/*
    * Copyright (C) 2008, 2013 Shawn O. Pearce <spearce@spearce.org> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  
  package org.eclipse.jgit.transport;
  
  import java.io.Serializable;
  import java.text.MessageFormat;
  import java.util.Objects;
  
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.Constants;
  import org.eclipse.jgit.lib.Ref;
  
  /**
   * Describes how refs in one repository copy into another repository.
   * <p>
   * A ref specification provides matching support and limited rules to rewrite a
   * reference in one repository to another reference in another repository.
   */
  public class RefSpec implements Serializable {
  	private static final long serialVersionUID = 1L;
  
  	/**
  	 * Suffix for wildcard ref spec component, that indicate matching all refs
  	 * with specified prefix.
  	 */
  	public static final String WILDCARD_SUFFIX = "/*"; //$NON-NLS-1$
  
  	/**
  	 * Check whether provided string is a wildcard ref spec component.
  	 *
  	 * @param s
  	 *            ref spec component - string to test. Can be null.
  	 * @return true if provided string is a wildcard ref spec component.
  	 */
  	public static boolean isWildcard(String s) {
  		return s != null && s.contains("*"); //$NON-NLS-1$
  	}
  
  	/** Does this specification ask for forced updated (rewind/reset)? */
  	private boolean force;
  
  	/** Is this specification actually a wildcard match? */
  	private boolean wildcard;
  
  	/** Is this the special ":" RefSpec? */
  	private boolean matching;
  
  	/** Is this a negative refspec. */
  	private boolean negative;
  
  	/**
  	 * How strict to be about wildcards.
  	 *
  	 * @since 4.5
  	 */
  	public enum WildcardMode {
  		/**
  		 * Reject refspecs with an asterisk on the source side and not the
  		 * destination side or vice versa. This is the mode used by FetchCommand
  		 * and PushCommand to create a one-to-one mapping between source and
  		 * destination refs.
  		 */
  		REQUIRE_MATCH,
  		/**
  		 * Allow refspecs with an asterisk on only one side. This can create a
  		 * many-to-one mapping between source and destination refs, so
  		 * expandFromSource and expandFromDestination are not usable in this
  		 * mode.
  		 */
  		ALLOW_MISMATCH
  	}
  
  	/** Whether a wildcard is allowed on one side but not the other. */
  	private WildcardMode allowMismatchedWildcards;
  
  	/** Name of the ref(s) we would copy from. */
  	private String srcName;
  
  	/** Name of the ref(s) we would copy into. */
  	private String dstName;
  
  	/**
  	 * Construct an empty RefSpec.
  	 * <p>
  	 * A newly created empty RefSpec is not suitable for use in most
  	 * applications, as at least one field must be set to match a source name.
  	 */
  	public RefSpec() {
  		matching = false;
  		force = false;
  		wildcard = false;
 		srcName = Constants.HEAD;
 		dstName = null;
 		negative =false;
 		allowMismatchedWildcards = WildcardMode.REQUIRE_MATCH;
 	}
 
 	/**
 	 * Parse a ref specification for use during transport operations.
 	 * <p>
 	 * {@link RefSpec}s can be regular or negative, regular RefSpecs indicate
 	 * what to include in transport operations while negative RefSpecs indicate
 	 * what to exclude in fetch.
 	 * <p>
 	 * Negative {@link RefSpec}s can't be force, must have only source or
 	 * destination. Wildcard patterns are also supported in negative RefSpecs
 	 * but they can not go with {@code WildcardMode.REQUIRE_MATCH} because they
 	 * are natually one to many mappings.
 	 *
 	 * <p>
 	 * Specifications are typically one of the following forms:
 	 * <ul>
 	 * <li><code>refs/heads/master</code></li>
 	 * <li><code>refs/heads/master:refs/remotes/origin/master</code></li>
 	 * <li><code>refs/heads/*:refs/remotes/origin/*</code></li>
 	 * <li><code>+refs/heads/master</code></li>
 	 * <li><code>+refs/heads/master:refs/remotes/origin/master</code></li>
 	 * <li><code>+refs/heads/*:refs/remotes/origin/*</code></li>
 	 * <li><code>+refs/pull/&#42;/head:refs/remotes/origin/pr/*</code></li>
 	 * <li><code>:refs/heads/master</code></li>
 	 * </ul>
 	 *
 	 * If the wildcard mode allows mismatches, then these ref specs are also
 	 * valid:
 	 * <ul>
 	 * <li><code>refs/heads/*</code></li>
 	 * <li><code>refs/heads/*:refs/heads/master</code></li>
 	 * </ul>
 	 *
 	 * Negative specifications are usually like:
 	 * <ul>
 	 * <li><code>^:refs/heads/master</code></li>
 	 * <li><code>^refs/heads/*</code></li>
 	 * </ul>
 	 *
 	 * @param spec
 	 *            string describing the specification.
 	 * @param mode
 	 *            whether to allow a wildcard on one side without a wildcard on
 	 *            the other.
 	 * @throws java.lang.IllegalArgumentException
 	 *             the specification is invalid.
 	 * @since 4.5
 	 */
 	public RefSpec(String spec, WildcardMode mode) {
 		this.allowMismatchedWildcards = mode;
 		String s = spec;
 
