/*
 * Copyright 2009 Google Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package com.google.jstestdriver.coverage;

import com.google.inject.Inject;
import com.google.jstestdriver.coverage.es3.ES3InstrumentLexer;
import com.google.jstestdriver.coverage.es3.ES3InstrumentParser;

import org.antlr.runtime.ANTLRStringStream;
import org.antlr.runtime.TokenRewriteStream;
import org.antlr.stringtemplate.StringTemplateGroup;

import java.io.CharArrayReader;
import java.util.Collections;
import java.util.List;

/**
 * Decorates the source code with coverage instrumentation.
 * @author corysmith@google.com (Cory Smith)
 */
public class CodeInstrumentor implements Instrumentor {

  /** Thrown when instrumentation fails.*/
  public class InstrumentationException extends Error {

    private static final long serialVersionUID = 6999317302885453217L;

    public InstrumentationException(String path, Throwable cause) {
      super("error instrumenting " + path, cause);
    }
  }

  private static final char[] TEMPLATE =
    ("group TestRewrite;\n" +
     "init_instrument(stmt, hash, name, lines) ::= \"LCOV_<hash>=" +
        "LCOV.initNoop(<name>,0,<lines>);<stmt>\"" +
     "instrument(stmt, hash, ln) ::= \"LCOV_<hash>[<ln>]++; <stmt>\"" +
     "pass(stmt) ::= \"<stmt>\"").toCharArray();
  private final CoverageNameMapper mapper;

  @Inject
  public CodeInstrumentor(CoverageNameMapper mapper) {
    this.mapper = mapper;
  }
  

  public InstrumentedCode instrument(Code code) {
    StringTemplateGroup templates = new StringTemplateGroup(new CharArrayReader(TEMPLATE));
    ANTLRStringStream stream = new ANTLRStringStream(code.getSourceCode());
    Integer fileId = mapper.map(code.getFilePath());
    String mappedName = String.valueOf(fileId);
    stream.name = mappedName;
    ES3InstrumentLexer lexer = new ES3InstrumentLexer(stream);
    TokenRewriteStream tokens = new TokenRewriteStream(lexer);
    ES3InstrumentParser parser = new ES3InstrumentParser(tokens);
    parser.setTemplateLib(templates);
    try {
      parser.program();
    } catch (Exception e) {
      throw new InstrumentationException(code.getFilePath(), e);
    }
    List<Integer> executableLines = parser.linesMap.get(mappedName);
    return new InstrumentedCode(fileId,
                                code.getFilePath(),
                                executableLines == null ?
                                    Collections.<Integer>emptyList() : executableLines,
                                tokens.toString());
  }
}