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 { updateMicrosoftEvent, deleteMicrosoftEvent } from "@/lib/services/microsoft-calendar-sync";
import { logger } from "@/lib/logger";
import { invalidateCalendarCache } from "@/lib/redis";

// 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 POST(req: NextRequest) {
  const session = await getServerSession(authOptions);

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

  try {
    const { title, description, start, end, allDay, location, calendarId } = await req.json();

    // Validation
    if (!title || !start || !end || !calendarId) {
      return NextResponse.json(
        { error: "Titre, début, fin et calendrier sont requis" },
        { status: 400 }
      );
    }

    // Verify calendar ownership
    const calendar = await prisma.calendar.findFirst({
      where: {
        id: calendarId,
        userId: session.user.id,
      },
    });

    if (!calendar) {
      return NextResponse.json(
        { error: "Calendrier non trouvé ou non autorisé" },
        { status: 404 }
      );
    }

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

    // Create event with all required fields
    const event = await prisma.event.create({
      data: {
        title,
        description: description || null,
        start: new Date(start),
        end: new Date(end),
        isAllDay: allDay || false,
        location: location || null,
        calendarId,
        userId: session.user.id,
      },
    });

    // Invalidate calendar cache so the new event appears immediately
    try {
      await invalidateCalendarCache(session.user.id);
      logger.debug('[EVENTS] Invalidated calendar cache after event creation', {
        eventId: event.id,
        calendarId,
        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),
      });
    }

    console.log("Created event:", event);
    return NextResponse.json(event, { status: 201 });
  } catch (error) {
    console.error("Erreur lors de la création de l'événement:", error);
    return NextResponse.json({ error: "Erreur serveur" }, { status: 500 });
  }
}

export async function PUT(req: NextRequest) {
  const session = await getServerSession(authOptions);

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

  try {
    const data = await req.json();
    console.log("Received event update data:", data);

    const { id, title, description, start, end, allDay, location, calendarId } = data;

    // Validation
    if (!id || !title || !start || !end || !calendarId) {
      console.log("Validation failed. Missing fields:", {
        id: !id,
        title: !title,
        start: !start,
        end: !end,
        calendarId: !calendarId
      });
      return NextResponse.json(
        { error: "ID, titre, début, fin et calendrier sont requis" },
        { status: 400 }
      );
    }

    // Verify calendar ownership and get event with sync config
    const calendar = await prisma.calendar.findFirst({
      where: {
        id: calendarId,
        userId: session.user.id,
      },
      include: {
        events: {
          where: {
            id
          }
        },
        syncConfig: {
          include: {
            mailCredential: true
          }
        }
      }
    });

    console.log("Found calendar:", calendar);

    if (!calendar || calendar.events.length === 0) {
      console.log("Calendar or event not found:", {
        calendarFound: !!calendar,
        eventsFound: calendar?.events.length
      });
      return NextResponse.json(
        { error: "Événement non trouvé ou non autorisé" },
        { status: 404 }
      );
    }

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

    const existingEvent = calendar.events[0];
    
    // Update event in local database
    const event = await prisma.event.update({
      where: { id },
      data: {
        title,
        description,
        start: new Date(start),
        end: new Date(end),
        isAllDay: allDay || false,
        location,
        calendarId,
      },
    });

    // Invalidate calendar cache so the updated event appears immediately
    try {
      await invalidateCalendarCache(session.user.id);
      logger.debug('[EVENTS] Invalidated calendar cache after event update', {
        eventId: event.id,
        calendarId,
        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),
      });
    }

    // If event has externalEventId and calendar has Microsoft sync, update Microsoft too
    if (existingEvent.externalEventId && calendar.syncConfig && calendar.syncConfig.provider === 'microsoft' && calendar.syncConfig.syncEnabled) {
      const syncConfig = calendar.syncConfig;
      const mailCredential = syncConfig.mailCredential;
      
      if (mailCredential && mailCredential.use_oauth && mailCredential.refresh_token) {
        try {
          // Prepare Microsoft event data
          const startDate = new Date(start);
          const endDate = new Date(end);
          
          // Microsoft Graph API expects timezone-aware dates
          const timeZone = Intl.DateTimeFormat().resolvedOptions().timeZone;
          
          const microsoftEventData: any = {
            subject: title,
          };
          
          if (allDay) {
            // For all-day events, Microsoft uses date format
            microsoftEventData.isAllDay = true;
            microsoftEventData.start = {
              date: startDate.toISOString().split('T')[0],
              timeZone: 'UTC'
            };
            microsoftEventData.end = {
              date: endDate.toISOString().split('T')[0],
              timeZone: 'UTC'
            };
          } else {
            // For timed events, use dateTime
            microsoftEventData.isAllDay = false;
            microsoftEventData.start = {
              dateTime: startDate.toISOString(),
              timeZone: timeZone
            };
            microsoftEventData.end = {
              dateTime: endDate.toISOString(),
              timeZone: timeZone
            };
          }
          
          if (description) {
            microsoftEventData.body = {
              contentType: 'HTML',
              content: description
            };
          }
          
          if (location) {
            microsoftEventData.location = {
              displayName: location
            };
          }
          
          // Update Microsoft event
          await updateMicrosoftEvent(
            session.user.id,
            mailCredential.email,
            syncConfig.externalCalendarId || '',
            existingEvent.externalEventId,
            microsoftEventData
          );
          
          logger.info('Successfully synced event update to Microsoft', {
            eventId: id,
            externalEventId: existingEvent.externalEventId,
            email: mailCredential.email,
          });
        } catch (syncError: any) {
          // Log error but don't fail the request - local update succeeded
          // 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 update to Microsoft', {
            eventId: id,
            externalEventId: existingEvent.externalEventId,
            error: syncError instanceof Error ? syncError.message : String(syncError),
            isPermissionError,
            suggestion: isPermissionError ? 'User needs to re-authenticate with Calendars.ReadWrite scope' : undefined,
          });
        }
      }
    }

    console.log("Updated event:", event);
    return NextResponse.json(event);
  } catch (error) {
    console.error("Erreur lors de la mise à jour de l'événement:", error);
    return NextResponse.json({ error: "Erreur serveur" }, { status: 500 });
  }
}