import type { Plugin } from 'vite';
import { WebSocketServer } from 'ws';
import { handle, synthTelemetryHistory } from './handlers';

const COOKIE = 'mocksid';
const WS_PATH = /^\/api\/ws\/satellite\/([0-9a-f-]{36})\/telemetry\/$/i;

function readCookie(header: string | undefined, name: string): string | null {
	if (!header) return null;
	for (const part of header.split(';')) {
		const [k, ...v] = part.trim().split('=');
		if (k === name) return decodeURIComponent(v.join('='));
	}
	return null;
}

/** Dev-only middleware that answers /api/* from the in-memory mock backend. */
export function mockApi(): Plugin {
	return {
		name: 'mock-api',
		configureServer(server) {
			// Live telemetry: a real WebSocket so the tracking flow is exercised
			// end-to-end (the read-only satellite consumer in the real backend).
			const wss = new WebSocketServer({ noServer: true });
			server.httpServer?.on('upgrade', (req, socket, head) => {
				const url = req.url ?? '';
				const match = url.split('?')[0].match(WS_PATH);
				if (!match) return; // let Vite's own HMR socket handle it
				wss.handleUpgrade(req, socket as never, head, (ws) => {
					// Continue the satellite's synthetic track from where history ended.
					const history = synthTelemetryHistory(match[1]);
					let next = history.length;
					const first = history[0] as { timestamp: number; lat: number; lon: number };
					const timer = setInterval(() => {
						ws.send(
							JSON.stringify({
								id: `${match[1]}-live-${next}`,
								timestamp: first.timestamp + (next - history.length + 1) * 60,
								lat: first.lat + (next - history.length + 1) * 0.004,
								lon: first.lon + (next - history.length + 1) * 0.01,
								alt: 18000 + (next - history.length + 1) * 900,
								payload: { live: true },
								raw_data: {}
							})
						);
						next += 1;
					}, 1000);
					ws.on('close', () => clearInterval(timer));
				});
			});

			server.middlewares.use((req, res, next) => {
				if (!req.url?.startsWith('/api/')) return next();
				let raw = '';
				req.on('data', (c) => (raw += c));
				req.on('end', () => {
					const body = raw ? JSON.parse(raw) : {};
					const sessionUser = readCookie(req.headers.cookie, COOKIE);
					const [pathname, search = ''] = req.url!.split('?');
					const result = handle(
						req.method ?? 'GET',
						pathname,
						body,
						sessionUser,
						new URLSearchParams(search)
					);
					res.statusCode = result.status;
					res.setHeader('content-type', 'application/json');
					res.setHeader('x-csrftoken', 'mock-csrf');
					if (result.session !== undefined) {
						res.setHeader(
							'set-cookie',
							result.session === null
								? `${COOKIE}=; Path=/; Max-Age=0; SameSite=Lax`
								: `${COOKIE}=${encodeURIComponent(result.session)}; Path=/; SameSite=Lax`
						);
					}
					res.end(JSON.stringify(result.body));
				});
			});
		}
	};
}