/*
    * dpkg - Debian Package library and the Debian Package Maven plugin
    * (c) Copyright 2016 Gerrit Hohl
    *
    * This program is free software; you can redistribute it and/or
    * modify it under the terms of the GNU General Public License
    * as published by the Free Software Foundation; either version 2
    * 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 General Public License for more details.
   *
   * You should have received a copy of the GNU 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 net.sourceforge.javadpkg.impl;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Date;
  import java.util.List;
  
  import net.sourceforge.javadpkg.ChangeLog;
  import net.sourceforge.javadpkg.ChangeLogConstants;
  import net.sourceforge.javadpkg.ChangeLogParser;
  import net.sourceforge.javadpkg.ChangeLogUrgency;
  import net.sourceforge.javadpkg.ChangeLogUrgencyParser;
  import net.sourceforge.javadpkg.ChangeLogVersionEntryDetail;
  import net.sourceforge.javadpkg.Context;
  import net.sourceforge.javadpkg.ParseException;
  import net.sourceforge.javadpkg.control.PackageMaintainer;
  import net.sourceforge.javadpkg.control.PackageMaintainerParser;
  import net.sourceforge.javadpkg.control.PackageName;
  import net.sourceforge.javadpkg.control.PackageNameParser;
  import net.sourceforge.javadpkg.control.PackageVersion;
  import net.sourceforge.javadpkg.control.PackageVersionParser;
  import net.sourceforge.javadpkg.control.impl.PackageMaintainerParserImpl;
  import net.sourceforge.javadpkg.control.impl.PackageNameParserImpl;
  import net.sourceforge.javadpkg.control.impl.PackageVersionParserImpl;
  import net.sourceforge.javadpkg.io.DataSource;
  
  
  /**
   * <p>
   * A {@link ChangeLogParser} implementation.
   * </p>
   *
   * @author Gerrit Hohl (gerrit-hohl@users.sourceforge.net)
   * @version <b>1.0</b>, 04.05.2016 by Gerrit Hohl
   */
  public class ChangeLogParserImpl implements ChangeLogParser, ChangeLogConstants {
  	
  	
  	/** The parser for the package name. */
  	private PackageNameParser		packageNameParser;
  	/** The parser for the version. */
  	private PackageVersionParser	packageVersionParser;
  	/** The parser for the urgency. */
  	private ChangeLogUrgencyParser	changeLogUrgencyParser;
  	/** The parser for the maintainer. */
  	private PackageMaintainerParser	packageMaintainerParser;
  	
  	
  	/**
  	 * <p>
  	 * Creates a parser.
  	 * </p>
  	 */
  	public ChangeLogParserImpl() {
  		super();
  		
  		this.packageNameParser = new PackageNameParserImpl();
  		this.packageVersionParser = new PackageVersionParserImpl();
  		this.changeLogUrgencyParser = new ChangeLogUrgencyParserImpl();
  		this.packageMaintainerParser = new PackageMaintainerParserImpl();
  	}
  	
  	
  	@Override
  	public ChangeLog parseChangeLog(DataSource source, Context context) throws IOException, ParseException {
  		ChangeLogImpl changeLog;
  		String line = null;
  		int lineNumber = 0;
  		ChangeLogVersionEntryImpl entry = null;
  		StringBuilder sb = null;
  		ChangeLogVersionEntryDetail detail;
  
  
  		if (source == null)
  			throw new IllegalArgumentException("Argument source is null.");
  		if (context == null)
  			throw new IllegalArgumentException("Argument context is null.");
  		
 		changeLog = new ChangeLogImpl();
 		try {
 			try (BufferedReader in = new BufferedReader(new InputStreamReader(source.getInputStream(), UTF_8_CHARSET))) {
 				while ((line = in.readLine()) != null) {
 					lineNumber++;
 
