sandevistan/server/vector-map.js at main · hmmhmmhm/sandevistan

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import { createTimeout, jsonResponse, readLimitedBytes } from "./http.js";

import { mapCell, normalizeMapPayload } from "./map.js";

import { vectorTileWindow, decodeMapTile } from "./vector-map-tiles.js";

const PROVIDER = 'https://tiles.openfreemap.org';

const USER_AGENT = 'SANDEVISTAN (+https://github.com/hmmhmmhm/sandevistan)';

export async function handleVectorMapRequest(request, _env, {fetchImpl=fetch,cache=globalThis.caches?.default}={}) {

const url=new URL(request.url);

const latText=url.searchParams.get('lat'),lngText=url.searchParams.get('lng');

const latitude=Number(latText),longitude=Number(lngText);

if (!latText?.trim() || !lngText?.trim() || !Number.isFinite(latitude) || !Number.isFinite(longitude)

|| Math.abs(latitude)>85.05 || Math.abs(longitude)>180) {

return jsonResponse({error:{code:'INVALID_COORDINATE',message:'Latitude or longitude is outside map coverage'}},{status:400});

}

const cell=mapCell(latitude,longitude);

const key=new Request(`https://sandevistan-map-cache.invalid/vector-v2?cell=${encodeURIComponent(cell)}`);

try { const hit=await cache?.match(key);if(hit)return hit; } catch {}

const timeout=createTimeout(8_000);

let stage = "metadata-fetch";

try {

const headers={'user-agent':USER_AGENT};

const metadata=await fetchImpl(PROVIDER+'/planet',{headers,signal:timeout.signal,redirect:'manual'});

if(!metadata.ok) { stage = `metadata-http-${metadata.status}`; throw new Error('MAP_PROVIDER_METADATA'); }

stage = 'metadata-decode';

const info=JSON.parse(new TextDecoder().decode(await readLimitedBytes(metadata,256_000)));

const template=info?.tiles?.[0];

if(typeof template!=='string' || new URL(template).origin!==PROVIDER)throw new Error('MAP_PROVIDER_TEMPLATE');

const elements=[];

for(const tile of vectorTileWindow(latitude,longitude)) {

const tileUrl=template.replace('{z}',tile.z).replace('{x}',tile.x).replace('{y}',tile.y);

stage = 'tile-fetch';

const response=await fetchImpl(tileUrl,{headers,signal:timeout.signal,redirect:'manual'});

if(!response.ok) { stage = `tile-http-${response.status}`; throw new Error('MAP_PROVIDER_TILE'); }

stage = 'tile-read';

const bytes=await readLimitedBytes(response,1_500_000);

stage = 'tile-decode';

elements.push(...decodeMapTile(bytes,tile,{latitude,longitude}));

}

stage = 'map-normalize';

const value={...normalizeMapPayload({elements},cell),tileSource:'openmaptiles'};

const response=jsonResponse(value,{headers:{'cache-control':'public, max-age=3600, s-maxage=86400'}});

try { await cache?.put(key,response.clone()); } catch {}

return response;

} catch {

return jsonResponse({error:{code:timeout.signal.aborted?'MAP_TIMEOUT':'MAP_UPSTREAM_ERROR',message:'Map tile service unavailable',stage}},{status:timeout.signal.aborted?504:502});

} finally {timeout.dispose();}

}

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