package aQute.bnd.version.maven;

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.
 */

import java.math.BigInteger;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Deque;
import java.util.Iterator;
import java.util.List;
import java.util.Locale;
import java.util.Properties;

/**
 * <p>
 * Generic implementation of version comparison.
 * </p>
 * Features:
 * <ul>
 * <li>mixing of '<code>-</code>' (hyphen) and '<code>.</code>' (dot)
 * separators,</li>
 * <li>transition between characters and digits also constitutes a separator:
 * <code>1.0alpha1 =&gt; [1, 0, alpha, 1]</code></li>
 * <li>unlimited number of version components,</li>
 * <li>version components in the text can be digits or strings,</li>
 * <li>strings are checked for well-known qualifiers and the qualifier ordering
 * is used for version ordering. Well-known qualifiers (case insensitive) are:
 * <ul>
 * <li><code>alpha</code> or <code>a</code></li>
 * <li><code>beta</code> or <code>b</code></li>
 * <li><code>milestone</code> or <code>m</code></li>
 * <li><code>rc</code> or <code>cr</code></li>
 * <li><code>snapshot</code></li>
 * <li><code>(the empty string)</code> or <code>ga</code> or
 * <code>final</code></li>
 * <li><code>sp</code></li>
 * </ul>
 * Unknown qualifiers are considered after known qualifiers, with lexical order
 * (always case insensitive),</li>
 * <li>a hyphen usually precedes a qualifier, and is always less important than
 * something preceded with a dot.</li>
 * </ul>
 *
 * @see <a href=
 *      "https://cwiki.apache.org/confluence/display/MAVENOLD/Versioning">"Versioning"
 *      on Maven Wiki</a>
 * @author <a href="mailto:kenney@apache.org">Kenney Westerhof</a>
 * @author <a href="mailto:hboutemy@apache.org">Hervé Boutemy</a>
 */
public class ComparableVersion implements Comparable<ComparableVersion> {
	private static final int	MAX_INTITEM_LENGTH	= 9;

	private static final int	MAX_LONGITEM_LENGTH	= 18;

	private String				value;

	private String				canonical;

	private ListItem			items;

	private interface Item {
		int	INT_ITEM		= 3;
		int	LONG_ITEM		= 4;
		int	BIGINTEGER_ITEM	= 0;
		int	STRING_ITEM		= 1;
		int	LIST_ITEM		= 2;

		int compareTo(Item item);

		int getType();

		boolean isNull();
	}

	/**
	 * Represents a numeric item in the version item list that can be
	 * represented with an int.
	 */
	private static class IntItem implements Item {
		private final int			value;

		public static final IntItem	ZERO	= new IntItem();

		private IntItem() {
			this.value = 0;
		}

		IntItem(String str) {
			this.value = Integer.parseInt(str);
		}

		@Override
		public int getType() {
			return INT_ITEM;
		}

		@Override
		public boolean isNull() {
			return value == 0;
		}

		@Override
		public int compareTo(Item item) {
			if (item == null) {
				return (value == 0) ? 0 : 1; // 1.0 == 1, 1.1 > 1
			}

			switch (item.getType()) {
				case INT_ITEM :
					int itemValue = ((IntItem) item).value;
					return (value < itemValue) ? -1 : ((value == itemValue) ? 0 : 1);
				case LONG_ITEM :
				case BIGINTEGER_ITEM :
					return -1;

				case STRING_ITEM :
					return 1; // 1.1 > 1-sp

				case LIST_ITEM :
					return 1; // 1.1 > 1-1

				default :
					throw new IllegalStateException("invalid item: " + item.getClass());
			}
		}

		@Override
		public boolean equals(Object o) {
			if (this == o) {
				return true;
			}
			if (o == null || getClass() != o.getClass()) {
				return false;
			}

			IntItem intItem = (IntItem) o;

			return value == intItem.value;

		}

		@Override
		public int hashCode() {
			return value;
		}

		@Override
		public String toString() {
			return Integer.toString(value);
		}
	}

	/**
	 * Represents a numeric item in the version item list that can be
	 * represented with a long.
	 */
	private static class LongItem implements Item {
		private final long value;

		LongItem(String str) {
			this.value = Long.parseLong(str);
		}

		@Override
		public int getType() {
			return LONG_ITEM;
		}

		@Override
		public boolean isNull() {
			return value == 0;
		}

		@Override
		public int compareTo(Item item) {
			if (item == null) {
				return (value == 0) ? 0 : 1; // 1.0 == 1, 1.1 > 1
			}

			switch (item.getType()) {
				case INT_ITEM :
					return 1;
				case LONG_ITEM :
					long itemValue = ((LongItem) item).value;
					return (value < itemValue) ? -1 : ((value == itemValue) ? 0 : 1);
				case BIGINTEGER_ITEM :
					return -1;

				case STRING_ITEM :
					return 1; // 1.1 > 1-sp

				case LIST_ITEM :
					return 1; // 1.1 > 1-1

				default :
					throw new IllegalStateException("invalid item: " + item.getClass());
			}
		}

