/*
    * Copyright 2013 Grzegorz Slowikowski (gslowikowski at gmail dot com)
    *
    * 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.
   */
  
  package com.google.code.sbt;
  
  import java.io.IOException;
  import java.io.File;
  import java.util.ArrayList;
  import java.util.Arrays;
  import java.util.Collection;
  import java.util.HashSet;
  import java.util.Iterator;
  import java.util.List;
  import java.util.Map;
  import java.util.Set;
  
  import org.apache.maven.artifact.Artifact;
  import org.apache.maven.artifact.factory.ArtifactFactory;
  import org.apache.maven.artifact.repository.ArtifactRepository;
  import org.apache.maven.artifact.resolver.ArtifactNotFoundException;
  import org.apache.maven.artifact.resolver.ArtifactResolutionException;
  import org.apache.maven.artifact.resolver.ArtifactResolver;
  import org.apache.maven.artifact.resolver.filter.AndArtifactFilter;
  import org.apache.maven.artifact.resolver.filter.ArtifactFilter;
  import org.apache.maven.artifact.resolver.filter.ScopeArtifactFilter;
  import org.apache.maven.plugin.AbstractMojo;
  import org.apache.maven.plugin.MojoExecutionException;
  import org.apache.maven.plugin.MojoFailureException;
  import org.apache.maven.plugins.annotations.Component;
  import org.apache.maven.plugins.annotations.Parameter;
  import org.apache.maven.project.MavenProject;
  import org.apache.maven.project.MavenProjectBuilder;
  import org.apache.maven.project.ProjectBuildingException;
  import org.apache.maven.project.artifact.InvalidDependencyVersionException;
  
  import org.codehaus.plexus.util.DirectoryScanner;
  
  import scala.Option;
  
  import com.typesafe.zinc.Compiler;
  import com.typesafe.zinc.IncOptions;
  import com.typesafe.zinc.Inputs;
  import com.typesafe.zinc.Setup;
  
  /**
   * Abstract base class for SBT compilation mojos.
   * 
   * @author <a href="mailto:gslowikowski@gmail.com">Grzegorz Slowikowski</a>
   */
  public abstract class AbstractSBTCompileMojo
      extends AbstractMojo
  {
      /**
       * Default Scala library and compiler version used when no scalaVersion
       * configuration property specified and org.scala-lang:scala-library
       * dependency not found in the project.
       */
      public static final String DEFAULT_SCALA_VERSION = "2.10.2";
  
      /**
       * Scala artifacts "groupId".
       */
      private static final String SCALA_GROUPID = "org.scala-lang";
  
      /**
       * Scala library "artifactId".
       */
      private static final String SCALA_LIBRARY_ARTIFACTID = "scala-library";
  
      /**
       * Scala compiler "artifactId".
       */
      private static final String SCALA_COMPILER_ARTIFACTID = "scala-compiler";
  
      /**
       * SBT artifacts "groupId".
       */
      private static final String SBT_GROUP_ID = "com.typesafe.sbt";
  
      /**
       * SBT compile interface "artifactId".
       */
      private static final String COMPILER_INTERFACE_ARTIFACT_ID = "compiler-interface";
  
      /**
      * SBT compile interface sources "classifier".
      */
     private static final String COMPILER_INTERFACE_CLASSIFIER = "sources";
 
     /**
      * SBT interface "artifactId".
      */
     private static final String XSBTI_ARTIFACT_ID = "sbt-interface";
 
     /**
      * SBT compilation order.
      */
     private static final String COMPILE_ORDER = "mixed";
 
     /**
      * Run compilation in forked JVM.
      */
     private static final boolean FORK_JAVA = false;
 
     /**
      * Scala Compiler version.
      * 
      * If not specified:
      * a) version of project's org.scala-lang:scala-library dependency is used
      * b) if org.scala-lang:scala-library dependency does not exist in the project DEFAULT_SCALA_VERSION is used
      * 
      * @since 1.0.0
      */
     @Parameter( property = "scala.version" )
     private String scalaVersion;
 
     /**
      * SBT version
      * 
      * @since 1.0.0
      */
     @Parameter( property = "sbt.version", defaultValue = "0.13.0" )
     private String sbtVersion;
 
     /**
      * The -encoding argument for Scala and Java compilers.
      * 
      * @since 1.0.0
      */
     @Parameter( property = "project.build.sourceEncoding" )
     protected String sourceEncoding;
 
     /**
      * Additional parameters for Java compiler.
      * 
      * @since 1.0.0
      */
     @Parameter( property = "sbt.javacOptions", defaultValue = "-g" )
     protected String javacOptions;
 
