package hudson.util;

import hudson.Util;
import hudson.model.TaskListener;
import org.apache.tools.ant.DirectoryScanner;
import org.apache.tools.ant.types.FileSet;

import java.io.File;
import java.io.FileFilter;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.io.Serializable;

import static hudson.Util.fixEmpty;

/**
 * Visits a directory and its contents and pass them to the {@link FileVisitor}.
 *
 * A {@link DirScanner} encapsulates the logic of how it filters files in the directory. It is also remotable.
 *
 * @since 1.343
 * @see FileVisitor
 */
public abstract class DirScanner implements Serializable {
    /**
     * Scans the given directory and pass files onto the given visitor.
     */
    public abstract void scan(File dir, FileVisitor visitor) throws IOException;

    /**
     * Scans everything recursively.
     */
    public static class Full extends DirScanner {
        private void scan(File f, String path, FileVisitor visitor) throws IOException {
            if (f.canRead()) {
                if (visitor.understandsSymlink()) {
                    try {
                        String target = Util.resolveSymlink(f, TaskListener.NULL);
                        if (target!=null) {
                            visitor.visitSymlink(f,target,path+f.getName());
                            return;
                        }
                    } catch (InterruptedException e) {
                        throw (IOException)new InterruptedIOException().initCause(e);
                    }
                }
                visitor.visit(f,path+f.getName());
                if(f.isDirectory()) {
                    for( File child : f.listFiles() )
                        scan(child,path+f.getName()+'/',visitor);
                }
            }
        }

        public void scan(File dir, FileVisitor visitor) throws IOException {
            scan(dir,"",visitor);
        }

        private static final long serialVersionUID = 1L;
    }

    /**
     * Scans by filtering things out from {@link FileFilter}
     */
    public static class Filter extends Full {
        private final FileFilter filter;

        public Filter(FileFilter filter) {
            this.filter = filter;
        }

        @Override
        public void scan(File dir, FileVisitor visitor) throws IOException {
            super.scan(dir,visitor.with(filter));
        }

        private static final long serialVersionUID = 1L;
    }

    /**
     * Scans by using Ant GLOB syntax.
     */
    public static class Glob extends DirScanner {
        private final String includes, excludes;

        public Glob(String includes, String excludes) {
            this.includes = includes;
            this.excludes = excludes;
        }

        public void scan(File dir, FileVisitor visitor) throws IOException {
            if(fixEmpty(includes)==null && excludes==null) {
                // optimization
                new Full().scan(dir,visitor);
                return;
            }

            FileSet fs = Util.createFileSet(dir,includes,excludes);

            if(dir.exists()) {
                DirectoryScanner ds = fs.getDirectoryScanner(new org.apache.tools.ant.Project());
                for( String f : ds.getIncludedFiles()) {
                    File file = new File(dir, f);
                    visitor.visit(file,f);
                }
            }
        }

        private static final long serialVersionUID = 1L;
    }

    private static final long serialVersionUID = 1L;
}