		@Override
		public boolean equals(Object o) {
			if (this == o) {
				return true;
			}
			if (o == null || getClass() != o.getClass()) {
				return false;
			}

			LongItem longItem = (LongItem) o;

			return value == longItem.value;

		}

		@Override
		public int hashCode() {
			return (int) (value ^ (value >>> 32));
		}

		@Override
		public String toString() {
			return Long.toString(value);
		}
	}

	/**
	 * Represents a numeric item in the version item list.
	 */
	private static class BigIntegerItem implements Item {
		private final BigInteger value;

		BigIntegerItem(String str) {
			this.value = new BigInteger(str);
		}

		@Override
		public int getType() {
			return BIGINTEGER_ITEM;
		}

		@Override
		public boolean isNull() {
			return BigInteger.ZERO.equals(value);
		}

		@Override
		public int compareTo(Item item) {
			if (item == null) {
				return BigInteger.ZERO.equals(value) ? 0 : 1; // 1.0 == 1, 1.1 >
																// 1
			}

			switch (item.getType()) {
				case INT_ITEM :
				case LONG_ITEM :
					return 1;

				case BIGINTEGER_ITEM :
					return value.compareTo(((BigIntegerItem) item).value);

				case STRING_ITEM :
					return 1; // 1.1 > 1-sp

				case LIST_ITEM :
					return 1; // 1.1 > 1-1

				default :
					throw new IllegalStateException("invalid item: " + item.getClass());
			}
		}

		@Override
		public boolean equals(Object o) {
			if (this == o) {
				return true;
			}
			if (o == null || getClass() != o.getClass()) {
				return false;
			}

			BigIntegerItem that = (BigIntegerItem) o;

			return value.equals(that.value);

		}

		@Override
		public int hashCode() {
			return value.hashCode();
		}

		@Override
		public String toString() {
			return value.toString();
		}
	}

	/**
	 * Represents a string in the version item list, usually a qualifier.
	 */
	private static class StringItem implements Item {
		private static final List<String>	QUALIFIERS	= Arrays.asList("alpha", "beta", "milestone", "rc", "snapshot",
			"", "sp");

		private static final Properties		ALIASES		= new Properties();
		static {
			ALIASES.put("ga", "");
			ALIASES.put("final", "");
			ALIASES.put("release", "");
			ALIASES.put("cr", "rc");
		}

		/**
		 * A comparable value for the empty-string qualifier. This one is used
		 * to determine if a given qualifier makes the version older than one
		 * without a qualifier, or more recent.
		 */
		private static final String	RELEASE_VERSION_INDEX	= String.valueOf(QUALIFIERS.indexOf(""));

		private final String		value;

		StringItem(String value, boolean followedByDigit) {
			if (followedByDigit && value.length() == 1) {
				// a1 = alpha-1, b1 = beta-1, m1 = milestone-1
				switch (value.charAt(0)) {
					case 'a' :
						value = "alpha";
						break;
					case 'b' :
						value = "beta";
						break;
					case 'm' :
						value = "milestone";
						break;
					default :
				}
			}
			this.value = ALIASES.getProperty(value, value);
		}

		@Override
		public int getType() {
			return STRING_ITEM;
		}

		@Override
		public boolean isNull() {
			return (comparableQualifier(value).compareTo(RELEASE_VERSION_INDEX) == 0);
		}

		/**
		 * Returns a comparable value for a qualifier. This method takes into
		 * account the ordering of known qualifiers then unknown qualifiers with
		 * lexical ordering. just returning an Integer with the index here is
		 * faster, but requires a lot of if/then/else to check for -1 or
		 * QUALIFIERS.size and then resort to lexical ordering. Most comparisons
		 * are decided by the first character, so this is still fast. If more
		 * characters are needed then it requires a lexical sort anyway.
		 *
		 * @param qualifier
		 * @return an equivalent value that can be used with lexical comparison
		 */
		public static String comparableQualifier(String qualifier) {
			int i = QUALIFIERS.indexOf(qualifier);

			return i == -1 ? (QUALIFIERS.size() + "-" + qualifier) : String.valueOf(i);
		}

		@Override
		public int compareTo(Item item) {
			if (item == null) {
				// 1-rc < 1, 1-ga > 1
				return comparableQualifier(value).compareTo(RELEASE_VERSION_INDEX);
			}
			switch (item.getType()) {
				case INT_ITEM :
				case LONG_ITEM :
				case BIGINTEGER_ITEM :
					return -1; // 1.any < 1.1 ?

				case STRING_ITEM :
					return comparableQualifier(value).compareTo(comparableQualifier(((StringItem) item).value));

				case LIST_ITEM :
					return -1; // 1.any < 1-1

				default :
					throw new IllegalStateException("invalid item: " + item.getClass());
			}
		}

		@Override
		public boolean equals(Object o) {
			if (this == o) {
				return true;
			}
			if (o == null || getClass() != o.getClass()) {
				return false;
			}

			StringItem that = (StringItem) o;

			return value.equals(that.value);

