (props.x1! - props.x2!) : (props.x2! - props.x1!);
      const dirY = nearIsStart ? (props.y1! - props.y2!) : (props.y2! - props.y1!);
      const len = Math.hypot(dirX, dirY);
      if (len === 0) { lengthenEl = null; return; }
      const ux = dirX / len;
      const uy = dirY / len;
      if (nearIsStart) {
        props.x1 = (props.x1 as number) + ux * delta;
        props.y1 = (props.y1 as number) + uy * delta;
      } else {
        props.x2 = (props.x2 as number) + ux * delta;
        props.y2 = (props.y2 as number) + uy * delta;
      }
      const nx1 = props.x1 as number;
      const ny1 = props.y1 as number;
      const nx2 = props.x2 as number;
      const ny2 = props.y2 as number;
      c.doc.transact(() => {
        c.doc!.updateElement(el.id, {
          x: (nx1 + nx2) / 2,
          y: (ny1 + ny2) / 2,
          width: Math.abs(nx2 - nx1),
          height: Math.abs(ny2 - ny1),
          properties: props,
        });
      });
      ctx.setStatus(`Lengthen: Linie um ${delta} angepasst`);
      lengthenEl = null;
    },
    cancel(ctx) {
      lengthenEl = null;
      ctx.setStatus('Lengthen abgebrochen');
    },
  },
};

// ─────────────────────────────────────────────────────────────
// Trim / Extend / Fillet (Task A4.10) — baut auf BUG-2-reparierter
// findIntersection-Geometrie (B2). Legacy-Ablauf:
// - trim/extend: Klick1=Boundary, Klick2=Ziel → Ziel wird angepasst
// - fillet:      Klick1+Klick2 = zwei Elemente → Paar wird angepasst
// Jede Operation committed in EINER Transaktion.
// ─────────────────────────────────────────────────────────────
let twoPickBoundary: CADElement | null = null;
let twoPickFirst: CADElement | null = null;

function make2PickGeometryTool(
  mode: 'trim' | 'extend' | 'fillet',
  filletRadius: number,
): ToolExtensionV2 {
  const labels = { trim: 'Trimmen', extend: 'Verlängern', fillet: 'Fillet' } as const;
  return {
    manifest: {
      id: mode,
      label: labels[mode],
      icon: mode === 'fillet' ? '\u23dc' : '\u2717',
      ribbonTab: 'canvas',
      tags: ['pro'],
      description: `${labels[mode]}: ${mode === 'fillet' ? 'zwei' : 'Kante, dann'} Element(e) anklicken`,
    },
    optionsSchema: [],
    handlers: {
      down(e, ctx) {
        const c = ctx as FullToolContext;
        if (!c.doc || !c.selection) return;
        const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
        if (!hit) return;

        if (mode === 'fillet') {
          if (!twoPickFirst) {
            twoPickFirst = hit;
            ctx.setStatus(`Fillet: zweites Element wählen`);
            return;
          }
          // Zweiter Pick → Paar-Commit
          const second = hit;
          const pair = filletElements(twoPickFirst, second, filletRadius);
          if (!pair) {
            ctx.setStatus('Fillet: kein Schnittpunkt gefunden');
            twoPickFirst = null;
            return;
          }
          const idA = twoPickFirst.id;
          const idB = second.id;
          c.doc.transact(() => {
            c.doc!.updateElement(idA, {
              x: pair[0].x, y: pair[0].y,
              width: pair[0].width, height: pair[0].height,
              properties: pair[0].properties,
            });
            c.doc!.updateElement(idB, {
              x: pair[1].x, y: pair[1].y,
              width: pair[1].width, height: pair[1].height,
              properties: pair[1].properties,
            });
          });
          ctx.setStatus(`Fillet angewendet (${idA}, ${idB})`);
          twoPickFirst = null;
          return;
        }

