/*
 **********************************************************************
 * Copyright (c) 2002-2004, International Business Machines
 * Corporation and others.  All Rights Reserved.
 **********************************************************************
 * Author: Mark Davis
 **********************************************************************
 */
package org.unicode.cldr.util;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.List;
import java.util.Stack;

import org.xml.sax.Attributes;
import org.xml.sax.ContentHandler;
import org.xml.sax.ErrorHandler;
import org.xml.sax.InputSource;
import org.xml.sax.Locator;
import org.xml.sax.SAXException;
import org.xml.sax.SAXParseException;
import org.xml.sax.XMLReader;
import org.xml.sax.ext.DeclHandler;
import org.xml.sax.ext.LexicalHandler;
import org.xml.sax.helpers.XMLReaderFactory;

/**
 * Convenience class to make reading XML data files easier. The main method is read();
 * This is meant for XML data files, so the contents of elements must either be all other elements, or
 * just text. It is thus not suitable for XML files with MIXED content;
 * all text content in a mixed element is discarded.
 * 
 * @author davis
 */
public class XMLFileReader {
    static final boolean SHOW_ALL = false;
    /**
     * Handlers to use in read()
     */
    public static int CONTENT_HANDLER = 1, ERROR_HANDLER = 2, LEXICAL_HANDLER = 4, DECLARATION_HANDLER = 8;

    private MyContentHandler DEFAULT_DECLHANDLER = new MyContentHandler();
    private SimpleHandler simpleHandler;

    public static class SimpleHandler {
        public void handlePathValue(String path, String value) {
        };

        public void handleComment(String path, String comment) {
        };

        public void handleElementDecl(String name, String model) {
        };

        public void handleAttributeDecl(String eName, String aName, String type, String mode, String value) {
        };

        public void handleEndDtd() {
        }

        public void handleStartDtd(String name, String publicId, String systemId) {
        };
    }

    public XMLFileReader setHandler(SimpleHandler simpleHandler) {
        this.simpleHandler = simpleHandler;
        return this;
    }

    /**
     * Read an XML file. Return a list of alternating items, where the even items are the paths,
     * and the odd ones are values. The order of the elements matches what was in the file.
     * 
     * @param fileName
     *            file to open
     * @param handlers
     *            a set of values for the handlers to use, eg CONTENT_HANDLER | ERROR_HANDLER
     * @param validating
     *            if a validating parse is requested
     * @return list of alternating values.
     */
    public XMLFileReader read(String fileName, int handlers, boolean validating) {
        try {
            InputStream fis = new FileInputStream(fileName);
            fis = new FilterBomInputStream(fis);
            return read(fileName, fis, handlers, validating);
        } catch (IOException e) {
            throw (IllegalArgumentException) new IllegalArgumentException("Can't read " + fileName).initCause(e);
        }
    }

    /**
     * read from a Stream
     * @param fileName
     * @param handlers
     * @param validating
     * @param fis
     * @return
     */
    public XMLFileReader read(String fileName, InputStream fis, int handlers, boolean validating) {
        return read(fileName, new InputStreamReader(fis, Charset.forName("UTF-8")), handlers, validating);
    }

    /**
     * read from a CLDR resource
     * @param fileName
     * @param handlers
     * @param validating
     * @param fis
     * @see CldrUtility#getInputStream(String)
     * @return
     */
    public XMLFileReader readCLDRResource(String resName, int handlers, boolean validating) {

        return read(resName, CldrUtility.getInputStream(resName), handlers, validating);
    }

    /**
     * read from an arbitrary
     * @param fileName
     * @param handlers
     * @param validating
     * @param fis
     * @see CldrUtility#getInputStream(String)
     * @return
     */
    public XMLFileReader read(String resName, Class<?> callingClass, int handlers, boolean validating) {

        return read(resName, CldrUtility.getInputStream(callingClass, resName), handlers, validating);
    }

    public XMLFileReader read(String systemID, Reader reader, int handlers, boolean validating) {
        try {
            XMLReader xmlReader = createXMLReader(validating);
            DEFAULT_DECLHANDLER.reset();
            if ((handlers & CONTENT_HANDLER) != 0) {
                xmlReader.setContentHandler(DEFAULT_DECLHANDLER);
            }
            if ((handlers & ERROR_HANDLER) != 0) {
                xmlReader.setErrorHandler(DEFAULT_DECLHANDLER);
            }
            if ((handlers & LEXICAL_HANDLER) != 0) {
                xmlReader.setProperty("http://xml.org/sax/properties/lexical-handler", DEFAULT_DECLHANDLER);
            }
            if ((handlers & DECLARATION_HANDLER) != 0) {
                xmlReader.setProperty("http://xml.org/sax/properties/declaration-handler", DEFAULT_DECLHANDLER);
            }
            InputSource is = new InputSource(reader);
            is.setSystemId(systemID);
            try {
                xmlReader.parse(is);
            } catch (AbortException e) {
            } // ok
            reader.close();
            return this;
        } catch (SAXParseException e) {
            throw (IllegalArgumentException) new IllegalArgumentException("Can't read " + systemID + "\tline:\t"
                + e.getLineNumber()).initCause(e);
        } catch (SAXException e) {
            throw (IllegalArgumentException) new IllegalArgumentException("Can't read " + systemID).initCause(e);
        } catch (IOException e) {
            throw (IllegalArgumentException) new IllegalArgumentException("Can't read " + systemID).initCause(e);
        }
    }

