chess-tools/eco/index.js

A collection of tools / libraries for programming chess applications.

"use strict";
const fs = require("fs");
const EventEmitter = require('events');
const Opening = require("./entry.js");
const Transform = require("stream").Transform;
function extract_value(text) {
  let match = text.match(/\"(.+)\"/)
  if (match) {
    // console.log("match", match[1]);
    return match[1];
  } else {
    return "";
  }
}
class ECOStream extends Transform {
  constructor() {
    super({ readableObjectMode: true });
    this._data = "";
    this._lines = [];
    this.in_comment = false;
    this.in_pgn = false;
    this.in_record = false;
    this.comment = "";
    this.current_record = false;
  }
  _flush(callback) {
    this._make_records_from_lines();
    callback();
  }
  _transform(chunk, encoding, callback) {
    let data = chunk.toString();
    let lines = data.split(/\n/m);
    if (this._lines.length > 0) {
      console.log("append to last line");
      this._lines[this.lines.length - 1] += lines.shift();
    }
    for (let line of lines) {
      this._lines.push(line);
    }
    this._make_records_from_lines();
    callback();
  }
  _make_records_from_lines() {

    let len = this._lines.length;
    for (let i = 0; i < len; i++) {
      let line = this._lines.shift();
      if (line.startsWith("{")) {
        this.in_comment = true;
      }
      if (line.startsWith("}")) {
        this.emit("has_comment", this.comment);
        this.in_comment = false;
      }
      if (this.in_comment && line !== "{") {
        this.comment = this.comment + line + "\n";
      }
      if (line.startsWith("[ECO")) {
        if (this.current_record) {
          this.current_record.pgn = this.current_record.pgn.trim();
          this.push(this.current_record);
        }
        this.current_record = new Opening();
        this.current_record.eco_code = extract_value(line);
      } else if (line.startsWith("[Opening")) {
        this.current_record.name = extract_value(line);
      } else if (line.startsWith("[Variation")) {
        this.current_record.variation = extract_value(line);
      } else if (line.startsWith("1.")) {
        this.in_pgn = true;
        this.current_record.pgn = line;
      } else if (this.in_pgn && line) {
        this.current_record.pgn = this.current_record.pgn + " " + line;
      } else if (this.in_pgn && !line) {
        this.in_pgn = false;
      }
    }
  }
}

class Eco extends EventEmitter {
  constructor() {
    super();
    this.loaded = false;
    this.comment = "";
    this.entries = [];
    this.stream = new ECOStream();
  }
  load_stream(stream) {
    this.stream.on("finish", () => {
      this.loaded = true;
      this.emit("loaded");
    });
    this.stream.on("data", (entry) => {
      this.entries.push(entry);
    });
    stream.pipe(this.stream);
  }
  load_default() {
    this.load_stream(fs.createReadStream(__dirname + "/eco.pgn"));
  }
  find(pgn) {
    if (!this.loaded) {
      throw new Error("wait for loaded event");
    }
    let best_match;
    for (let record of this.entries) {
      let r_pgn = record.pgn.substring(0, record.pgn.indexOf("*"));
      if (pgn.includes(r_pgn)) {
        if (best_match && record.pgn.length > best_match.pgn.length) {
          best_match = record;
        } else {
          best_match = record;
        }
      }
    }
    return best_match;
  }
}

module.exports = Eco;