/*
 * Copyright (c) 2012-2018 Institut National des Sciences Appliquées de Lyon (INSA Lyon) and others
 *
 * This program and the accompanying materials are made available under the
 * terms of the Eclipse Public License 2.0 which is available at
 * http://www.eclipse.org/legal/epl-2.0.
 *
 * SPDX-License-Identifier: EPL-2.0
 */
package org.eclipse.golo.compiler.parser;

import static gololang.Messages.message;

/**
 * This exception is thrown when parse errors are encountered.
 * You can explicitly create objects of this exception type by
 * calling the method generateParseException in the generated
 * parser.
 *
 * You can modify this class to customize your error reporting
 * mechanisms so long as you retain the public fields.
 */
public class ParseException extends Exception {

  /**
   * The version identifier for this Serializable class.
   * Increment only if the <i>serialized</i> form of the
   * class changes.
   */
  private static final long serialVersionUID = 1L;

  /**
   * The end of line string for this machine.
   */
  protected static String EOL = System.getProperty("line.separator", "\n");

  /**
   * This constructor is used by the method "generateParseException"
   * in the generated parser.  Calling this constructor generates
   * a new object of this type with the fields "currentToken",
   * "expectedTokenSequences", and "tokenImage" set.
   */
  public ParseException(Token currentTokenVal,
                        int[][] expectedTokenSequencesVal,
                        String[] tokenImageVal
  ) {
    super(initialise(currentTokenVal, expectedTokenSequencesVal, tokenImageVal));
    currentToken = currentTokenVal;
    expectedTokenSequences = expectedTokenSequencesVal;
    tokenImage = tokenImageVal;
  }

  /**
   * The following constructors are for use by you for whatever
   * purpose you can think of.  Constructing the exception in this
   * manner makes the exception behave in the normal way - i.e., as
   * documented in the class "Throwable".  The fields "errorToken",
   * "expectedTokenSequences", and "tokenImage" do not contain
   * relevant information.  The JavaCC generated code does not use
   * these constructors.
   */

  public ParseException() {
    super();
  }

  /**
   * Constructor with message.
   */
  public ParseException(String message) {
    super(message);
  }


  /**
   * This is the last token that has been consumed successfully.  If
   * this object has been created due to a parse error, the token
   * followng this token will (therefore) be the first error token.
   */
  public Token currentToken;

  /**
   * Each entry in this array is an array of integers.  Each array
   * of integers represents a sequence of tokens (by their ordinal
   * values) that is expected at this point of the parse.
   */
  public int[][] expectedTokenSequences;

  /**
   * This is a reference to the "tokenImage" array of the generated
   * parser within which the parse error occurred.  This array is
   * defined in the generated ...Constants interface.
   */
  public String[] tokenImage;

  /**
   * It uses "currentToken" and "expectedTokenSequences" to generate a parse
   * error message and returns it.  If this object has been created
   * due to a parse error, and you do not catch it (it gets thrown
   * from the parser) the correct error message
   * gets displayed.
   */
  private static String initialise(Token currentToken,
                                   int[][] expectedTokenSequences,
                                   String[] tokenImage) {

    StringBuffer expected = new StringBuffer();
    int maxSize = 0;
    for (int[] expectedTokenSequence : expectedTokenSequences) {
      if (maxSize < expectedTokenSequence.length) {
        maxSize = expectedTokenSequence.length;
      }
      for (int j = 0; j < expectedTokenSequence.length; j++) {
        expected.append(tokenImage[expectedTokenSequence[j]]).append(' ');
      }
      if (expectedTokenSequence[expectedTokenSequence.length - 1] != 0) {
        expected.append("...");
      }
      expected.append(EOL).append("    ");
    }
    StringBuilder retval = new StringBuilder(message("unexpected_token"));
    Token tok = currentToken.next;
    for (int i = 0; i < maxSize; i++) {
      if (i != 0) {
        retval.append(" ");
      }
      if (tok.kind == 0) {
        retval.append(tokenImage[0]);
        break;
      }
      retval.append(" ").append(tokenImage[tok.kind]);
      retval.append(" `").append(addEscapes(tok.image)).append("` ");
      tok = tok.next;
    }
    retval.append(message("source_position", currentToken.next.beginLine, currentToken.next.beginColumn));

    return retval.toString();
  }

  /**
   * Used to convert raw characters to their escaped version
   * when these raw version cannot be used as part of an ASCII
   * string literal.
   */
  static String addEscapes(String str) {
    StringBuffer retval = new StringBuffer();
    char ch;
    for (int i = 0; i < str.length(); i++) {
      switch (str.charAt(i)) {
        case '\b':
          retval.append("\\b");
          continue;
        case '\t':
          retval.append("\\t");
          continue;
        case '\n':
          retval.append("\\n");
          continue;
        case '\f':
          retval.append("\\f");
          continue;
        case '\r':
          retval.append("\\r");
          continue;
        case '\"':
          retval.append("\\\"");
          continue;
        case '\'':
          retval.append("\\\'");
          continue;
        case '\\':
          retval.append("\\\\");
          continue;
        default:
          if ((ch = str.charAt(i)) < 0x20 || ch > 0x7e) {
            String s = "0000" + Integer.toString(ch, 16);
            retval.append("\\u" + s.substring(s.length() - 4, s.length()));
          } else {
            retval.append(ch);
          }
          continue;
      }
    }
    return retval.toString();
  }

}