     /**
      * Additional parameters for Scala compiler.
      * 
      * @since 1.0.0
      */
     @Parameter( property = "sbt.scalacOptions", defaultValue = "-deprecation -unchecked" )
     protected String scalacOptions;
 
     /**
      * <i>Maven Internal</i>: Project to interact with.
      */
     @Component
     protected MavenProject project;
 
     /**
      * Maven project builder used to resolve artifacts.
      */
     @Component
     protected MavenProjectBuilder mavenProjectBuilder;
 
     /**
      * All projects in the reactor.
      */
     @Parameter( defaultValue = "${reactorProjects}", required = true, readonly = true )
     protected List<MavenProject> reactorProjects;
 
     /**
      * Artifact factory used to look up artifacts in the remote repository.
      */
     @Component
     protected ArtifactFactory factory;
 
     /**
      * Artifact resolver used to resolve artifacts.
      */
     @Component
     protected ArtifactResolver resolver;
 
     /**
      * Location of the local repository.
      */
     @Parameter( property = "localRepository", readonly = true, required = true )
     protected ArtifactRepository localRepo;
 
     /**
      * List of Remote Repositories used by the resolver
      */
     @Parameter( property = "project.remoteArtifactRepositories", readonly = true, required = true )
     protected List<?> remoteRepos;
 
     /**
      * Performs compilation.
      * 
      * @throws MojoExecutionException if an unexpected problem occurs.
      * Throwing this exception causes a "BUILD ERROR" message to be displayed.
      * @throws MojoFailureException if an expected problem (such as a compilation failure) occurs.
      * Throwing this exception causes a "BUILD FAILURE" message to be displayed.
      */
     public void execute()
         throws MojoExecutionException, MojoFailureException
     {
         if ( "pom".equals( project.getPackaging() ) )
         {
             return;
         }
 
         try
         {
             long ts = System.currentTimeMillis();
             internalExecute();
             long te = System.currentTimeMillis();
             getLog().debug( String.format( "Mojo execution time: %d ms", te - ts ) );
         }
         catch ( IOException e )
         {
             throw new MojoExecutionException( "Scala compilation failed", e );
         }
     }
 
     /**
      * Actual compilation code, to be overridden.
      * 
      * @throws MojoExecutionException if an unexpected problem occurs.
      * @throws MojoFailureException if an expected problem (such as a compilation failure) occurs.
      * @throws IOException if an IO exception occurs.
      */
     protected void internalExecute()
         throws MojoExecutionException, MojoFailureException, IOException
     {
         List<String> compileSourceRoots = getCompileSourceRoots();
 
         if ( compileSourceRoots.isEmpty() )// ?
         {
             getLog().info( "No sources to compile" );
 
             return;
         }
 
         List<File> sourceRootDirs = new ArrayList<File>( compileSourceRoots.size() );
         for ( String compileSourceRoot : compileSourceRoots )
         {
             sourceRootDirs.add( new File( compileSourceRoot ) );
         }
 
         List<File> sourceFiles = getSourceFiles( sourceRootDirs );
         if ( sourceFiles.isEmpty() )
         {
             getLog().info( "No sources to compile" );
 
             return;
         }
 
         try
         {
             String resolvedScalaVersion = getScalaVersion();
 
             Artifact scalaLibraryArtifact =
                 getResolvedArtifact( SCALA_GROUPID, SCALA_LIBRARY_ARTIFACTID, resolvedScalaVersion );
             if ( scalaLibraryArtifact == null )
             {
                 throw new MojoExecutionException(
                                                   String.format( "Required %s:%s:%s:jar artifact not found",
                                                                  SCALA_GROUPID, SCALA_LIBRARY_ARTIFACTID,
                                                                  resolvedScalaVersion ) );
             }
 
             Artifact scalaCompilerArtifact =
                 getResolvedArtifact( SCALA_GROUPID, SCALA_COMPILER_ARTIFACTID, resolvedScalaVersion );
             if ( scalaCompilerArtifact == null )
             {
                 throw new MojoExecutionException(
                                                   String.format( "Required %s:%s:%s:jar artifact not found",
                                                                  SCALA_GROUPID, SCALA_COMPILER_ARTIFACTID,
                                                                  resolvedScalaVersion ) );
             }
 
             List<File> scalaExtraJars = getCompilerDependencies( scalaCompilerArtifact );
             scalaExtraJars.remove( scalaLibraryArtifact.getFile() );
 
