/*
 * The Apache Software License, Version 1.1
 *
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 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
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 * 2. Redistributions in binary form must reproduce the above copyright
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 *    distribution.
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 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:  
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 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
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package org.apache.tools.ant.taskdefs;

import org.apache.tools.ant.*;
import org.apache.tools.ant.taskdefs.*;

import org.apache.oro.text.regex.*;

import java.io.*;
import java.util.*;

/**
 * Replaces all occurrences of one or more tokens with given values
 * in the indicated set of files.
 *
 * This task works virtually the same (and code-wise is 95% identical)
 * to the vanilla Replace task, except that I used the Apache ORO 
 * package to interpret the tokens and values.  The token can be any 
 * Perl5Pattern and the value can be any Perl5Substitution.  See 
 * <a href="http://jakarta.apache.org/oro/apidocs/org/apache/oro/text/regex/package-summary.html">
 * the org.apache.coro.text.regex documentation</a> for more details 
 * about how these work.
 *
 * <br><br>
 * Somebody should probably do this right by making the stringReplace
 * method protected, and building this task by extending Replace and
 * overriding stringReplace, but I will leave that up to whoever at
 * Apache makes such decisions...
 *
 * @author David Martin <a href="mailto:dave.martin@wilytech.com">dave.martin@wilytech.com</a>
 * @author Stefano Mazzocchi <a href="mailto:stefano@apache.org">stefano@apache.org</a>
 * @author <a href="mailto:erik@desknetinc.com">Erik Langenbach</a>
 */
public class REReplace extends MatchingTask {
    
    private File src = null;
    private NestedString token = null;
    private NestedString value = new NestedString();

    private File propertyFile = null;
    private Properties properties = null;
    private Vector replacefilters = new Vector();

    private File dir = null;
   
    //Inner class
    public class NestedString {

        private StringBuffer buf = new StringBuffer();

        public void addText(String val) {
            buf.append(val);
        }

        public String getText() {
            return buf.toString();
        }
    }

    //Inner class
    public class Replacefilter
    {
        private String token;
        private String value;
        private String property;

        public void validate() throws BuildException {
            //Validate mandatory attributes
            if (token == null) {
                String message = "token is a mandatory attribute " + "of replacefilter.";
                throw new BuildException(message);
            }

            if ("".equals(token)) {
                String message ="The token attribute must not be an empty string.";
                throw new BuildException(message);
            }

            //value and property are mutually exclusive attributes
            if ((value != null) && (property != null)) {
                String message = "Either value or property " + "can be specified, but a replacefilter " + "element cannot have both.";
                throw new BuildException(message);
            }

            if ((property != null)) {
                //the property attribute must have access to a property file
                if (propertyFile == null) {
                    String message = "The replacefilter's property attribute " + "can only be used with the replacetask's " + "propertyFile attribute.";
                    throw new BuildException(message);
                }

                //Make sure property exists in property file
                if (properties == null ||
                        properties.getProperty(property) == null) {
                    String message = "property \"" + property + "\" was not found in " + propertyFile.getPath();
                    throw new BuildException(message);
                }
            }
        }

        public String getReplaceValue()
        {
            if (property != null) {
                return (String)properties.getProperty(property);
            }
            else if (value != null) {
                return value;
            }
            else if (REReplace.this.value != null) {
                return REReplace.this.value.getText();
            }
            else {
                //Default is empty string
                return new String("");
            }
        }

        public void setToken(String token) {
            this.token = token;
        }

        public String getToken() {
            return token;
        }

        public void setValue(String value) {
            this.value = value;
        }

        public String getValue() {
            return value;
        }

        public void setProperty(String property) {
            this.property = property;
        }

        public String getProperty() {
            return property;
        }
    }

    /**
     * Do the execution.
     */
    public void execute() throws BuildException {
        validateAttributes();

        if (propertyFile != null) {
            properties = getProperties(propertyFile);
        }

        validateReplacefilters();

        if (src != null) {
            processFile(src);
        }

        if (dir != null) {
        DirectoryScanner ds = super.getDirectoryScanner(dir);
            String[] srcs = ds.getIncludedFiles();

            for(int i=0; i<srcs.length; i++) {
                File file = new File(dir,srcs[i]);
                processFile(file);
            }
        }
    }
    
    /**
     * Validate attributes provided for this task in .xml build file.
     *
     * @exception BuildException if any supplied attribute is invalid or any
     * mandatory attribute is missing
     */
    public void validateAttributes() throws BuildException {
        if (src == null && dir == null) {
            String message = "Either the file or the dir attribute " + "must be specified";
            throw new BuildException(message, location);
        }
        if (propertyFile != null && !propertyFile.exists()) {
            String message = "Property file " + propertyFile.getPath() + " does not exist.";
            throw new BuildException(message, location);
        }
        if (token == null && replacefilters.size() == 0) {
            String message = "Either token or a nested replacefilter "
                + "must be specified";
            throw new BuildException(message, location);
        }
        if (token != null && "".equals(token.getText())) {
            String message ="The token attribute must not be an empty string.";
            throw new BuildException(message, location);
        }
    }

