import { SoundManager } from './SoundManager.js';
import { evaluateStroke } from './StrokeEvaluator.js';
import { createConfig } from './StrokeConfig.js';

export const KANJI_CONSTANTS = {
  BASE_SIZE: 109,
  SVG_NS: 'http://www.w3.org/2000/svg',
  API_URL: 'https://raw.githubusercontent.com/KanjiVG/kanjivg/master/kanji',

  STROKE_WIDTH_BASE: 6,
  DASH_ARRAY_GRID: [5, 5],
  DASH_ARRAY_HINT: [10, 15],

  ANIMATION_DURATION: 300,
  SAMPLE_POINTS: 60,

  COLORS: {
    USER: { r: 255, g: 118, b: 117 },
    FINAL: { r: 0, g: 206, b: 201 },
    HINT: '#3f3f46',
    GRID: 'rgba(255, 255, 255, 0.08)',
  },
};

export class KanjiController {
  constructor(options = {}) {
    this.size = options.size || 300;
    this.onComplete = options.onComplete || (() => {});
    this.onMistake = options.onMistake || (() => {});

    // Stroke evaluation config (from StrokeConfig presets)
    this.config = options.config || createConfig('medium');
    this.lastEvaluation = null;

    this.scale = this.size / KANJI_CONSTANTS.BASE_SIZE;
    this.paths = [];
    this.currentStrokeIdx = 0;
    this.mistakes = 0;
    this.userPath = [];
    this.isDrawing = false;
    this.isAnimating = false;

    this.ctx = { bg: null, hint: null, draw: null };
    this.hintAnimationFrame = null;
  }

  static createPathElement(d) {
    const path = document.createElementNS(KANJI_CONSTANTS.SVG_NS, 'path');
    path.setAttribute('d', d);
    return path;
  }

  static setContextDefaults(ctx) {
    ctx.lineCap = 'round';
    ctx.lineJoin = 'round';
    ctx.lineWidth = KANJI_CONSTANTS.STROKE_WIDTH_BASE;
  }

  static resamplePoints(points, count) {
    if (!points || points.length === 0) return [];

    let totalLen = 0;
    const dists = [0];
    points.slice(1).forEach((p, i) => {
      const prev = points[i];
      const d = Math.hypot(p.x - prev.x, p.y - prev.y);
      totalLen += d;
      dists.push(totalLen);
    });

    const step = totalLen / (count - 1);

    return Array.from({ length: count }).map((_, i) => {
      const targetDist = i * step;
      let idx = dists.findIndex((d) => d >= targetDist);
      if (idx === -1) idx = dists.length - 1;
      if (idx > 0) idx -= 1;

      if (idx >= points.length - 1) {
        return points[points.length - 1];
      }

      const dStart = dists[idx];
      const dEnd = dists[idx + 1];
      const segmentLen = dEnd - dStart;
      const t = segmentLen === 0 ? 0 : (targetDist - dStart) / segmentLen;

      const p1 = points[idx];
      const p2 = points[idx + 1];

      return {
        x: p1.x + (p2.x - p1.x) * t,
        y: p1.y + (p2.y - p1.y) * t,
      };
    });
  }

  mount(canvasRefs) {
    this.ctx.bg = canvasRefs.bg.getContext('2d');
    this.ctx.hint = canvasRefs.hint.getContext('2d');
    this.ctx.draw = canvasRefs.draw.getContext('2d');
    this.resize(this.size);
  }

  setConfig(config) {
    this.config = config;
  }

  getLastEvaluation() {
    return this.lastEvaluation;
  }

  resize(newSize) {
    this.size = newSize;
    this.scale = this.size / KANJI_CONSTANTS.BASE_SIZE;

    Object.values(this.ctx).forEach((ctx) => {
      if (ctx && ctx.canvas) {
        ctx.canvas.width = this.size;
        ctx.canvas.height = this.size;
        KanjiController.setContextDefaults(ctx);
      }
    });

    this.drawGrid();
    if (this.paths.length) {
      this.redrawAllPerfectStrokes();
    }
  }

  setAutoHint(val) {
    this.autoHint = val;
    if (!val) {
      this.clearCanvas(this.ctx.hint);
    }
  }

  async loadChar(char, autoHint = false) {
    this.autoHint = autoHint;
    this.paths = [];
    this.reset();
    const hex = char.charCodeAt(0).toString(16).padStart(5, '0');

    try {
      const res = await fetch(`${KANJI_CONSTANTS.API_URL}/${hex}.svg`);
      const txt = await res.text();
      const parser = new DOMParser();
      const doc = parser.parseFromString(txt, 'image/svg+xml');
      this.paths = Array.from(doc.getElementsByTagName('path')).map((p) => p.getAttribute('d'));

      this.drawGrid();
      if (autoHint) this.showHint();
    } catch (e) {
      console.error('Failed to load Kanji:', e);
    }
  }

  reset() {
    if (this.hintAnimationFrame) {
      cancelAnimationFrame(this.hintAnimationFrame);
      this.hintAnimationFrame = null;
    }

