//
// Copyright (C) Stanislaw Adaszewski, 2020
// Contact: s.adaszewski@gmail.com
// Website: https://adared.ch/wba
// License: GNU Affero General Public License, Version 3
//

//
// Directory: Hash[string, [Directory, File]]
// File = [blockRefs, size]
// blockRefs: Array[blockRef]
// blockRef: [locator, position, size]
// locator: String
// position: Number
// size: Number
//

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

    if (!manifest_text)
      return;

    this.parse(manifest_text);
  }

  makeDir(parent, name) {
    if (!(name in parent))
      parent[name] = {};
    if (parent[name] instanceof Array)
      throw Error('Conflict trying to create a directory - a file with the same name already exists: ' + name);
    return parent[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))
      dir[fileName] = [[], 0];
    if (!(dir[fileName] instanceof Array))
      throw Error('Conflict trying to create a file - a directory with the same name already exists: ' + fileName);
    //this.appendReferences(dir[fileName], locators, position, size);
  }

  appendReferences(file, 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;
    }

    file[0] = file[0].concat(blockRefs);
    file[1] += size;
  }

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

    let streams = manifest_text.split('\n');
    if (!streams[streams.length - 1])
      streams = streams.slice(0, streams.length - 1);

    streams.map(s => {
      let tokens = s.split(' ');
      let streamName = this.unescapeName(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(':');
        fileName = fileName.join(':');
        fileName = this.unescapeName(fileName);
        this.appendFile(streamName, locators,
          Number(position), Number(size), fileName);
      });
    });
  }

  findDir(path) {
    if (typeof(path) === 'string')
      path = path.split('/');
    if (path[0] !== '.')
      throw Error('Path must begin with a dot component');
    let dir = this.rootDir;
    for (let i = 1; i < path.length; i++) {
      if (!(path[i] in dir))
        throw Error('Directory not found');
      if (dir[path[i]] instanceof Array)
        throw Error('Path is a file not directory');
      dir = dir[path[i]];
    }
    return dir;
  }

  listDirectory(path) {
    let dir = this.findDir(path);
    let keys = Object.keys(dir);
    keys.sort();
    let subdirs = keys.filter(k => !(dir[k] instanceof Array));
    let files = keys.filter(k => (dir[k] instanceof Array));
    let res = subdirs.map(k => [ 'd', k, null ]);
    res = res.concat(files.map(k => [ 'f', k, dir[k][1] ]));
    return res;
  }

  unescapeName(name) {
    return name.replace(/(\\\\|\\[0-9]{3})/g, (_, $1) => ($1 === '\\\\' ? '\\' : String.fromCharCode(parseInt($1.substr(1), 8))));
  }

  escapeName(name) {
    return name.replace(/ /g, '\\040');
  }
  /*  let ids = { '\\': 1, '0': 2, '4': 3 };
    let transitions = [
      [ [0, 0], [1, ''], [0, 0], [0, 0] ],
      [ [0, 0], [0, '\\'], [2, ''], [0, 0] ],
    ];
    let mode = 0;
    for (let i = 0; i < name.length; i++) {
      let b = name[i];
      let tokenId = Number(ids[b]);
      [ mode, out ] = transitions[mode][tokenId];
      if (out === 0)
        out = b;
    }
  }*/
  getFile(path) {
    if (typeof(path) === 'string')
      path = path.split('/');
    if (path.length < 2)
      throw Error('Invalid file path');
    let name = path[path.length - 1];
    let dir = this.findDir(path.slice(0, path.length - 1));
    if (!(name in dir))
      throw Error('File not found');
    if (!(dir[name] instanceof Array))
      throw Error('Path points to a directory not a file');
    return dir[name];
  }
}

export { WBManifestReader };