import { NextRequest, NextResponse } from 'next/server';
import { prisma } from '@/lib/prisma';
import { getCurrentUser } from '@/lib/auth';

// Types de période: day | 7days | 30days | month | quarter | year
// Ou plage personnalisée via from & to (format ISO)
function getDateRange(period: string | null, from: string | null, to: string | null): {
  start: Date;
  end: Date;
  prevStart: Date;
  prevEnd: Date;
  periodLabel: string;
} {
  const now = new Date();
  const endOfDay = (d: Date) => new Date(d.getFullYear(), d.getMonth(), d.getDate(), 23, 59, 59, 999);
  const startOfDay = (d: Date) => new Date(d.getFullYear(), d.getMonth(), d.getDate());

  if (from && to) {
    const start = new Date(from);
    const end = endOfDay(new Date(to));
    const diff = end.getTime() - start.getTime();
    const prevEnd = new Date(start.getTime() - 1);
    const prevStart = new Date(prevEnd.getTime() - diff);
    return {
      start: startOfDay(start),
      end,
      prevStart: startOfDay(prevStart),
      prevEnd: endOfDay(prevEnd),
      periodLabel: `${start.toLocaleDateString('fr-FR')} - ${new Date(to).toLocaleDateString('fr-FR')}`,
    };
  }

  switch (period) {
    case 'day': {
      const start = startOfDay(now);
      const end = endOfDay(now);
      const yesterday = new Date(now);
      yesterday.setDate(yesterday.getDate() - 1);
      return {
        start,
        end,
        prevStart: startOfDay(yesterday),
        prevEnd: endOfDay(yesterday),
        periodLabel: "Aujourd'hui",
      };
    }
    case 'yesterday': {
      const yesterday = new Date(now);
      yesterday.setDate(yesterday.getDate() - 1);
      const start = startOfDay(yesterday);
      const end = endOfDay(yesterday);
      const dayBefore = new Date(yesterday);
      dayBefore.setDate(dayBefore.getDate() - 1);
      return {
        start,
        end,
        prevStart: startOfDay(dayBefore),
        prevEnd: endOfDay(dayBefore),
        periodLabel: 'Hier',
      };
    }
    case 'week': {
      // Cette semaine : lundi à aujourd'hui (ISO week, lundi = 1)
      const dayOfWeek = now.getDay();
      const mondayOffset = dayOfWeek === 0 ? -6 : 1 - dayOfWeek;
      const startOfWeek = new Date(now);
      startOfWeek.setDate(startOfWeek.getDate() + mondayOffset);
      const start = startOfDay(startOfWeek);
      const end = endOfDay(now);
      const prevWeekStart = new Date(start);
      prevWeekStart.setDate(prevWeekStart.getDate() - 7);
      const prevWeekEnd = new Date(start);
      prevWeekEnd.setDate(prevWeekEnd.getDate() - 1);
      return {
        start,
        end,
        prevStart: startOfDay(prevWeekStart),
        prevEnd: endOfDay(prevWeekEnd),
        periodLabel: 'Cette semaine',
      };
    }
    case '7days': {
      const start = new Date(now);
      start.setDate(start.getDate() - 6);
      const end = endOfDay(now);
      const prevEnd = new Date(start.getTime() - 1);
      const prevStart = new Date(prevEnd);
      prevStart.setDate(prevStart.getDate() - 6);
      return {
        start: startOfDay(start),
        end,
        prevStart: startOfDay(prevStart),
        prevEnd: endOfDay(prevEnd),
        periodLabel: '7 derniers jours',
      };
    }
    case '30days': {
      const start = new Date(now);
      start.setDate(start.getDate() - 29);
      const end = endOfDay(now);
      const prevEnd = new Date(start.getTime() - 1);
      const prevStart = new Date(prevEnd);
      prevStart.setDate(prevStart.getDate() - 29);
      return {
        start: startOfDay(start),
        end,
        prevStart: startOfDay(prevStart),
        prevEnd: endOfDay(prevEnd),
        periodLabel: '30 derniers jours',
      };
    }
    case 'quarter': {
      const q = Math.floor(now.getMonth() / 3) + 1;
      const startOfQuarter = new Date(now.getFullYear(), (q - 1) * 3, 1);
      const endOfQuarter = new Date(now.getFullYear(), q * 3, 0, 23, 59, 59, 999);
      const prevQuarter = q === 1 ? 4 : q - 1;
      const prevYear = q === 1 ? now.getFullYear() - 1 : now.getFullYear();
      const prevStart = new Date(prevYear, (prevQuarter - 1) * 3, 1);
      const prevEnd = new Date(prevYear, prevQuarter * 3, 0, 23, 59, 59, 999);
      return {
        start: startOfQuarter,
        end: endOfQuarter,
        prevStart: prevStart,
        prevEnd: prevEnd,
        periodLabel: `T${q} ${now.getFullYear()}`,
      };
    }
    case 'year': {
      const startOfYear = new Date(now.getFullYear(), 0, 1);
      const endOfYear = new Date(now.getFullYear(), 11, 31, 23, 59, 59, 999);
      const prevStart = new Date(now.getFullYear() - 1, 0, 1);
      const prevEnd = new Date(now.getFullYear() - 1, 11, 31, 23, 59, 59, 999);
      return {
        start: startOfYear,
        end: endOfYear,
        prevStart: prevStart,
        prevEnd: prevEnd,
        periodLabel: `Année ${now.getFullYear()}`,
      };
    }
    case 'month':
    default: {
      const startOfMonth = new Date(now.getFullYear(), now.getMonth(), 1);
      const endOfMonth = new Date(now.getFullYear(), now.getMonth() + 1, 0, 23, 59, 59, 999);
      const startOfLastMonth = new Date(now.getFullYear(), now.getMonth() - 1, 1);
      const endOfLastMonth = new Date(now.getFullYear(), now.getMonth(), 0, 23, 59, 59, 999);
      return {
        start: startOfMonth,
        end: endOfMonth,
        prevStart: startOfLastMonth,
        prevEnd: endOfLastMonth,
        periodLabel: 'Mois en cours',
      };
    }
  }
}