             Artifact xsbtiArtifact = getResolvedArtifact( SBT_GROUP_ID, XSBTI_ARTIFACT_ID, sbtVersion );
             if ( xsbtiArtifact == null )
             {
                 throw new MojoExecutionException( String.format( "Required %s:%s:%s:jar dependency not found",
                                                                  SBT_GROUP_ID, XSBTI_ARTIFACT_ID, sbtVersion ) );
             }
 
             Artifact compilerInterfaceSrc =
                 getResolvedArtifact( SBT_GROUP_ID, COMPILER_INTERFACE_ARTIFACT_ID, sbtVersion,
                                      COMPILER_INTERFACE_CLASSIFIER );
             if ( compilerInterfaceSrc == null )
             {
                 throw new MojoExecutionException( String.format( "Required %s:%s:%s:%s:jar dependency not found",
                                                                  SBT_GROUP_ID, COMPILER_INTERFACE_ARTIFACT_ID,
                                                                  sbtVersion, COMPILER_INTERFACE_CLASSIFIER ) );
             }
 
             List<String> classpathElements = getClasspathElements();
             classpathElements.remove( getOutputDirectory().getAbsolutePath() );
             List<File> classpathFiles = new ArrayList<File>( classpathElements.size() );
             for ( String path : classpathElements )
             {
                 classpathFiles.add( new File( path ) );
             }
 
             SBTLogger sbtLogger = new SBTLogger( getLog() );
             Setup setup =
                 Setup.create( scalaCompilerArtifact.getFile(), scalaLibraryArtifact.getFile(), scalaExtraJars,
                               xsbtiArtifact.getFile(), compilerInterfaceSrc.getFile(), null, FORK_JAVA );
             if ( getLog().isDebugEnabled() )
             {
                 Setup.debug( setup, sbtLogger );
             }
             Compiler compiler = Compiler.create( setup, sbtLogger );
 
             Inputs inputs =
                 Inputs.create( classpathFiles, sourceFiles, getOutputDirectory(), getScalacOptions(),
                                getJavacOptions(), getAnalysisCacheFile(), getAnalysisCacheMap(), COMPILE_ORDER,
                                getIncOptions(), getLog().isDebugEnabled() /* mirrorAnalysisCache */ );
             if ( getLog().isDebugEnabled() )
             {
                 Inputs.debug( inputs, sbtLogger );
             }
 
             compiler.compile( inputs, sbtLogger );
         }
         catch ( xsbti.CompileFailed e )
         {
             throw new MojoFailureException( "Scala compilation failed", e );
         }
         catch ( ArtifactNotFoundException e )
         {
             throw new MojoFailureException( "Scala compilation failed", e );
         }
         catch ( ArtifactResolutionException e )
         {
             throw new MojoFailureException( "Scala compilation failed", e );
         }
         catch ( InvalidDependencyVersionException e )
         {
             throw new MojoFailureException( "Scala compilation failed", e );
         }
         catch ( ProjectBuildingException e )
         {
             throw new MojoFailureException( "Scala compilation failed", e );
         }
     }
 
     /**
      * Returns compilation classpath elements.
      * 
      * @return classpath elements
      */
     protected abstract List<String> getClasspathElements();
 
     /**
      * Returns compilation source roots.
      * 
      * @return source roots
      */
     protected abstract List<String> getCompileSourceRoots();
 
     /**
      * A list of inclusion filters for the compiler.
      * 
      * @return inclusion filters
      */
     protected abstract Set<String> getSourceIncludes();
     
     /**
      * A list of exclusion filters for the compiler.
      * 
      * @return exclusion filters
      */
     protected abstract Set<String> getSourceExcludes();
     
     /**
      * Returns output directory.
      * 
      * @return output directory
      */
     protected abstract File getOutputDirectory();
 
     /**
      * Returns incremental compilation analysis cache file.
      * 
      * @return analysis cache file
      */
     protected abstract File getAnalysisCacheFile();
 
     /**
      * Returns incremental compilation analyses map for reactor projects.
      * 
      * @return analysis cache map
      */
     protected abstract Map<File, File> getAnalysisCacheMap();
 
     private Artifact getDependencyArtifact( Collection<?> classPathArtifacts, String groupId, String artifactId,
                                               String type )
     {
         Artifact result = null;
         for ( Iterator<?> iter = classPathArtifacts.iterator(); iter.hasNext(); )
         {
             Artifact artifact = (Artifact) iter.next();
             if ( groupId.equals( artifact.getGroupId() ) && artifactId.equals( artifact.getArtifactId() )
                 && type.equals( artifact.getType() ) )
             {
                 result = artifact;
                 break;
             }
         }
         return result;
     }
 
     private List<File> getSourceFiles( List<File> sourceRootDirs )
     {
         List<File> sourceFiles = new ArrayList<File>();
 
