/**
 * SvelteKit server hooks (TRUEREF-0009).
 *
 * Runs once when the Node.js server process starts. Initialises the database
 * and kicks off the indexing pipeline + job queue so queued jobs resume
 * automatically after a restart.
 */

import { initializeDatabase } from '$lib/server/db/index.js';
import { getClient } from '$lib/server/db/client.js';
import { initializePipeline } from '$lib/server/pipeline/startup.js';
import { createProviderFromProfile } from '$lib/server/embeddings/registry.js';
import { EmbeddingService } from '$lib/server/embeddings/embedding.service.js';
import {
	EmbeddingProfileEntity,
	type EmbeddingProfileEntityProps
} from '$lib/server/models/embedding-profile.js';
import { EmbeddingProfileMapper } from '$lib/server/mappers/embedding-profile.mapper.js';
import { env } from '$env/dynamic/private';
import type { Handle } from '@sveltejs/kit';

// ---------------------------------------------------------------------------
// Server initialisation — runs once on startup
// ---------------------------------------------------------------------------

try {
	initializeDatabase();
} catch (err) {
	console.error('[hooks.server] FATAL: database initialisation failed:', err);
	process.exit(1);
}

try {
	const db = getClient();
	const activeProfileRow = db
		.prepare<[], EmbeddingProfileEntityProps>(
			'SELECT * FROM embedding_profiles WHERE is_default = 1 AND enabled = 1 LIMIT 1'
		)
		.get();

	let embeddingService: EmbeddingService | null = null;

	if (activeProfileRow) {
		const activeProfile = EmbeddingProfileMapper.fromEntity(
			new EmbeddingProfileEntity(activeProfileRow)
		);
		const provider = createProviderFromProfile(activeProfile);
		embeddingService = new EmbeddingService(db, provider, activeProfile.id);
	}

	// Read database path from environment
	const dbPath = env.DATABASE_URL;

	// Read indexing concurrency setting from database
	let concurrency = 2; // default
	if (dbPath) {
		const concurrencyRow = db
			.prepare<[], { value: string }>(
				"SELECT value FROM settings WHERE key = 'indexing.concurrency' LIMIT 1"
			)
			.get();
		if (concurrencyRow) {
			try {
				const parsed = JSON.parse(concurrencyRow.value);
				concurrency = parsed.value ?? 2;
			} catch {
				// If parsing fails, use default
				concurrency = 2;
			}
		}
	}

	initializePipeline(db, embeddingService, { concurrency, dbPath });
	console.log('[hooks.server] Indexing pipeline initialised.');
} catch (err) {
	console.error(
		'[hooks.server] Failed to initialise pipeline:',
		err instanceof Error ? err.message : String(err)
	);
}

// ---------------------------------------------------------------------------
// CORS headers applied to all /api/* responses
// ---------------------------------------------------------------------------

const CORS_HEADERS = {
	'Access-Control-Allow-Origin': '*',
	'Access-Control-Allow-Methods': 'GET, POST, PATCH, DELETE, OPTIONS',
	'Access-Control-Allow-Headers': 'Content-Type, Authorization'
} as const;

// ---------------------------------------------------------------------------
// Request handler — CORS + pass-through
// ---------------------------------------------------------------------------

export const handle: Handle = async ({ event, resolve }) => {
	const { pathname } = event.url;

	// Handle CORS pre-flight for all API routes.
	if (event.request.method === 'OPTIONS' && pathname.startsWith('/api/')) {
		return new Response(null, {
			status: 204,
			headers: CORS_HEADERS
		});
	}

	const response = await resolve(event);

	// Attach CORS headers to all API responses.
	if (pathname.startsWith('/api/')) {
		for (const [key, value] of Object.entries(CORS_HEADERS)) {
			response.headers.set(key, value);
		}
	}

	return response;
};