    /**
     * Validate nested elements.
     *
     * @exception BuildException if any supplied attribute is invalid or any
     * mandatory attribute is missing
     */
    public void validateReplacefilters()
            throws BuildException {
        for (int i = 0; i < replacefilters.size(); i++) {
            Replacefilter element = (Replacefilter) replacefilters.elementAt(i);
            element.validate();
        }
    }

    public Properties getProperties(File propertyFile) throws BuildException {
        Properties properties = new Properties();

        try {
            properties.load(new FileInputStream(propertyFile));
        }
        catch (FileNotFoundException e) {
            String message = "Property file (" + propertyFile.getPath() + ") not found.";
            throw new BuildException(message);
        }
        catch (IOException e) {
            String message = "Property file (" + propertyFile.getPath() + ") cannot be loaded.";
            throw new BuildException(message);
        }

        return properties;
    }

    /**
     * Perform the replacement on the given file.
     *
     * The replacement is performed on a temporary file which then
     * replaces the original file.
     *
     * @param src the source file
     */
    private void processFile(File src) throws BuildException {
        if (!src.exists()) {
            throw new BuildException("REReplace: source file " + src.getPath() + " doesn't exist", location);
        }

        File temp = new File(src.getPath() + ".temp");

        if (temp.exists()) {
            throw new BuildException("REReplace: temporary file " + temp.getPath() + " already exists", location);
        }

        try {
            BufferedReader br = new BufferedReader(new FileReader(src));
            BufferedWriter bw = new BufferedWriter(new FileWriter(temp));

            // read the entire file into a char[]
            int fileLength = (int)(src.length());
            char[] tmpBuf = new char[fileLength];
            int numread = 0;
            int totread = 0;
            while (numread != -1 && totread < fileLength) {
                numread = br.read(tmpBuf,totread,fileLength);
                totread += numread;
            }

            // create a String so we can use indexOf
            String buf = new String(tmpBuf);

            //Preserve original string (buf) so we can compare the result
            String newString = new String(buf);

            if (token != null)
            {
                // line separators in values and tokens are "\n"
                // in order to compare with the file contents, replace them
                // as needed
                String linesep = System.getProperty("line.separator");
                String val = stringReplace(value.getText(), "\n", linesep);
                String tok = stringReplace(token.getText(), "\n", linesep);

                // for each found token, replace with value
                log("Replacing in " + src.getPath() + ": " + token.getText() + " --> " + value.getText(), Project.MSG_VERBOSE);
                newString = stringReplace(newString, tok, val);
            }

            if (replacefilters.size() > 0) {
                newString = processReplacefilters(newString, src.getPath());
            }

            boolean changes = !newString.equals(buf);
            if (changes) {
                bw.write(newString,0,newString.length());
                bw.flush();
            }

            // cleanup
            bw.close();
            br.close();

            // If there were changes, move the new one to the old one;
            // otherwise, delete the new one
            if (changes) {
                src.delete();
                temp.renameTo(src);
            } else {
                temp.delete();
            }
        } catch (IOException ioe) {
            ioe.printStackTrace();
            throw new BuildException(ioe, location);
        }
    }

    private String processReplacefilters(String buffer, String filename) {
        String newString = new String(buffer);

        for (int i = 0; i < replacefilters.size(); i++) {
            Replacefilter filter = (Replacefilter) replacefilters.elementAt(i);

            //for each found token, replace with value
            log("Replacing in " + filename + ": " + filter.getToken() + " --> " + filter.getReplaceValue(), Project.MSG_VERBOSE);
            newString = stringReplace(newString, filter.getToken(), filter.getReplaceValue());
        }

        return newString;
    }


    /**
     * Set the source file.
     */
    public void setFile(File file) {
        this.src = file;
    }

    /**
     * Set the source files path when using matching tasks.
     */
    public void setDir(File dir) {
        this.dir = dir;
    }

    /**
     * Set the string token to replace.
     */
    public void setToken(String token) {
        createReplaceToken().addText(token);
    }

    /**
     * Set the string value to use as token replacement.
     */
    public void setValue(String value) {
        createReplaceValue().addText(value);
    }

    /**
     * Nested <replacetoken> element.
     */
    public NestedString createReplaceToken() {
        if (token == null) {
            token = new NestedString();
        }
        return token;
    }

    /**
     * Nested <replacevalue> element.
     */
    public NestedString createReplaceValue() {
        return value;
    }

    /**
     * Sets a file to be searched for property values.
     */
    public void setPropertyFile(String filename) {
        propertyFile = project.resolveFile(filename);
    }

    /**
     * Add nested <replacefilter> element.
     */
    public Replacefilter createReplacefilter() {
        Replacefilter filter = new Replacefilter();
        replacefilters.addElement(filter);
        return filter;
    }

    /**
     * <p>Match and replace occurences of pattern pat in string str with substitution sub
	 * The pattern may be a valid Perl5Pattern, the substitution a valid Perl5Substition.
	 * 
	 * <p>See
	 * <a href="http://jakarta.apache.org/oro/apidocs/org/apache/oro/text/regex/package-summary.html">
	 * the org.apache.coro.text.regex documentation</a> for more details. 
	 */    
    private String stringReplace(String str, String pat, String sub) 
		throws BuildException {

		Perl5Matcher matcher = new Perl5Matcher();
		Perl5Compiler compiler = new Perl5Compiler();

		Pattern pattern;
		try {

			pattern = compiler.compile( pat );

		} catch (MalformedPatternException mpe) {
			
            String message = "Malformed perl 5 pattern for token: " + pat;
            throw new BuildException(message);

		}

		Perl5Substitution substitution = new Perl5Substitution( sub );

		String ret = Util.substitute( 
										matcher, 
										pattern, 
										substitution, 
										str, 
										Util.SUBSTITUTE_ALL 
									);

		return ret;
    	}

}