/**
 * Migration script to move data from Supabase to the new PostgreSQL database
 *
 * Prerequisites:
 * 1. Set SUPABASE_URL and SUPABASE_SERVICE_KEY environment variables
 * 2. Set DATABASE_URL for the new PostgreSQL database
 * 3. Run migrations on the new database first: pnpm db:migrate
 *
 * Usage:
 * SUPABASE_URL=... SUPABASE_SERVICE_KEY=... DATABASE_URL=... tsx src/migrate-from-supabase.ts
 */

import { createClient as createSupabaseClient } from '@supabase/supabase-js';
import { getDb, closeDb } from './client.js';
import {
	decks,
	cards,
	studySessions,
	cardProgress,
	deckTemplates,
	aiGenerations,
	userStats,
} from './schema/index.js';

// Initialize Supabase client
const supabaseUrl = process.env.SUPABASE_URL;
const supabaseServiceKey = process.env.SUPABASE_SERVICE_KEY;

if (!supabaseUrl || !supabaseServiceKey) {
	console.error('Missing SUPABASE_URL or SUPABASE_SERVICE_KEY environment variables');
	process.exit(1);
}

const supabase = createSupabaseClient(supabaseUrl, supabaseServiceKey);
const db = getDb();

interface MigrationStats {
	table: string;
	migrated: number;
	errors: number;
}

const stats: MigrationStats[] = [];

async function migrateTable<T>(
	tableName: string,
	supabaseTableName: string,
	drizzleTable: any,
	transformer: (row: any) => T
) {
	console.log(`\nMigrating ${tableName}...`);
	let migrated = 0;
	let errors = 0;

	try {
		// Fetch all data from Supabase
		const { data, error } = await supabase.from(supabaseTableName).select('*');

		if (error) {
			console.error(`Error fetching ${tableName}:`, error);
			stats.push({ table: tableName, migrated: 0, errors: 1 });
			return;
		}

		if (!data || data.length === 0) {
			console.log(`No data found in ${tableName}`);
			stats.push({ table: tableName, migrated: 0, errors: 0 });
			return;
		}

		console.log(`Found ${data.length} rows in ${tableName}`);

		// Process in batches of 100
		const batchSize = 100;
		for (let i = 0; i < data.length; i += batchSize) {
			const batch = data.slice(i, i + batchSize);
			const transformed = batch.map(transformer);

			try {
				await db.insert(drizzleTable).values(transformed).onConflictDoNothing();
				migrated += batch.length;
				process.stdout.write(`\r  Migrated ${migrated}/${data.length} rows`);
			} catch (err) {
				console.error(`\n  Error inserting batch:`, err);
				errors += batch.length;
			}
		}

		console.log(`\n  Completed: ${migrated} migrated, ${errors} errors`);
	} catch (err) {
		console.error(`Error migrating ${tableName}:`, err);
		errors++;
	}

	stats.push({ table: tableName, migrated, errors });
}

async function main() {
	console.log('=== Cards Data Migration ===');
	console.log('From: Supabase');
	console.log('To: PostgreSQL (Drizzle)');
	console.log('==============================\n');

	try {
		// 1. Migrate decks
		await migrateTable('decks', 'decks', decks, (row) => ({
			id: row.id,
			userId: row.user_id,
			title: row.title,
			description: row.description,
			coverImageUrl: row.cover_image_url,
			isPublic: row.is_public ?? false,
			isFeatured: row.is_featured ?? false,
			featuredAt: row.featured_at ? new Date(row.featured_at) : null,
			settings: row.settings ?? {},
			tags: row.tags ?? [],
			metadata: row.metadata ?? {},
			createdAt: new Date(row.created_at),
			updatedAt: new Date(row.updated_at),
		}));

