/*
 *  This file is part of the Jikes RVM project (http://jikesrvm.org).
 *
 *  This file is licensed to You under the Eclipse Public License (EPL);
 *  You may not use this file except in compliance with the License. You
 *  may obtain a copy of the License at
 *
 *      http://www.opensource.org/licenses/eclipse-1.0.php
 *
 *  See the COPYRIGHT.txt file distributed with this work for information
 *  regarding copyright ownership.
 */
package org.jikesrvm.adaptive.util;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.List;
import java.util.NoSuchElementException;
import java.util.StringTokenizer;
import org.jikesrvm.VM;
import org.jikesrvm.classloader.Atom;

/**
 * Utility to read compiler advice annotations from file in ascii format.
 * Takes a single argument: the name of the file containing the ascii
 * annotations.  Each line of the file corresponds to an annotation
 * for one method and has the following format:
 * <p>
 * <pre>
 * <class> <method> <signature> <advice> <optLevel>
 * </pre>
 * Where the types and meanings of the fields is as follows:
 * <ul>
 * <li><code><class></code> <i>string</i> The name of the class</li>
 * <li><code><method></code> <i>string</i> The name of the method</li>
 * <li><code><signature></code> <i>string</i> The method signature</li>
 * <li><code><advice></code> <i>int</i> The compiler type to be used --
 * an integer value corresponding to the compiler enumeration in
 CompiledMethod</li>
 * <li><code><optLevel></code> <i>int</i> (Optional) The opt level to use
 if compiler is optimizing compiler</li>
 * </ul>
 *
 *
 * @see CompilerAdvice
 * @see CompilerAdviceAttribute
 */
class CompilerAdviceInfoReader {

  /**
   * Read annoations from a specified file. Reads all annotations at
   * once and returns a collection of compiler advice attributes.
   *
   * @param file The annoation file to be read
   * @return A list of compileration advice attributes
   */
  public static List<CompilerAdviceAttribute> readCompilerAdviceFile(String file) {
    List<CompilerAdviceAttribute> compilerAdviceInfo = new ArrayList<CompilerAdviceAttribute>();
    BufferedReader fileIn = null;

    if (file == null) return null;

    try {
      fileIn = new BufferedReader(new InputStreamReader(new FileInputStream(file), "UTF-8"));

      try {
        for (String s = fileIn.readLine(); s != null; s = fileIn.readLine()) {
          StringTokenizer parser = new StringTokenizer(s, " \n,");
          compilerAdviceInfo.add(readOneAttribute(parser));

        }
      } catch (IOException e) {
        e.printStackTrace();
        VM.sysFail("Error parsing input compilation advice file " + file);
      }

      fileIn.close();
    } catch (java.io.FileNotFoundException e) {
      System.out.println("IO: Couldn't read compiler advice attribute file: " + file + e);
      return null;
    } catch (java.io.UnsupportedEncodingException e) {
      System.out.println("IO: UTF-8 is not supported: " + e);
      return null;
    } catch (java.io.IOException e) {
      System.out.println("IO: Couldn't close compiler advice attribute file: " + file + e);
      return null;
    }

    return compilerAdviceInfo;
  }

  /**
   * Actual reading is done here.  This method reads one attribute
   * from a single line of an input stream.  There are six elements
   * per line corresponding to each call site. First three are
   * strings, <i>class name</i>, <i>method name</i>, <i>method
   * signature</i>, followed by one number,
   * <i>compiler advice</i>.
   *
   * @param st an input stream
   * @return an compileration advice atribute
   */
  private static CompilerAdviceAttribute readOneAttribute(StringTokenizer st) {
    int compiler, optLevel = -1;

    try {
      Atom cls = Atom.findOrCreateUnicodeAtom(st.nextToken());
      Atom mth = Atom.findOrCreateUnicodeAtom(st.nextToken());
      Atom sig = Atom.findOrCreateUnicodeAtom(st.nextToken());
      compiler = Integer.parseInt(st.nextToken());
      optLevel = Integer.parseInt(st.nextToken());
      // this is the attribute which will be returned
      CompilerAdviceAttribute newAttrib;

      if (optLevel >= 0) {
        newAttrib = new CompilerAdviceAttribute(cls, mth, sig, compiler, optLevel);
      } else {
        newAttrib = new CompilerAdviceAttribute(cls, mth, sig, compiler);
      }

      return newAttrib;
    } catch (NoSuchElementException e) {
      return null;
    }

  }
}