/**

 * Alt2XML

 * Copyright © 2014 František Kučera (frantovo.cz)

 *

 * This program is free software: you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation, version 3 of the License.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the

 * GNU General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program. If not, see <http://www.gnu.org/licenses/>.

 */

package cz.frantovo.alt2xml.in.fs;

import cz.frantovo.alt2xml.AbstractAlt2XmlReader;

import java.io.File;

import java.io.IOException;

import java.net.URI;

import java.net.URISyntaxException;

import java.nio.ByteBuffer;

import java.nio.file.Files;

import java.nio.file.LinkOption;

import java.nio.file.Path;

import java.nio.file.attribute.PosixFilePermission;

import java.nio.file.attribute.UserDefinedFileAttributeView;

import java.nio.file.spi.FileSystemProvider;

import java.util.List;

import java.util.ArrayList;

import java.util.Set;

import java.util.logging.Logger;

import org.xml.sax.Attributes;

import org.xml.sax.InputSource;

import org.xml.sax.SAXException;

import org.xml.sax.helpers.AttributesImpl;

/**

 * Reads filesystem – hierarchical structure of directories and files.

 *

 * @author Ing. František Kučera (frantovo.cz)

 */

public class Reader extends AbstractAlt2XmlReader {

	public static final String ROOT_ELEMENT = "fs";

	public static final String DIR_ELEMENT = "dir";

	public static final String FILE_ELEMENT = "file";

	public static final String XATTR_ELEMENT = "xattr";

	public static final String PERMISSIONS_ELEMENT = "mode";

	public static final String PERMISSIONS_U_ELEMENT = "user";

	public static final String PERMISSIONS_G_ELEMENT = "group";

	public static final String PERMISSIONS_O_ELEMENT = "others";

	public static final String NAME_ATTRIBUTE = "name";

	public static final String ABSOLUTE_PATH_ATTRIBUTE = "path";

	public static final String SIZE_ATTRIBUTE = "size";

	private static final Logger log = Logger.getLogger(Reader.class.getName());

	/**

	 * indentation level

	 */

	private int level = 0;

	@Override

	public void parse(InputSource input) throws IOException, SAXException {

		File dir = getFile(input.getSystemId());

		outputStart(dir);

		outputDir(dir);

		outputEnd();

	}

	private File getFile(String systemId) throws IOException {

		try {

			return new File(new URI(systemId));

		} catch (URISyntaxException e) {

			throw new IOException("Invalid dir URI", e);

		}

	}

	private String getAbsolutePath(File file) throws IOException {

		return file.getCanonicalFile().getAbsolutePath();

	}

	private Attributes singleAttribute(String name, int value) {

		AttributesImpl attributes = new AttributesImpl();

		addAttribute(attributes, name, value);

		return attributes;

	}

	private Attributes singleAttribute(String name, String value) {

		AttributesImpl attributes = new AttributesImpl();

		addAttribute(attributes, name, value);

		return attributes;

	}

	private void addAttribute(AttributesImpl attributes, String name, int value) {

		attributes.addAttribute(null, name, name, "xs:int", String.valueOf(value));

	}

	private void addAttribute(AttributesImpl attributes, String name, long value) {

		attributes.addAttribute(null, name, name, "xs:long", String.valueOf(value));

	}

	private void addAttribute(AttributesImpl attributes, String name, String value) {

		attributes.addAttribute(null, name, name, "xs:string", value);

	}

	private void outputStart(File root) throws SAXException, IOException {

		contentHandler.startDocument();

		contentHandler.lineBreak();

		contentHandler.startElement(null, null, ROOT_ELEMENT, singleAttribute(ABSOLUTE_PATH_ATTRIBUTE, getAbsolutePath(root)));

		contentHandler.lineBreak();

	}

	private void outputEnd() throws SAXException {

		contentHandler.endElement(null, null, ROOT_ELEMENT);

		contentHandler.lineBreak();

		contentHandler.endDocument();

	}

	private void outputFile(File file) throws SAXException, IOException {

		level++;

		AttributesImpl attributes = new AttributesImpl();

		addAttribute(attributes, NAME_ATTRIBUTE, file.getName());

		addAttribute(attributes, ABSOLUTE_PATH_ATTRIBUTE, getAbsolutePath(file));

		addAttribute(attributes, SIZE_ATTRIBUTE, file.length());

		contentHandler.indentation(level);

		contentHandler.startElement(null, null, FILE_ELEMENT, attributes);

		contentHandler.lineBreak();

		outputPermissions(file.toPath());

		outputExtendedAttributes(file);

		contentHandler.indentation(level);

		contentHandler.endElement(null, null, FILE_ELEMENT);

		contentHandler.lineBreak();

		level--;

	}

	private void outputDir(File dir) throws SAXException, IOException {

		level++;

		final File[] children = dir.listFiles();

		AttributesImpl attributes = new AttributesImpl();

		addAttribute(attributes, NAME_ATTRIBUTE, dir.getName());

		addAttribute(attributes, ABSOLUTE_PATH_ATTRIBUTE, getAbsolutePath(dir));

		addAttribute(attributes, SIZE_ATTRIBUTE, children.length);

		contentHandler.indentation(level);

		contentHandler.startElement(null, null, DIR_ELEMENT, attributes);

		contentHandler.lineBreak();

		outputPermissions(dir.toPath());

		outputExtendedAttributes(dir);

		for (File file : children) {

			if (file.isDirectory()) {

				outputDir(file);

