const express = require('express');
const { Readable } = require('stream');
const { requireAuth } = require('../auth');
const { createCastMediaUrlService } = require('../services/castMediaUrlService');
const { createCastSessionService } = require('../services/castSessionService');

const router = express.Router();
const publicBaseUrl = process.env.CAST_PUBLIC_BASE_URL;
const mediaUrls = createCastMediaUrlService({
    publicBaseUrl: publicBaseUrl || 'http://127.0.0.1',
    secret: process.env.CAST_SIGNING_SECRET
});
const cast = createCastSessionService({ publicBaseUrl, mediaUrlSigner: mediaUrls });

function statusFor(error) {
    if (error.code === 'CAST_DEVICE_NOT_FOUND' || error.code === 'CAST_SESSION_NOT_FOUND') return 404;
    if (error.code === 'CAST_ADAPTER_UNAVAILABLE' || error.code === 'CAST_CONTROL_UNAVAILABLE' || error.code === 'CAST_CONFIG_INVALID') return 503;
    if (error.code?.startsWith('CAST_')) return 409;
    return 400;
}

function validateCommandBody(action, body) {
    if (!body || typeof body !== 'object' || Array.isArray(body)) throw new Error('Command body must be an object');
    const keys = Object.keys(body);
    if (action === 'seek') {
        if (keys.length !== 1 || keys[0] !== 'currentTime' || !Number.isFinite(body.currentTime) || body.currentTime < 0) {
            throw new Error('seek requires currentTime as a number greater than or equal to 0');
        }
        return { currentTime: body.currentTime };
    }
    if (action === 'volume') {
        if (keys.some(key => !['level', 'muted'].includes(key)) || !keys.length) throw new Error('volume accepts only level and muted');
        if (body.level !== undefined && (!Number.isFinite(body.level) || body.level < 0 || body.level > 1)) throw new Error('volume level must be between 0 and 1');
        if (body.muted !== undefined && typeof body.muted !== 'boolean') throw new Error('volume muted must be boolean');
        return { ...(body.level !== undefined ? { level: body.level } : {}), ...(body.muted !== undefined ? { muted: body.muted } : {}) };
    }
    if (keys.length) throw new Error(`${action} does not accept a request body`);
    return {};
}

function validId(value) {
    return typeof value === 'string' && /^[A-Za-z0-9_-]{1,128}$/.test(value);
}

// Signed media delivery intentionally precedes authentication: a Cast receiver has
// no browser cookie. The short-lived opaque HMAC token is the authorization.
router.get('/media/:id', async (req, res) => {
    try {
        const { path } = mediaUrls.validate(req.params.id, req.query.token);
        if (path.startsWith('/api/cast/')) return res.status(400).json({ error: 'Invalid cast media target' });
        const target = new URL(path, publicBaseUrl || `${req.protocol}://${req.get('host')}`);
        const headers = {};
        if (req.get('range')) headers.range = req.get('range');
        const response = await fetch(target, { headers, redirect: 'follow' });
        res.status(response.status);
        for (const header of ['content-type', 'content-length', 'content-range', 'accept-ranges', 'cache-control']) {
            const value = response.headers.get(header);
            if (value) res.setHeader(header, value);
        }
        if (!response.body) return res.end();
        Readable.fromWeb(response.body).pipe(res);
    } catch (error) {
        console.warn('[Cast] Public media request failed:', error.message);
        return res.status(/token/i.test(error.message) ? 401 : 502).json({ error: 'Cast media is unavailable' });
    }
});

router.use(requireAuth);

router.get('/devices', async (req, res) => {
    try { res.json({ devices: await cast.getDevices() }); }
    catch (error) { res.status(statusFor(error)).json({ error: error.message, code: error.code }); }
});

router.post('/devices/refresh', async (req, res) => {
    try { res.json({ devices: await cast.refreshDevices() }); }
    catch (error) { res.status(statusFor(error)).json({ error: error.message, code: error.code }); }
});

router.get('/sessions', (req, res) => res.json({ sessions: cast.listSessions() }));

router.post('/sessions', async (req, res) => {
    try { res.status(201).json(await cast.startSession(req.body)); }
    catch (error) { res.status(statusFor(error)).json({ error: error.message, code: error.code }); }
});

router.get('/sessions/:id', (req, res) => {
    if (!validId(req.params.id)) return res.status(400).json({ error: 'Invalid session ID' });
    const session = cast.getSession(req.params.id);
    return session ? res.json(session) : res.status(404).json({ error: 'Cast session not found' });
});

router.delete('/sessions/:id', async (req, res) => {
    try {
        if (!validId(req.params.id)) return res.status(400).json({ error: 'Invalid session ID' });
        const stopped = await cast.stopSession(req.params.id);
        return stopped ? res.status(204).end() : res.status(404).json({ error: 'Cast session not found' });
    } catch (error) { return res.status(statusFor(error)).json({ error: error.message, code: error.code }); }
});

for (const action of ['play', 'pause', 'stop', 'seek', 'volume']) {
    router.post(`/sessions/:id/${action}`, async (req, res) => {
        try {
            if (!validId(req.params.id)) return res.status(400).json({ error: 'Invalid session ID' });
            const body = validateCommandBody(action, req.body || {});
            if (action === 'stop') {
                const stopped = await cast.stopSession(req.params.id);
                return stopped ? res.json({ success: true }) : res.status(404).json({ error: 'Cast session not found' });
            }
            res.json(await cast.command(req.params.id, action, body));
        }
        catch (error) { res.status(statusFor(error)).json({ error: error.message, code: error.code }); }
    });
}

module.exports = router;
module.exports.validateCommandBody = validateCommandBody;