/**
 * (c) 2011, Alejandro Serrano
 * Released under the terms of the EPL.
 */
package net.sf.eclipsefp.haskell.ui.internal.refactoring.participants;

import java.util.ArrayList;
import java.util.HashSet;
import java.util.List;
import java.util.Set;
import net.sf.eclipsefp.haskell.core.cabalmodel.CabalSyntax;
import net.sf.eclipsefp.haskell.core.cabalmodel.PackageDescription;
import net.sf.eclipsefp.haskell.core.cabalmodel.PackageDescriptionLoader;
import net.sf.eclipsefp.haskell.core.cabalmodel.PackageDescriptionStanza;
import net.sf.eclipsefp.haskell.core.cabalmodel.RealValuePosition;
import net.sf.eclipsefp.haskell.scion.client.ScionInstance;
import net.sf.eclipsefp.haskell.util.FileUtil;
import org.eclipse.core.resources.IFile;
import org.eclipse.core.resources.IProject;
import org.eclipse.core.resources.IResource;
import org.eclipse.core.resources.IResourceVisitor;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.core.runtime.IPath;
import org.eclipse.core.runtime.Path;
import org.eclipse.jface.text.BadLocationException;
import org.eclipse.jface.text.IDocument;
import org.eclipse.jface.text.IRegion;
import org.eclipse.ui.editors.text.TextFileDocumentProvider;

/**
 * Utilities and shared changes creation for participants.
 * @author Alejandro Serrano
 *
 */
public class Util {

  public static Set<IPath> getPaths( final IProject project ) {
    HashSet<IPath> paths = new HashSet<IPath>();

    try {
      IFile cabalF = ScionInstance.getCabalFile( project );
      PackageDescription pd = PackageDescriptionLoader.load( cabalF );
      List<PackageDescriptionStanza> lpds = pd.getStanzas();
      for( PackageDescriptionStanza pds: lpds ) {
        String propList = pds.getProperties().get(
            CabalSyntax.FIELD_HS_SOURCE_DIRS.getCabalName().toLowerCase() );
        propList = propList == null ? "" : propList;
        List<String> props = PackageDescriptionLoader.parseList( propList );

        for (String prop : props) {
          IPath prefixPath = Path.fromPortableString( prop );
          paths.add( prefixPath );
        }
      }
    } catch (Exception e) {
      return new HashSet<IPath>();
    }

    return paths;
  }

  public static Set<IPath> getStanzaPaths( final IProject project,
      final IFile file ) {
    HashSet<IPath> paths = new HashSet<IPath>();

    try {
      IFile cabalF = ScionInstance.getCabalFile( project );
      PackageDescription pd = PackageDescriptionLoader.load( cabalF );
      List<PackageDescriptionStanza> lpds = pd.getStanzas();
      for( PackageDescriptionStanza pds: lpds ) {
        String propList = pds.getProperties().get(
            CabalSyntax.FIELD_HS_SOURCE_DIRS.getCabalName().toLowerCase() );
        propList = propList == null ? "" : propList;
        List<String> props = PackageDescriptionLoader.parseList( propList );

        // If the file is in one of these directories, we should change it
        boolean shouldBeAdded = false;
        for (String prop : props) {
          IPath prefixPath = Path.fromPortableString( prop );
          if (prefixPath.isPrefixOf( file.getProjectRelativePath() )) {
            shouldBeAdded = true;
          }
        }

        // If should be changed, add every directory in the stanza
        if (shouldBeAdded) {
          for (String prop : props) {
            IPath prefixPath = Path.fromPortableString( prop );
            paths.add( prefixPath );
          }
        }
      }
    } catch (Exception e) {
      return new HashSet<IPath>();
    }

    return paths;
  }

  public static String getModuleName( final IResource resource ) {
    return getModuleName( resource.getProject(),
        resource.getProjectRelativePath() );
  }

  public static List<IResource> getHaskellFiles( final IProject project,
      final IFile file ) {
    final ArrayList<IResource> resources = new ArrayList<IResource>();
    final Set<IPath> allowedPaths = getStanzaPaths( project, file );
    try {
      project.accept( new IResourceVisitor() {