		// 2. Migrate cards
		await migrateTable('cards', 'cards', cards, (row) => ({
			id: row.id,
			deckId: row.deck_id,
			position: row.position ?? 0,
			title: row.title,
			content: row.content,
			cardType: row.card_type,
			aiModel: row.ai_model,
			aiPrompt: row.ai_prompt,
			version: row.version ?? 1,
			isFavorite: row.is_favorite ?? false,
			createdAt: new Date(row.created_at),
			updatedAt: new Date(row.updated_at),
		}));

		// 3. Migrate study sessions
		await migrateTable('study_sessions', 'study_sessions', studySessions, (row) => ({
			id: row.id,
			deckId: row.deck_id,
			userId: row.user_id,
			mode: row.mode,
			totalCards: row.total_cards ?? 0,
			completedCards: row.completed_cards ?? 0,
			correctCards: row.correct_cards ?? 0,
			startedAt: new Date(row.started_at),
			completedAt: row.completed_at ? new Date(row.completed_at) : null,
			timeSpentSeconds: row.time_spent_seconds ?? 0,
		}));

		// 4. Migrate card progress
		await migrateTable('card_progress', 'card_progress', cardProgress, (row) => ({
			id: row.id,
			userId: row.user_id,
			cardId: row.card_id,
			easeFactor: row.ease_factor?.toString() ?? '2.5',
			interval: row.interval ?? 0,
			repetitions: row.repetitions ?? 0,
			lastReviewed: row.last_reviewed ? new Date(row.last_reviewed) : null,
			nextReview: row.next_review ? new Date(row.next_review) : null,
			status: row.status ?? 'new',
			createdAt: new Date(row.created_at),
			updatedAt: new Date(row.updated_at),
		}));

		// 5. Migrate deck templates
		await migrateTable('deck_templates', 'deck_templates', deckTemplates, (row) => ({
			id: row.id,
			title: row.title,
			description: row.description,
			category: row.category,
			templateData: row.template_data ?? { cards: [] },
			isActive: row.is_active ?? true,
			isPublic: row.is_public ?? true,
			popularity: row.popularity ?? 0,
			createdAt: new Date(row.created_at),
			updatedAt: new Date(row.updated_at),
		}));

		// 6. Migrate AI generations
		await migrateTable('ai_generations', 'ai_generations', aiGenerations, (row) => ({
			id: row.id,
			userId: row.user_id,
			deckId: row.deck_id,
			functionName: row.function_name,
			prompt: row.prompt,
			model: row.model,
			status: row.status ?? 'pending',
			metadata: row.metadata ?? {},
			completedAt: row.completed_at ? new Date(row.completed_at) : null,
			createdAt: new Date(row.created_at),
		}));

		// 7. Migrate user stats
		await migrateTable('user_stats', 'user_stats', userStats, (row) => ({
			userId: row.user_id,
			totalWins: row.total_wins ?? 0,
			totalSessions: row.total_sessions ?? 0,
			totalCardsStudied: row.total_cards_studied ?? 0,
			totalTimeSeconds: row.total_time_seconds ?? 0,
			averageAccuracy: row.average_accuracy?.toString() ?? '0',
			streakDays: row.streak_days ?? 0,
			longestStreak: row.longest_streak ?? 0,
			lastStudyDate: row.last_study_date,
			createdAt: new Date(row.created_at),
			updatedAt: new Date(row.updated_at),
		}));

		// Print summary
		console.log('\n\n=== Migration Summary ===');
		console.log('-------------------------');
		let totalMigrated = 0;
		let totalErrors = 0;
		for (const stat of stats) {
			console.log(`${stat.table}: ${stat.migrated} migrated, ${stat.errors} errors`);
			totalMigrated += stat.migrated;
			totalErrors += stat.errors;
		}
		console.log('-------------------------');
		console.log(`Total: ${totalMigrated} rows migrated, ${totalErrors} errors`);

		if (totalErrors === 0) {
			console.log('\n✅ Migration completed successfully!');
		} else {
			console.log('\n⚠️  Migration completed with some errors. Please review.');
		}
	} catch (error) {
		console.error('Migration failed:', error);
		process.exit(1);
	} finally {
		await closeDb();
	}
}

main();