    this.currentStrokeIdx = 0;
    this.mistakes = 0;
    this.isAnimating = false;
    this.userPath = [];

    this.clearCanvas(this.ctx.draw);
    this.clearCanvas(this.ctx.hint);
    this.drawGrid();
    this.resetDrawStyle();

    if (this.autoHint && this.paths.length > 0) {
      this.showHint();
    }
  }

  startStroke(point) {
    if (this.currentStrokeIdx >= this.paths.length || this.isAnimating) return;

    this.isDrawing = true;
    this.userPath = [point];

    this.ctx.draw.beginPath();
    this.ctx.draw.moveTo(point.x, point.y);
    this.resetDrawStyle();
  }

  moveStroke(point) {
    if (!this.isDrawing) return;
    this.userPath.push(point);
    this.ctx.draw.lineTo(point.x, point.y);
    this.ctx.draw.stroke();
  }

  endStroke() {
    if (!this.isDrawing) return;
    this.isDrawing = false;
    this.validateStroke();
  }

  drawGrid() {
    if (!this.ctx.bg) return;
    const ctx = this.ctx.bg;
    this.clearCanvas(ctx);

    ctx.strokeStyle = KANJI_CONSTANTS.COLORS.GRID;
    ctx.lineWidth = 1;
    ctx.setLineDash(KANJI_CONSTANTS.DASH_ARRAY_GRID);

    const s = this.size;
    ctx.beginPath();
    ctx.moveTo(s / 2, 0); ctx.lineTo(s / 2, s);
    ctx.moveTo(0, s / 2); ctx.lineTo(s, s / 2);
    ctx.stroke();
  }

  showHint() {
    if (this.hintAnimationFrame) {
      cancelAnimationFrame(this.hintAnimationFrame);
      this.hintAnimationFrame = null;
    }

    this.clearCanvas(this.ctx.hint);
    if (this.currentStrokeIdx >= this.paths.length) return;

    const d = this.paths[this.currentStrokeIdx];
    const pathEl = KanjiController.createPathElement(d);
    const len = pathEl.getTotalLength();

    const ctx = this.ctx.hint;
    ctx.strokeStyle = KANJI_CONSTANTS.COLORS.HINT;
    ctx.setLineDash(KANJI_CONSTANTS.DASH_ARRAY_HINT);

    const startTime = performance.now();
    const DURATION = 600;

    const animate = (now) => {
      const elapsed = now - startTime;
      const progress = Math.min(elapsed / DURATION, 1);

      this.clearCanvas(ctx);
      ctx.beginPath();

      const drawLen = len * progress;
      const step = 5;

      let first = true;
      for (let dist = 0; dist <= drawLen; dist += step) {
        const pt = pathEl.getPointAtLength(dist);
        if (first) {
          ctx.moveTo(pt.x * this.scale, pt.y * this.scale);
          first = false;
        } else {
          ctx.lineTo(pt.x * this.scale, pt.y * this.scale);
        }
      }

      if (drawLen > 0) {
        const pt = pathEl.getPointAtLength(drawLen);
        if (first) ctx.moveTo(pt.x * this.scale, pt.y * this.scale);
        else ctx.lineTo(pt.x * this.scale, pt.y * this.scale);
      }

      ctx.stroke();

      if (progress < 1) {
        this.hintAnimationFrame = requestAnimationFrame(animate);
      } else {
        this.hintAnimationFrame = null;
      }
    };

    this.hintAnimationFrame = requestAnimationFrame(animate);
  }

  redrawAllPerfectStrokes(includeCurrent = false) {
    const ctx = this.ctx.draw;
    this.clearCanvas(ctx);
    ctx.save();
    ctx.scale(this.scale, this.scale);

    const { r, g, b } = KANJI_CONSTANTS.COLORS.FINAL;
    ctx.strokeStyle = `rgb(${r}, ${g}, ${b})`;
    ctx.lineWidth = KANJI_CONSTANTS.STROKE_WIDTH_BASE / this.scale;
    ctx.setLineDash([]);

    const limit = includeCurrent ? this.currentStrokeIdx + 1 : this.currentStrokeIdx;
    this.paths.slice(0, limit).forEach((d) => {
      ctx.stroke(new Path2D(d));
    });

    ctx.restore();

    if (!this.isAnimating) this.resetDrawStyle();
  }

  clearCanvas(ctx) {
    if (ctx) ctx.clearRect(0, 0, this.size, this.size);
  }

  resetDrawStyle() {
    const { r, g, b } = KANJI_CONSTANTS.COLORS.USER;
    if (this.ctx.draw) {
      this.ctx.draw.strokeStyle = `rgb(${r}, ${g}, ${b})`;
      this.ctx.draw.lineWidth = KANJI_CONSTANTS.STROKE_WIDTH_BASE;
      this.ctx.draw.setLineDash([]);
    }
  }

