import path = require('path');
import fs = require('fs');

/**
 * Given a folder that contains the contents of a JAR file, parses the MANIFEST
 * file and other metadata and makes it available to Doppio in a convenient
 * format.
 *
 * @see http://docs.oracle.com/javase/7/docs/technotes/guides/jar/jar.html#Notes_on_Manifest_and_Signature_Files
 * @todo Add a function for producing a Java object from this.
 */
class JAR {
  private attributes: {[name: string]: string} = {};
  private classpath: string[] = [];
  /**
   * Calls doneCb when it is finished opening and parsing the MANIFEST file.
   */
  constructor(dir: string, doneCb: (err?: Error) => void) {
    // Try to read the MANIFEST file.
    fs.readFile(path.resolve(dir, 'META-INF/MANIFEST.MF'), (err, data) => {
      if (err) return doneCb(err);
      // Parse the file!
      // If a line *begins* with a space, then it's a continuation of the
      // previous value.
      var currentAttribute: string = null;
      var currentValue: string = "";
      // Figure out which line ending the MANIFEST uses.
      var ending = '\n';
      var dataStr = data.toString("utf8");
      var npos = dataStr.indexOf('\n');
      var rpos = dataStr.indexOf('\r');
      if (npos === rpos + 1) ending = '\r\n';
      else if (rpos > -1) ending = '\r';

      var lines = dataStr.split(ending);
      for (var i = 0; i < lines.length; i++) {
        var line = lines[i];
        if (line === '\r') {
          // Windows-style line endings...
          continue;
        }
        if (line.length === 0) {
          // EOF!
          if (currentAttribute !== null) {
            // Set the previously-parsed value.
            this._setAttribute(currentAttribute, currentValue);
            currentAttribute = null;
          }
        }
        else if (line.charAt(0) === " ") {
          // Continuation of previous value. Shave off the initial space.
          currentValue += line.substr(1);
        } else {
          // New value.
          if (currentAttribute !== null) {
            // Set the previously-parsed value.
            this._setAttribute(currentAttribute, currentValue);
          }
          // Split on :.
          var split = line.split(':');
          // TODO: Print a warning if parsing fails.
          currentAttribute = split[0];
          // Shave off the space separator.
          currentValue = split[1].substr(1);
        }
      }
      // Completed without error.
      doneCb();
    });
  }

  /**
   * Sets the given attribute from parsed information. This function decides if
   * we digest the information further, or toss it.
   */
  private _setAttribute(attribute: string, value: string) {
    // Attribute names are case insensitive.
    attribute = attribute.toLowerCase();
    this.attributes[attribute] = value;
    if (attribute === 'class-path') {
      // Parse this! All items are JAR files and are separated by spaces, and
      // may contain \ as separator.
      // We'll just process all words that end in "JAR".
      var words = value.split(' ');
      for (var i = 0; i < words.length; i++) {
        var word = words[i];
        if (word.substr(-4) === '.jar') {
          this.classpath.push(word);
        }
      }
    }
  }

  /**
   * Return the items in this JAR file's classpath.
   */
  public getClassPath(): string[] {
    return this.classpath.slice(0);
  }

  /**
   * Returns NULL if the attribute does not exist.
   * Attribute names are case insensitive
   */
  public getAttribute(attribute: string): string {
    return this.attributes[attribute.toLowerCase()];
  }

  /**
   * Primarily used for debugging.
   */
  public toString() {
    return JSON.stringify(this.attributes);
  }
}

export = JAR;