			} else {

				outputFile(file);

			}

		}

		contentHandler.indentation(level);

		contentHandler.endElement(null, null, DIR_ELEMENT);

		contentHandler.lineBreak();

		level--;

	}

	private String encodeElementName(String originalName) {

		/**

		 * TODO: encode and/or skip invalid characters

		 */

		return originalName;

	}

	private void outputPermissions(Path path) throws IOException, SAXException {

		level++;

		Set<PosixFilePermission> permissions = Files.getPosixFilePermissions(path); // TODO: maybe symlinks: LinkOption.NOFOLLOW_LINKS

		contentHandler.indentation(level);

		contentHandler.startElement(null, PERMISSIONS_ELEMENT, PERMISSIONS_ELEMENT, singleAttribute("octal", getOctal(permissions)));

		contentHandler.lineBreak();

		level++;

		outputPermission("owner", permissions.contains(PosixFilePermission.OWNER_READ), permissions.contains(PosixFilePermission.OWNER_WRITE), permissions.contains(PosixFilePermission.OWNER_EXECUTE));

		outputPermission("group", permissions.contains(PosixFilePermission.GROUP_READ), permissions.contains(PosixFilePermission.GROUP_WRITE), permissions.contains(PosixFilePermission.GROUP_EXECUTE));

		outputPermission("others", permissions.contains(PosixFilePermission.OTHERS_READ), permissions.contains(PosixFilePermission.OTHERS_WRITE), permissions.contains(PosixFilePermission.OTHERS_EXECUTE));

		level--;

		contentHandler.indentation(level);

		contentHandler.endElement(null, PERMISSIONS_ELEMENT, PERMISSIONS_ELEMENT);

		contentHandler.lineBreak();

		level--;

	}

	private int getOctal(Set<PosixFilePermission> permissions) {

		int octal = 0;

		octal = octal + 100 * (permissions.contains(PosixFilePermission.OWNER_READ) ? 4 : 0);

		octal = octal + 100 * (permissions.contains(PosixFilePermission.OWNER_WRITE) ? 2 : 0);

		octal = octal + 100 * (permissions.contains(PosixFilePermission.OWNER_EXECUTE) ? 1 : 0);

		octal = octal + 10 * (permissions.contains(PosixFilePermission.GROUP_READ) ? 4 : 0);

		octal = octal + 10 * (permissions.contains(PosixFilePermission.GROUP_WRITE) ? 2 : 0);

		octal = octal + 10 * (permissions.contains(PosixFilePermission.GROUP_EXECUTE) ? 1 : 0);

		octal = octal + 1 * (permissions.contains(PosixFilePermission.OTHERS_READ) ? 4 : 0);

		octal = octal + 1 * (permissions.contains(PosixFilePermission.OTHERS_WRITE) ? 2 : 0);

		octal = octal + 1 * (permissions.contains(PosixFilePermission.OTHERS_EXECUTE) ? 1 : 0);

		return octal;

	}

	private void outputPermission(String name, boolean read, boolean write, boolean execute) throws SAXException {

		contentHandler.indentation(level);

		AttributesImpl attributes = new AttributesImpl();

		attributes.addAttribute(null, "read", "read", "xs:boolean", String.valueOf(read));

		attributes.addAttribute(null, "write", "write", "xs:boolean", String.valueOf(write));

		attributes.addAttribute(null, "execute", "execute", "xs:boolean", String.valueOf(execute));

		contentHandler.startElement(null, name, name, attributes);

		contentHandler.endElement(null, name, name);

		contentHandler.lineBreak();

	}

	private void outputExtendedAttributes(File file) throws IOException, SAXException {

		level++;

		final List<ExtendedAttribute> extendedAttributes = getExtendedAttributes(file);

		if (!extendedAttributes.isEmpty()) {

			contentHandler.indentation(level);

			contentHandler.startElement(null, XATTR_ELEMENT, XATTR_ELEMENT, null);

			contentHandler.lineBreak();

			level++;

			for (ExtendedAttribute ea : extendedAttributes) {

				contentHandler.indentation(level);

				String elementName = encodeElementName(ea.getKey());

				contentHandler.textElement(ea.getValue(), null, elementName, elementName, null);

				contentHandler.lineBreak();

			}

			level--;

			contentHandler.indentation(level);

			contentHandler.endElement(null, XATTR_ELEMENT, XATTR_ELEMENT);

			contentHandler.lineBreak();

		}

		level--;

	}

	private List<ExtendedAttribute> getExtendedAttributes(File file) throws IOException {

		List<ExtendedAttribute> l = new ArrayList<>();

		Path path = file.toPath();

		FileSystemProvider provider = path.getFileSystem().provider();

		UserDefinedFileAttributeView attributes = provider.getFileAttributeView(path, UserDefinedFileAttributeView.class);

		for (String jménoAtributu : attributes.list()) {

			ByteBuffer hodnotaAtributu = ByteBuffer.allocate(attributes.size(jménoAtributu));

			attributes.read(jménoAtributu, hodnotaAtributu);

			l.add(new ExtendedAttribute(jménoAtributu, hodnotaAtributu));

		}

		return l;

	}

}