wba/frontend/src/js/misc/wb-collection-manifest.js

class CMDirectory {
  constructor() {
    this.directories = {};
    this.files = {};
  }
}

class CMFile {
  constructor() {
    this.blockRefs = [];
    this.size = 0;
  }

  append(locators, position, size) {
    if (size === 0)
      return;

    let cum = 0;
    let locHashes = locators.map(loc => loc[0]);
    let locSizes = locators.map(loc => loc[1]);
    let locPositions = locators.map(loc => {
      let res = cum;
      cum += loc[1];
      return res;
    });

    let used = locators.map((_, i) => (locPositions[i] + locSizes[i] > position &&
      locPositions[i] < position + size));

    let startBlock = used.indexOf(true);
    let endBlock = used.lastIndexOf(true) + 1;

    console.log('startBlock: ' + startBlock + ', endBlock: ' + endBlock);

    if (startBlock === -1)
      return;

    let blockRefs = [];
    let runPos = position;
    let runSize = size;

    for (let i = startBlock; i < endBlock; i++) {
      let blockPos = runPos - locPositions[i];
      let blockSize = Math.min(runSize, locSizes[i] - blockPos);
      blockRefs.push([ locHashes[i], blockPos, blockSize ]);
      runPos += blockSize;
      runSize -= blockSize;
    }

    this.blockRefs = this.blockRefs.concat(blockRefs);
    this.size += size;
  }
}

class WBManifestReader {
  constructor(manifest_text) {
    this.rootDir = new CMDirectory();

    if (!manifest_text)
      return;

    this.parse(manifest_text);
  }

  makeDir(parent, name) {
    if (!(name in parent.directories))
      parent.directories[name] = new CMDirectory();
    return parent.directories[name];
  }

  makePath(path) {
    if (typeof(path) === 'string')
      path = path.split('/');
    let dir = this.rootDir;
    for (let i = 1; i < path.length; i++)
      dir = this.makeDir(dir, path[i]);
    return dir;
  }

  appendFile(streamName, locators, position, size, fileName) {
    let path = streamName + '/' + fileName;
    path = path.split('/');
    let dir = this.makePath(path.slice(0, path.length - 1));
    if (!(fileName in dir.files))
      dir.files[fileName] = new CMFile();
    dir.files[fileName].append(locators, position, size);
  }

  parse(manifest_text) {
    let rx = /^[a-f0-9]{32}\+[0-9]+/;

    let streams = manifest_text.split('\n');

    streams.map(s => {
      let tokens = s.split(' ');
      let streamName = tokens[0];

      let n = tokens.map(t => rx.exec(t));
      n = n.indexOf(null, 1);

      let locators = tokens.slice(1, n);
      locators = locators.map(loc => [ loc, Number(loc.split('+')[1]) ]);

      let fileTokens = tokens.slice(n);
      fileTokens.map(t => {
        let [ position, size, fileName ] = t.split(':');
        this.appendFile(streamName, locators,
          Number(position), Number(size), fileName);
      });
    });
  }
}

export { WBManifestReader };