import { NextRequest, NextResponse } from "next/server";
import { getServerSession } from "next-auth/next";
import { authOptions } from "@/app/api/auth/options";
import { prisma } from "@/lib/prisma";
import { deleteMicrosoftEvent } from "@/lib/services/microsoft-calendar-sync";
import { logger } from "@/lib/logger";

// Helper function to check if user can manage events in a mission calendar
async function canManageMissionCalendar(userId: string, calendarId: string): Promise<boolean> {
  const calendar = await prisma.calendar.findUnique({
    where: { id: calendarId },
    include: {
      mission: {
        include: {
          missionUsers: true
        }
      }
    }
  });

  // If calendar is not linked to a mission, allow (it's a regular calendar)
  if (!calendar?.missionId || !calendar.mission) {
    return true;
  }

  const mission = calendar.mission;

  // Check if user is the creator of the mission
  if (mission.creatorId === userId) {
    return true;
  }

  // Check if user is a gardien-temps (time guardian) for this mission
  const isGardienTemps = mission.missionUsers.some(
    (mu) => mu.userId === userId && mu.role === 'gardien-temps'
  );

  return isGardienTemps;
}

export async function DELETE(req: NextRequest, props: { params: Promise<{ id: string }> }) {
  const params = await props.params;
  const session = await getServerSession(authOptions);

  if (!session?.user?.id) {
    return NextResponse.json({ error: "Non authentifié" }, { status: 401 });
  }

  try {
    // First, find the event and its associated calendar with sync config
    const event = await prisma.event.findUnique({
      where: { id: params.id },
      include: { 
        calendar: {
          include: {
            syncConfig: {
              include: {
                mailCredential: true
              }
            }
          }
        }
      },
    });

    if (!event) {
      return NextResponse.json(
        { error: "Événement non trouvé" },
        { status: 404 }
      );
    }

    // Verify that the user owns the calendar
    if (event.calendar.userId !== session.user.id) {
      return NextResponse.json(
        { error: "Non autorisé" },
        { status: 403 }
      );
    }

    // If calendar is linked to a mission, check permissions
    if (event.calendar.missionId) {
      const canManage = await canManageMissionCalendar(session.user.id, event.calendarId);
      if (!canManage) {
        return NextResponse.json(
          { error: "Seul le créateur de la mission ou le gardien-temps peut supprimer des événements" },
          { status: 403 }
        );
      }
    }

    // If event has externalEventId and calendar has Microsoft sync, delete from Microsoft too
    if (event.externalEventId && event.calendar.syncConfig && event.calendar.syncConfig.provider === 'microsoft' && event.calendar.syncConfig.syncEnabled) {
      const syncConfig = event.calendar.syncConfig;
      const mailCredential = syncConfig.mailCredential;
      
      if (mailCredential && mailCredential.use_oauth && mailCredential.refresh_token) {
        try {
          await deleteMicrosoftEvent(
            session.user.id,
            mailCredential.email,
            syncConfig.externalCalendarId || '',
            event.externalEventId
          );
          
          logger.info('Successfully synced event deletion to Microsoft', {
            eventId: params.id,
            externalEventId: event.externalEventId,
            email: mailCredential.email,
          });
        } catch (syncError: any) {
          // Log error but don't fail the request - local deletion will proceed
          // Don't disable syncConfig for permission errors (403) - user just needs to re-authenticate
          const isPermissionError = syncError.response?.status === 403;
          logger.error('Failed to sync event deletion to Microsoft', {
            eventId: params.id,
            externalEventId: event.externalEventId,
            error: syncError instanceof Error ? syncError.message : String(syncError),
            isPermissionError,
            suggestion: isPermissionError ? 'User needs to re-authenticate with Calendars.ReadWrite scope' : undefined,
          });
        }
      }
    }

    // Delete the event from local database
    await prisma.event.delete({
      where: { id: params.id },
    });

    // Invalidate calendar cache so the deletion appears immediately
    try {
      const { invalidateCalendarCache } = await import('@/lib/redis');
      await invalidateCalendarCache(session.user.id);
      logger.debug('[EVENTS] Invalidated calendar cache after event deletion', {
        eventId: params.id,
        userId: session.user.id,
      });
    } catch (cacheError) {
      // Log but don't fail the request if cache invalidation fails
      logger.error('[EVENTS] Error invalidating calendar cache', {
        error: cacheError instanceof Error ? cacheError.message : String(cacheError),
      });
    }

    return new NextResponse(null, { status: 204 });
  } catch (error) {
    console.error("Erreur lors de la suppression de l'événement:", error);
    return NextResponse.json(
      { error: "Erreur serveur" },
      { status: 500 }
    );
  }
}