/**
 * elementDrawers – Reine Beschreibungs-Fabrik (Task C2).
 *
 * Wandelt CADElemente in eine Liste von Primitiven um (line/rect/circle/
 * polyline/text/arc). Der PixiRenderer (C3) konsumiert diese Deskriptoren
 * und überführt sie in konkrete Grafikobjekte.
 *
 * Vorteil dieser Zwischenschicht:
 * - Vollständig unit-testbar OHNE WebGL/GPU
 * - Backend-unabhängig (Pixi jetzt, Canvas2D oder andere später)
 *
 * Konventionen entsprechen dem Legacy RenderEngine.draw*:
 * - rect: x/y = Zentrum der BBox
 * - circle/arc: radius über properties.radius (Fallback width/2)
 * - arc-Winkel in Grad, 0° = 3 Uhr, gegen den Uhrzeigersinn
 */
import type { CADElement } from '../../types/cad.types';
import type { Pt } from '../../tools/modification/geometry';

/** Zeichenprimitiv — kleinste darstellbare Einheit. */
export type ShapePrimitive =
  | { kind: 'line'; from: Pt; to: Pt; stroke: string; strokeWidth: number }
  | { kind: 'rect'; x: number; y: number; w: number; h: number; fill: string | null; stroke: string; strokeWidth: number }
  | { kind: 'circle'; center: Pt; radius: number; fill: string | null; stroke: string; strokeWidth: number }
  | { kind: 'polyline'; points: Pt[]; close: boolean; stroke: string; strokeWidth: number }
  | { kind: 'text'; at: Pt; text: string; fontSize: number; color: string }
  | { kind: 'arc'; center: Pt; radius: number; startDeg: number; endDeg: number; stroke: string; strokeWidth: number };

const FALLBACK_STROKE = '#e0e0e0';

function asPoint(p: unknown): Pt {
  const q = p as { x?: number; y?: number };
  return { x: Number(q?.x ?? 0), y: Number(q?.y ?? 0) };
}

function fillOrNull(raw: unknown): string | null {
  return typeof raw === 'string' && raw !== 'none' ? raw : null;
}

/**
 * Wandelt ein CADElement in seine Zeichenprimitive um.
 * Gibt ein leeres Array zurück für unbekannte Typen bzw. Elemente,
 * die nichts Sichtbares beitragen (z.B. leerer Text).
 */
export function elementToPrimitives(el: CADElement): ShapePrimitive[] {
  const props = (el.properties ?? {}) as Record<string, unknown>;
  const stroke = (props.stroke as string | undefined) ?? FALLBACK_STROKE;
  const sw = (props.strokeWidth as number | undefined) ?? 1;

  switch (el.type) {
    case 'line': {
      if (
        props.x1 === undefined || props.y1 === undefined ||
        props.x2 === undefined || props.y2 === undefined
      ) {
        return [];
      }
      return [{
        kind: 'line',
        from: { x: props.x1 as number, y: props.y1 as number },
        to: { x: props.x2 as number, y: props.y2 as number },
        stroke,
        strokeWidth: sw,
      }];
    }

    case 'rect': {
      // Legacy-BBox-Konvention: x/y ist das Zentrum des Rechtecks
      return [{
        kind: 'rect',
        x: el.x - el.width / 2,
        y: el.y - el.height / 2,
        w: el.width,
        h: el.height,
        fill: fillOrNull(props.fill),
        stroke,
        strokeWidth: sw,
      }];
    }

    case 'circle': {
      const radius = (props.radius as number | undefined) ?? el.width / 2;
      return [{
        kind: 'circle',
        center: { x: el.x, y: el.y },
        radius,
        fill: fillOrNull(props.fill),
        stroke,
        strokeWidth: sw,
      }];
    }

    case 'arc': {
      const radius = (props.radius as number | undefined) ?? el.width / 2;
      return [{
        kind: 'arc',
        center: { x: el.x, y: el.y },
        radius,
        startDeg: (props.startAngle as number | undefined) ?? 0,
        endDeg: (props.endAngle as number | undefined) ?? 360,
        stroke,
        strokeWidth: sw,
      }];
    }

    case 'polyline':
    case 'polygon': {
      const pts = Array.isArray(props.points)
        ? (props.points as unknown[]).map(asPoint)
        : [];
      if (pts.length < 2) return [];
      return [{
        kind: 'polyline',
        points: pts,
        close: el.type === 'polygon',
        stroke,
        strokeWidth: sw,
      }];
    }

    case 'text': {
      const txt = String(props.text ?? '');
      if (!txt) return []; // leeren Platzhalter nicht rendern
      return [{
        kind: 'text',
        at: { x: el.x, y: el.y },
        text: txt,
        fontSize: (props.fontSize as number | undefined) ?? 12,
        color: (props.color as string | undefined) ?? stroke,
      }];
    }