 		if (s.startsWith("^+") || s.startsWith("+^")) {
 			throw new IllegalArgumentException(
 					JGitText.get().invalidNegativeAndForce);
 		}
 
 		if (s.startsWith("+")) { //$NON-NLS-1$
 			force = true;
 			s = s.substring(1);
 		}
 
 		if(s.startsWith("^")) {
 			negative = true;
 			s = s.substring(1);
 		}
 
 		boolean matchPushSpec = false;
 		final int c = s.lastIndexOf(':');
 		if (c == 0) {
 			s = s.substring(1);
 			if (s.isEmpty()) {
 				matchPushSpec = true;
 				wildcard = true;
 				srcName = Constants.R_HEADS + '*';
 				dstName = srcName;
 			} else {
 				if (isWildcard(s)) {
 					wildcard = true;
 					if (mode == WildcardMode.REQUIRE_MATCH) {
 						throw new IllegalArgumentException(MessageFormat
 								.format(JGitText.get().invalidWildcards, spec));
 					}
 				}
 				dstName = checkValid(s);
 			}
 		} else if (c > 0) {
 			String src = s.substring(0, c);
 			String dst = s.substring(c + 1);
 			if (isWildcard(src) && isWildcard(dst)) {
 				// Both contain wildcard
 				wildcard = true;
 			} else if (isWildcard(src) || isWildcard(dst)) {
 				wildcard = true;
 				if (mode == WildcardMode.REQUIRE_MATCH)
 					throw new IllegalArgumentException(MessageFormat
 							.format(JGitText.get().invalidWildcards, spec));
 			}
 			srcName = checkValid(src);
 			dstName = checkValid(dst);
 		} else {
 			if (isWildcard(s)) {
 				if (mode == WildcardMode.REQUIRE_MATCH) {
 					throw new IllegalArgumentException(MessageFormat
 							.format(JGitText.get().invalidWildcards, spec));
 				}
 				wildcard = true;
 			}
 			srcName = checkValid(s);
 		}
 
 		// Negative refspecs must only have dstName or srcName.
 		if (isNegative()) {
 			if (isNullOrEmpty(srcName) && isNullOrEmpty(dstName)) {
 				throw new IllegalArgumentException(MessageFormat
 						.format(JGitText.get().invalidRefSpec, spec));
 			}
 			if (!isNullOrEmpty(srcName) && !isNullOrEmpty(dstName)) {
 				throw new IllegalArgumentException(MessageFormat
 						.format(JGitText.get().invalidRefSpec, spec));
 			}
 			if(wildcard && mode == WildcardMode.REQUIRE_MATCH) {
 				throw new IllegalArgumentException(MessageFormat
 						.format(JGitText.get().invalidRefSpec, spec));}
 		}
 		matching = matchPushSpec;
 	}
 
 	/**
 	 * Parse a ref specification for use during transport operations.
 	 * <p>
 	 * Specifications are typically one of the following forms:
 	 * <ul>
 	 * <li><code>refs/heads/master</code></li>
 	 * <li><code>refs/heads/master:refs/remotes/origin/master</code></li>
 	 * <li><code>refs/heads/*:refs/remotes/origin/*</code></li>
 	 * <li><code>+refs/heads/master</code></li>
 	 * <li><code>+refs/heads/master:refs/remotes/origin/master</code></li>
 	 * <li><code>+refs/heads/*:refs/remotes/origin/*</code></li>
 	 * <li><code>+refs/pull/&#42;/head:refs/remotes/origin/pr/*</code></li>
 	 * <li><code>:refs/heads/master</code></li>
 	 * </ul>
 	 *
 	 * @param spec
 	 *            string describing the specification.
 	 * @throws java.lang.IllegalArgumentException
 	 *             the specification is invalid.
 	 */
 	public RefSpec(String spec) {
 		this(spec, spec.startsWith("^") ? WildcardMode.ALLOW_MISMATCH
 				: WildcardMode.REQUIRE_MATCH);
 	}
 
 	private RefSpec(RefSpec p) {
 		matching = false;
 		force = p.isForceUpdate();
 		wildcard = p.isWildcard();
 		negative = p.isNegative();
 		srcName = p.getSource();
 		dstName = p.getDestination();
 		allowMismatchedWildcards = p.allowMismatchedWildcards;
 	}
 
