/*
 * SonarQube JavaScript Plugin
 * Copyright (C) 2011-2016 SonarSource SA
 * mailto:contact AT sonarsource DOT com
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 3 of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 */
package org.sonar.javascript.lexer;

import com.sonar.sslr.api.GenericTokenType;
import com.sonar.sslr.impl.Lexer;
import com.sonar.sslr.impl.channel.BlackHoleChannel;
import com.sonar.sslr.impl.channel.IdentifierAndKeywordChannel;
import com.sonar.sslr.impl.channel.PunctuatorChannel;
import com.sonar.sslr.impl.channel.UnknownCharacterChannel;
import java.nio.charset.Charset;

import static com.sonar.sslr.impl.channel.RegexpChannelBuilder.commentRegexp;
import static com.sonar.sslr.impl.channel.RegexpChannelBuilder.regexp;

public final class JavaScriptLexer {

  private static final String EXP = "([Ee][+-]?+[0-9_]++)";
  private static final String BINARY_EXP = "([Pp][+-]?+[0-9_]++)";

  public static final String NUMERIC_LITERAL = "(?:"
    // Decimal
    + "[0-9]++\\.([0-9]++)?+" + EXP + "?+"
    // Decimal
    + "|\\.[0-9]++" + EXP + "?+"
    // Decimal
    + "|[0-9]++" + EXP
    // Hexadecimal
    + "|0[xX][0-9a-fA-F]++\\.[0-9a-fA-F_]*+" + BINARY_EXP + "?+"
    // Hexadecimal
    + "|0[xX][0-9a-fA-F]++" + BINARY_EXP

    // Integer Literals
    // Hexadecimal
    + "|0[xX][0-9a-fA-F]++"
    // Binary (Java 7)
    + "|0[bB][01]++"
    // Octal
    + "|0[oO][0-7]++"
    // Decimal and octal
    + "|[0-9]++"
    + ")";

  public static final String LITERAL = "(?:"
    + "\"([^\"\\\\]*+(\\\\[\\s\\S])?+)*+\""
    + "|'([^'\\\\]*+(\\\\[\\s\\S])?+)*+'"
    + ")";

  public static final String SINGLE_LINE_COMMENT = "//[^\\n\\r]*+|<!--[^\\n\\r]*+";
  public static final String MULTI_LINE_COMMENT = "/\\*[\\s\\S]*?\\*/";
  public static final String MULTI_LINE_COMMENT_NO_LB = "/\\*[^\\n\\r]*?\\*/";

  public static final String COMMENT = "(?:" + SINGLE_LINE_COMMENT + "|" + MULTI_LINE_COMMENT + ")";

  private static final String HEX_DIGIT = "[0-9a-fA-F]";
  private static final String UNICODE_ESCAPE_SEQUENCE = "u" + HEX_DIGIT + HEX_DIGIT + HEX_DIGIT + HEX_DIGIT;

  private static final String UNICODE_LETTER = "\\p{Lu}\\p{Ll}\\p{Lt}\\p{Lm}\\p{Lo}\\p{Nl}";
  private static final String UNICODE_COMBINING_MARK = "\\p{Mn}\\p{Mc}";
  private static final String UNICODE_DIGIT = "\\p{Nd}";
  private static final String UNICODE_CONNECTOR_PUNCTUATION = "\\p{Pc}";

  private static final String IDENTIFIER_START = "(?:[$_" + UNICODE_LETTER + "]|\\\\" + UNICODE_ESCAPE_SEQUENCE + ")";
  private static final String IDENTIFIER_PART = "(?:" + IDENTIFIER_START + "|[" + UNICODE_COMBINING_MARK + UNICODE_DIGIT + UNICODE_CONNECTOR_PUNCTUATION + "])";

  public static final String IDENTIFIER = IDENTIFIER_START + IDENTIFIER_PART + "*+";

  /**
   * LF, CR, LS, PS
   */
  public static final String LINE_TERMINATOR = "\\n\\r\\u2028\\u2029";
  public static final String LINE_TERMINATOR_SEQUENCE = "(?:\\n|\\r\\n|\\r|\\u2028|\\u2029)";

  /**
   * Tab, Vertical Tab, Form Feed, Space, No-break space, Byte Order Mark, Any other Unicode "space separator"
   */
  public static final String WHITESPACE = "\\t\\u000B\\f\\u0020\\u00A0\\uFEFF\\p{Zs}";

  private JavaScriptLexer() {
  }

  public static Lexer create(Charset charset) {
    return Lexer.builder()
      .withCharset(charset)

      .withFailIfNoChannelToConsumeOneCharacter(true)

      // Channels, which consumes more frequently should come first.
      // Whitespace character occurs more frequently than any other, and thus come first:
      .withChannel(new BlackHoleChannel("[" + LINE_TERMINATOR + WHITESPACE + "]++"))

      // Comments
      .withChannel(commentRegexp(COMMENT))

      // String Literals
      .withChannel(regexp(GenericTokenType.LITERAL, LITERAL))

      // Regular Expression Literals
      .withChannel(new JavaScriptRegexpChannel())

      .withChannel(regexp(JavaScriptTokenType.NUMERIC_LITERAL, NUMERIC_LITERAL))

      .withChannel(new IdentifierAndKeywordChannel(IDENTIFIER, true, JavaScriptKeyword.values()))
      .withChannel(new PunctuatorChannel(JavaScriptPunctuator.values()))

      .withChannel(new UnknownCharacterChannel())

      .build();
  }
}
