import type {
  DailyMileageReport,
  MileageReportGroup,
  MileageReportInsight,
  MileageReportQualityNote,
  MileageReportSource,
  MileageReportStatus,
  MileageReportTotals,
  MileageReportTrendPoint,
} from '../../../shared/mileage/daily-report.js';

export function roundMileage(value: number): number {
  return Math.round((Number(value) || 0) * 10) / 10;
}

export function isOperatingStatus(status: string | null | undefined): boolean {
  return status === '租赁' || status === '自营';
}

export function mileageBand(
  status: string | null | undefined,
  dailyMileage: number,
): 'LOW' | 'HIGH' | 'INVENTORY' {
  if (!isOperatingStatus(status)) return 'INVENTORY';
  return dailyMileage <= 100 ? 'LOW' : 'HIGH';
}

export function compactMileageTargetName(name: string): string {
  return name
    .replace(/^交投/, '')
    .replace(/^羚牛/, '')
    .replace(/辆/g, '台')
    .replace(/4\.5T冷链车/g, '冷链')
    .replace(/4\.5T冷链/g, '冷链')
    .replace(/4\.5T普货/g, '普货')
    .replace(/18T$/, '18T双飞翼');
}

function percentChange(current: number, previous: number): number | null {
  if (previous <= 0) return null;
  return Math.round(((current - previous) / previous) * 1000) / 10;
}

function sum(groups: MileageReportGroup[], key: keyof MileageReportGroup): number {
  return groups.reduce((total, group) => total + Number(group[key] || 0), 0);
}

export function buildReportTotals(groups: MileageReportGroup[]): MileageReportTotals {
  const dailyMileage = roundMileage(sum(groups, 'dailyMileage'));
  const yesterdayMileage = roundMileage(sum(groups, 'yesterdayMileage'));
  const operatingCount = sum(groups, 'operatingCount');
  const operatingMileage = roundMileage(sum(groups, 'operatingMileage'));
  const dailyRequiredMileage = roundMileage(sum(groups, 'dailyRequiredMileage'));
  return {
    vehicleCount: sum(groups, 'vehicleCount'),
    operatingCount,
    inventoryCount: sum(groups, 'inventoryCount'),
    dailyMileage,
    operatingMileage,
    inventoryMileage: roundMileage(sum(groups, 'inventoryMileage')),
    yesterdayMileage,
    dayOverDayDelta: roundMileage(dailyMileage - yesterdayMileage),
    dayOverDayRate: percentChange(dailyMileage, yesterdayMileage),
    averageOperatingMileage: operatingCount > 0 ? roundMileage(operatingMileage / operatingCount) : 0,
    lowMileageCount: sum(groups, 'lowMileageCount'),
    highMileageCount: sum(groups, 'highMileageCount'),
    qualifiedCount: sum(groups, 'qualifiedCount'),
    halfQualifiedCount: sum(groups, 'halfQualifiedCount'),
    dailyRequiredMileage,
    dailyTaskGap: roundMileage(dailyMileage - dailyRequiredMileage),
  };
}

function describeDelta(value: number, rate: number | null): string {
  const direction = value >= 0 ? '增加' : '减少';
  const rateText = rate == null ? '' : `，${Math.abs(rate).toFixed(1)}%`;
  return `较前一日${direction} ${Math.abs(value).toLocaleString('zh-CN', { maximumFractionDigits: 1 })} km${rateText}`;
}

export function buildReportInsights(
  groups: MileageReportGroup[],
  totals: MileageReportTotals,
): MileageReportInsight[] {
  if (groups.length === 0) return [];
  const largest = [...groups].sort((a, b) => b.dailyMileage - a.dailyMileage)[0];
  const weakest = [...groups].sort((a, b) => a.dayOverDayDelta - b.dayOverDayDelta)[0];
  const lowRate = totals.operatingCount > 0 ? totals.lowMileageCount / totals.operatingCount : 0;
  const insights: MileageReportInsight[] = [
    {
      tone: totals.dayOverDayDelta >= 0 ? 'positive' : 'warning',
      title: totals.dayOverDayDelta >= 0 ? '总里程回升' : '总里程回落',
      detail: describeDelta(totals.dayOverDayDelta, totals.dayOverDayRate),
    },
    {
      tone: 'neutral',
      title: `${largest.displayName}贡献最高`,
      detail: `当日 ${largest.dailyMileage.toLocaleString('zh-CN', { maximumFractionDigits: 1 })} km，占全量 ${totals.dailyMileage > 0 ? ((largest.dailyMileage / totals.dailyMileage) * 100).toFixed(1) : '0.0'}%`,
    },
  ];

  if (weakest.dayOverDayDelta < 0) {
    insights.push({
      tone: 'warning',
      title: `${weakest.displayName}降幅最大`,
      detail: describeDelta(weakest.dayOverDayDelta, weakest.dayOverDayRate),
    });
  } else {
    insights.push({
      tone: 'positive',
      title: '各车型未出现环比下降',
      detail: `增幅最低为 ${weakest.displayName}，仍增加 ${weakest.dayOverDayDelta.toLocaleString('zh-CN', { maximumFractionDigits: 1 })} km`,
    });
  }

  if (totals.inventoryMileage > 0) {
    insights.push({
      tone: 'critical',
      title: '库存车辆产生里程',
      detail: `${totals.inventoryCount} 台库存车辆合计产生 ${totals.inventoryMileage.toLocaleString('zh-CN', { maximumFractionDigits: 1 })} km，建议核对状态`,
    });
  } else {
    insights.push({
      tone: lowRate >= 0.5 ? 'warning' : 'neutral',
      title: `${(lowRate * 100).toFixed(1)}% 运营车辆不超过 100km`,
      detail: `${totals.lowMileageCount} 台低里程，${totals.highMileageCount} 台超过 100km`,
    });
  }
  return insights.slice(0, 4);
}

export function buildOverallTrend(groups: MileageReportGroup[]): MileageReportTrendPoint[] {
  const totals = new Map<string, number>();
  for (const group of groups) {
    for (const point of group.trend) {
      totals.set(point.date, (totals.get(point.date) || 0) + point.totalMileage);
    }
  }
  return Array.from(totals.entries())
    .sort(([a], [b]) => a.localeCompare(b))
    .map(([date, totalMileage]) => ({ date, totalMileage: roundMileage(totalMileage) }));
}

export function buildDailyMileageReport(input: {
  reportDate: string;
  status: MileageReportStatus;
  source: MileageReportSource;
  generatedAt: string;
  sourceUpdatedAt: string | null;
  groups: MileageReportGroup[];
  qualityNotes?: MileageReportQualityNote[];
}): DailyMileageReport {
  const groups = input.groups.map(group => ({
    ...group,
    dayOverDayDelta: roundMileage(group.dailyMileage - group.yesterdayMileage),
    dayOverDayRate: percentChange(group.dailyMileage, group.yesterdayMileage),
  }));
  const totals = buildReportTotals(groups);
  return {
    version: 1,
    reportDate: input.reportDate,
    title: `广州现代 ${totals.vehicleCount} 台车辆运营日报`,
    status: input.status,
    source: input.source,
    generatedAt: input.generatedAt,
    sourceUpdatedAt: input.sourceUpdatedAt,
    totals,
    trend: buildOverallTrend(groups),
    groups,
    insights: buildReportInsights(groups, totals),
    qualityNotes: input.qualityNotes || [],
  };
}