 	/**
 	 * Tells whether this {@link RefSpec} is the special "matching" RefSpec ":"
 	 * for pushing.
 	 *
 	 * @return whether this is a "matching" RefSpec
 	 * @since 6.1
 	 */
 	public boolean isMatching() {
 		return matching;
 	}
 
 	/**
 	 * Check if this specification wants to forcefully update the destination.
 	 *
 	 * @return true if this specification asks for updates without merge tests.
 	 */
 	public boolean isForceUpdate() {
 		return force;
 	}
 
 	/**
 	 * Create a new RefSpec with a different force update setting.
 	 *
 	 * @param forceUpdate
 	 *            new value for force update in the returned instance.
 	 * @return a new RefSpec with force update as specified.
 	 */
 	public RefSpec setForceUpdate(boolean forceUpdate) {
 		final RefSpec r = new RefSpec(this);
 		if (forceUpdate && isNegative()) {
 			throw new IllegalArgumentException(
 					JGitText.get().invalidNegativeAndForce);
 		}
 		r.matching = matching;
 		r.force = forceUpdate;
 		return r;
 	}
 
 	/**
 	 * Check if this specification is actually a wildcard pattern.
 	 * <p>
 	 * If this is a wildcard pattern then the source and destination names
 	 * returned by {@link #getSource()} and {@link #getDestination()} will not
 	 * be actual ref names, but instead will be patterns.
 	 *
 	 * @return true if this specification could match more than one ref.
 	 */
 	public boolean isWildcard() {
 		return wildcard;
 	}
 
 	/**
 	 * Check if this specification is a negative one.
 	 *
 	 * @return true if this specification is negative.
 	 * @since 6.2
 	 */
 	public boolean isNegative() {
 		return negative;
 	}
 
 	/**
 	 * Get the source ref description.
 	 * <p>
 	 * During a fetch this is the name of the ref on the remote repository we
 	 * are fetching from. During a push this is the name of the ref on the local
 	 * repository we are pushing out from.
 	 *
 	 * @return name (or wildcard pattern) to match the source ref.
 	 */
 	public String getSource() {
 		return srcName;
 	}
 
 	/**
 	 * Create a new RefSpec with a different source name setting.
 	 *
 	 * @param source
 	 *            new value for source in the returned instance.
 	 * @return a new RefSpec with source as specified.
 	 * @throws java.lang.IllegalStateException
 	 *             There is already a destination configured, and the wildcard
 	 *             status of the existing destination disagrees with the
 	 *             wildcard status of the new source.
 	 */
 	public RefSpec setSource(String source) {
 		final RefSpec r = new RefSpec(this);
 		r.srcName = checkValid(source);
 		if (isWildcard(r.srcName) && r.dstName == null)
 			throw new IllegalStateException(JGitText.get().destinationIsNotAWildcard);
 		if (isWildcard(r.srcName) != isWildcard(r.dstName))
 			throw new IllegalStateException(JGitText.get().sourceDestinationMustMatch);
 		return r;
 	}
 
 	/**
 	 * Get the destination ref description.
 	 * <p>
 	 * During a fetch this is the local tracking branch that will be updated
 	 * with the new ObjectId after fetching is complete. During a push this is
 	 * the remote ref that will be updated by the remote's receive-pack process.
 	 * <p>
 	 * If null during a fetch no tracking branch should be updated and the
 	 * ObjectId should be stored transiently in order to prepare a merge.
 	 * <p>
 	 * If null during a push, use {@link #getSource()} instead.
 	 *
 	 * @return name (or wildcard) pattern to match the destination ref.
 	 */
 	public String getDestination() {
 		return dstName;
 	}
 
 	/**
 	 * Create a new RefSpec with a different destination name setting.
 	 *
 	 * @param destination
 	 *            new value for destination in the returned instance.
 	 * @return a new RefSpec with destination as specified.
 	 * @throws java.lang.IllegalStateException
 	 *             There is already a source configured, and the wildcard status
 	 *             of the existing source disagrees with the wildcard status of
 	 *             the new destination.
 	 */
 	public RefSpec setDestination(String destination) {
 		final RefSpec r = new RefSpec(this);
 		r.dstName = checkValid(destination);
 		if (isWildcard(r.dstName) && r.srcName == null)
 			throw new IllegalStateException(JGitText.get().sourceIsNotAWildcard);
 		if (isWildcard(r.srcName) != isWildcard(r.dstName))
 			throw new IllegalStateException(JGitText.get().sourceDestinationMustMatch);
 		return r;
 	}
 