        public boolean visit( final IResource resource ) {
          if( resource instanceof IFile && !( file.equals( resource ) )
              && FileUtil.hasHaskellExtension( resource )) {
            // Check if we are in one of the allowed paths
            for (IPath allowedPath : allowedPaths) {
              if (allowedPath.isPrefixOf( resource.getProjectRelativePath() )) {
                resources.add( resource );
                break;
              }
            }
          }
          return true;
        }
      } );
    } catch( Exception e ) {
      // Do nothing
    }
    return resources;
  }

  public static String getModuleName( final IProject project,
      final IPath projectRelativePath ) {
    String path = projectRelativePath.toPortableString();
    for( IPath prefix: getPaths( project ) ) {
      String prefixPath = prefix.toPortableString();
      if( path.startsWith( prefixPath ) ) {
        String filePath = path.substring( prefixPath.length() + 1 );
        if( filePath.endsWith( ".hs" ) ) {
          return filePath.substring( 0, filePath.length() - 3 ).replace( '/',
              '.' );
        } else if( filePath.endsWith( ".lhs" ) ) {
          return filePath.substring( 0, filePath.length() - 4 ).replace( '/',
              '.' );
        }
      }
    }

    return null;
  }

  public static int getModuleNameOffset( final IResource resource ) {
    TextFileDocumentProvider provider = new TextFileDocumentProvider();

    try {
      provider.connect( resource );
    } catch( CoreException e ) {
      return -1;
    }

    int offset = -1;
    try {
      IDocument doc = provider.getDocument( resource );
      int numberOfLines = doc.getNumberOfLines();
      for( int i = 0; i < numberOfLines; i++ ) {
        IRegion region = doc.getLineInformation( i );
        String text = doc.get( region.getOffset(), region.getLength() );
        String[] words = text.split( " " );
        if( words[ 0 ].equals( "module" ) ) {
          // We are in a module declaration
          String moduleName = words[ 1 ];
          if( moduleName.length() == 0 ) {
            moduleName = words[ 2 ];
          }
          int moduleNamePos = text.indexOf( moduleName );
          offset = region.getOffset() + moduleNamePos;
          break;
        }
      }
    } catch( BadLocationException e ) {
      // This should not happen
    } finally {
      provider.disconnect( resource );
    }

    return offset;
  }

  public static List<Integer> getImportModuleOffsets( final IResource resource,
      final String moduleName ) {
    TextFileDocumentProvider provider = new TextFileDocumentProvider();
    ArrayList<Integer> offsets = new ArrayList<Integer>();

    try {
      provider.connect( resource );
    } catch( CoreException e ) {
      return offsets;
    }

    try {
      IDocument doc = provider.getDocument( resource );
      int numberOfLines = doc.getNumberOfLines();
      for( int i = 0; i < numberOfLines; i++ ) {
        IRegion region = doc.getLineInformation( i );
        String text = doc.get( region.getOffset(), region.getLength() );
        String[] words = text.split( " " );

        for( int j = 0; j < words.length; j++ ) {
          if( words[ j ].equals( "module" ) ) {
            try {
              String mname = words[ j + 1 ];
              if( mname.length() == 0 ) {
                mname = words[ j + 2 ];
              }
              if( mname.equals( moduleName ) ) {
                int modulePos = text.indexOf( mname );
                offsets.add( region.getOffset() + modulePos );
              }
            } catch( Exception e ) {
              // We are out of bounds
            }
            break;
          } else if( words[ j ].equals( "import" ) ) {
            try {
              String mname = words[ j + 1 ];
              if( mname.length() == 0 ) {
                mname = words[ j + 2 ];
              }
              if( mname.equals( "qualified" ) ) {
                mname = words[ j + 3 ];
                if( mname.length() == 0 ) {
                  mname = words[ j + 4 ];
                }
              }
              if( mname.equals( moduleName ) ) {
                int modulePos = text.indexOf( mname );
                offsets.add( region.getOffset() + modulePos );
              }
            } catch( Exception e ) {
              // We are out of bounds
            }
            break;
          }
        }
      }
    } catch( BadLocationException e ) {
      // This should not happen
    } finally {
      provider.disconnect( resource );
    }

    return offsets;
  }

  public static String newCabalFile( final IProject project,
      final IFile oldFile, final String newModuleName ) {
    TextFileDocumentProvider provider = new TextFileDocumentProvider();
    String oldModuleName = getModuleName( oldFile );