        // trim/extend: Boundary dann Ziel
        if (!twoPickBoundary) {
          twoPickBoundary = hit;
          ctx.setStatus(`${labels[mode]}: jetzt das zu bearbeitende Element wählen`);
          return;
        }
        const target = hit;
        const fn = mode === 'trim' ? trimElement : extendElement;
        const result = fn(target, twoPickBoundary);
        if (!result) {
          ctx.setStatus(`${labels[mode]}: keine Schnittmenge mit der Kante`);
          twoPickBoundary = null;
          return;
        }
        c.doc.transact(() => {
          c.doc!.updateElement(target.id, {
            x: result.x, y: result.y,
            width: result.width, height: result.height,
            properties: result.properties,
          });
        });
        ctx.setStatus(`${labels[mode]} auf ${target.id} angewendet`);
        twoPickBoundary = null;
      },
      cancel(ctx) {
        twoPickBoundary = null;
        twoPickFirst = null;
        ctx.setStatus(`${labels[mode]} abgebrochen`);
      },
    },
  };
}
export const trimTool: ToolExtensionV2 = make2PickGeometryTool('trim', 0);
export const extendTool: ToolExtensionV2 = make2PickGeometryTool('extend', 0);
export const filletTool: ToolExtensionV2 = make2PickGeometryTool('fillet', 5);
// Einzelnklick auf Element löscht es sofort (kein up/Bestätigung).
// Jetzt via doc.deleteElements → undo-fähig.
// ─────────────────────────────────────────────────────────────
export const deleteTool: ToolExtensionV2 = {
  manifest: {
    id: 'delete', label: 'Löschen', icon: '\u2715', ribbonTab: 'canvas', tags: ['basic'],
    description: 'Element anklicken zum Löschen',
  },
  optionsSchema: [],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc || !c.selection) return;
      const ids = c.selection.getIds();
      if (ids.length > 0) {
        // Selektion vorhanden → alles selektierte löschen
        c.doc.deleteElements(ids);
        c.selection.setIds([]);
        ctx.setStatus(`${ids.length} Element(e) gelöscht`);
        return;
      }
      // Sonst: direkter Klick-Treffer
      const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
      if (!hit) return;
      c.doc.deleteElements([hit.id]);
      ctx.setStatus(`Gelöscht: ${hit.id}`);
    },
  },
};

// ─────────────────────────────────────────────────────────────
// Offset (Task A4.8) — nutzt die BUG-3-reparierte offsetElement-
// Signatur mit Seitenparameter; Legacy-Ablauf:
// Klick1 = Element wählen, Klick2 = Richtung+Distanz → NEUES Element.
// ─────────────────────────────────────────────────────────────
let offsetSource: CADElement | null = null;
let offsetBase: Pt | null = null;

export const offsetTool: ToolExtensionV2 = {
  manifest: {
    id: 'offset', label: 'Versatz', icon: '\u2937', ribbonTab: 'canvas', tags: ['pro'],
    description: 'Element anklicken, dann seitlichen Versatz klicken',
  },
  optionsSchema: [],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc || !c.selection) return;
      if (!offsetSource) {
        const hit = c.selection.hitTest(e.world.x, e.world.y, 5);
        if (!hit) return;
        offsetSource = hit;
        offsetBase = e.world;
        ctx.setStatus(`Offset: Element ${hit.id} gewählt – Versatz klicken`);
        return;
      }
      // Zweiter Klick: Distanz + Seite (Kreuzprodukt für Linien, Radius sonst)
      const src = c.doc.getElement(offsetSource.id);
      if (!src) { offsetSource = null; offsetBase = null; return; }
      const dist = Math.hypot(e.world.x - offsetBase!.x, e.world.y - offsetBase!.y);
      let side: 1 | -1 = 1;
      if (src.type === 'line' && src.properties.x1 !== undefined && src.properties.y1 !== undefined) {
        const p1x = src.properties.x1 as number;
        const p1y = src.properties.y1 as number;
        const p2x = src.properties.x2 as number;
        const p2y = src.properties.y2 as number;
        side = (p2x - p1x) * (e.world.y - p1y) - (p2y - p1y) * (e.world.x - p1x) >= 0 ? 1 : -1;
      } else if ((src.type === 'circle' || src.type === 'arc') && src.properties.radius !== undefined) {
        side = Math.hypot(e.world.x - src.x, e.world.y - src.y) >= (src.properties.radius as number) ? 1 : -1;
      }
      const next = offsetElement(src, dist, side);
      let newEl: CADElement | null = null;
      c.doc.transact(() => {
        newEl = { ...next, id: uid('off') };
        c.doc!.addElement(newEl!);
      });
      ctx.setStatus(`Offset erstellt (${(newEl as unknown as CADElement).id})`);
      offsetSource = null;
      offsetBase = null;
    },
    cancel(ctx) {
      offsetSource = null;
      offsetBase = null;
      ctx.setStatus('Offset abgebrochen');
    },
  },
};