 	/**
 	 * Create a new RefSpec with a different source/destination name setting.
 	 *
 	 * @param source
 	 *            new value for source in the returned instance.
 	 * @param destination
 	 *            new value for destination in the returned instance.
 	 * @return a new RefSpec with destination as specified.
 	 * @throws java.lang.IllegalArgumentException
 	 *             The wildcard status of the new source disagrees with the
 	 *             wildcard status of the new destination.
 	 */
 	public RefSpec setSourceDestination(String source, String destination) {
 		if (isWildcard(source) != isWildcard(destination))
 			throw new IllegalStateException(JGitText.get().sourceDestinationMustMatch);
 		final RefSpec r = new RefSpec(this);
 		r.wildcard = isWildcard(source);
 		r.srcName = source;
 		r.dstName = destination;
 		return r;
 	}
 
 	/**
 	 * Does this specification's source description match the ref name?
 	 *
 	 * @param r
 	 *            ref name that should be tested.
 	 * @return true if the names match; false otherwise.
 	 */
 	public boolean matchSource(String r) {
 		return match(r, getSource());
 	}
 
 	/**
 	 * Does this specification's source description match the ref?
 	 *
 	 * @param r
 	 *            ref whose name should be tested.
 	 * @return true if the names match; false otherwise.
 	 */
 	public boolean matchSource(Ref r) {
 		return match(r.getName(), getSource());
 	}
 
 	/**
 	 * Does this specification's destination description match the ref name?
 	 *
 	 * @param r
 	 *            ref name that should be tested.
 	 * @return true if the names match; false otherwise.
 	 */
 	public boolean matchDestination(String r) {
 		return match(r, getDestination());
 	}
 
 	/**
 	 * Does this specification's destination description match the ref?
 	 *
 	 * @param r
 	 *            ref whose name should be tested.
 	 * @return true if the names match; false otherwise.
 	 */
 	public boolean matchDestination(Ref r) {
 		return match(r.getName(), getDestination());
 	}
 
 	/**
 	 * Expand this specification to exactly match a ref name.
 	 * <p>
 	 * Callers must first verify the passed ref name matches this specification,
 	 * otherwise expansion results may be unpredictable.
 	 *
 	 * @param r
 	 *            a ref name that matched our source specification. Could be a
 	 *            wildcard also.
 	 * @return a new specification expanded from provided ref name. Result
 	 *         specification is wildcard if and only if provided ref name is
 	 *         wildcard.
 	 * @throws java.lang.IllegalStateException
 	 *             when the RefSpec was constructed with wildcard mode that
 	 *             doesn't require matching wildcards.
 	 */
 	public RefSpec expandFromSource(String r) {
 		if (allowMismatchedWildcards != WildcardMode.REQUIRE_MATCH) {
 			throw new IllegalStateException(
 					JGitText.get().invalidExpandWildcard);
 		}
 		return isWildcard() ? new RefSpec(this).expandFromSourceImp(r) : this;
 	}
 
 	private RefSpec expandFromSourceImp(String name) {
 		final String psrc = srcName, pdst = dstName;
 		wildcard = false;
 		srcName = name;
 		dstName = expandWildcard(name, psrc, pdst);
 		return this;
 	}
 
 	private static boolean isNullOrEmpty(String refName) {
 		return refName == null || refName.isEmpty();
 	}
 
 	/**
 	 * Expand this specification to exactly match a ref.
 	 * <p>
 	 * Callers must first verify the passed ref matches this specification,
 	 * otherwise expansion results may be unpredictable.
 	 *
 	 * @param r
 	 *            a ref that matched our source specification. Could be a
 	 *            wildcard also.
 	 * @return a new specification expanded from provided ref name. Result
 	 *         specification is wildcard if and only if provided ref name is
 	 *         wildcard.
 	 * @throws java.lang.IllegalStateException
 	 *             when the RefSpec was constructed with wildcard mode that
 	 *             doesn't require matching wildcards.
 	 */
 	public RefSpec expandFromSource(Ref r) {
 		return expandFromSource(r.getName());
 	}
 