    IFile cabalF = ScionInstance.getCabalFile( project );
    PackageDescription pd = null;
    try {
      pd = PackageDescriptionLoader.load( cabalF );
      provider.connect( cabalF );
    } catch( Exception e ) {
      return null;
    }

    IDocument doc = provider.getDocument( cabalF );
    try {
      List<PackageDescriptionStanza> lpds = pd.getStanzas();
      for( PackageDescriptionStanza pds: lpds ) {

        // Should we change this stanza?
        String srcList = pds.getProperties().get(
            CabalSyntax.FIELD_HS_SOURCE_DIRS.getCabalName().toLowerCase() );
        srcList = srcList == null ? "" : srcList;
        List<String> srcs = PackageDescriptionLoader.parseList( srcList );
        final Set<IPath> allowedPaths = getStanzaPaths( project, oldFile );
        boolean shouldBeChanged = false;
        for (String src : srcs) {
          IPath srcPath = Path.fromPortableString( src );
          if (allowedPaths.contains( srcPath )) {
            shouldBeChanged = true;
            break;
          }
        }
        if (!shouldBeChanged) {
          continue; // We should not
        }

        // Modules sections
        CabalSyntax[] elements = new CabalSyntax[] {
            CabalSyntax.FIELD_EXPOSED_MODULES, CabalSyntax.FIELD_OTHER_MODULES };
        for( CabalSyntax element: elements ) {
          pds = pd.getSameStanza( pds );
          String propList = pds.getProperties().get(
              element.getCabalName().toLowerCase() );
          propList = propList == null ? "" : propList;
          List<String> props = PackageDescriptionLoader.parseList( propList );
          if( props.indexOf( oldModuleName ) != -1 ) {
            RealValuePosition rvp = pds.removeFromPropertyList( element,
                oldModuleName );
            rvp.updateDocument( doc );
            pd = PackageDescriptionLoader.load( doc.get() );
            pds = pd.getSameStanza( pds );

            rvp = pds.addToPropertyList( element, newModuleName );
            rvp.updateDocument( doc );
            pd = PackageDescriptionLoader.load( doc.get() );
            pds = pd.getSameStanza( pds );
          }
        }

        // Main-is section
        String oldMainName = oldModuleName.replace( '.', '/' ) + ".hs";
        String newMainName = newModuleName.replace( '.', '/' ) + ".hs";
        pds = pd.getSameStanza( pds );
        String mainProp = pds.getProperties().get(
            CabalSyntax.FIELD_MAIN_IS.getCabalName().toLowerCase() );
        mainProp = mainProp == null ? "" : mainProp;
        if( oldMainName.equals( mainProp ) ) {
          RealValuePosition rvp = pds.update( CabalSyntax.FIELD_MAIN_IS,
              newMainName );
          rvp.updateDocument( doc );
          pd = PackageDescriptionLoader.load( doc.get() );
          pds = pd.getSameStanza( pds );
        }

      }
    } catch( Exception e ) {
      // Do nothing
    } finally {
      provider.disconnect( cabalF );
    }

    return doc.get();
  }

  public static String newRemoveModuleCabalFile( final IProject project,
      final IFile oldFile ) {
    TextFileDocumentProvider provider = new TextFileDocumentProvider();
    String oldModuleName = getModuleName( oldFile );

    IFile cabalF = ScionInstance.getCabalFile( project );
    PackageDescription pd = null;
    try {
      pd = PackageDescriptionLoader.load( cabalF );
      provider.connect( cabalF );
    } catch( Exception e ) {
      return null;
    }

    IDocument doc = provider.getDocument( cabalF );
    try {
      List<PackageDescriptionStanza> lpds = pd.getStanzas();
      for( PackageDescriptionStanza pds: lpds ) {

