/*
 *   Copyright 2013 Brian Rosenberger (Brutex Network)
 *
 *   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 net.brutex.svn;

import java.io.BufferedReader;
import java.io.File;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Date;
import java.util.List;
import java.util.StringTokenizer;

import net.brutex.svn.SVNCommitInfo.ChangeType;

import org.apache.log4j.Logger;

/* Executes the svnlook utility
 * 
 * @author Brian Rosenberger bru(at)brutex.de
 * @since 0.1

 */
public class SVNLookExecutor {
	
	private Logger logger = Logger.getLogger(SVNLookExecutor.class);
	private final File svnlook;
	private final String repos;
	private String TXN = null;
	private String rev = null;
	
	/**
	 * Instantiates a new sVN look executor.
	 *
	 * @param svnlook the svnlook
	 * @param repos the repos
	 */
	public SVNLookExecutor(File svnlook, String repos) {
		if(! svnlook.exists() ) throw new IllegalArgumentException( String.format("The svnlook executable at '%s' does not exist.", svnlook.toString()));
		if(! svnlook.isFile() ) throw new IllegalArgumentException( String.format("The svnlook utility at'%s' is not a file.", svnlook.toString()));
		logger.debug(String.format("Instantiating '%s' with svnlook at '%s'.", this.getClass().getCanonicalName(), svnlook.toString()));
		this.svnlook = svnlook;
		logger.debug(String.format("Working against svn repository at '%s'.", repos));
		this.repos = repos;
	}
	

	/**
	 * Execute svn look.
	 *
	 * @param command the command
	 * @return the string
	 */
	private String executeSVNLook(SVNLookCommand command) {
		StringBuilder sb = new StringBuilder();
		StringBuilder sberr = new StringBuilder();
		
		//This throws an IllegalArgumentException when neither TXN nor REV is valid
		String[] params;
		try {
			params = getTargetParam();
		} catch (IllegalArgumentException e) {
			logger.error(e.getMessage());
			throw e;
		}
		try {
			List<String> cmdline =  new ArrayList<String>(5);
			cmdline.add(svnlook.toString());
			cmdline.add(command.getValue());
			cmdline.add(params[0]);
			cmdline.add(params[1]);
			cmdline.add(repos);

			ProcessBuilder pf = new ProcessBuilder(cmdline);
			logger.debug(String.format("Executing svnlook with commandline '%s'.", pf.command()));
			
			Process svnprocess = pf.start();
			BufferedReader stdin = new BufferedReader(new InputStreamReader(svnprocess.getInputStream()));
			BufferedReader stderr = new BufferedReader(new InputStreamReader(svnprocess.getErrorStream()));
			String s;
			 while( (s = stdin.readLine()) != null ) {
				 sb.append(s + '\n');
			 }
			 while( (s = stderr.readLine()) != null ) {
				 sberr.append(s + '\n');
			 }
			 stdin.close(); stderr.close();
		} catch (IOException e) {
			logger.error( String.format( "Error calling the svnlook utility: '%s'", e.getMessage()));
			e.printStackTrace();
		}
		
		String error = sberr.toString();
		if( error.length()>0 ) {
			error = "Failed to call svnlook. The STDERR was '"+error+"'";
			logger.error(error);
			throw new IllegalArgumentException(error);
		}
		String output = sb.toString().trim();
		logger.debug(String.format("Svnlook output was '%s'", output));
		return output;		
	}
	
	/*
	 * Returns either -t TXN oder -rev REVISION
	 * 
	 * @returns
	 */
	private String[] getTargetParam() {
		String[] result = new String[2];
		if( (TXN==null || TXN.length()<=0) && (rev==null || rev.length()<=0) ) throw new IllegalArgumentException("Either TXN or revision must be provided.");
		if( TXN!=null && TXN.length()>0 && rev!=null && rev.length()>0 ) throw new IllegalArgumentException("Both, TXN and revision are given. Don't know what to use.");
		if( TXN!=null && TXN.length()>0) {
			result[0] = "-t";
			result[1] = TXN;
			return result;
		}
		if( rev!=null && rev.length()>0) {
			result[0] = "-r";
			result[1] = rev;
			return result;
		}
		throw new IllegalArgumentException("Either TXN or revision must be provided.");
	}
	
	public void setTXN(String TXN) {
		if(TXN==null || TXN.length()<=0) throw new IllegalArgumentException("TXN cannot be null or empty.");
		this.TXN = TXN;
	}
	
	public void setRev(String rev) {
		if(rev==null || rev.length()<=0) throw new IllegalArgumentException("Revision cannot be null or empty.");
		this.rev = rev;
	}
	
	public SVNCommitInfo getCommitInfo() {
		String author = executeSVNLook(SVNLookCommand.AUTHOR);
		String logmessage = executeSVNLook(SVNLookCommand.LOG);
		String files = executeSVNLook(SVNLookCommand.CHANGED);
		
		SVNCommitInfo result = new SVNCommitInfo(author,
												new Date(),
												logmessage);
		
		
		files += "\n";
		StringTokenizer tokenizer = new StringTokenizer(files, "\n");		
		String s;
		while( tokenizer.hasMoreTokens()) {
			s=tokenizer.nextToken();
			logger.debug(String.format("Tokenizing file list. Token '%s'.", s));
			if(s.startsWith("A")) { result.addFileInfo(ChangeType.ADDED, s.substring(1).trim()); continue; }
			if(s.startsWith("D")) { result.addFileInfo(ChangeType.DELETED, s.substring(1).trim()); continue; }
			if(s.startsWith("UU")) { result.addFileInfo(ChangeType.BOTHUPDATE, s.substring(2).trim()); continue; }
			if(s.startsWith("_U")) { result.addFileInfo(ChangeType.METAUPDATE, s.substring(2).trim()); continue; }
			if(s.startsWith("U")) { result.addFileInfo(ChangeType.UPDATED, s.substring(1).trim()); continue; }
		}
		result.setTxn(TXN);
		result.setRev(rev);
		
		return result;
	}

}