         Set<String> sourceIncludes = getSourceIncludes();
         if ( sourceIncludes.isEmpty() )
         {
             sourceIncludes.add( "**/*.java" );
             sourceIncludes.add( "**/*.scala" );
         }
         Set<String> sourceExcludes = getSourceExcludes();
 
         DirectoryScanner scanner = new DirectoryScanner();
         scanner.setIncludes( sourceIncludes.toArray( new String[sourceIncludes.size()] ) );
         if ( !sourceExcludes.isEmpty() )
         {
             scanner.setExcludes( sourceExcludes.toArray( new String[sourceExcludes.size()] ) );
         }
         scanner.addDefaultExcludes();
 
         for ( File dir : sourceRootDirs )
         {
             if ( dir.isDirectory() )
             {
                 scanner.setBasedir( dir );
                 scanner.scan();
                 String[] includedFileNames = scanner.getIncludedFiles();
                 for ( String includedFileName : includedFileNames )
                 {
                     File tmpAbsFile = new File( dir, includedFileName ).getAbsoluteFile(); // ?
                     sourceFiles.add( tmpAbsFile );
                 }
             }
         }
         // scalac is sensible to scala file order, file system can't guarantee file order => unreproductible build error
         // across platform
         // to guarantee reproductible command line we order file by path (os dependend).
         // Collections.sort( sourceFiles );
         return sourceFiles;
     }
 
     private String getScalaVersion()
     {
         String result = scalaVersion;
         if ( result == null || result.length() == 0 )
         {
             result = DEFAULT_SCALA_VERSION;
             Artifact scalaLibraryArtifact =
                             getDependencyArtifact( project.getArtifacts(), SCALA_GROUPID, SCALA_LIBRARY_ARTIFACTID, "jar" );
             if ( scalaLibraryArtifact != null )
             {
                 result = scalaLibraryArtifact.getVersion();
             }
         }
         return result;
     }
 
     private List<String> getScalacOptions()
     {
         List<String> result = new ArrayList<String>( Arrays.asList( scalacOptions.split( " " ) ) );
         if ( !result.contains( "-encoding" ) && sourceEncoding != null && sourceEncoding.length() > 0 )
         {
             result.add( "-encoding" );
             result.add( sourceEncoding );
         }
         return result;
     }
 
     private List<String> getJavacOptions()
     {
         List<String> result = new ArrayList<String>( Arrays.asList( javacOptions.split( " " ) ) );
         if ( !result.contains( "-encoding" ) && sourceEncoding != null && sourceEncoding.length() > 0 )
         {
             result.add( "-encoding" );
             result.add( sourceEncoding );
         }
         return result;
     }
 
     private File defaultAnalysisDirectory( MavenProject p )
     {
         return new File( p.getBuild().getDirectory(), "cache" );
     }
 
     /**
      * Returns incremental main compilation analysis cache file location for a project.
      * 
      * @param p Maven project
      * @return analysis cache file location
      */
     protected File defaultAnalysisCacheFile( MavenProject p )
     {
         return new File( defaultAnalysisDirectory( p ), "compile" );
     }
 
     /**
      * Returns incremental test compilation analysis cache file location for a project.
      * 
      * @param p Maven project
      * @return analysis cache file location
      */
     protected File defaultTestAnalysisCacheFile( MavenProject p )
     {
         return new File( defaultAnalysisDirectory( p ), "test-compile" );
     }
 
     private IncOptions getIncOptions()
     {
         // comment from SBT (sbt.inc.IncOptions.scala):
         // After which step include whole transitive closure of invalidated source files.
         //
         // comment from Zinc (com.typesafe.zinc.Settings.scala):
         // Steps before transitive closure
         int transitiveStep = 3;
 
         // comment from SBT (sbt.inc.IncOptions.scala):
         // What's the fraction of invalidated source files when we switch to recompiling
         // all files and giving up incremental compilation altogether. That's useful in
         // cases when probability that we end up recompiling most of source files but
         // in multiple steps is high. Multi-step incremental recompilation is slower
         // than recompiling everything in one step.
         //
         // comment from Zinc (com.typesafe.zinc.Settings.scala):
         // Limit before recompiling all sources
         double recompileAllFraction = 0.5d;
 
         // comment from SBT (sbt.inc.IncOptions.scala):
         // Print very detailed information about relations, such as dependencies between source files.
         //
         // comment from Zinc (com.typesafe.zinc.Settings.scala):
         // Enable debug logging of analysis relations
         boolean relationsDebug = false;
 