    private class MyContentHandler implements ContentHandler, LexicalHandler, DeclHandler, ErrorHandler {
        StringBuffer chars = new StringBuffer();
        StringBuffer commentChars = new StringBuffer();
        Stack<String> startElements = new Stack<String>();
        StringBuffer tempPath = new StringBuffer();
        boolean lastIsStart = false;

        public void reset() {
            chars.setLength(0);
            tempPath = new StringBuffer("/");
            startElements.clear();
            startElements.push("/");
        }

        public void characters(char[] ch, int start, int length) throws SAXException {
            if (lastIsStart) chars.append(ch, start, length);
        }

        public void startElement(String namespaceURI, String localName, String qName, Attributes atts)
            throws SAXException {
            tempPath.setLength(0);
            tempPath.append(startElements.peek()).append('/').append(qName);
            for (int i = 0; i < atts.getLength(); ++i) {
                tempPath.append("[@").append(atts.getQName(i)).append("=\"").append(atts.getValue(i)).append("\"]");
            }
            startElements.push(tempPath.toString());
            chars.setLength(0); // clear garbage
            lastIsStart = true;
        }

        public void endElement(String namespaceURI, String localName, String qName) throws SAXException {
            String startElement = (String) startElements.pop();
            if (lastIsStart) {
                // System.out.println(startElement + ":" + chars);
                simpleHandler.handlePathValue(startElement, chars.toString());
            }
            chars.setLength(0);
            lastIsStart = false;
        }

        public void startDTD(String name, String publicId, String systemId) throws SAXException {
            if (SHOW_ALL) Log.logln("startDTD name: " + name
                + ", publicId: " + publicId
                + ", systemId: " + systemId
                );
            simpleHandler.handleStartDtd(name, publicId, systemId);
        }

        public void endDTD() throws SAXException {
            if (SHOW_ALL) Log.logln("endDTD");
            simpleHandler.handleEndDtd();
        }

        public void comment(char[] ch, int start, int length) throws SAXException {
            if (SHOW_ALL) Log.logln(" comment " + new String(ch, start, length));
            commentChars.append(ch, start, length);
            simpleHandler.handleComment((String) startElements.peek(), commentChars.toString());
            commentChars.setLength(0);
        }

        public void elementDecl(String name, String model) throws SAXException {
            simpleHandler.handleElementDecl(name, model);
        }

        public void attributeDecl(String eName, String aName, String type, String mode, String value)
            throws SAXException {
            simpleHandler.handleAttributeDecl(eName, aName, type, mode, value);
        }

        // ==== The following are just for debuggin =====

        public void startDocument() throws SAXException {
            if (SHOW_ALL) Log.logln("startDocument");
        }

        public void ignorableWhitespace(char[] ch, int start, int length) throws SAXException {
            if (SHOW_ALL) Log.logln("ignorableWhitespace length: " + length);
        }

        public void endDocument() throws SAXException {
            if (SHOW_ALL) Log.logln("endDocument");
        }

        public void internalEntityDecl(String name, String value) throws SAXException {
            if (SHOW_ALL) Log.logln("Internal Entity\t" + name + "\t" + value);
        }

        public void externalEntityDecl(String name, String publicId, String systemId) throws SAXException {
            if (SHOW_ALL) Log.logln("Internal Entity\t" + name + "\t" + publicId + "\t" + systemId);
        }

        public void notationDecl(String name, String publicId, String systemId) {
            if (SHOW_ALL) Log.logln("notationDecl: " + name
                + ", " + publicId
                + ", " + systemId
                );
        }

        public void processingInstruction(String target, String data)
            throws SAXException {
            if (SHOW_ALL) Log.logln("processingInstruction: " + target + ", " + data);
        }

        public void skippedEntity(String name)
            throws SAXException {
            if (SHOW_ALL) Log.logln("skippedEntity: " + name);
        }

        public void unparsedEntityDecl(String name, String publicId,
            String systemId, String notationName) {
            if (SHOW_ALL) Log.logln("unparsedEntityDecl: " + name
                + ", " + publicId
                + ", " + systemId
                + ", " + notationName
                );
        }

        public void setDocumentLocator(Locator locator) {
            if (SHOW_ALL) Log.logln("setDocumentLocator Locator " + locator);
        }

        public void startPrefixMapping(String prefix, String uri) throws SAXException {
            if (SHOW_ALL) Log.logln("startPrefixMapping prefix: " + prefix +
                ", uri: " + uri);
        }

        public void endPrefixMapping(String prefix) throws SAXException {
            if (SHOW_ALL) Log.logln("endPrefixMapping prefix: " + prefix);
        }

        public void startEntity(String name) throws SAXException {
            if (SHOW_ALL) Log.logln("startEntity name: " + name);
        }

        public void endEntity(String name) throws SAXException {
            if (SHOW_ALL) Log.logln("endEntity name: " + name);
        }

        public void startCDATA() throws SAXException {
            if (SHOW_ALL) Log.logln("startCDATA");
        }

        public void endCDATA() throws SAXException {
            if (SHOW_ALL) Log.logln("endCDATA");
        }