 					// --- Ignore comments --
 					if ("#".equals(line) || line.startsWith("# ")) {
 						continue;
 					} else
 					// --- Is this the first line of a version block? ---
 					if (entry == null) {
 						// --- Ignore empty lines between entries ---
 						if (line.isEmpty() || line.trim().isEmpty()) {
 							continue;
 						}
 						
 						entry = this.parseInitialLine(line, context);
 						if (entry == null) {
 							break;
 						}
 						changeLog.addEntry(entry);
 					}
 					// --- Is this the last line of a version block? ---
 					else if (line.startsWith(TERMINATION_PREFIX)) {
 						// --- Do we have some detail text left? ---
 						if (sb != null) {
 							// --- Add the detail ---
 							detail = new ChangeLogVersionEntryDetailImpl(sb.toString());
 							entry.addDetail(detail);
 							sb = null;
 						}
 						this.parseTerminationLine(line, entry, context);
 						entry = null;
 					}
 					// --- Is this a new detail of the current version entry? ---
 					else if (line.startsWith(DETAIL_START_PREFIX)) {
 						// --- Do we have some detail text left? ---
 						if (sb != null) {
 							// --- Add the detail ---
 							detail = new ChangeLogVersionEntryDetailImpl(sb.toString());
 							entry.addDetail(detail);
 							sb = null;
 						}
 						sb = this.parseDetailLine(line, null, context);
 					}
 					// --- Is this an additional line of the current detail? ---
 					else if (line.startsWith(DETAIL_LINE_PREFIX)) {
 						if (sb == null) {
 							context.addWarning(new ChangeLogUnsupportedLineWarning(line));
 						} else {
 							sb = this.parseDetailLine(line, sb, context);
 						}
 					}
 					// --- Empty lines are stripped away. But is this line empty? ---
 					else if (!line.isEmpty()) {
 						context.addWarning(new ChangeLogUnsupportedLineWarning(line));
 					}
 				}
 				// --- Did we not reach the end? ---
 				if (entry != null)
 					throw new ParseException("End of last version entry in the change log is missing.");
 				if (lineNumber == 0)
 					throw new ParseException("Change log is empty.");
 			}
 		} catch (IOException e) {
 			throw new IOException("An error occurred while parsing source |" + source.getName() + "|: " + e.getMessage(), e);
 		} catch (ParseException e) {
 			throw new ParseException(
 					"Line |" + line + "| (Line number: " + lineNumber + ") couldn't be parsed: " + e.getMessage(), e);
 		}
 		return changeLog;
 	}
 	
 	
 	/**
 	 * <p>
 	 * Parses the initial line of a version.
 	 * </p>
 	 *
 	 * @param line
 	 *            The line.
 	 * @param context
 	 *            The context.
 	 * @return The entry containing the content of the first line.
 	 * @throws ParseException
 	 *             If an error occurs while parsing.
 	 */
 	private ChangeLogVersionEntryImpl parseInitialLine(String line, Context context) throws ParseException {
 		ChangeLogVersionEntryImpl entry;
 		int index, lastIndex;
 		String value;
 		PackageName packageName;
 		PackageVersion version;
 		List<String> distributions;
 		ChangeLogUrgency urgency;
 		
 		
 		// --- Package name ---
 		index = line.indexOf(' ');
 		if (index == -1) {
 			context.addWarning(new ChangeLogInitialLineUnsupportedWarning(line,
 					"Didn't find first whitespace in the first line of the change log entry."));
 			return null;
 		}
 		value = line.substring(0, index);
 		try {
 			packageName = this.packageNameParser.parsePackageName(value, context);
 		} catch (ParseException e) {
 			context.addWarning(new ChangeLogInitialLineUnsupportedWarning(line,
 					"Couldn't parser package name |" + value + "| of first line of change log entry: " + e.getMessage()));
 			return null;
 		}
 		
 		// --- Version ---
 		index++;
 		if (line.length() <= index) {
 			context.addWarning(new ChangeLogInitialLineUnsupportedWarning(line,
 					"First line of change log entry is too short. Only found the package name."));
 			return null;
 		}
 		if (line.charAt(index) != '(') {
 			context.addWarning(new ChangeLogInitialLineUnsupportedWarning(line,
 					"Couldn't find the beginning of version of the package in the first line of change log entry."));
 			return null;
 		}
 		lastIndex = ++index;
 		index = line.indexOf(')', lastIndex);
 		if (index == -1) {
 			context.addWarning(new ChangeLogInitialLineUnsupportedWarning(line,
 					"Couldn't find the end of version of the package in the first line of change log entry."));
 			return null;
 		}
 		value = line.substring(lastIndex, index);
 		try {
 			version = this.packageVersionParser.parsePackageVersion(value, context);
 		} catch (ParseException e) {
 			context.addWarning(new ChangeLogInitialLineUnsupportedWarning(line,
 					"Couldn't parser version |" + value + "| of first line of change log entry: " + e.getMessage()));
 			return null;
 		}
 		lastIndex = index + 1;
 		
