/*
 * Copyright (c) 2010-2011 TMate Software Ltd
 *  
 * 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; version 2 of the License.
 *
 * 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.
 *
 * For information on how to redistribute this software under
 * the terms of a license other than GNU General Public License
 * contact TMate Software at support@hg4j.com
 */
package org.tmatesoft.hg.repo;

import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Calendar;
import java.util.Collections;
import java.util.Date;
import java.util.Formatter;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.TimeZone;

import org.tmatesoft.hg.core.Nodeid;
import org.tmatesoft.hg.internal.RevlogStream;


/**
 * Representation of the Mercurial changelog file (list of ChangeSets)
 *
 * @author Artem Tikhomirov
 * @author TMate Software Ltd.
 */
public class HgChangelog extends Revlog {

	/*package-local*/ HgChangelog(HgRepository hgRepo, RevlogStream content) {
		super(hgRepo, content);
	}

	public void all(final HgChangelog.Inspector inspector) {
		range(0, getLastRevision(), inspector);
	}

	public void range(int start, int end, final HgChangelog.Inspector inspector) {
		RevlogStream.Inspector i = new RevlogStream.Inspector() {
			
			public void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, byte[] data) {
				Changeset cset = Changeset.parse(data, 0, data.length);
				// XXX there's no guarantee for Changeset.Callback that distinct instance comes each time, consider instance reuse
				inspector.next(revisionNumber, Nodeid.fromBinary(nodeid, 0), cset);
			}
		};
		content.iterate(start, end, true, i);
	}

	public List<Changeset> range(int start, int end) {
		final ArrayList<Changeset> rv = new ArrayList<Changeset>(end - start + 1);
		RevlogStream.Inspector i = new RevlogStream.Inspector() {
			
			public void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, byte[] data) {
				Changeset cset = Changeset.parse(data, 0, data.length);
				rv.add(cset);
			}
		};
		content.iterate(start, end, true, i);
		return rv; 
	}

	public void range(final HgChangelog.Inspector inspector, final int... revisions) {
		if (revisions == null || revisions.length == 0) {
			return;
		}
		RevlogStream.Inspector i = new RevlogStream.Inspector() {
			
			public void next(int revisionNumber, int actualLen, int baseRevision, int linkRevision, int parent1Revision, int parent2Revision, byte[] nodeid, byte[] data) {
				if (Arrays.binarySearch(revisions, revisionNumber) >= 0) {
					Changeset cset = Changeset.parse(data, 0, data.length);
					inspector.next(revisionNumber, Nodeid.fromBinary(nodeid, 0), cset);
				}
			}
		};
		Arrays.sort(revisions);
		content.iterate(revisions[0], revisions[revisions.length - 1], true, i);
	}

	
	public interface Inspector {
		// TODO describe whether cset is new instance each time
		void next(int revisionNumber, Nodeid nodeid, Changeset cset);
	}


	/**
	 * Entry in the Changelog
	 */
	public static class Changeset implements Cloneable /* for those that would like to keep a copy */{
		// TODO immutable
		private/* final */Nodeid manifest;
			private String user;
			private String comment;
			private List<String> files; // unmodifiable collection (otherwise #files() and implicit #clone() shall be revised)
			private Date time;
			private int timezone;
			private Map<String, String> extras;

			/**
			 * @see mercurial/changelog.py:read()
			 * 
			 * <pre>
			 *         format used:
				 *         nodeid\n        : manifest node in ascii
				 *         user\n          : user, no \n or \r allowed
				 *         time tz extra\n : date (time is int or float, timezone is int)
				 *                         : extra is metadatas, encoded and separated by '\0'
				 *                         : older versions ignore it
				 *         files\n\n       : files modified by the cset, no \n or \r allowed
				 *         (.*)            : comment (free text, ideally utf-8)
				 * 
				 *         changelog v0 doesn't use extra
				 * </pre>
				 */
					private Changeset() {
					}

					public Nodeid manifest() {
						return manifest;
					}

					public String user() {
						return user;
					}

					public String comment() {
						return comment;
					}

					public List<String> files() {
						return files;
					}

					public Date date() {
						return time;
					}

					public String dateString() {
						// XXX keep once formatted? Perhaps, there's faster way to set up calendar/time zone?
						StringBuilder sb = new StringBuilder(30);
						Formatter f = new Formatter(sb, Locale.US);
						TimeZone tz = TimeZone.getTimeZone("GMT");
						// apparently timezone field records number of seconds time differs from UTC,
						// i.e. value to substract from time to get UTC time. Calendar seems to add 
						// timezone offset to UTC, instead, hence sign change.
						tz.setRawOffset(timezone * -1000);
						Calendar c = Calendar.getInstance(tz, Locale.US);
						c.setTime(time);
						f.format("%ta %<tb %<td %<tH:%<tM:%<tS %<tY %<tz", c);
						return sb.toString();
					}

					public Map<String, String> extras() {
						return extras;
					}

					public String branch() {
						return extras.get("branch");
					}

					@Override
					public String toString() {
						StringBuilder sb = new StringBuilder();
						sb.append("Changeset {");
						sb.append("User: ").append(user).append(", ");
						sb.append("Comment: ").append(comment).append(", ");
						sb.append("Manifest: ").append(manifest).append(", ");
						sb.append("Date: ").append(time).append(", ");
						sb.append("Files: ").append(files.size());
						for (String s : files) {
							sb.append(", ").append(s);
						}
						if (extras != null) {
							sb.append(", Extra: ").append(extras);
						}
						sb.append("}");
						return sb.toString();
					}

