frontend/src/app/auth/callback/route.ts

import { createServerClient, type CookieOptions } from '@supabase/ssr'
import { createClient } from '@supabase/supabase-js'
import { cookies } from 'next/headers'
import { NextResponse } from 'next/server'

export async function GET(request: Request) {
    console.log("\n=== AUTH CALLBACK START ===");
    const { searchParams, origin } = new URL(request.url)
    const code = searchParams.get('code')
    const next = searchParams.get('next') ?? '/'

    console.log("Code present:", !!code);
    console.log("Redirect target:", next);

    if (code) {
        const cookieStore = await cookies()

        const supabase = createServerClient(
            process.env.NEXT_PUBLIC_SUPABASE_URL!,
            process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY!,
            {
                cookies: {
                    getAll() {
                        return cookieStore.getAll()
                    },
                    setAll(cookiesToSet) {
                        cookiesToSet.forEach(({ name, value, options }) => {
                            cookieStore.set(name, value, options)
                        })
                    },
                },
            }
        )

        console.log("Exchanging code for session...");
        const { data: { session }, error } = await supabase.auth.exchangeCodeForSession(code)

        if (error) {
            console.error('❌ Auth exchange error:', error)
            return NextResponse.redirect(`${origin}/auth/error?error=${encodeURIComponent(error.message)}`)
        }

        if (session?.user) {
            console.log("✅ Auth successful. User ID:", session.user.id);
            console.log("User email:", session.user.email);

            // SYNC USER TO DATABASE
            console.log("Checking if user exists in DB...");

            // Use the authenticated supabase client (has the session)
            const { data: existingUser, error: fetchError } = await supabase
                .from('users')
                .select('id')
                .eq('id', session.user.id)
                .single();

            console.log("Fetch result:", { existingUser, fetchError });

            if (fetchError && fetchError.code !== 'PGRST116') {
                console.error("❌ Error checking user existence:", fetchError);
            }

            if (!existingUser) {
                console.log("🔄 User not found in DB. Attempting insert...");

                const insertData = {
                    id: session.user.id,
                    email: session.user.email,
                    full_name: session.user.user_metadata.full_name || null,
                    avatar_url: session.user.user_metadata.avatar_url || null,
                    credits: 5
                };

                console.log("Insert data:", insertData);

                const { data: insertResult, error: insertError } = await supabase
                    .from('users')
                    .insert(insertData)
                    .select();

                if (insertError) {
                    console.error("❌ INSERT FAILED:", insertError);
                    console.error("Error code:", insertError.code);
                    console.error("Error message:", insertError.message);
                    console.error("Error details:", insertError.details);
                    console.error("Error hint:", insertError.hint);
                } else {
                    console.log("✅ Successfully inserted user:", insertResult);
                }
            } else {
                console.log("✅ User already exists in DB");
            }
        }
    }

    console.log("Redirecting to:", `${origin}${next}`);
    console.log("=== AUTH CALLBACK END ===\n");
    return NextResponse.redirect(`${origin}${next}`)
}