 		// --- Distributions ---
 		index = line.indexOf(';', lastIndex);
 		if (index == -1) {
 			context.addWarning(new ChangeLogInitialLineUnsupportedWarning(line,
 					"Couldn't find the semi-colon between the distributions and the urgency in the first line of change log entry."));
 			return null;
 		}
 		value = line.substring(lastIndex, index).trim();
 		distributions = new ArrayList<>(Arrays.asList(value.split(" ")));
 		lastIndex = index + 1;
 		
 		// --- Urgency ---
 		value = line.substring(lastIndex).trim();
 		if (!value.startsWith("urgency=")) {
 			context.addWarning(
 					new ChangeLogInitialLineUnsupportedWarning(line, "Couldn't the urgency prefix |urgency=| in the part |"
 							+ value + "| after the semi-colon in the first line of change log entry."));
 			return null;
 		}
 		value = value.substring(8);
 		try {
 			urgency = this.changeLogUrgencyParser.parseChangeLogUrgency(value, context);
 		} catch (ParseException e) {
 			context.addWarning(new ChangeLogInitialLineUnsupportedWarning(line,
 					"Couldn't parser urgency |" + value + "| of first line of change log entry: " + e.getMessage()));
 			return null;
 		}
 		
 		entry = new ChangeLogVersionEntryImpl();
 		entry.setPackageName(packageName);
 		entry.setVersion(version);
 		entry.setDistributions(distributions);
 		entry.setUrgency(urgency);
 		return entry;
 	}
 
 
 	/**
 	 * <p>
 	 * Parses a line of a detail.
 	 * </p>
 	 *
 	 * @param line
 	 *            The line.
 	 * @param detail
 	 *            The current detail (optional).
 	 * @param context
 	 *            The context.
 	 * @return The current detail.
 	 * @throws ParseException
 	 *             If an error occurs while parsing.
 	 */
 	private StringBuilder parseDetailLine(String line, StringBuilder detail, Context context) throws ParseException {
 		StringBuilder sb;
 		String value;
 
 
 		if (detail == null) {
 			sb = new StringBuilder();
 		} else {
 			sb = detail;
 		}
 		value = line.substring(4);
 		if (sb.length() > 0) {
 			sb.append('\n');
 		}
 		// --- Only add the value if it is not just an empty line ---
 		if (!".".equals(value)) {
 			sb.append(value);
 		}
 
 		return sb;
 	}
 
 
 	/**
 	 * <p>
 	 * Parses the termination line of a version.
 	 * </p>
 	 *
 	 * @param line
 	 *            The line.
 	 * @param entry
 	 *            The entry.
 	 * @param context
 	 *            The context.
 	 * @throws ParseException
 	 *             If an error occurs while parsing.
 	 */
 	private void parseTerminationLine(String line, ChangeLogVersionEntryImpl entry, Context context) throws ParseException {
 		int index;
 		String rest, value;
 		PackageMaintainer maintainer;
 		Date date;
 
 
 		rest = line.substring(TERMINATION_PREFIX.length());
 		index = rest.indexOf(MAINTAINER_TIMESTAMP_SEPARATOR);
 		if (index == -1)
 			throw new ParseException("Couldn't parse last line |" + line
 					+ "| of change log entry as the separator between maintainer and timestamp couldn't be found.");
 		
 		// --- Maintainer ---
 		value = rest.substring(0, index);
 		try {
 			maintainer = this.packageMaintainerParser.parsePackageMaintainer(value, context);
 		} catch (ParseException e) {
 			throw new ParseException(
 					"Couldn't parser maintainer |" + value + "| of last line of change log entry: " + e.getMessage(), e);
 		}
 		
 		// --- Timestamp ---
 		value = rest.substring(index + 2);
 		try {
 			date = TIMESTAMP_FORMAT.parse(value);
 		} catch (java.text.ParseException e) {
 			throw new ParseException(
 					"Couldn't parse timestamp |" + value + "| of last line of change log entry: " + e.getMessage(), e);
 		}
 
 		entry.setMaintainer(maintainer);
 		entry.setDate(date);
 	}
 
 
 	@Override
 	public ChangeLog parseChangeLogHtml(DataSource source, Context context) throws IOException, ParseException {
 		// TODO Implement method.
 		throw new ParseException("Not yet implemented");
 	}
 	
 	
 }