import { loadEnv, type Plugin } from 'vite';
import type { SessionPersona } from '../../project/persona.js';
import { NoopAnalyticsRecorder, SqliteAnalyticsRecorder } from './analytics.js';
import { loadConfig } from './config.js';
import { resolveSessionDefaults } from './defaults.js';
import { selectProvider } from './providers/index.js';
import type { ToolRegistry } from './tools.js';
import { handleRealtimeUpgrade } from './ws-handler.js';

export interface RealtimeDevWsPluginOptions {
	/**
	 * Raw, env-independent pieces (project persona + tool registry) — taken as
	 * parameters rather than imported here so this module (server/core) never
	 * has to import project code directly. See vite.config.ts, the
	 * composition root that supplies these, and docs/TOOLS.md.
	 *
	 * Deliberately NOT pre-resolved against env vars by the caller: resolving
	 * them happens inside configureServer below, gated by the VITEST check —
	 * see the comment on that check for why.
	 */
	persona: SessionPersona;
	toolRegistry: ToolRegistry;
}

/**
 * Wires the same upgrade handling used in production (see repo-root
 * server.js) into Vite's dev server, so `npm run dev` supports the realtime
 * WS endpoint without a production build.
 *
 * Loads .env itself: this hook runs at dev-server startup, outside
 * SvelteKit's own request/module graph, so `$env/...` isn't available here —
 * see the note in ./tokens.ts for why this whole module tree reads
 * `process.env` directly instead.
 */
export function realtimeDevWsPlugin(options: RealtimeDevWsPluginOptions): Plugin {
	return {
		name: 'webavatar-realtime-ws-dev',
		configureServer(server) {
			// vitest's browser-mode project boots its own Vite dev server for
			// component tests; this plugin has nothing to do there. Critically,
			// this guard is also what keeps loadConfig()'s fail-fast validation
			// (below) from running during `npm run test:unit` — that suite's
			// `test.projects` entries both `extends: './vite.config.ts'`, so this
			// plugin's config gets evaluated there too, and unit tests need no env
			// vars set at all. Don't move config resolution above this line.
			if (process.env.VITEST) return;

			const loaded = loadEnv('development', process.cwd(), '');
			for (const [key, value] of Object.entries(loaded)) {
				if (process.env[key] === undefined) process.env[key] = value;
			}

			const config = loadConfig();
			const provider = selectProvider(config);
			const recorder = config.analytics.enabled
				? new SqliteAnalyticsRecorder(config.analytics.dbPath, config.analytics)
				: new NoopAnalyticsRecorder();
			const defaults = {
				...resolveSessionDefaults(options.persona, config.session),
				toolRegistry: options.toolRegistry
			};

			server.httpServer?.on('upgrade', (req, socket, head) => {
				handleRealtimeUpgrade(req, socket, head, {
					provider,
					defaults,
					recorder,
					clientToolTimeoutMs: config.session.clientToolTimeoutMs,
					// This plugin only ever runs in dev (see the VITEST guard above),
					// so this is a literal, not an env lookup — debug-log forwarding
					// is frictionless here. See ../../../../server.js for the prod side.
					isDev: true,
					// Unlike isDev, this reads from config (not a literal) — a
					// developer may still want DEBUG_LOG_MESSAGES=false locally, e.g.
					// to rehearse prod-like log hygiene. See docs/LOGGING.md.
					logMessages: config.debug.messages
				});
			});
		}
	};
}