/*
 Copyright 2007 Scott Gasch

 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 org.guru.wannabe.genetic;

import java.io.*;
import java.util.regex.*;

import java.util.Map;
import java.util.TreeMap;
import java.util.List;
import java.util.ArrayList;
import java.util.Arrays;

public class ParallelChessGeneticProcess implements GeneticProcess {
    private static final int numProcessors = 4;
    private static final String baselineDna = "./baseline.dna";
    private static final String baselineLog = "./baseline.log";
    private static final String scriptName = "./trial.ep_";

    private int numGenerations;
    private int numPerGeneration;
    private int numSeeds;

    // Helper function to emulate system(3).
    private static void system(String cmd[]) {
        Runtime runtime = Runtime.getRuntime();
        try {
            Process ps = runtime.exec(cmd);
            InputStream stdin = ps.getInputStream();
            InputStreamReader isr = new InputStreamReader(stdin);
            BufferedReader br = new BufferedReader(isr);
            String line = null;
            while((line = br.readLine()) != null) ; 
            ps.waitFor();
        } catch(Exception e) {
            throw new AssertionError(e);
        }
    }

    // Private helpers to build filenames
    private static String seedFilename(int generation, int which) {
        return "./gen" + generation + "_seed" + which + ".dna";
    }

    private static String logFilename(int generation, int which) {
        return "./gen" + generation + "_" + which + ".log";
    }

    private static String dnaFilename(int generation, int which) {
        return "./gen" + generation + "_" + which + ".dna";
    }

    // Uses mutate.pl to cause dna mutations 
    private static void mutate(String from, String to) {
        String cmd[] = new String[] { "./mutate.pl", from, to };
        system(cmd);
        try {
            BufferedWriter out = 
                new BufferedWriter(new FileWriter(to, true));
            out.write("# mutate " + from + " -> " + to + "\n");
            out.close();
        } catch(IOException e) {
            throw new AssertionError(e);
        }
    }

    // Runs a chess trial event
    private static void chessTrial(String dnaFile, String logFile) {
        String cmd[] = new String[] { "./typhoon",
                             "--cpus", "1",
                             "--hash", "128m",
                             "--batch",
                             "--logfile", logFile,
                             "--dnafile", dnaFile,
                             "--command", "script ./trial.ep_" };
        system(cmd);                      
    }

    // The mainInitialize method produces the 0th generation DNA from
    // a seed file called "baseline.dna" using a helper script called
    // mutate.pl (the generic DNA mutation routine).
    public boolean mainInitialize(int numGenerations,
                                  int numPerGeneration) {

        System.out.println("Performing pre-generation setup tasks.");
        this.numGenerations = numGenerations;
        this.numPerGeneration = numPerGeneration;
        this.numSeeds = numPerGeneration / 5;
        if ((numGenerations <= 0) || 
            (numPerGeneration <= 0) ||
            (numSeeds <= 0)) {
            throw new IllegalArgumentException("Bad value");
        }

        // Create generation zero seeds based on mutations of baseline.dna
        for (int x = 0; x < numSeeds; x++) {
            String seedFile = seedFilename(0, x);
            if (!new File(seedFile).exists()) {
                mutate(baselineDna, seedFile);
            } else {
                System.out.println("Using existing " + seedFile);
            }
        }

        // Run baseline.dna trial to get a starting point.
        if (!new File(baselineLog).exists()) {
            chessTrial(baselineDna, baselineLog);
        } else {
            System.out.println("Using existing " + baselineLog);
        }
        return true;
    }

    public boolean generationInitialize(int generationNumber) {

        // Using the seed dna of the previous generation, build the
        // genes for the current generation.
        System.out.println("Initializing generation " + generationNumber);
        for (int x = 0; x < numPerGeneration; x++) {
            String dnaFile = dnaFilename(generationNumber, x);
            String seedFile = seedFilename(generationNumber, x % numSeeds);
            mutate(seedFile, dnaFile);
        }
        return true;
    }

    public boolean generationEvaluation(int generationNumber) {
        class ChessGame implements Runnable {
            public String dnaFile;
            public String logFile;
            public ChessGame(String dnaFile, String logFile) {
                this.dnaFile = dnaFile; this.logFile = logFile;
            }
            public void run() {
                if (!new File(logFile).exists()) {
                    System.out.println("Creating " + logFile);
                    chessTrial(dnaFile, logFile);
                } else {
                    System.out.println("Using existing " + logFile);
                }
            }
        }