// GET - Récupérer les statistiques du dashboard
export async function GET(request: NextRequest) {
  try {
    const user = await getCurrentUser();
    if (!user) {
      return NextResponse.json({ error: 'Non autorisé' }, { status: 401 });
    }

    const { searchParams } = new URL(request.url);
    const period = searchParams.get('period') || 'month';
    const from = searchParams.get('from');
    const to = searchParams.get('to');

    const { start, end, prevStart, prevEnd, periodLabel } = getDateRange(period, from, to);

    // 1. Participations sur la période (trajets validés/terminés)
    const participationsMoisData = await prisma.participationFinanciere.findMany({
      where: {
        trajet: {
          date: {
            gte: start,
            lte: end,
          },
        },
      },
      include: { trajet: { select: { date: true } } },
    });

    const participationsCeMois = participationsMoisData;
    const montantMoyenParTrajet = 6.80;
    const participationsMois = participationsCeMois.reduce(
      (sum, p) => sum + (p.montant ?? montantMoyenParTrajet),
      0
    );
    const nombreFactures = participationsCeMois.length;

    // 2. Trajets sur la période
    const trajetsPeriode = await prisma.trajet.count({
      where: {
        archived: false,
        date: {
          gte: start,
          lte: end,
        },
      },
    });

    // Trajets période précédente pour comparaison
    const trajetsPeriodePrecedente = await prisma.trajet.count({
      where: {
        archived: false,
        date: {
          gte: prevStart,
          lte: prevEnd,
        },
      },
    });

    const differenceTrajets = trajetsPeriode - trajetsPeriodePrecedente;

    // 3. Trajets réalisés sur la période (terminés)
    const trajetsRealisesPeriode = await prisma.trajet.count({
      where: {
        archived: false,
        statut: 'Terminé',
        date: {
          gte: start,
          lte: end,
        },
      },
    });

    // Trajets réalisés période précédente pour comparaison
    const trajetsRealisesPeriodePrecedente = await prisma.trajet.count({
      where: {
        archived: false,
        statut: 'Terminé',
        date: {
          gte: prevStart,
          lte: prevEnd,
        },
      },
    });

    const pourcentageEvolution = trajetsRealisesPeriodePrecedente > 0
      ? Math.round(((trajetsRealisesPeriode - trajetsRealisesPeriodePrecedente) / trajetsRealisesPeriodePrecedente) * 100)
      : trajetsRealisesPeriode > 0 ? 100 : 0;

    // 4. Chauffeurs actifs (disponibles)
    const totalChauffeurs = await prisma.chauffeur.count();
    const chauffeursActifs = await prisma.chauffeur.count({
      where: {
        status: 'Disponible',
      },
    });

    return NextResponse.json({
      periodLabel,
      participationsMois: {
        montant: participationsMois,
        nombreFactures: nombreFactures,
      },
      trajetsAujourdhui: {
        nombre: trajetsPeriode,
        difference: differenceTrajets,
      },
      trajetsRealisesMois: {
        nombre: trajetsRealisesPeriode,
        pourcentageEvolution: pourcentageEvolution,
      },
      chauffeursActifs: {
        nombre: chauffeursActifs,
        total: totalChauffeurs,
      },
    });
  } catch (error) {
    console.error('Erreur lors de la récupération des statistiques:', error);
    return NextResponse.json(
      { error: 'Erreur serveur' },
      { status: 500 }
    );
  }
}