export type CustomerKind = 'external' | 'lingniu' | 'all';
export type EnergyDateRangeKind = 'thisWeek' | 'thisMonth' | 'last15';

export interface EnergyDateRange {
  start: string;
  end: string;
}

const YMD_RE = /^\d{4}-\d{2}-\d{2}$/;

// 车辆归属以账本 vehicle_id 为准，与氢能总览的筛选口径一致。
// 账本未关联车辆的记录归入外部车辆，避免在日报中遗漏真实加氢数据。
export function customerClause(customer: CustomerKind): string {
  if (customer === 'external') return 'vehicle_id IS NULL';
  if (customer === 'lingniu') return 'vehicle_id IS NOT NULL';
  return '1=1';
}

function formatYmd(date: Date): string {
  return `${date.getFullYear()}-${String(date.getMonth() + 1).padStart(2, '0')}-${String(date.getDate()).padStart(2, '0')}`;
}

function addDays(date: Date, days: number): Date {
  const next = new Date(date);
  next.setDate(next.getDate() + days);
  return next;
}

function parseYmd(value: string | undefined): string | null {
  if (!value || !YMD_RE.test(value)) return null;
  const date = new Date(`${value}T00:00:00`);
  return Number.isNaN(date.getTime()) ? null : value;
}

export function resolveDateRange(
  range: EnergyDateRangeKind,
  startParam?: string,
  endParam?: string,
  now: Date = new Date(),
): EnergyDateRange {
  const customStart = parseYmd(startParam);
  const customEnd = parseYmd(endParam);
  if (customStart && customEnd) {
    return customStart <= customEnd
      ? { start: customStart, end: customEnd }
      : { start: customEnd, end: customStart };
  }

  const today = new Date(now);
  today.setHours(0, 0, 0, 0);
  if (range === 'thisWeek') {
    const day = today.getDay() || 7;
    return { start: formatYmd(addDays(today, -(day - 1))), end: formatYmd(today) };
  }
  if (range === 'thisMonth') {
    return {
      start: formatYmd(new Date(today.getFullYear(), today.getMonth(), 1)),
      end: formatYmd(today),
    };
  }
  return { start: formatYmd(addDays(today, -14)), end: formatYmd(today) };
}

export function dateRangeClause(localExpression: string): string {
  return `${localExpression} >= ? AND ${localExpression} < DATE_ADD(?, INTERVAL 1 DAY)`;
}

export function enumerateDateRange(startYmd: string, endYmd: string): string[] {
  const result: string[] = [];
  const cursor = new Date(`${startYmd}T00:00:00`);
  const end = new Date(`${endYmd}T00:00:00`);
  while (cursor <= end) {
    result.push(formatYmd(cursor));
    cursor.setDate(cursor.getDate() + 1);
  }
  return result;
}