MyIP/api/google-map.js

import { Readable } from 'node:stream';
import { pipeline } from 'node:stream/promises';
import { fetchUpstream } from '../common/fetch-with-timeout.js';
import logger from '../server/logger.js';

// Validate request legitimacy. `language` is the UI locale code, region
// subtag included (`pt-BR`, `zh-TW`); like every `?lang` it is not
// allow-listed, but it must be tag-shaped: every distinct value is an
// uncached Static Maps call whose answer is edge-cached for a year.
const LANGUAGE_TAG = /^[a-z]{2,3}(-[A-Za-z0-9]{2,4}){0,2}$/;

function isValidRequest(req) {
    const isLatitudeValid = /^-?\d+(\.\d+)?$/.test(req.query.latitude);
    const isLongitudeValid = /^-?\d+(\.\d+)?$/.test(req.query.longitude);
    const isLanguageValid = typeof req.query.language === 'string' && LANGUAGE_TAG.test(req.query.language);

    if (!isLatitudeValid || !isLongitudeValid || !isLanguageValid) {
        return false;
    } else {
        return true;
    }
}

// Define day and night mode style strings
const styles = {
    Dark: [
        "feature:all|element:geometry.fill|color:0x242f3e",
        "feature:all|element:labels.text.stroke|color:0x242f3e",
        "feature:all|element:labels.text.fill|color:0x746855",
        "feature:administrative.locality|element:labels.text.fill|color:0xd59563",
        "feature:poi|element:labels.text.fill|color:0xd59563",
        "feature:poi.park|element:geometry|color:0x263c3f",
        "feature:poi.park|element:labels.text.fill|color:0x6b9a76",
        "feature:road|element:geometry|color:0x38414e",
        "feature:road|element:geometry.stroke|color:0x212a37",
        "feature:road|element:labels.text.fill|color:0x9ca5b3",
        "feature:road.highway|element:geometry|color:0x746855",
        "feature:road.highway|element:geometry.stroke|color:0x1f2835",
        "feature:road.highway|element:labels.text.fill|color:0xf3d19c",
        "feature:transit|element:geometry|color:0x2f3948",
        "feature:transit.station|element:labels.text.fill|color:0xd59563",
        "feature:water|element:geometry|color:0x17263c",
        "feature:water|element:labels.text.fill|color:0x515c6d",
        "feature:all|element:labels.text.stroke|color:0x17263c"
    ]
};

export default async (req, res) => {
    // Check if request is legitimate
    if (!isValidRequest(req)) {
        return res.status(400).json({ error: 'Invalid request' });
    }

    // Use req.query to get parameters
    const { latitude, longitude, language, CanvasMode } = req.query;

    if (!latitude || !longitude || !language) {
        return res.status(400).json({ error: 'Missing latitude, longitude, or language' });
    }

    // Size targets the Dialog-based map viewer: aspect-2/1 at up to ~768px wide.
    // Standard Static Maps plan caps each dimension at 640, so 640x320 + scale=2
    // yields a 1280x640 effective image — sharp when downscaled into the Dialog.
    const mapSize = '640x320';
    const fmt = 'jpg';
    const scale = 2;
    const zoom = 3;

    const apiKeys = (process.env.GOOGLE_MAP_API_KEY || '').split(',');
    const apiKey = apiKeys[Math.floor(Math.random() * apiKeys.length)];

    let styleParam = '';
    if (CanvasMode === 'Dark') {
        styleParam = styles.Dark.join('&style=');
    }

    const url = `https://maps.googleapis.com/maps/api/staticmap?center=${latitude},${longitude}&markers=color:blue%7C${latitude},${longitude}&scale=${scale}&zoom=${zoom}&maptype=roadmap&language=${encodeURIComponent(language)}&format=${fmt}&size=${mapSize}&style=${styleParam}&key=${apiKey}`;

    // Unlike the JSON handlers, the Static Maps response is a binary JPEG
    // and must be passed through to the client. pipeline() propagates errors
    // both ways: an upstream reset destroys the response, a client
    // disconnect cancels the upstream body.
    try {
        const apiRes = await fetchUpstream(url);
        if (!apiRes.ok) {
            return res.status(apiRes.status).json({ error: `Upstream map API returned ${apiRes.status}` });
        }
        res.setHeader('Content-Type', apiRes.headers.get('content-type') || 'image/jpeg');
        // Binary streams bypass the res.json hook in the cacheable() middleware,
        // so apply the cache value it stashed on res.locals here on the 2xx path.
        if (res.locals.cacheControl) {
            res.setHeader('Cache-Control', res.locals.cacheControl);
        }
        await pipeline(Readable.fromWeb(apiRes.body), res);
    } catch (e) {
        // Visitors abandoning a half-loaded image are routine, not a failure.
        if (e?.code === 'ERR_STREAM_PREMATURE_CLOSE') return;
        logger.error({ err: e, latitude, longitude, language, CanvasMode }, 'google-map handler failed');
        if (!res.headersSent && !res.destroyed) {
            return res.status(500).json({ error: e.message });
        }
        if (!res.destroyed) res.destroy();
    }
};