        // Should we change this stanza?
        String srcList = pds.getProperties().get(
            CabalSyntax.FIELD_HS_SOURCE_DIRS.getCabalName().toLowerCase() );
        srcList = srcList == null ? "" : srcList;
        List<String> srcs = PackageDescriptionLoader.parseList( srcList );
        final Set<IPath> allowedPaths = getStanzaPaths( project, oldFile );
        boolean shouldBeChanged = false;
        for (String src : srcs) {
          IPath srcPath = Path.fromPortableString( src );
          if (allowedPaths.contains( srcPath )) {
            shouldBeChanged = true;
            break;
          }
        }
        if (!shouldBeChanged) {
          continue; // We should not
        }

        // Modules sections
        CabalSyntax[] elements = new CabalSyntax[] {
            CabalSyntax.FIELD_EXPOSED_MODULES, CabalSyntax.FIELD_OTHER_MODULES };
        for( CabalSyntax element: elements ) {
          pds = pd.getSameStanza( pds );
          String propList = pds.getProperties().get(
              element.getCabalName().toLowerCase() );
          propList = propList == null ? "" : propList;
          List<String> props = PackageDescriptionLoader.parseList( propList );
          if( props.indexOf( oldModuleName ) != -1 ) {
            RealValuePosition rvp = pds.removeFromPropertyList( element,
                oldModuleName );
            rvp.updateDocument( doc );
            pd = PackageDescriptionLoader.load( doc.get() );
            pds = pd.getSameStanza( pds );
          }
        }

        // Main-is section
        String oldMainName = oldModuleName.replace( '.', '/' ) + ".hs";
        pds = pd.getSameStanza( pds );
        String mainProp = pds.getProperties().get(
            CabalSyntax.FIELD_MAIN_IS.getCabalName().toLowerCase() );
        mainProp = mainProp == null ? "" : mainProp;
        if( oldMainName.equals( mainProp ) ) {
          RealValuePosition rvp = pds.update( CabalSyntax.FIELD_MAIN_IS, "" );
          rvp.updateDocument( doc );
          pd = PackageDescriptionLoader.load( doc.get() );
          pds = pd.getSameStanza( pds );
        }

      }
    } catch( Exception e ) {
      // Do nothing
    } finally {
      provider.disconnect( cabalF );
    }

    return doc.get();
  }

  public static String newSourceFolderCabalFile(final IProject project,
      final IPath oldPath, final IPath newPath) {
    TextFileDocumentProvider provider = new TextFileDocumentProvider();
    IFile cabalF = ScionInstance.getCabalFile( project );
    PackageDescription pd = null;
    try {
      pd = PackageDescriptionLoader.load( cabalF );
      provider.connect( cabalF );
    } catch( Exception e ) {
      return null;
    }

    IDocument doc = provider.getDocument( cabalF );
    try {
      List<PackageDescriptionStanza> lpds = pd.getStanzas();
      for( PackageDescriptionStanza pds: lpds ) {

        // Should we change this stanza?
        String srcList = pds.getProperties().get(
            CabalSyntax.FIELD_HS_SOURCE_DIRS.getCabalName().toLowerCase() );
        srcList = srcList == null ? "" : srcList;
        List<String> srcs = PackageDescriptionLoader.parseList( srcList );
        for (String src : srcs) {
          IPath srcPath = Path.fromPortableString( src );
          if (srcPath.equals( oldPath )) {
            RealValuePosition rvp = pds.removeFromPropertyList(
                CabalSyntax.FIELD_HS_SOURCE_DIRS,
                oldPath.toPortableString() );
            rvp.updateDocument( doc );
            pd = PackageDescriptionLoader.load( doc.get() );
            pds = pd.getSameStanza( pds );

            rvp = pds.addToPropertyList(
                CabalSyntax.FIELD_HS_SOURCE_DIRS,
                newPath.toPortableString() );
            rvp.updateDocument( doc );
            pd = PackageDescriptionLoader.load( doc.get() );
            pds = pd.getSameStanza( pds );

            break;
          }
        }
      }
    } catch( Exception e ) {
      // Do nothing
    } finally {
      provider.disconnect( cabalF );
    }

    return doc.get();
  }
}