import { Texture } from './Texture.js';

export class TextRenderer {
  constructor(gl) {
    this.gl = gl;
    this.canvas = document.createElement('canvas');
    this.ctx = this.canvas.getContext('2d');
    this._cachedKey = null;
    this._cachedEntry = null;
  }

  draw(renderer, text, x, y, options = {}) {
    const entry = this._resolve(text, options);
    renderer.drawTexture(entry.texture, x, y, entry.width, entry.height);
    return entry;
  }

  measure(text, options = {}) {
    return this._resolve(text, options);
  }

  _resolve(text, options = {}) {
    const key = this._makeKey(text, options);
    if (this._cachedKey !== key) {
      this._flushCache();
      this._cachedKey = key;
      this._cachedEntry = this._rasterize(text, options);
    }
    return this._cachedEntry;
  }

  _makeKey(text, { size = 20, font = 'arial', fillStyle = 'black', bold = true }) {
    return `${text}|${size}|${font}|${fillStyle}|${bold}`;
  }

  _rasterize(text, { size = 20, font = 'arial', fillStyle = 'black', bold = true }) {
    const { ctx, canvas } = this;
    const pad = 4;
    const fontString = `${bold ? 'bold ' : ''}${size}px ${font}`;

    ctx.font = fontString;
    const textWidth = Math.ceil(ctx.measureText(text).width);
    const width = textWidth + pad * 2;
    const height = Math.ceil(size * 1.3) + pad * 2;
    const scale = Math.min(window.devicePixelRatio || 1, 2);

    canvas.width = Math.max(1, Math.ceil(width * scale));
    canvas.height = Math.max(1, Math.ceil(height * scale));
    ctx.setTransform(scale, 0, 0, scale, 0, 0);
    ctx.clearRect(0, 0, width, height);

    ctx.font = fontString;
    ctx.fillStyle = fillStyle;
    ctx.textAlign = 'left';
    ctx.textBaseline = 'alphabetic';
    ctx.fillText(text, pad, pad + size);

    const texture = new Texture(this.gl, canvas.width, canvas.height);
    texture.uploadCanvas(canvas);

    return { texture, width, height };
  }

  _flushCache() {
    if (this._cachedEntry) {
      this._cachedEntry.texture.dispose();
      this._cachedEntry = null;
    }
  }
}