					@Override
					public Changeset clone() {
						try {
							return (Changeset) super.clone();
						} catch (CloneNotSupportedException ex) {
							throw new InternalError(ex.toString());
						}
					}

					public static Changeset parse(byte[] data, int offset, int length) {
						Changeset rv = new Changeset();
						rv.init(data, offset, length);
						return rv;
					}

					/* package-local */void init(byte[] data, int offset, int length) {
						final int bufferEndIndex = offset + length;
						final byte lineBreak = (byte) '\n';
						int breakIndex1 = indexOf(data, lineBreak, offset, bufferEndIndex);
						if (breakIndex1 == -1) {
							throw new IllegalArgumentException("Bad Changeset data");
						}
						Nodeid _nodeid = Nodeid.fromAscii(data, 0, breakIndex1);
						int breakIndex2 = indexOf(data, lineBreak, breakIndex1 + 1, bufferEndIndex);
						if (breakIndex2 == -1) {
							throw new IllegalArgumentException("Bad Changeset data");
						}
						String _user = new String(data, breakIndex1 + 1, breakIndex2 - breakIndex1 - 1);
						int breakIndex3 = indexOf(data, lineBreak, breakIndex2 + 1, bufferEndIndex);
						if (breakIndex3 == -1) {
							throw new IllegalArgumentException("Bad Changeset data");
						}
						String _timeString = new String(data, breakIndex2 + 1, breakIndex3 - breakIndex2 - 1);
						int space1 = _timeString.indexOf(' ');
						if (space1 == -1) {
							throw new IllegalArgumentException("Bad Changeset data");
						}
						int space2 = _timeString.indexOf(' ', space1 + 1);
						if (space2 == -1) {
							space2 = _timeString.length();
						}
						long unixTime = Long.parseLong(_timeString.substring(0, space1)); // XXX Float, perhaps
						int _timezone = Integer.parseInt(_timeString.substring(space1 + 1, space2));
						// XXX not sure need to add timezone here - I can't figure out whether Hg keeps GMT time, and records timezone just for info, or unixTime is taken local
						// on commit and timezone is recorded to adjust it to UTC.
						Date _time = new Date(unixTime * 1000);
								String _extras = space2 < _timeString.length() ? _timeString.substring(space2 + 1) : null;
								Map<String, String> _extrasMap;
								if (_extras == null) {
									_extrasMap = Collections.singletonMap("branch", "default");
								} else {
									_extrasMap = new HashMap<String, String>();
									for (String pair : _extras.split("\00")) {
										int eq = pair.indexOf(':');
											// FIXME need to decode key/value, @see changelog.py:decodeextra
											_extrasMap.put(pair.substring(0, eq), pair.substring(eq + 1));
									}
									if (!_extrasMap.containsKey("branch")) {
										_extrasMap.put("branch", "default");
									}
									_extrasMap = Collections.unmodifiableMap(_extrasMap);
								}

								//
								int lastStart = breakIndex3 + 1;
								int breakIndex4 = indexOf(data, lineBreak, lastStart, bufferEndIndex);
								ArrayList<String> _files = null;
								if (breakIndex4 > lastStart) {
									// if breakIndex4 == lastStart, we already found \n\n and hence there are no files (e.g. merge revision)
									_files = new ArrayList<String>(5);
									while (breakIndex4 != -1 && breakIndex4 + 1 < bufferEndIndex) {
										_files.add(new String(data, lastStart, breakIndex4 - lastStart));
										lastStart = breakIndex4 + 1;
										if (data[breakIndex4 + 1] == lineBreak) {
											// found \n\n
											break;
										} else {
											breakIndex4 = indexOf(data, lineBreak, lastStart, bufferEndIndex);
										}
									}
									if (breakIndex4 == -1 || breakIndex4 >= bufferEndIndex) {
										throw new IllegalArgumentException("Bad Changeset data");
									}
								} else {
									breakIndex4--;
								}
								String _comment;
								try {
									_comment = new String(data, breakIndex4 + 2, bufferEndIndex - breakIndex4 - 2, "UTF-8");
									// FIXME respect ui.fallbackencoding and try to decode if set
								} catch (UnsupportedEncodingException ex) {
									_comment = "";
									throw new IllegalStateException("Could hardly happen");
								}
								// change this instance at once, don't leave it partially changes in case of error
								this.manifest = _nodeid;
								this.user = _user;
								this.time = _time;
								this.timezone = _timezone;
								this.files = _files == null ? Collections.<String> emptyList() : Collections.unmodifiableList(_files);
								this.comment = _comment;
								this.extras = _extrasMap;
					}

					private static int indexOf(byte[] src, byte what, int startOffset, int endIndex) {
						for (int i = startOffset; i < endIndex; i++) {
							if (src[i] == what) {
								return i;
							}
						}
						return -1;
					}
	}

}