		}

		@Override
		public int hashCode() {
			return value.hashCode();
		}

		@Override
		public String toString() {
			return value;
		}
	}

	/**
	 * Represents a version list item. This class is used both for the global
	 * item list and for sub-lists (which start with '-(number)' in the version
	 * specification).
	 */
	private static class ListItem extends ArrayList<Item> implements Item {
		/**
		 *
		 */
		private static final long serialVersionUID = 1L;

		@Override
		public int getType() {
			return LIST_ITEM;
		}

		@Override
		public boolean isNull() {
			return (size() == 0);
		}

		void normalize() {
			for (int i = size() - 1; i >= 0; i--) {
				Item lastItem = get(i);

				if (lastItem.isNull()) {
					// remove null trailing items: 0, "", empty list
					remove(i);
				} else if (!(lastItem instanceof ListItem)) {
					break;
				}
			}
		}

		@Override
		public int compareTo(Item item) {
			if (item == null) {
				if (size() == 0) {
					return 0; // 1-0 = 1- (normalize) = 1
				}
				Item first = get(0);
				return first.compareTo(null);
			}
			switch (item.getType()) {
				case INT_ITEM :
				case LONG_ITEM :
				case BIGINTEGER_ITEM :
					return -1; // 1-1 < 1.0.x

				case STRING_ITEM :
					return 1; // 1-1 > 1-sp

				case LIST_ITEM :
					Iterator<Item> left = iterator();
					Iterator<Item> right = ((ListItem) item).iterator();

					while (left.hasNext() || right.hasNext()) {
						Item l = left.hasNext() ? left.next() : null;
						Item r = right.hasNext() ? right.next() : null;

						// if this is shorter, then invert the compare and mul
						// with -1
						int result = l == null ? (r == null ? 0 : -1 * r.compareTo(l)) : l.compareTo(r);

						if (result != 0) {
							return result;
						}
					}

					return 0;

				default :
					throw new IllegalStateException("invalid item: " + item.getClass());
			}
		}

		@Override
		public String toString() {
			StringBuilder buffer = new StringBuilder();
			for (Item item : this) {
				if (buffer.length() > 0) {
					buffer.append((item instanceof ListItem) ? '-' : '.');
				}
				buffer.append(item);
			}
			return buffer.toString();
		}
	}

	public ComparableVersion(String version) {
		parseVersion(version);
	}

	public final void parseVersion(String version) {
		this.value = version;

		items = new ListItem();

		version = version.toLowerCase(Locale.ENGLISH);

		ListItem list = items;

		Deque<Item> stack = new ArrayDeque<>();
		stack.push(list);

		boolean isDigit = false;

		int startIndex = 0;

		for (int i = 0; i < version.length(); i++) {
			char c = version.charAt(i);

			if (c == '.') {
				if (i == startIndex) {
					list.add(IntItem.ZERO);
				} else {
					list.add(parseItem(isDigit, version.substring(startIndex, i)));
				}
				startIndex = i + 1;
			} else if (c == '-') {
				if (i == startIndex) {
					list.add(IntItem.ZERO);
				} else {
					list.add(parseItem(isDigit, version.substring(startIndex, i)));
				}
				startIndex = i + 1;

				list.add(list = new ListItem());
				stack.push(list);
			} else if (Character.isDigit(c)) {
				if (!isDigit && i > startIndex) {
					list.add(new StringItem(version.substring(startIndex, i), true));
					startIndex = i;

					list.add(list = new ListItem());
					stack.push(list);
				}

				isDigit = true;
			} else {
				if (isDigit && i > startIndex) {
					list.add(parseItem(true, version.substring(startIndex, i)));
					startIndex = i;

					list.add(list = new ListItem());
					stack.push(list);
				}

				isDigit = false;
			}
		}

		if (version.length() > startIndex) {
			list.add(parseItem(isDigit, version.substring(startIndex)));
		}

		while (!stack.isEmpty()) {
			list = (ListItem) stack.pop();
			list.normalize();
		}
	}

	private static Item parseItem(boolean isDigit, String buf) {
		if (isDigit) {
			buf = stripLeadingZeroes(buf);
			if (buf.length() <= MAX_INTITEM_LENGTH) {
				// lower than 2^31
				return new IntItem(buf);
			} else if (buf.length() <= MAX_LONGITEM_LENGTH) {
				// lower than 2^63
				return new LongItem(buf);
			}
			return new BigIntegerItem(buf);
		}
		return new StringItem(buf, false);
	}

	private static String stripLeadingZeroes(String buf) {
		if (buf == null || buf.isEmpty()) {
			return "0";
		}
		for (int i = 0; i < buf.length(); ++i) {
			char c = buf.charAt(i);
			if (c != '0') {
				return buf.substring(i);
			}
		}
		return buf;
	}

	@Override
	public int compareTo(ComparableVersion o) {
		return items.compareTo(o.items);
	}

	@Override
	public String toString() {
		return value;
	}

	public String getCanonical() {
		if (canonical == null) {
			canonical = items.toString();
		}
		return canonical;
	}

	@Override
	public boolean equals(Object o) {
		return (o instanceof ComparableVersion) && items.equals(((ComparableVersion) o).items);
	}

	@Override
	public int hashCode() {
		return items.hashCode();
	}
}