        /*
         * (non-Javadoc)
         * 
         * @see org.xml.sax.ErrorHandler#error(org.xml.sax.SAXParseException)
         */
        public void error(SAXParseException exception) throws SAXException {
            if (SHOW_ALL) Log.logln("error: " + showSAX(exception));
            throw exception;
        }

        /*
         * (non-Javadoc)
         * 
         * @see org.xml.sax.ErrorHandler#fatalError(org.xml.sax.SAXParseException)
         */
        public void fatalError(SAXParseException exception) throws SAXException {
            if (SHOW_ALL) Log.logln("fatalError: " + showSAX(exception));
            throw exception;
        }

        /*
         * (non-Javadoc)
         * 
         * @see org.xml.sax.ErrorHandler#warning(org.xml.sax.SAXParseException)
         */
        public void warning(SAXParseException exception) throws SAXException {
            if (SHOW_ALL) Log.logln("warning: " + showSAX(exception));
            throw exception;
        }
    }

    static final class AbortException extends RuntimeException {
        private static final long serialVersionUID = 1L;
    }

    /**
     * Show a SAX exception in a readable form.
     */
    public static String showSAX(SAXParseException exception) {
        return exception.getMessage()
            + ";\t SystemID: " + exception.getSystemId()
            + ";\t PublicID: " + exception.getPublicId()
            + ";\t LineNumber: " + exception.getLineNumber()
            + ";\t ColumnNumber: " + exception.getColumnNumber();
    }

    public static XMLReader createXMLReader(boolean validating) {
        // weiv 07/20/2007: The laundry list below is somewhat obsolete
        // I have moved the system's default parser (instantiated when "" is
        // passed) to the top, so that we will always use that. I have also
        // removed "org.apache.crimson.parser.XMLReaderImpl" as this one gets
        // confused regarding UTF-8 encoding name.
        String[] testList = {
            System.getProperty("CLDR_DEFAULT_SAX_PARSER", ""), // defaults to "", system default.
            "org.apache.xerces.parsers.SAXParser",
            "gnu.xml.aelfred2.XmlReader",
            "com.bluecast.xml.Piccolo",
            "oracle.xml.parser.v2.SAXParser"
        };
        XMLReader result = null;
        for (int i = 0; i < testList.length; ++i) {
            try {
                result = (testList[i].length() != 0)
                    ? XMLReaderFactory.createXMLReader(testList[i])
                    : XMLReaderFactory.createXMLReader();
                result.setFeature("http://xml.org/sax/features/validation", validating);
                break;
            } catch (SAXException e1) {
            }
        }
        if (result == null)
            throw new NoClassDefFoundError("No SAX parser is available, or unable to set validation correctly");
        try {
            result.setEntityResolver(new CachingEntityResolver());
        } catch (Throwable e) {
            System.err
                .println("WARNING: Can't set caching entity resolver  -  error "
                    + e.toString());
            e.printStackTrace();
        }
        return result;
    }

    static final class DebuggingInputStream extends InputStream {
        InputStream contents;

        public void close() throws IOException {
            contents.close();
        }

        public DebuggingInputStream(InputStream fis) {
            contents = fis;
        }

        public int read() throws IOException {
            int x = contents.read();
            System.out.println(Integer.toHexString(x) + ",");
            return x;
        }
    }

    static final class FilterBomInputStream extends InputStream {
        InputStream contents;
        boolean first = true;

        public void close() throws IOException {
            contents.close();
        }

        public FilterBomInputStream(InputStream fis) {
            contents = fis;
        }

        public int read() throws IOException {
            int x = contents.read();
            if (first) {
                first = false;
                // 0xEF,0xBB,0xBF
                // SKIP bom
                if (x == 0xEF) {
                    int y = contents.read();
                    if (y == 0xBB) {
                        int z = contents.read();
                        if (z == 0xBF) {
                            x = contents.read();
                        }
                    }
                }
            }
            return x;
        }
    }

    public static List<Pair<String, String>> loadPathValues(String filename, List<Pair<String, String>> data, boolean validating) {
        try {
            new XMLFileReader()
                .setHandler(new PathValueListHandler(data))
                .read(filename, -1, validating);
            return data;
        } catch (Exception e) {
            throw new IllegalArgumentException(filename, e);
        }
    }

    static final class PathValueListHandler extends SimpleHandler {
        List<Pair<String, String>> data = new ArrayList<Pair<String, String>>();

        public PathValueListHandler(List<Pair<String, String>> data) {
            super();
            this.data = data;
        }

        @Override
        public void handlePathValue(String path, String value) {
            data.add(Pair.of(path, value));
        }
    }
}