/** V2-Plugin: Kern-Bearbeitungswerkzeuge. */
// ──────────────────────────────────────────────────────────
// Task CAD-4: DIVIDE/MEASURE — Punkte entlang eines Pfads
// (Polyline) verteilen. DIVIDE: n gleiche Segmente → n+1 Punkte
// inkl. Enden. MEASURE: fester Abstand inkl. Start, Rest verworfen.
// Punkte = Konstruktionsmarker auf defpoints (1 Transaktion).
// ──────────────────────────────────────────────────────────

/**
 * Punkte entlang eines Polylinien-Pfads (Task CAD-4, rein).
 * segments > 0: DIVIDE — n+1 gleichmäßige Punkte inkl. Enden.
 * fixedSpacing > 0: MEASURE — Punkte bei 0, spacing, 2*spacing, …
 * solange s ≤ Gesamtlänge; Rest am Ende wird verworfen.
 */
export function pointsAlongPath(pts: Pt[], segments: number, fixedSpacing?: number): Pt[] {
  if (!Array.isArray(pts) || pts.length < 2) return [];
  let total = 0;
  for (let i = 0; i < pts.length - 1; i++) {
    total += Math.hypot(pts[i + 1].x - pts[i].x, pts[i + 1].y - pts[i].y);
  }
  if (total <= 0) return [...pts];
  const out: Pt[] = [];
  if (segments > 0) {
    for (let i = 0; i <= segments; i++) {
      out.push(pointAlongPolyline(pts, (total * i) / segments));
    }
  } else if (fixedSpacing && fixedSpacing > 0) {
    for (let s = 0; s <= total + 1e-9; s += fixedSpacing) {
      out.push(pointAlongPolyline(pts, s));
    }
  }
  return out;
}

/** defpoints-Layer sicherstellen (CAD-4, lokal im core-modify). */
function ensureDefpoints(ctx: FullToolContext): void {
  const doc = ctx.doc as unknown as {
    getLayer(id: string): unknown;
    addLayer(l: unknown): void;
  } | undefined;
  if (!doc || doc.getLayer('defpoints')) return;
  doc.addLayer({
    id: 'defpoints', name: 'defpoints', visible: true, locked: false,
    color: '#8a8f98', lineType: 'dotted', transparency: 0.5, sortOrder: 999, parentId: null,
  });
}

/** Pfad-Treffer validieren: muss polyline/polygon mit ≥2 Punkten sein. */
function requirePathHit(
  c: FullToolContext,
  wx: number,
  wy: number,
): { pts: Pt[]; path: CADElement } | null {
  if (!c.selection) return null;
  const hit = c.selection.hitTest(wx, wy, 8);
  if (!hit || (hit.type !== 'polyline' && hit.type !== 'polygon')) return null;
  const pts = (hit.properties as Record<string, unknown>).points as Pt[] | undefined;
  if (!pts || pts.length < 2) return null;
  return { pts, path: hit };
}

/** Konstruktions-Marker-Punkt auf defpoints platzieren. */
function makePathMarker(p: Pt): CADElement {
  return {
    id: uid('pathmark'),
    type: 'circle',
    layerId: 'defpoints',
    x: p.x,
    y: p.y,
    width: 3,
    height: 3,
    properties: { radius: 1.5, point: true, construction: true, stroke: '#8a8f98', strokeWidth: 1 },
  } as unknown as CADElement;
}

export const divideTool: ToolExtensionV2 = {
  manifest: {
    id: 'divide',
    label: 'Teilen',
    icon: '÷',
    ribbonTab: 'canvas',
    tags: ['pro'],
    description: 'Pfad in n gleiche Segmente teilen (DIVIDE, Task CAD-4)',
  },
  optionsSchema: [
    { key: 'count', label: 'Anzahl Segmente', type: 'number', min: 1, max: 100 },
  ],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc) return;
      const found = requirePathHit(c, e.world.x, e.world.y);
      if (!found) {
        ctx.setStatus('Teilen: Polyline als Pfad anklicken');
        return;
      }
      const segments = Math.max(1, (c.options.count as number | undefined) ?? 4);
      ensureDefpoints(c);
      const marks = pointsAlongPath(found.pts, segments);
      c.doc.transact(() => {
        for (const p of marks) c.doc!.addElement(makePathMarker(p));
      });
      ctx.setStatus(`Geteilt: ${marks.length} Punkte auf ${segments} Segmente`);
    },
    cancel(ctx) {
      ctx.setPreview?.(null);
      ctx.setStatus('Teilen abgebrochen');
    },
  },
};