  validateStroke() {
    const targetD = this.paths[this.currentStrokeIdx];
    const pathEl = KanjiController.createPathElement(targetD);

    const result = evaluateStroke(
      this.userPath,
      pathEl,
      this.scale,
      this.config,
      { isFirstStroke: this.currentStrokeIdx === 0 },
    );

    this.lastEvaluation = result;

    if (result.pass) {
      if (this.hintAnimationFrame) {
        cancelAnimationFrame(this.hintAnimationFrame);
        this.hintAnimationFrame = null;
      }

      this.animateMorph(this.userPath, targetD, () => {
        this.currentStrokeIdx += 1;
        this.mistakes = 0;
        this.redrawAllPerfectStrokes();

        this.clearCanvas(this.ctx.hint);

        if (this.currentStrokeIdx >= this.paths.length) {
          SoundManager.playDrawingComplete();
          this.onComplete();
        } else {
          if (this.autoHint) {
            this.showHint();
          }
        }
      });
    } else {
      SoundManager.playStrokeError();
      this.mistakes += 1;
      this.animateErrorFade(this.userPath, () => {
        this.redrawAllPerfectStrokes();
        const needsHint = this.mistakes >= 3;
        if (needsHint) this.showHint();
        this.onMistake(needsHint);
      });
    }
  }

  // Old checkMatch, normalizeAngle, classifyOrientation, measureCurvature
  // have been replaced by StrokeEvaluator.evaluateStroke().

  animateErrorFade(userPath, onComplete) {
    this.isAnimating = true;
    const startTime = performance.now();
    const DURATION = 300;

    const tick = (now) => {
      const elapsed = now - startTime;
      const progress = Math.min(elapsed / DURATION, 1);
      const opacity = 1 - progress;

      this.redrawAllPerfectStrokes();

      if (opacity > 0) {
        const ctx = this.ctx.draw;
        ctx.save();
        ctx.beginPath();

        const { r, g, b } = KANJI_CONSTANTS.COLORS.USER;
        ctx.strokeStyle = `rgba(${r}, ${g}, ${b}, ${opacity})`;
        ctx.lineWidth = KANJI_CONSTANTS.STROKE_WIDTH_BASE;
        ctx.lineCap = 'round';
        ctx.lineJoin = 'round';

        if (userPath.length > 0) {
          ctx.moveTo(userPath[0].x, userPath[0].y);
          userPath.slice(1).forEach((p) => ctx.lineTo(p.x, p.y));
        }
        ctx.stroke();
        ctx.restore();
      }

      if (progress < 1) {
        requestAnimationFrame(tick);
      } else {
        this.isAnimating = false;
        this.resetDrawStyle();
        onComplete();
      }
    };
    requestAnimationFrame(tick);
  }

  animateMorph(userPoints, targetD, onComplete) {
    this.isAnimating = true;
    const targetPoints = this.getSvgPoints(targetD, KANJI_CONSTANTS.SAMPLE_POINTS);
    const startPoints = KanjiController.resamplePoints(userPoints, KANJI_CONSTANTS.SAMPLE_POINTS);

    const startTime = performance.now();
    const { USER, FINAL } = KANJI_CONSTANTS.COLORS;

    const tick = (now) => {
      const elapsed = now - startTime;
      const progress = Math.min(elapsed / KANJI_CONSTANTS.ANIMATION_DURATION, 1);
      const ease = 1 - (1 - progress) ** 3;

      this.redrawAllPerfectStrokes(false);

      const r = USER.r + (FINAL.r - USER.r) * ease;
      const g = USER.g + (FINAL.g - USER.g) * ease;
      const b = USER.b + (FINAL.b - USER.b) * ease;

      const ctx = this.ctx.draw;
      ctx.strokeStyle = `rgb(${Math.round(r)}, ${Math.round(g)}, ${Math.round(b)})`;
      ctx.lineWidth = KANJI_CONSTANTS.STROKE_WIDTH_BASE;
      ctx.beginPath();

      Array.from({ length: KANJI_CONSTANTS.SAMPLE_POINTS }).forEach((_, i) => {
        const sx = startPoints[i].x;
        const sy = startPoints[i].y;
        const ex = targetPoints[i].x;
        const ey = targetPoints[i].y;

        const cx = sx + (ex - sx) * ease;
        const cy = sy + (ey - sy) * ease;

        if (i === 0) ctx.moveTo(cx, cy);
        else ctx.lineTo(cx, cy);
      });
      ctx.stroke();

      if (progress < 1) {
        requestAnimationFrame(tick);
      } else {
        this.isAnimating = false;
        this.resetDrawStyle();
        onComplete();
      }
    };

    requestAnimationFrame(tick);
  }

  getSvgPoints(d, count) {
    const path = KanjiController.createPathElement(d);
    const len = path.getTotalLength();

    return Array.from({ length: count }).map((_, i) => {
      const pt = path.getPointAtLength((i / (count - 1)) * len);
      return { x: pt.x * this.scale, y: pt.y * this.scale };
    });
  }
}