        // Populate work queue
        System.out.println("Evaluating generation " + generationNumber);
        List<ChessGame> workQueue = new ArrayList<ChessGame>();
        for (int x = 0; x < numPerGeneration; x++) {
            String dnaFile = dnaFilename(generationNumber, x);
            String logFile = logFilename(generationNumber, x);
            workQueue.add(new ChessGame(dnaFile, logFile));
        }

        // Depopulate the work queue in parallel
        Thread threadPool[] = new Thread[numProcessors];
        while(!workQueue.isEmpty()) {
            ChessGame next = workQueue.remove(0);
            int x = 0;
            do {
                if ((threadPool[x] == null) ||
                    (!threadPool[x].isAlive())) {
                    threadPool[x] = new Thread(next);
                    threadPool[x].setPriority(Thread.MAX_PRIORITY);
                    threadPool[x].start();
                    break;
                }
                x++;
                if (x >= numProcessors) {
                    x = 0;
                    try {
                        Thread.sleep(2000);
                    } catch(Exception e) {
                        ;
                    }
                }
            }
            while(true);
        }

        // Wait for all threads to become idle again
        int x = 0;
        do {
            if (threadPool[x] != null && threadPool[x].isAlive()) {
                x = 0;
            }
            x++;
            try {
                Thread.sleep(2000);
            } catch(Exception e) {
                ;
            }
        } while(x < numProcessors);
        return true;
    }

    public boolean generationReproduction(int generationNumber) {

        // Helper data class
        class FileAndScore implements Comparable<FileAndScore> {
            public final String file;
            public final int score;
            public final int number;
            public FileAndScore(String file, int score, int number) {
                this.file = file; this.score = score; this.number = number;
            }
            public int compareTo(FileAndScore other) {
                return other.score - score;
            }
        }

        System.out.println("Seeding subsequent generation.");
        List<FileAndScore> scores = new ArrayList<FileAndScore>();
        for (int x = 0; x < numPerGeneration; x++) {
            String logFile = logFilename(generationNumber, x);
            try {
                BufferedReader log = new BufferedReader(
                                         new FileReader(logFile));
                String line = null;
                Pattern p = 
                    Pattern.compile("\\s+correct solutions\\s+:\\s+(\\d+)");
                while ((line = log.readLine()) != null) {
                    Matcher m = p.matcher(line);
                    if (m.matches()) {
                        int score = Integer.parseInt(m.group(1));
                        FileAndScore fas = 
                            new FileAndScore(logFile, score, x);
                        scores.add(fas);
                        break;
                    }
                }
                log.close();
            }
            catch (Exception e) {
                throw new AssertionError(e);
            }
        }
        java.util.Collections.sort(scores);
        for (int x = 0; x < numSeeds; x++) {
            FileAndScore breeder = scores.get(0);
            scores.remove(0);
            String dnaFile = dnaFilename(generationNumber, breeder.number);
            String seedFile = seedFilename(generationNumber + 1, x);
            if (!new File(seedFile).exists()) {
                System.out.println("Number " + breeder.number + " got score " +
                                   breeder.score + " and will propagate.");
                String cmd[] = new String[] { "/bin/cp", "-f", dnaFile, seedFile };
                system(cmd);
            } else {
                System.out.println("Using existing " + seedFile);
            }
        }
        return true;
    }
}