/**
 * dispatcher.ts – InteractionDispatcher (Task A2).
 *
 * Ersetzt langfristig den 1157-Zeilen-Switch der InteractionEngine:
 * - Routet DOM-Pointer-/Key-Events an das AKTIVE V2-Werkzeug (ToolExtensionV2)
 * - Normalisiert Events (pointer.ts) zu Weltkoordinaten
 * - Führt eine ToolSession als Down/Up-Guard
 * - Kein Werkzeugwissen! Alle Logik liegt in den Plugins.
 *
 * Aktivierung per Feature-Flag VITE_TOOL_DISPATCHER=v2 (CanvasArea, A2 Schritt 4).
 */
import type { ToolExtensionV2, ToolContext } from '../plugins/types';
import { pluginRegistry } from '../plugins/PluginRegistry';
import { toToolPointerEvent } from './pointer';
import { ToolSession } from './session';
import type { ZoomPanController } from '../canvas/ZoomPanController';

export interface DispatcherDeps {
  zoomPan: ZoomPanController;
  /** CAD-14 Phase 4c: Snap-Funktion (Weltkoordinaten) fuer Tool-Events. */
  snap?(x: number, y: number): { x: number; y: number };
  /** CAD-14 Phase 4c: Cursor-Meldung (auch ohne aktives Tool). */
  onCursorMoved?(worldX: number, worldY: number): void;
  /** CAD-14 Phase 4c: Render-Anstoess nach Pan/Wheel (CanvasArea ruft renderEngine.render). */
  requestRender?(): void;
  /** CAD-14 Phase 4c: Ortho-Anwendung gegen den letzten gesnappten Down-Punkt. */
  ortho?(x: number, y: number, last: { x: number; y: number } | null): { x: number; y: number };
  /** Liefert Optionsstände je ToolId (typisch: toolStore.optionValues). */
  getOptions?(toolId: string): Record<string, unknown>;
  /** Statuszeile (typisch: StatusBar-Bridge). */
  setStatus?(msg: string): void;
  /** Live-Vorschau-Ziel (typisch RenderEngine.setPreviewElement). */
  setPreview?(el: unknown | null): void;
  /** Tool-Nachschlag überschreibbar (Default: aktive Registry-Tools). */
  toolLookup?(toolId: string): ToolExtensionV2 | undefined;
  /** Dokument-Fassade für Tools (ab A3; lazy pro Event abgefragt). */
  getDoc?(): import('../kernel/document/CADDocument').CADDocument | undefined;
  /** Selektions-Bridge für Tools (ab A3; lazy pro Event abgefragt). */
  getSelectionBridge?(): import('../plugins/types').ToolSelectionBridge;
}

export class InteractionDispatcher {
  private readonly canvas: HTMLCanvasElement;
  private readonly deps: DispatcherDeps;
  private readonly session = new ToolSession();
  private active: ToolExtensionV2 | null = null;
  private bound = false;

  /** Zuletzt gesetzter Status-Text (für Tests/Debug). */
  lastStatus = '';

  constructor(canvas: HTMLCanvasElement, deps: DispatcherDeps) {
    this.canvas = canvas;
    this.deps = deps;
    this.attach();
  }

  /** Setzt das aktive Werkzeug (null = deaktiviert Routing). */
  setActive(toolId: string | null): void {
    if (this.active && this.session.isActive) {
      // Sitzung sauber abbrechen, bevor gewechselt wird
      this.active.handlers.cancel?.(this.buildContext());
      this.session.end();
    }
    if (!toolId) {
      this.active = null;
      return;
    }
    const lookup = this.deps.toolLookup ?? ((id: string) => pluginRegistry.getToolV2(id));
    const tool = lookup(toolId);
    if (!tool) {
      console.warn(`[InteractionDispatcher] kein aktives V2-Tool '${toolId}'`);
      this.active = null;
      return;
    }
    this.active = tool;
    this.setStatus(`${tool.manifest.label} aktiv`);
  }

  /** Aktives Werkzeug (oder null). */
  getActive(): ToolExtensionV2 | null {
    return this.active;
  }

  /** Entfernt alle Event-Listener (aufräumen beim Unmount). */
  destroy(): void {
    if (!this.bound) return;
    this.canvas.removeEventListener('pointerdown', this.onDown);
    window.removeEventListener('pointermove', this.onMove);
    window.removeEventListener('pointerup', this.onUp);
    window.removeEventListener('keydown', this.onKey);
    this.canvas.removeEventListener('wheel', this.onWheelNative as EventListener);
    window.removeEventListener('pointermove', this.onPanMove);
    window.removeEventListener('pointerup', this.onPanEnd);
    this.bound = false;
  }