export const measureTool: ToolExtensionV2 = {
  manifest: {
    id: 'measure',
    label: 'Abmessen (Punkte)',
    icon: '⋮',
    ribbonTab: 'canvas',
    tags: ['pro'],
    description: 'Punkte im festen Abstand auf Pfad (MEASURE, Task CAD-4)',
  },
  optionsSchema: [
    { key: 'spacing', label: 'Abstand', type: 'number', min: 1 },
  ],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc) return;
      const found = requirePathHit(c, e.world.x, e.world.y);
      if (!found) {
        ctx.setStatus('Abmessen: Polyline als Pfad anklicken');
        return;
      }
      const spacing = Math.max(1, (c.options.spacing as number | undefined) ?? 20);
      ensureDefpoints(c);
      const marks = pointsAlongPath(found.pts, 0, spacing);
      c.doc.transact(() => {
        for (const p of marks) c.doc!.addElement(makePathMarker(p));
      });
      ctx.setStatus(`Abgemessen: ${marks.length} Punkte alle ${spacing} Einheiten`);
    },
    cancel(ctx) {
      ctx.setPreview?.(null);
      ctx.setStatus('Abmessen abgebrochen');
    },
  },
};

// ─────────────────────────────────────────────────────────────
// Task CAD-5: Block-Editor — Blockdefinition in-place bearbeiten.
// Klick 1 auf Block-Instanz oeffnet (markierte Kopien erscheinen),
// Kopien normal bearbeiten, Klick 2 speichert zurueck in die
// Definition, cancel verwirft. (Service: blockEditorService)
// ─────────────────────────────────────────────────────────────

export const blockEditTool: ToolExtensionV2 = {
  manifest: {
    id: 'block-edit',
    label: 'Block bearbeiten',
    icon: '\u2699',
    ribbonTab: 'canvas',
    tags: ['pro'],
    description: 'Block-Instanz anklicken um die Definition zu bearbeiten (CAD-5)',
  },
  optionsSchema: [],
  handlers: {
    down(e, ctx) {
      const c = ctx as FullToolContext;
      if (!c.doc || !c.selection) return;
      // Offene Sitzung? → speichern
      if ((c.doc.getAllElements() as CADElement[]).some(
        (el) => (el.properties as Record<string, unknown>)[BLOCK_EDIT_MARKER],
      )) {
        const saved = saveBlockEdit(c.doc as never);
        ctx.setStatus(saved ? `Block "${saved}" gespeichert` : 'Speichern fehlgeschlagen');
        return;
      }
      const hit = c.selection.hitTest(e.world.x, e.world.y, 8);
      if (!hit || hit.type !== 'block_instance') {
        ctx.setStatus('Block bearbeiten: Block-Instanz anklicken');
        return;
      }
      const blockId = (hit.properties as Record<string, unknown>).blockId as string | undefined;
      if (!blockId) {
        ctx.setStatus('Block bearbeiten: Instanz ohne Block-Referenz');
        return;
      }
      const opened = openBlockForEdit(c.doc as never, blockId);
      ctx.setStatus(opened ? `Block "${blockId}" geöffnet — Elemente bearbeiten, erneut klicken speichert` : 'Block konnte nicht geöffnet werden');
    },
    cancel(ctx) {
      const c = ctx as FullToolContext;
      if (c.doc) discardBlockEdit(c.doc as never);
      ctx.setPreview?.(null);
      ctx.setStatus('Block-Bearbeitung verworfen');
    },
  },
};

export const coreModifyPlugin: PluginV2 = {
  manifest: {
    id: 'core-modify',
    name: 'Bearbeiten (Kern)',
    version: '1.9.0',
    author: 'web-cad team',
    description: 'Auswahl, Schraffur, Move/Copy/Rotate/Scale/Mirror/Delete/Offset/Trim/Extend/Fillet/Arrays/Chamfer/Lengthen/Join/Explode/Align/Polyline-Edit/Stretch/Break (V2).',
    category: 'tools',
    enabledByDefault: true,
  },
  tools: [selectTool, hatchTool, moveTool, copyTool, rotateTool, scaleTool, mirrorTool, deleteTool, offsetTool, trimTool, extendTool, filletTool, arrayRectTool, arrayPolarTool, chamferTool, lengthenTool, joinTool, explodeTool, alignTool, polylineEditTool, stretchTool, breakTool, arrayPathTool, divideTool, measureTool, blockEditTool],
};