import { redirect, fail } from '@sveltejs/kit';
import type { Actions } from './$types';
import * as auth from '$lib/server/auth';
import { db } from '$lib/server/db';
import { dailyCompletions } from '$lib/server/db/schema';
import { eq, inArray } from 'drizzle-orm';

export const actions: Actions = {
	default: async ({ request, cookies }) => {
		const data = await request.formData();
		const email = data.get('email')?.toString();
		const password = data.get('password')?.toString();
		const anonymousId = data.get('anonymousId')?.toString();

		if (!email || !password) {
			return fail(400, { error: 'Email and password are required' });
		}

		// Basic email validation
		const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/;
		if (!emailRegex.test(email)) {
			return fail(400, { error: 'Please enter a valid email address' });
		}

		if (password.length < 6) {
			return fail(400, { error: 'Password must be at least 6 characters' });
		}

		try {
			// Get user by email
			const user = await auth.getUserByEmail(email);
			if (!user || !user.passwordHash) {
				return fail(400, { error: 'Invalid email or password' });
			}

			// Verify password
			const isValidPassword = await auth.verifyPassword(password, user.passwordHash);
			if (!isValidPassword) {
				return fail(400, { error: 'Invalid email or password' });
			}

			// Migrate anonymous stats if different anonymous ID
			if (anonymousId && anonymousId !== user.id) {
				try {
					// Update all daily completions from the local anonymous ID to the user's ID
					await db
						.update(dailyCompletions)
						.set({ anonymousId: user.id })
						.where(eq(dailyCompletions.anonymousId, anonymousId));
					
					console.log(`Migrated stats from ${anonymousId} to ${user.id}`);

					// Deduplicate any entries for the same date after migration
					const allUserCompletions = await db
						.select()
						.from(dailyCompletions)
						.where(eq(dailyCompletions.anonymousId, user.id));

					// Group by date to find duplicates
					const dateGroups = new Map<string, typeof allUserCompletions>();
					for (const completion of allUserCompletions) {
						const date = completion.date;
						if (!dateGroups.has(date)) {
							dateGroups.set(date, []);
						}
						dateGroups.get(date)!.push(completion);
					}

					// Process dates with duplicates
					const duplicateIds: string[] = [];
					for (const [date, completions] of dateGroups) {
						if (completions.length > 1) {
							// Sort by completedAt timestamp (earliest first)
							completions.sort((a, b) => a.completedAt.getTime() - b.completedAt.getTime());
							
							// Keep the first (earliest), mark the rest for deletion
							const toDelete = completions.slice(1);
							duplicateIds.push(...toDelete.map(c => c.id));
							
							console.log(`Found ${completions.length} duplicates for date ${date}, keeping earliest, deleting ${toDelete.length}`);
						}
					}

					// Delete duplicate entries
					if (duplicateIds.length > 0) {
						await db
							.delete(dailyCompletions)
							.where(inArray(dailyCompletions.id, duplicateIds));
						
						console.log(`Deleted ${duplicateIds.length} duplicate completion entries`);
					}

				} catch (error) {
					console.error('Error migrating anonymous stats:', error);
					// Don't fail the signin if stats migration fails
				}
			}

			// Create session
			const sessionToken = auth.generateSessionToken();
			const session = await auth.createSession(sessionToken, user.id);
			auth.setSessionTokenCookie({ cookies }, sessionToken, session.expiresAt);

			return { success: true };
		} catch (error) {
			console.error('Sign in error:', error);
			return fail(500, { error: 'An error occurred during sign in' });
		}
	}
};