         // comment from SBT (sbt.inc.IncOptions.scala):
         // Enable tools for debugging API changes. At the moment this option is unused but in the
         // future it will enable for example:
         //   - disabling API hashing and API minimization (potentially very memory consuming)
         //   - diffing textual API representation which helps understanding what kind of changes
         //     to APIs are visible to the incremental compiler
         //
         // comment from Zinc (com.typesafe.zinc.Settings.scala):
         // Enable analysis API debugging
         boolean apiDebug = false;
 
         // comment from SBT (sbt.inc.IncOptions.scala):
         // Controls context size (in lines) displayed when diffs are produced for textual API
         // representation.
         //
         // This option is used only when `apiDebug == true`.
         //
         // comment from Zinc (com.typesafe.zinc.Settings.scala):
         // Diff context size (in lines) for API debug
         int apiDiffContextSize = 5;
 
         // comment from SBT (sbt.inc.IncOptions.scala):
         // The directory where we dump textual representation of APIs. This method might be called
         // only if apiDebug returns true. This is unused option at the moment as the needed functionality
         // is not implemented yet.
         //
         // comment from Zinc (com.typesafe.zinc.Settings.scala):
         // Destination for analysis API dump
         Option<File> apiDumpDirectory = Option.empty();
 
         // comment from Zinc (com.typesafe.zinc.Settings.scala):
         // Restore previous class files on failure
         boolean transactional = false;
 
         // comment from Zinc (com.typesafe.zinc.Settings.scala):
         // Backup location (if transactional)
         Option<File> backup = Option.empty();
 
         return new IncOptions( transitiveStep, recompileAllFraction, relationsDebug, apiDebug, apiDiffContextSize, apiDumpDirectory, transactional, backup );
     }
 
     // Private utility methods
 
     private Artifact getResolvedArtifact( String groupId, String artifactId, String version )
         throws ArtifactNotFoundException, ArtifactResolutionException
     {
         Artifact artifact = factory.createArtifact( groupId, artifactId, version, Artifact.SCOPE_RUNTIME, "jar" );
         resolver.resolve( artifact, remoteRepos, localRepo );
         return artifact;
     }
 
     private Artifact getResolvedArtifact( String groupId, String artifactId, String version, String classifier )
         throws ArtifactNotFoundException, ArtifactResolutionException
     {
         Artifact artifact = factory.createArtifactWithClassifier( groupId, artifactId, version, "jar", classifier );
         resolver.resolve( artifact, remoteRepos, localRepo );
         return artifact;
     }
 
     private List<File> getCompilerDependencies( Artifact scalaCompilerArtifact )
         throws ArtifactNotFoundException, ArtifactResolutionException, InvalidDependencyVersionException,
         ProjectBuildingException
     {
         List<File> d = new ArrayList<File>();
         for ( Artifact artifact : getAllDependencies( scalaCompilerArtifact ) )
         {
             d.add( artifact.getFile() );
         }
         return d;
     }
 
     private Set<Artifact> getAllDependencies( Artifact artifact )
         throws ArtifactNotFoundException, ArtifactResolutionException, InvalidDependencyVersionException,
         ProjectBuildingException
     {
         Set<Artifact> result = new HashSet<Artifact>();
         MavenProject p = mavenProjectBuilder.buildFromRepository( artifact, remoteRepos, localRepo );
         Set<Artifact> d = resolveDependencyArtifacts( p );
         result.addAll( d );
         for ( Artifact dependency : d )
         {
             Set<Artifact> transitive = getAllDependencies( dependency );
             result.addAll( transitive );
         }
         return result;
     }
 
     /**
      * This method resolves the dependency artifacts from the project.
      * 
      * @param theProject The POM.
      * @return resolved set of dependency artifacts.
      * @throws ArtifactResolutionException
      * @throws ArtifactNotFoundException
      * @throws InvalidDependencyVersionException
      */
     private Set<Artifact> resolveDependencyArtifacts( MavenProject theProject )
         throws ArtifactNotFoundException, ArtifactResolutionException, InvalidDependencyVersionException
     {
         AndArtifactFilter filter = new AndArtifactFilter();
         filter.add( new ScopeArtifactFilter( Artifact.SCOPE_TEST ) );
         filter.add( new ArtifactFilter()
         {
             public boolean include( Artifact artifact )
             {
                 return !artifact.isOptional();
             }
         } );
         // TODO follow the dependenciesManagement and override rules
         Set<Artifact> artifacts = theProject.createArtifacts( factory, Artifact.SCOPE_RUNTIME, filter );
         for ( Artifact artifact : artifacts )
         {
             resolver.resolve( artifact, remoteRepos, localRepo );
         }
         return artifacts;
     }
 
 }