matrix-public-archive/shared/lib/mxc-url-to-http.js

'use strict';

const assert = require('./assert');

// Based off of https://github.com/matrix-org/matrix-bifrost/blob/c7161dd998c4fe968dba4d5da668dc914248f260/src/MessageFormatter.ts#L45-L60
function mxcUrlToHttp({ mxcUrl, homeserverUrl }) {
  assert(mxcUrl, '`mxcUrl` must be provided to `mxcUrlToHttp(...)`');
  assert(homeserverUrl, '`homeserverUrl` must be provided to `mxcUrlToHttp(...)`');
  const [serverName, mediaId] = mxcUrl.substr('mxc://'.length).split('/', 2);
  const url = homeserverUrl.replace(/\/$/, '');
  return `${url}/_matrix/media/v1/download/${encodeURIComponent(serverName)}/${encodeURIComponent(
    mediaId
  )}`;
}

const ALLOWED_RESIZE_METHODS = ['scale', 'crop'];
function mxcUrlToHttpThumbnail({ mxcUrl, homeserverUrl, size, resizeMethod = 'scale' }) {
  assert(mxcUrl, '`mxcUrl` must be provided to `mxcUrlToHttp(...)`');
  assert(homeserverUrl, '`homeserverUrl` must be provided to `mxcUrlToHttp(...)`');
  assert(size, '`size` must be provided to `mxcUrlToHttp(...)`');
  assert(
    ALLOWED_RESIZE_METHODS.includes(resizeMethod),
    `\`resizeMethod\` must be ${JSON.stringify(ALLOWED_RESIZE_METHODS)}`
  );
  const [serverName, mediaId] = mxcUrl.substr('mxc://'.length).split('/');

  let qs = new URLSearchParams();
  qs.append('width', Math.round(size));
  qs.append('height', Math.round(size));
  qs.append('method', resizeMethod);

  const url = homeserverUrl.replace(/\/$/, '');
  return `${url}/_matrix/media/r0/thumbnail/${encodeURIComponent(serverName)}/${encodeURIComponent(
    mediaId
  )}?${qs.toString()}`;
}

module.exports = { mxcUrlToHttp, mxcUrlToHttpThumbnail };