package me.blvckbytes.vocabsucker;

import java.util.Arrays;
import java.util.List;

public class LetterConverter {

  /**
   * Tries to parse a letter from the href attribute out of a
   * use tag representing a letter in the SVG page
   * @param href Href attribute's value of use tag
   */
  public static String tryParse( String href ) {

    // Invalid href provided
    if( href == null )
      return "?";

    // Resource ranges
    String alphabet = "abcdefghijklmnopqrstuvwxyz";
    String numbers = "0123456789";
    String mutations = "ß??ÄÖÜä??öü";
    String symbols = "(),-./";
    List< String > gluedLetters = Arrays.asList( "fi", "ff", "fl", "ffi" );

    try {

      // The #T1_1 charset is the only one needed for vocabulary
      if( !href.startsWith( "#T1_1_" ) )
        return "?";

      // Cut out the charset index and parse it
      int index = Integer.parseInt( href.substring( 6 ) );

      // Numbers
      if( index <= 22 && index >= 13 ) {
        index -= 13;
        return numbers.substring( index, index + 1 );
      }

      // Lowercase letters
      if( index <= 82 && index >= 56 ) {
        index -= 56;
        return alphabet.substring( index, index + 1 );
      }

      // Uppercase letters
      if( index <= 51 && index >= 27 ) {
        // They just skipped Y in uppercase alphabet...
        alphabet = alphabet.substring( 0, alphabet.length() - 2 ) + "Z";

        index -= 27;
        return alphabet.substring( index, index + 1 ).toUpperCase();
      }

      // Mutations
      if( index >= 88 && index <= 88 + mutations.length() ) {
        index -= 88;
        return mutations.substring( index, index + 1 );
      }

      // Symbols
      if( index >= 7 && index <= 7 + symbols.length() ) {
        index -= 7;
        return symbols.substring( index, index + 1 );
      }

      // Glued letters
      if( index >= 100 && index <= 100 + gluedLetters.size() ) {
        index -= 100;
        return gluedLetters.get( index );
      }

      // Opening square bracket
      if( index == 52 )
        return "[";

      // Closing square bracket
      if( index == 53 )
        return "]";

      // Single quote
      if( index == 6 )
        return "'";

      // Nothing matched
      return "?";

    } catch ( Exception e ) {
      // Error occoured while parsing
      return "?";
    }

  }

}