class PetrolAction {
  constructor($UD, context) {
    this.$UD = $UD;
    this.context = context;
    this.config = {
      url: '',
      stationUuid: '',
      fuelType: '',
      refreshRate: '1',
    };
    this.refreshTimer = null;
    this.debounceTimer = 0;
    this.previousPrice = null;
    this.lastDelta = null;

    this.$UD.onDidReceiveSettings(jsn => {
      if (jsn.context !== this.context) return;
      const s = jsn.settings || {};
      this.config = Object.assign(this.config, s);
      if (s.previousPrice != null) this.previousPrice = s.previousPrice;
      if (s.lastDelta != null) this.lastDelta = s.lastDelta;
    });
  }

  setActive() {}

  onClear() {
    if (this.refreshTimer) {
      clearInterval(this.refreshTimer);
      this.refreshTimer = null;
    }
    if (this.debounceTimer) {
      clearTimeout(this.debounceTimer);
      this.debounceTimer = 0;
    }
  }

  setParams(jsn) {
    const params = (jsn && jsn.param) || {};
    this.config = Object.assign(this.config, params);
    this.$UD.getSettings(this.context);
    this.start();
  }

  onRun() {
    this.fetchPrice();
  }

  start() {
    this.onClear();
    this.fetchPrice();
    const duration = this.getRefreshDuration();
    if (duration > 0) {
      this.refreshTimer = setInterval(() => this.fetchPrice(), duration * 60 * 1000);
    }
  }

  async fetchPrice() {
    if (this.debounceTimer) clearTimeout(this.debounceTimer);
    this.debounceTimer = setTimeout(async () => {
      if (!this.config.url || !this.config.stationUuid || !this.config.fuelType) {
        this.renderButton('?', null);
        return;
      }
      try {
        const response = await fetch(this.config.url);
        const text = await response.text();
        const raw = this.parsePrometheus(text);
        if (raw) {
          const current = parseFloat(raw);
          if (this.previousPrice !== null) {
            const delta = current - this.previousPrice;
            if (delta !== 0) this.lastDelta = delta;
          }
          this.previousPrice = current;
          this.renderButton(`${raw}€`, this.lastDelta);
          this.$UD.setSettings({ ...this.config, previousPrice: this.previousPrice, lastDelta: this.lastDelta }, this.context);
        } else {
          this.renderButton('N/A', null);
        }
      } catch (e) {
        this.renderButton('ERR', null);
      }
    }, 300);
  }

  parsePrometheus(text) {
    for (const line of text.split('\n')) {
      const trimmed = line.trim();
      if (!trimmed || trimmed.startsWith('#')) continue;
      if (trimmed.startsWith('petrol_price_euro') && trimmed.includes(this.config.stationUuid) && trimmed.includes(this.config.fuelType)) {
        const closingBrace = trimmed.indexOf('}');
        if (closingBrace !== -1) return trimmed.slice(closingBrace + 1).trim();
      }
    }
    return null;
  }

  renderButton(priceText, delta) {
    const canvas = document.createElement('canvas');
    canvas.width = 196;
    canvas.height = 196;
    const ctx = canvas.getContext('2d');

    ctx.fillStyle = '#000000';
    ctx.fillRect(0, 0, 196, 196);

    ctx.strokeStyle = '#000';
    ctx.lineWidth = 3;
    ctx.textBaseline = 'middle';
    ctx.textAlign = 'center';

    // Fuel type — top, light blue
    ctx.fillStyle = '#7ec8e3';
    ctx.font = 'bold 28px "Source Han Sans SC"';
    ctx.strokeText(this.config.fuelType, 98, 45);
    ctx.fillText(this.config.fuelType, 98, 45);

    // Price — middle, yellow
    const fSize = priceText.length > 6 ? 34 - priceText.length : 40;
    ctx.fillStyle = '#f0c040';
    ctx.font = `bold ${fSize}px "Source Han Sans SC"`;
    ctx.strokeText(priceText, 98, 105);
    ctx.fillText(priceText, 98, 105);

    // Delta — bottom
    if (delta !== null) {
      const arrow = delta > 0 ? '▲' : '▼';
      const color = delta > 0 ? '#ff6b6b' : '#6bff6b';
      const deltaText = `${arrow} ${Math.abs(delta).toFixed(3)}`;
      ctx.fillStyle = color;
      ctx.font = '18px "Source Han Sans SC"';
      ctx.strokeText(deltaText, 98, 142);
      ctx.fillText(deltaText, 98, 142);
    }

    this.$UD.setBaseDataIcon(this.context, canvas.toDataURL('image/png'));
  }

  getRefreshDuration() {
    switch (this.config.refreshRate) {
      case '1': return 1;
      case '2': return 2;
      case '3': return 5;
      case '4': return 10;
      case '5': return 30;
      case '6': return 60;
      default:  return 0;
    }
  }
}