import { NextResponse } from 'next/server';
import { PrismaClient } from '@prisma/client';
import { requireAdminAuth } from '@/lib/auth';
import { getReleaseYearFromItunes } from '@/lib/itunes';

const prisma = new PrismaClient();

// Helper to delay execution to avoid rate limits
const sleep = (ms: number) => new Promise(resolve => setTimeout(resolve, ms));

export async function POST(request: Request) {
    // Check authentication
    const authError = await requireAdminAuth(request as any);
    if (authError) return authError;

    try {
        const { offset = 0, limit = 20 } = await request.json();

        // Fetch batch of songs
        const songs = await prisma.song.findMany({
            select: { id: true, title: true, artist: true },
            orderBy: { id: 'asc' },
            skip: offset,
            take: limit
        });

        const totalSongs = await prisma.song.count();

        console.log(`Processing batch: offset=${offset}, limit=${limit}, found=${songs.length}`);

        let updatedCount = 0;
        let failedCount = 0;
        let skippedCount = 0;
        const results = [];

        for (const song of songs) {
            try {
                // Rate limiting: wait 2000ms between requests to be safe (iTunes can be strict)
                await sleep(2000);

                const year = await getReleaseYearFromItunes(song.artist, song.title);

                if (year) {
                    await prisma.song.update({
                        where: { id: song.id },
                        data: { releaseYear: year }
                    });
                    updatedCount++;
                    results.push({ id: song.id, title: song.title, artist: song.artist, year, status: 'updated' });
                } else {
                    skippedCount++;
                    results.push({ id: song.id, title: song.title, artist: song.artist, status: 'not_found' });
                }
            } catch (error) {
                console.error(`Failed to update year for ${song.title} - ${song.artist}:`, error);
                failedCount++;
                results.push({ id: song.id, title: song.title, artist: song.artist, status: 'error' });
            }
        }

        return NextResponse.json({
            success: true,
            processed: songs.length,
            total: totalSongs,
            hasMore: offset + songs.length < totalSongs,
            nextOffset: offset + songs.length,
            updated: updatedCount,
            failed: failedCount,
            skipped: skippedCount,
            results
        });

    } catch (error) {
        console.error('Error refreshing release years:', error);
        return NextResponse.json({ error: 'Internal Server Error' }, { status: 500 });
    }
}