// TimeCalculator：时间轴计算器，负责时间与像素的转换、生成时间刻度等
export default class TimeCalculator {
  constructor(config) {
    this.config = config;
    this.scaleMap = { day: 40, week: 80, month: 200, quarter: 600 }; // 每单位像素宽度
  }
  // 日期转像素坐标
  dateToPixel(date) {
    const start = new Date(this.config.startDate);
    const d = new Date(date);
    const scale = this.scaleMap[this.config.timeScale] || 80;
    let diff = 0;
    if (this.config.timeScale === 'day') {
      diff = (d - start) / (1000 * 3600 * 24);
    } else if (this.config.timeScale === 'week') {
      diff = (d - start) / (1000 * 3600 * 24 * 7);
    } else if (this.config.timeScale === 'month') {
      diff = (d.getFullYear() - start.getFullYear()) * 12 + (d.getMonth() - start.getMonth());
    } else if (this.config.timeScale === 'quarter') {
      diff = ((d.getFullYear() - start.getFullYear()) * 12 + (d.getMonth() - start.getMonth())) / 3;
    }
    return diff * scale;
  }
  // 像素转日期（仅简单实现，实际可扩展）
  pixelToDate(pixel) {
    const start = new Date(this.config.startDate);
    const scale = this.scaleMap[this.config.timeScale] || 80;
    let d = new Date(start);
    if (this.config.timeScale === 'day') {
      d.setDate(start.getDate() + pixel / scale);
    } else if (this.config.timeScale === 'week') {
      d.setDate(start.getDate() + (pixel / scale) * 7);
    } else if (this.config.timeScale === 'month') {
      d.setMonth(start.getMonth() + pixel / scale);
    } else if (this.config.timeScale === 'quarter') {
      d.setMonth(start.getMonth() + (pixel / scale) * 3);
    }
    return d;
  }
  // 生成时间轴刻度
  getTimelineTicks() {
    const ticks = [];
    const start = new Date(this.config.startDate);
    const end = new Date(this.config.endDate);
    let cur = new Date(start);
    while (cur <= end) {
      ticks.push({
        label: this.formatTick(cur),
        date: new Date(cur)
      });
      if (this.config.timeScale === 'day') {
        cur.setDate(cur.getDate() + 1);
      } else if (this.config.timeScale === 'week') {
        cur.setDate(cur.getDate() + 7);
      } else if (this.config.timeScale === 'month') {
        cur.setMonth(cur.getMonth() + 1);
      } else if (this.config.timeScale === 'quarter') {
        cur.setMonth(cur.getMonth() + 3);
      }
    }
    return ticks;
  }
  // 格式化刻度
  formatTick(date) {
    if (this.config.timeScale === 'day') {
      return date.toISOString().slice(5, 10);
    } else if (this.config.timeScale === 'week') {
      return 'W' + this.getWeekNumber(date);
    } else if (this.config.timeScale === 'month') {
      return date.getFullYear() + '-' + (date.getMonth() + 1);
    } else if (this.config.timeScale === 'quarter') {
      return date.getFullYear() + ' Q' + (Math.floor(date.getMonth() / 3) + 1);
    }
    return '';
  }
  // 获取周数
  getWeekNumber(date) {
    const firstDay = new Date(date.getFullYear(), 0, 1);
    const dayOfYear = ((date - firstDay) / 86400000) + 1;
    return Math.ceil(dayOfYear / 7);
  }
}