  // ── intern ───────────────────────────────────────────────

  private attach(): void {
    if (this.bound) return;
    this.canvas.addEventListener('pointerdown', this.onDown);
    window.addEventListener('pointermove', this.onMove);
    window.addEventListener('pointerup', this.onUp);
    window.addEventListener('keydown', this.onKey);
    // CAD-14 Phase 4c: natives Pan + Wheel (ersetzt Legacy-Engine)
    this.canvas.addEventListener('wheel', this.onWheelNative as EventListener, { passive: false });
    window.addEventListener('pointermove', this.onPanMove);
    window.addEventListener('pointerup', this.onPanEnd);
    this.bound = true;
  }

  // ── CAD-14 Phase 4c: natives Pan (Mittel-/Rechtsklick-Drag) ──
  private panActive = false;
  private lastPanScreen = { x: 0, y: 0 };
  /** CAD-14 Phase 4c: Letzter gesnappter Down-Punkt (Ortho-Referenz). */
  private lastSnappedDown: { x: number; y: number } | null = null;

  private onPanMove = (e: PointerEvent): void => {
    if (!this.panActive) return;
    const dx = e.clientX - this.lastPanScreen.x;
    const dy = e.clientY - this.lastPanScreen.y;
    this.lastPanScreen = { x: e.clientX, y: e.clientY };
    this.deps.zoomPan.pan(dx, dy);
    this.requestRender();
  };

  private onPanEnd = (): void => {
    this.panActive = false;
  };

  private onWheelNative = (e: WheelEvent): void => {
    e.preventDefault();
    const factor = e.deltaY > 0 ? 0.9 : 1.1;
    const rect = this.canvas.getBoundingClientRect();
    const cx = e.clientX - rect.left;
    const cy = e.clientY - rect.top;
    this.deps.zoomPan.zoomAt(cx, cy, factor);
    this.requestRender();
  };

  private requestRender(): void {
    this.deps.requestRender?.();
  }

  private buildContext(): import('../plugins/types').FullToolContext {
    const toolId = this.active?.manifest.id ?? '';
    return {
      options: this.deps.getOptions?.(toolId) ?? {},
      setStatus: (msg) => this.setStatus(msg),
      setPreview: (el) => this.deps.setPreview?.(el),
      doc: this.deps.getDoc?.(),
      selection: this.deps.getSelectionBridge?.(),
    };
  }

  private setStatus(msg: string): void {
    this.lastStatus = msg;
    this.deps.setStatus?.(msg);
  }

  private onDown = (e: PointerEvent): void => {
    // CAD-14 Phase 4c: natives Pan bei Mittel-/Rechtsklick (auch ohne Tool)
    if (e.button === 1 || e.button === 2) {
      this.panActive = true;
      this.lastPanScreen = { x: e.clientX, y: e.clientY };
      return;
    }
    if (!this.active) return;
    const tpe = this.applySnapToEvent(toToolPointerEvent(e, this.canvas, this.deps.zoomPan));
    this.lastSnappedDown = { x: tpe.world.x, y: tpe.world.y };
    this.session.begin();
    this.active.handlers.down?.(tpe, this.buildContext());
  };

  private onMove = (e: PointerEvent): void => {
    const tpeRaw = toToolPointerEvent(e, this.canvas, this.deps.zoomPan);
    // CAD-14 Phase 4c: Cursor-Meldung auch ohne aktives Tool (Statusleiste)
    this.deps.onCursorMoved?.(tpeRaw.world.x, tpeRaw.world.y);
    if (!this.active || !this.session.isActive) return;
    const tpe = this.applySnapToEvent(tpeRaw);
    this.active.handlers.move?.(tpe, this.buildContext());
  };

  private onUp = (e: PointerEvent): void => {
    if (!this.active || !this.session.isActive) return;
    const tpe = this.applySnapToEvent(toToolPointerEvent(e, this.canvas, this.deps.zoomPan));
    try {
      this.active.handlers.up?.(tpe, this.buildContext());
    } finally {
      this.session.end();
    }
  };

  private onKey = (e: KeyboardEvent): void => {
    if (!this.active) return;
    if (e.key === 'Escape') {
      this.cancelActive();
      return;
    }
    const consumed = this.active.handlers.key?.(e, this.buildContext()) === true;
    if (consumed) e.preventDefault();
  };

  /** CAD-14 Phase 4c: wendet Snap aus Deps auf ein Tool-Pointer-Event an. */
  private applySnapToEvent(tpe: import('../plugins/types').ToolPointerEvent): import('../plugins/types').ToolPointerEvent {
    if (!this.deps.snap && !this.deps.ortho) return tpe;
    let p = { x: tpe.world.x, y: tpe.world.y };
    if (this.deps.snap) {
      const snapped = this.deps.snap(p.x, p.y);
      p = { x: snapped.x, y: snapped.y };
    }
    if (this.deps.ortho) {
      p = this.deps.ortho(p.x, p.y, this.lastSnappedDown);
    }
    return { ...tpe, world: p };
  }

  private cancelActive(): void {
    if (!this.active) return;
    this.active.handlers.cancel?.(this.buildContext());
    this.session.end();
  }
}