/*
 * Copyright 2002-2016 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.security.core;

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>
 *
 * NOTE: This is a copy from
 * https://github.com/apache/maven/blob/maven-3.6.3/maven-artifact/src/main/java/org/apache/maven/artifact/versioning/ComparableVersion.java
 *
 * 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>
 */
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
			}

			return switch (item.getType()) {
				case INT_ITEM -> Integer.compare(value, ((IntItem) item).value);
				case LONG_ITEM, BIGINTEGER_ITEM -> -1;
				case STRING_ITEM -> 1; // 1.1 > 1-sp
				case LIST_ITEM -> 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
			}

			return switch (item.getType()) {
				case INT_ITEM -> 1;
				case LONG_ITEM -> Long.compare(value, ((LongItem) item).value);
				case BIGINTEGER_ITEM -> -1;
				case STRING_ITEM -> 1; // 1.1 > 1-sp
				case LIST_ITEM -> 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
			}

			return switch (item.getType()) {
				case INT_ITEM, LONG_ITEM -> 1;
				case BIGINTEGER_ITEM -> value.compareTo(((BigIntegerItem) item).value);
				case STRING_ITEM -> 1; // 1.1 > 1-sp
				case LIST_ITEM -> 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();
		}

		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
				value = switch (value.charAt(0)) {
					case 'a' -> "alpha";
					case 'b' -> "beta";
					case 'm' -> "milestone";
					default -> value;
				};
			}
			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);
			}
			return switch (item.getType()) {
				case INT_ITEM, LONG_ITEM, BIGINTEGER_ITEM -> -1; // 1.any < 1.1 ?
				case STRING_ITEM ->
						comparableQualifier(value).compareTo(comparableQualifier(((StringItem) item).value));
				case LIST_ITEM -> -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();
		}

		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 {

		@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);
			}
			return switch (item.getType()) {
				case INT_ITEM, LONG_ITEM, BIGINTEGER_ITEM -> -1; // 1-1 < 1.0.x
				case STRING_ITEM -> 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) {
							yield result;
						}
					}
					yield 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);
	}

	@SuppressWarnings("checkstyle:innerassignment")
	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();
	}

	// CHECKSTYLE_OFF: LineLength
	/**
	 * Main to test version parsing and comparison.
	 * <p>
	 * To check how "1.2.7" compares to "1.2-SNAPSHOT", for example, you can issue
	 * <pre>java -jar ${maven.repo.local}/org/apache/maven/maven-artifact/${maven.version}/maven-artifact-${maven.version}.jar "1.2.7" "1.2-SNAPSHOT"</pre>
	 * command to command line. Result of given command will be something like this: <pre>
	 * Display parameters as parsed by Maven (in canonical form) and comparison result:
	 * 1. 1.2.7 == 1.2.7
	 *    1.2.7 &gt; 1.2-SNAPSHOT
	 * 2. 1.2-SNAPSHOT == 1.2-snapshot
	 * </pre>
	 * @param args the version strings to parse and compare. You can pass arbitrary number
	 * of version strings and always two adjacent will be compared
	 */
	// CHECKSTYLE_ON: LineLength
	public static void main(String... args) {
		System.out.println("Display parameters as parsed by Maven (in canonical form) and comparison result:");
		if (args.length == 0) {
			return;
		}

		ComparableVersion prev = null;
		int i = 1;
		for (String version : args) {
			ComparableVersion c = new ComparableVersion(version);

			if (prev != null) {
				int compare = prev.compareTo(c);
				System.out.println("   " + prev.toString() + ' ' + ((compare == 0) ? "==" : ((compare < 0) ? "<" : ">"))
						+ ' ' + version);
			}

			System.out.println(String.valueOf(i++) + ". " + version + " == " + c.getCanonical());

			prev = c;
		}
	}

}