    // ── Task C3: bisher im Pixi-Pfad fehlende Typen ──

    case 'dimension': {
      // Legacy-Konvention: x1..y2 in properties, BBox-Zentrum als x/y,
      // Extension lines + Hauptlinie; Pfeilspitzen sind Detail (C3+)
      const x1 = (props.x1 as number | undefined) ?? el.x - el.width / 2;
      const y1 = (props.y1 as number | undefined) ?? el.y;
      const x2 = (props.x2 as number | undefined) ?? el.x + el.width / 2;
      const y2 = (props.y2 as number | undefined) ?? el.y;
      const color = (props.color as string | undefined) ?? '#aaaaaa';
      const dimColor = (props.dimColor as string | undefined) ?? color;
      const label = String(props.value ?? props.text ?? '');
      const out: ShapePrimitive[] = [
        { kind: 'line', from: { x: x1, y: y1 }, to: { x: x2, y: y2 }, stroke: dimColor, strokeWidth: 1 },
      ];
      if (label) {
        out.push({
          kind: 'text',
          at: { x: (x1 + x2) / 2, y: (y1 + y2) / 2 - 12 },
          text: label,
          fontSize: 10,
          color: dimColor,
        });
      }
      return out;
    }

    case 'leader': {
      // Legacy-Konvention: Linie p1→p2 + optionaler Text am Ende
      const lx1 = (props.x1 as number | undefined) ?? el.x;
      const ly1 = (props.y1 as number | undefined) ?? el.y;
      const lx2 = (props.x2 as number | undefined) ?? el.x + el.width;
      const ly2 = (props.y2 as number | undefined) ?? el.y + el.height;
      const out: ShapePrimitive[] = [
        { kind: 'line', from: { x: lx1, y: ly1 }, to: { x: lx2, y: ly2 }, stroke, strokeWidth: sw },
      ];
      const label = String(props.text ?? '');
      if (label) {
        out.push({
          kind: 'text',
          at: { x: lx2 + 4, y: ly2 - 4 },
          text: label,
          fontSize: (props.fontSize as number | undefined) ?? 12,
          color: stroke,
        });
      }
      return out;
    }

    case 'revcloud': {
      // Revisionswolke: Punkte-Zug (Bogen-Detail folgt in C3+)
      const pts = Array.isArray(props.points)
        ? (props.points as unknown[]).map(asPoint)
        : [];
      if (pts.length < 2) return [];
      return [{
        kind: 'polyline',
        points: pts,
        close: true,
        stroke,
        strokeWidth: sw,
      }];
    }

    case 'chair': {
      // Stuhl: gefülltes Quadrat in Element-Farbe + Umrandung
      const fill = (props.fill as string | undefined) ?? '#4a90d9';
      return [{
        kind: 'rect',
        x: el.x - el.width / 2,
        y: el.y - el.height / 2,
        w: el.width,
        h: el.height,
        fill,
        stroke: (props.outlineColor as string | undefined) ?? '#2a5a99',
        strokeWidth: 1,
      }];
    }

    case 'table': {
      // Tisch: Kreis in Element-Größe mit Füllung
      const fill = (props.fill as string | undefined) ?? '#8b7355';
      return [{
        kind: 'circle',
        center: { x: el.x, y: el.y },
        radius: Math.max(el.width, el.height) / 2,
        fill,
        stroke: '#5a4a35',
        strokeWidth: 1,
      }];
    }

    case 'stage': {
      // Bühne: Rechteck mit dunkler Füllung
      return [{
        kind: 'rect',
        x: el.x - el.width / 2,
        y: el.y - el.height / 2,
        w: el.width,
        h: el.height,
        fill: (props.fill as string | undefined) ?? '#3a3a4a',
        stroke,
        strokeWidth: 1.5,
      }];
    }

    default:
      return [];
  }
}