import { NextRequest, NextResponse } from 'next/server';
import { getServerSession } from 'next-auth';
import { authOptions } from '@/app/api/auth/[...nextauth]/route';
import { prisma } from '@/lib/prisma';
import { getTokens, getUserCalendars } from '@/lib/outlook-calendar';

export async function GET(request: NextRequest) {
    try {
        const session = await getServerSession(authOptions);

        if (!session?.user?.email) {
            return NextResponse.redirect(new URL('/auth/login', request.url));
        }

        const { searchParams } = new URL(request.url);
        const code = searchParams.get('code');
        const error = searchParams.get('error');

        if (error) {
            console.error('Outlook OAuth error:', error);
            return NextResponse.redirect(new URL('/?error=outlook_auth_failed', request.url));
        }

        if (!code) {
            return NextResponse.redirect(new URL('/?error=no_code', request.url));
        }

        // Exchange code for tokens
        const tokenData = await getTokens(code);
        const accessToken = tokenData.access_token;
        const refreshToken = tokenData.refresh_token;
        const expiresIn = tokenData.expires_in;

        // Fetch user's calendars to store initial list
        const calendars = await getUserCalendars(accessToken);

        const user = await prisma.user.findUnique({
            where: { email: session.user.email }
        });

        if (!user) {
            return NextResponse.redirect(new URL('/auth/login', request.url));
        }

        // Calculate expiry date
        const expiresAt = new Date();
        expiresAt.setSeconds(expiresAt.getSeconds() + expiresIn);

        // Check for existing connection
        const existingConnection = await prisma.calendarConnection.findFirst({
            where: {
                userId: user.id,
                provider: 'outlook'
            }
        });

        const calendarData = calendars.map(cal => ({
            id: cal.id,
            title: cal.name,
            isPrimary: cal.isDefaultCalendar,
            selected: true,
            editable: cal.canEdit
        }));

        if (existingConnection) {
            await prisma.calendarConnection.update({
                where: { id: existingConnection.id },
                data: {
                    accessToken,
                    refreshToken,
                    expiresAt,
                    calendars: calendarData,
                    updatedAt: new Date()
                }
            });
        } else {
            // Create new connection
            await prisma.calendarConnection.create({
                data: {
                    userId: user.id,
                    provider: 'outlook',
                    accessToken,
                    refreshToken,
                    expiresAt,
                    calendars: calendarData,
                }
            });
        }

        return NextResponse.redirect(new URL('/tasks?calendar=connected', request.url));
    } catch (error) {
        console.error('Error in Outlook callback:', error);
        return NextResponse.redirect(new URL('/auth/login?error=outlook_callback_failed', request.url));
    }
}