package org.apache.maven.scm.provider.svn;

/*
 * Copyright 2003-2005 The Apache Software Foundation.
 *
 * 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
 *
 *      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 org.apache.maven.scm.provider.svn.repository.SvnScmProviderRepository;
import org.codehaus.plexus.util.StringUtils;

public class SvnTagBranchUtils
{

    public final static String[] REVISION_SPECIFIERS = new String[] { "HEAD", "BASE", "COMMITTED", "PREV" };

    public final static String SVN_TRUNK = "trunk";

    public final static String SVN_BRANCHES = "branches";

    public final static String SVN_TAGS = "tags";

    public final static String[] SVN_BASE_DIRS = new String[] { SVN_TRUNK, SVN_BRANCHES, SVN_TAGS };

    /**
     * Simple helper function to concatenate two paths together with a "/".
     * Handles trailing / on basePath. 
     * Returns no trailing "/" if the addlPath is null
     */
    static String appendPath( String basePath, String addlPath )
    {
        basePath = StringUtils.stripEnd( basePath, "/" );

        if ( StringUtils.isEmpty( addlPath ) )
        {
            return basePath;
        }
        else
        {
            return basePath + "/" + StringUtils.stripStart( addlPath, "/" );
        }
    }

    /** Returns the project root for the given repository url, 
     * where "project root" is the root of the /trunk, /branches, /tags 
     * directories
     * 
     * @param repoPath  Repository path/url to be searched
     * @return
     */
    public static String getProjectRoot( String repoPath )
    {
        for ( int i = 0; i < SVN_BASE_DIRS.length; i++ )
        {
            String base = "/" + SVN_BASE_DIRS[i];
            int pos = repoPath.indexOf( base + "/" );
            if ( pos >= 0 )
            {
                return repoPath.substring( 0, pos );
            }
            else if ( repoPath.endsWith( base ) )
            {
                return repoPath.substring( 0, repoPath.length() - base.length() );
            }
        }

        // At this point we were unable to locate the project root of this url
        // so assume that the repository url specified is the project root
        return appendPath( repoPath, null );
    }

    /**
     * Resolves a tag to a repository url.
     * 
     * 
     * @param repository  the repository to use as a base for tag resolution
     * @param branchTagName  tag name
     * @return
     * @see #resolveUrl(SvnScmProviderRepository, String, String)
     */
    public static String resolveTagUrl( SvnScmProviderRepository repository, String tag )
    {
        return resolveUrl( repository, SVN_TAGS, tag );
    }

    /**
     * Resolves a tag to a repository url.
     * 
     * 
     * @param repository  the repository to use as a base for tag resolution
     * @param branchTagName  tag name
     * @return
     * @see #resolveUrl(SvnScmProviderRepository, String, String)
     */
    public static String resolveBranchUrl( SvnScmProviderRepository repository, String tag )
    {
        return resolveUrl( repository, SVN_BRANCHES, tag );
    }

    /**
     * Resolves a tag or branch name to a repository url.<br>
     * If the <code>branchTagName</code> is an absolute URL, that value is returned. 
     * (i.e. http://foo.com/svn/myproject/tags/my-tag)<br>
     *
     * If the repository has a {@link SvnScmProviderRepository#getTagBase()} specified, 
     * the tag is simply appended to the tagBase value. Note that at this time, we are using 
     * the tagBase as a base for both branches and tags.<br>
     * 
     * If the <code>branchTagName</code> contains a branch/tag specifier (i.e. "/branches", "/tags", "/trunk"),
     * the <code>branchTagName</code> is appended to the <code>projectRoot</code> without adding the subdir.<br> 
     * Else, the result is in the format of <code>projectRoot/subdir/branchTagName</code> directory.<br>
     *
     * @param projectRoot   Project root to use when building the url.
     * @param subdir        Subdirectory to append to the project root 
     *                      (for branching use "branches", tags use "tags")
     * @param branchTagName Name of the actual branch or tag. Can be an absolute url, simple tag/branch name, 
     *                      or even contain a relative path to the root like "branches/my-branch"
     * @return
     */
    public static String resolveUrl( SvnScmProviderRepository repository, String subdir, String branchTagName )
    {
        String projectRoot = getProjectRoot( repository.getUrl() );
        branchTagName = StringUtils.strip( branchTagName, "/" );

        if ( StringUtils.isEmpty( branchTagName ) )
        {
            return null;
        }

        if ( branchTagName.indexOf( "://" ) >= 0 )
        {
            // branch/tag is already an absolute url so just return it. 
            return branchTagName;
        }

        // User has a tagBase specified so just return the name appended to the tagBase
        if ( StringUtils.isNotEmpty( repository.getTagBase() ) )
        {
            return appendPath( repository.getTagBase(), branchTagName );
        }

        // Look for any "branches/" or "tags/" specifiers in the branchTagName. If one occurs,
        // don't append the subdir to the projectRoot when appending the name
        for ( int i = 0; i < SVN_BASE_DIRS.length; i++ )
        {
            if ( branchTagName.startsWith( SVN_BASE_DIRS[i] + "/" ) )
            {
                return appendPath( projectRoot, branchTagName );
            }
        }

        return appendPath( appendPath( projectRoot, subdir ), branchTagName );
    }

    /* Helper function that does the checking for {@link #isRevisionSpecifier} 
     */
    private static boolean checkRevisionArg( String arg )
    {
        if ( StringUtils.isNumeric( arg ) || ( arg.startsWith( "{" ) && arg.endsWith( "}" ) ) )
        {
            return true;
        }

        for ( int i = 0; i < REVISION_SPECIFIERS.length; i++ )
        {
            if ( REVISION_SPECIFIERS[i].equalsIgnoreCase( arg ) )
            {
                return true;
            }
        }

        return false;
    }

    /**
     * Returns whether the supplied tag refers to an actual revision or 
     * is specifying a tag/branch url in the repository.  
     * According to the subversion documentation, the following are valid revision specifiers:
     *  NUMBER       revision number
     *  "{" DATE "}" revision at start of the date
     *  "HEAD"       latest in repository
     *  "BASE"       base rev of item's working copy
     *  "COMMITTED"  last commit at or before BASE
     *  "PREV"
     *  
     *  For command such as diff, the revision argument can be in the format of:
     *  IDENTIFIER:IDENTIFIER   where IDENTIFIER is one of the args listed above
     */
    public static boolean isRevisionSpecifier( String tag )
    {
        if ( StringUtils.isEmpty( tag ) )
        {
            return false;
        }

        if ( checkRevisionArg( tag ) )
        {
            return true;
        }

        String[] parts = StringUtils.split( tag, ":" );
        if ( parts.length == 2 && StringUtils.isNotEmpty( parts[0] ) && StringUtils.isNotEmpty( parts[1] ) )
        {
            return checkRevisionArg( parts[0] ) && checkRevisionArg( parts[1] );
        }

        return false;
    }
}