import type {
  MileageReportGroup,
  MileageReportVehicle,
} from '../api';

export type VehicleFilter = 'ALL' | 'LOW' | 'HIGH' | 'INVENTORY';
export type VehicleSortKey = 'dailyMileage' | 'sevenDayMileage' | 'completionRate';
export type SortDirection = 'asc' | 'desc';

const REPORT_DATE_PATTERN = /^\d{4}-\d{2}-\d{2}$/;
const HIDDEN_QUALITY_NOTE = '日行驶总里程延续人工汇报口径，包含库存车辆产生的里程。';

export function shanghaiYmd(offsetDays = 0, now = new Date()): string {
  // 日报按上海自然日归档，不能依赖浏览器所在时区计算“昨天”。
  const parts = new Intl.DateTimeFormat('en-CA', {
    timeZone: 'Asia/Shanghai',
    year: 'numeric',
    month: '2-digit',
    day: '2-digit',
  }).format(now);
  const date = new Date(`${parts}T00:00:00Z`);
  date.setUTCDate(date.getUTCDate() + offsetDays);
  return date.toISOString().slice(0, 10);
}

export function dateShift(date: string, days: number): string {
  const value = new Date(`${date}T00:00:00Z`);
  value.setUTCDate(value.getUTCDate() + days);
  return value.toISOString().slice(0, 10);
}

export function monthShift(month: string, months: number): string {
  const value = new Date(`${month}-01T00:00:00Z`);
  value.setUTCMonth(value.getUTCMonth() + months);
  return value.toISOString().slice(0, 7);
}

export function reportDateLabel(value: string): string {
  const date = new Date(`${value}T00:00:00Z`);
  return new Intl.DateTimeFormat('zh-CN', {
    timeZone: 'UTC',
    year: 'numeric',
    month: 'long',
    day: 'numeric',
    weekday: 'short',
  }).format(date).replace(/日(?=周)/, '日 ');
}

export function initialReportDate(search: string, fallbackDate = shanghaiYmd(-1)): string {
  const value = new URLSearchParams(search).get('mileageReportDate');
  return REPORT_DATE_PATTERN.test(value || '') ? value! : fallbackDate;
}

export function fmtKm(value: number): string {
  if (Math.abs(value) >= 10000) return `${(value / 10000).toFixed(2)}万`;
  return value.toLocaleString('zh-CN', { maximumFractionDigits: 1 });
}

export function fmtDate(value: string): string {
  const [, month, day] = value.split('-');
  return `${Number(month)}月${Number(day)}日`;
}

export function fmtDateTime(value: string | null): string {
  if (!value) return '数据时间未返回';
  const date = new Date(value);
  if (Number.isNaN(date.getTime())) return value;
  return date.toLocaleString('zh-CN', {
    month: '2-digit',
    day: '2-digit',
    hour: '2-digit',
    minute: '2-digit',
    hour12: false,
  });
}

export function deltaLabel(value: number, rate: number | null): string {
  const sign = value >= 0 ? '+' : '';
  return `${sign}${fmtKm(value)} km${rate == null ? '' : ` · ${sign}${rate.toFixed(1)}%`}`;
}

export function currentAssessmentYearLabel(periods: string[], reportDate: string): string | null {
  const report = new Date(`${reportDate}T00:00:00Z`);
  if (Number.isNaN(report.getTime())) return null;
  const years = new Set<number>();

  // 同一车型可能分批交付，因此一个日报日期可能同时落在多个考核年度。
  for (const period of periods) {
    const dates = Array.from(period.matchAll(/(\d{4})[/-](\d{1,2})[/-](\d{1,2})/g));
    const start = dates[0];
    const end = dates[1];
    if (!start || !end) continue;
    const startDate = new Date(Date.UTC(Number(start[1]), Number(start[2]) - 1, Number(start[3])));
    const endDate = new Date(Date.UTC(Number(end[1]), Number(end[2]) - 1, Number(end[3])));
    if (report < startDate || report > endDate) continue;

    let yearNumber = report.getUTCFullYear() - startDate.getUTCFullYear() + 1;
    if (
      report.getUTCMonth() < startDate.getUTCMonth()
      || (report.getUTCMonth() === startDate.getUTCMonth() && report.getUTCDate() < startDate.getUTCDate())
    ) yearNumber -= 1;
    if (yearNumber > 0) years.add(yearNumber);
  }

  if (years.size === 0) return null;
  const labels = Array.from(years).sort((a, b) => a - b).map(year => String(year));
  return `考核第${labels.join('/')}年`;
}

export function dailyMileageStatus(group: Pick<
  MileageReportGroup,
  'dailyRequiredMileage' | 'remainingMileage' | 'dailyMileage'
>): {
  label: string;
  detail: string;
  tone: 'positive' | 'warning' | 'neutral';
} {
  if (group.dailyRequiredMileage <= 0) {
    if (group.remainingMileage <= 0) {
      return { label: '本年度已完成', detail: '当前年度剩余任务为 0，无需设置每日应完成里程。', tone: 'positive' };
    }
    return { label: '暂无法计算', detail: '缺少有效的当前考核年度截止日，暂不设每日应完成里程。', tone: 'warning' };
  }

  const gap = group.dailyMileage - group.dailyRequiredMileage;
  const rate = (group.dailyMileage / group.dailyRequiredMileage) * 100;
  if (gap >= 0) {
    return { label: '今日已达标', detail: `超出应完成 ${fmtKm(gap)} km，完成 ${rate.toFixed(1)}%。`, tone: 'positive' };
  }
  return { label: '今日未达标', detail: `距应完成差 ${fmtKm(Math.abs(gap))} km，完成 ${rate.toFixed(1)}%。`, tone: 'warning' };
}

export function sevenDayMileageOf(vehicle: MileageReportVehicle): number {
  return (vehicle.trend || []).reduce((total, point) => total + point.totalMileage, 0);
}

function vehicleSortValue(vehicle: MileageReportVehicle, sortKey: VehicleSortKey): number {
  return sortKey === 'sevenDayMileage' ? sevenDayMileageOf(vehicle) : vehicle[sortKey];
}

export function filterAndSortVehicles(
  vehicles: MileageReportVehicle[],
  filter: VehicleFilter,
  search: string,
  sortKey: VehicleSortKey,
  sortDirection: SortDirection,
): MileageReportVehicle[] {
  const query = search.trim().toLowerCase();
  return vehicles
    .filter(vehicle => {
      if (filter !== 'ALL' && vehicle.mileageBand !== filter) return false;
      if (!query) return true;
      return vehicle.plate.toLowerCase().includes(query)
        || (vehicle.customer || '').toLowerCase().includes(query)
        || (vehicle.department || '').toLowerCase().includes(query);
    })
    .sort((left, right) => {
      const difference = vehicleSortValue(left, sortKey) - vehicleSortValue(right, sortKey);
      if (difference !== 0) return sortDirection === 'asc' ? difference : -difference;
      return left.plate.localeCompare(right.plate, 'zh-CN');
    });
}

export function roundMileageForDisplay(value: number): number {
  return Math.round(value * 10) / 10;
}

export function isVisibleQualityNote(message: string): boolean {
  return message !== HIDDEN_QUALITY_NOTE;
}