import { NextRequest, NextResponse } from "next/server";
import { getServerSession } from "next-auth/next";
import { authOptions } from "@/app/api/auth/options";
import { prisma } from "@/lib/prisma";

/**
 * Handles the GET request to retrieve a specific event from a calendar.
 *
 * @param req - The incoming Next.js request object.
 * @param params - An object containing the route parameters.
 * @param params.id - The ID of the calendar.
 * @param params.eventId - The ID of the event.
 * @returns A JSON response containing the event data or an error message.
 *
 * The function performs the following steps:
 * 1. Checks if the user is authenticated.
 * 2. Verifies that the calendar exists and belongs to the authenticated user.
 * 3. Verifies that the event exists and belongs to the specified calendar.
 * 4. Returns the event data if all checks pass.
 *
 * Possible error responses:
 * - 401: User is not authenticated.
 * - 403: User is not authorized to access the calendar.
 * - 404: Calendar or event not found.
 * - 500: Server error occurred while retrieving the event.
 */
export async function GET(
  req: NextRequest,
  props: { params: Promise<{ id: string; eventId: string }> }
) {
  const params = await props.params;
  const session = await getServerSession(authOptions);

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

  try {
    // Vérifier que le calendrier appartient à l'utilisateur
    const calendar = await prisma.calendar.findUnique({
      where: {
        id: params.id,
      },
    });

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

    if (calendar.userId !== session.user.username) {
      return NextResponse.json({ error: "Non autorisé" }, { status: 403 });
    }

    const event = await prisma.event.findUnique({
      where: {
        id: params.eventId,
      },
    });

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

    // Vérifier que l'événement appartient bien au calendrier
    if (event.calendarId !== params.id) {
      return NextResponse.json(
        { error: "Événement non trouvé dans ce calendrier" },
        { status: 404 }
      );
    }

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

/**
 * Handles the PUT request to update an event in a calendar.
 *
 * @param req - The incoming request object.
 * @param params - The route parameters containing the calendar ID and event ID.
 * @returns A JSON response indicating the result of the update operation.
 *
 * The function performs the following steps:
 * 1. Retrieves the server session to check if the user is authenticated.
 * 2. Verifies that the calendar belongs to the authenticated user.
 * 3. Checks if the event exists and belongs to the specified calendar.
 * 4. Validates the request payload to ensure required fields are present.
 * 5. Updates the event with the provided data.
 * 6. Returns the updated event or an appropriate error response.
 *
 * Possible error responses:
 * - 401: User is not authenticated.
 * - 403: User is not authorized to update the calendar.
 * - 404: Calendar or event not found.
 * - 400: Validation error for missing required fields.
 * - 500: Server error during the update process.
 */
export async function PUT(
  req: NextRequest,
  props: { params: Promise<{ id: string; eventId: string }> }
) {
  const params = await props.params;
  const session = await getServerSession(authOptions);

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

  try {
    // Vérifier que le calendrier appartient à l'utilisateur
    const calendar = await prisma.calendar.findUnique({
      where: {
        id: params.id,
      },
    });

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

    if (calendar.userId !== session.user.username) {
      return NextResponse.json({ error: "Non autorisé" }, { status: 403 });
    }

    // Vérifier que l'événement existe et appartient au calendrier
    const existingEvent = await prisma.event.findUnique({
      where: {
        id: params.eventId,
      },
    });

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

    if (existingEvent.calendarId !== params.id) {
      return NextResponse.json(
        { error: "Événement non trouvé dans ce calendrier" },
        { status: 404 }
      );
    }

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

    // Validation
    if (!title) {
      return NextResponse.json(
        { error: "Le titre est requis" },
        { status: 400 }
      );
    }

    if (!start || !end) {
      return NextResponse.json(
        { error: "Les dates de début et de fin sont requises" },
        { status: 400 }
      );
    }

    const updatedEvent = await prisma.event.update({
      where: {
        id: params.eventId,
      },
      data: {
        title,
        description,
        start: new Date(start),
        end: new Date(end),
        location,
        isAllDay: isAllDay || false,
      },
    });

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

/**
 * Handles the DELETE request to remove an event from a calendar.
 *
 * @param req - The incoming Next.js request object.
 * @param params - An object containing the parameters from the request URL.
 * @param params.id - The ID of the calendar.
 * @param params.eventId - The ID of the event to be deleted.
 * @returns A JSON response indicating the result of the deletion operation.
 *
 * @throws Will return a 401 status if the user is not authenticated.
 * @throws Will return a 404 status if the calendar or event is not found.
 * @throws Will return a 403 status if the user is not authorized to delete the event.
 * @throws Will return a 500 status if there is a server error during the deletion process.
 */
export async function DELETE(
  req: NextRequest,
  props: { params: Promise<{ id: string; eventId: string }> }
) {
  const params = await props.params;
  const session = await getServerSession(authOptions);

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

  try {
    // Vérifier que le calendrier appartient à l'utilisateur
    const calendar = await prisma.calendar.findUnique({
      where: {
        id: params.id,
      },
    });

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

    if (calendar.userId !== session.user.username) {
      return NextResponse.json({ error: "Non autorisé" }, { status: 403 });
    }

    // Vérifier que l'événement existe et appartient au calendrier
    const existingEvent = await prisma.event.findUnique({
      where: {
        id: params.eventId,
      },
    });

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

    if (existingEvent.calendarId !== params.id) {
      return NextResponse.json(
        { error: "Événement non trouvé dans ce calendrier" },
        { status: 404 }
      );
    }

    await prisma.event.delete({
      where: {
        id: params.eventId,
      },
    });

    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 });
  }
}