 	/**
 	 * Expand this specification to exactly match a ref name.
 	 * <p>
 	 * Callers must first verify the passed ref name matches this specification,
 	 * otherwise expansion results may be unpredictable.
 	 *
 	 * @param r
 	 *            a ref name that matched our destination specification. Could
 	 *            be a wildcard also.
 	 * @return a new specification expanded from provided ref name. Result
 	 *         specification is wildcard if and only if provided ref name is
 	 *         wildcard.
 	 * @throws java.lang.IllegalStateException
 	 *             when the RefSpec was constructed with wildcard mode that
 	 *             doesn't require matching wildcards.
 	 */
 	public RefSpec expandFromDestination(String r) {
 		if (allowMismatchedWildcards != WildcardMode.REQUIRE_MATCH) {
 			throw new IllegalStateException(
 					JGitText.get().invalidExpandWildcard);
 		}
 		return isWildcard() ? new RefSpec(this).expandFromDstImp(r) : this;
 	}
 
 	private RefSpec expandFromDstImp(String name) {
 		final String psrc = srcName, pdst = dstName;
 		wildcard = false;
 		srcName = expandWildcard(name, pdst, psrc);
 		dstName = name;
 		return this;
 	}
 
 	/**
 	 * Expand this specification to exactly match a ref.
 	 * <p>
 	 * Callers must first verify the passed ref matches this specification,
 	 * otherwise expansion results may be unpredictable.
 	 *
 	 * @param r
 	 *            a ref that matched our destination specification.
 	 * @return a new specification expanded from provided ref name. Result
 	 *         specification is wildcard if and only if provided ref name is
 	 *         wildcard.
 	 * @throws java.lang.IllegalStateException
 	 *             when the RefSpec was constructed with wildcard mode that
 	 *             doesn't require matching wildcards.
 	 */
 	public RefSpec expandFromDestination(Ref r) {
 		return expandFromDestination(r.getName());
 	}
 
 	private boolean match(String name, String s) {
 		if (s == null)
 			return false;
 		if (isWildcard(s)) {
 			int wildcardIndex = s.indexOf('*');
 			String prefix = s.substring(0, wildcardIndex);
 			String suffix = s.substring(wildcardIndex + 1);
 			return name.length() > prefix.length() + suffix.length()
 					&& name.startsWith(prefix) && name.endsWith(suffix);
 		}
 		return name.equals(s);
 	}
 
 	private static String expandWildcard(String name, String patternA,
 			String patternB) {
 		int a = patternA.indexOf('*');
 		int trailingA = patternA.length() - (a + 1);
 		int b = patternB.indexOf('*');
 		String match = name.substring(a, name.length() - trailingA);
 		return patternB.substring(0, b) + match + patternB.substring(b + 1);
 	}
 
 	private static String checkValid(String spec) {
 		if (spec != null && !isValid(spec))
 			throw new IllegalArgumentException(MessageFormat.format(
 					JGitText.get().invalidRefSpec, spec));
 		return spec;
 	}
 
 	private static boolean isValid(String s) {
 		if (s.startsWith("/")) //$NON-NLS-1$
 			return false;
 		if (s.contains("//")) //$NON-NLS-1$
 			return false;
 		if (s.endsWith("/")) //$NON-NLS-1$
 			return false;
 		int i = s.indexOf('*');
 		if (i != -1) {
 			if (s.indexOf('*', i + 1) > i)
 				return false;
 		}
 		return true;
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public int hashCode() {
 		int hc = 0;
 		if (getSource() != null)
 			hc = hc * 31 + getSource().hashCode();
 		if (getDestination() != null)
 			hc = hc * 31 + getDestination().hashCode();
 		return hc;
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public boolean equals(Object obj) {
 		if (!(obj instanceof RefSpec))
 			return false;
 		final RefSpec b = (RefSpec) obj;
 		if (isForceUpdate() != b.isForceUpdate()) {
 			return false;
 		}
 		if(isNegative() != b.isNegative()) {
 			return false;
 		}
 		if (isMatching()) {
 			return b.isMatching();
 		} else if (b.isMatching()) {
 			return false;
 		}
 		return isWildcard() == b.isWildcard()
 				&& Objects.equals(getSource(), b.getSource())
 				&& Objects.equals(getDestination(), b.getDestination());
 	}
 
 	/** {@inheritDoc} */
 	@Override
 	public String toString() {
 		final StringBuilder r = new StringBuilder();
 		if (isForceUpdate()) {
 			r.append('+');
 		}
 		if(isNegative()) {
 			r.append('^');
 		}
 		if (isMatching()) {
 			r.append(':');
 		} else {
 			if (getSource() != null) {
 				r.append(getSource());
 			}
 			if (getDestination() != null) {
 				r.append(':');
 				r.append(getDestination());
 			}
 		}
 		return r.toString();
 	}
 }