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 *   Licensed to the Apache Software Foundation (ASF) under one
 *  or more contributor license agreements.  See the NOTICE file
 *  distributed with this work for additional information
 *  regarding copyright ownership.  The ASF licenses this file
 *  to you under the Apache License, Version 2.0 (the
 *  "License"); you may not use this file except in compliance
 *  with the License.  You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing,
 *  software distributed under the License is distributed on an
 *  "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 *  KIND, either express or implied.  See the License for the
 *  specific language governing permissions and limitations
 *  under the License.
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package org.apache.cayenne.wocompat;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileWriter;
import java.io.IOException;
import java.io.InputStream;
import java.io.Writer;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.apache.cayenne.CayenneRuntimeException;
import org.apache.cayenne.wocompat.parser.Parser;

/**
 * A PropertyListSerialization is a utility class 
 * that reads and stores files in NeXT/Apple
 * property list format. Unlike corresponding WebObjects 
 * class, PropertyListSerialization uses standard
 * Java collections (lists and maps) to store property lists.
 * 
 * @author Andrei Adamchik
 */
public class PropertyListSerialization {
	/**
	 * Reads a property list file. Returns a property list object, that is
	 * normally a java.util.List or a java.util.Map, but can also be a String
	 * or a Number. 
	 */
	public static Object propertyListFromFile(File f) throws FileNotFoundException {
		if (!f.isFile()) {
			throw new FileNotFoundException("No such file: " + f);
		}

		return new Parser(f).propertyList();
	}

	/**
	 * Reads a property list data from InputStream. Returns a property list o
	 * bject, that is normally a java.util.List or a java.util.Map, 
	 * but can also be a String or a Number. 
	 */
	public static Object propertyListFromStream(InputStream in) {
		return new Parser(in).propertyList();
	}

	/**
	 * Saves property list to file.
	 */
	public static void propertyListToFile(File f, Object plist) {
		try {
			BufferedWriter out = new BufferedWriter(new FileWriter(f));
			try {
				writeObject("", out, plist);
			} finally {
				out.close();
			}
		} catch (IOException ioex) {
			throw new CayenneRuntimeException("Error saving plist.", ioex);
		}
	}

    /**
     * Internal method to recursively write a property list object.
     */
	protected static void writeObject(String offset, Writer out, Object plist)
		throws IOException {
		if (plist == null) {
			return;
		}

		if (plist instanceof List) {
			List list = (List) plist;

			out.write('\n');
			out.write(offset);

			if (list.size() == 0) {
				out.write("()");
				return;
			}

			out.write("(\n");

			String childOffset = offset + "   ";
			Iterator it = list.iterator();
			boolean appended = false;
			while (it.hasNext()) {
				// Java collections can contain nulls, skip them
				Object obj = it.next();
				if (obj != null) {
					if (appended) {
						out.write(", \n");
					}

					out.write(childOffset);
					writeObject(childOffset, out, obj);
					appended = true;
				}
			}

			out.write('\n');
			out.write(offset);
			out.write(')');
		} else if (plist instanceof Map) {
			Map map = (Map) plist;
			out.write('\n');
			out.write(offset);

			if (map.size() == 0) {
				out.write("{}");
				return;
			}

			out.write("{");

			String childOffset = offset + "    ";

			Iterator it = map.entrySet().iterator();
			while (it.hasNext()) {
				// Java collections can contain nulls, skip them
				Map.Entry entry = (Map.Entry) it.next();
				Object key = entry.getKey();
				if (key == null) {
					continue;
				}
				Object obj = entry.getValue();
				if (obj == null) {
					continue;
				}
				out.write('\n');
				out.write(childOffset);
				out.write(quoteString(key.toString()));
				out.write(" = ");
				writeObject(childOffset, out, obj);
				out.write(';');
			}

			out.write('\n');
			out.write(offset);
			out.write('}');
		} else if (plist instanceof String) {
			out.write(quoteString(plist.toString()));
		} else if (plist instanceof Number) {
			out.write(plist.toString());
		} else {
			throw new CayenneRuntimeException(
				"Unsupported class for property list serialization: "
					+ plist.getClass().getName());
		}
	}

	/** 
	 * Escapes all doublequotes and backslashes.
	 */
	protected static String escapeString(String str) {
		char[] chars = str.toCharArray();
		int len = chars.length;
		StringBuffer buf = new StringBuffer(len + 3);

		for (int i = 0; i < len; i++) {
			if (chars[i] == '\"' || chars[i] == '\\') {
				buf.append('\\');
			}			
			buf.append(chars[i]);
		}

		return buf.toString();
	}

    /**
     * Returns a quoted String, with all the escapes preprocessed. May return an unquoted
     * String if it contains no special characters. The rule for a non-special character
     * is the following:
     * 
     *      *      c >= 'a' && c <= 'z'
     *      c >= 'A' && c <= 'Z'
     *      c >= '0' && c <= '9'
     *      c == '_'
     *      c == '$'
     *      c == ':'
     *      c == '.'
     *      c == '/'
     * 
     */
	protected static String quoteString(String str) {
		boolean shouldQuote = false;
		
		// scan string for special chars, 
        // if we have them, string must be quoted
        
		String noQuoteExtras = "_$:./";
		char[] chars = str.toCharArray();
		int len = chars.length;
        if (len == 0) {
            shouldQuote = true;
        }
		for (int i = 0; !shouldQuote && i < len; i++) {
            char c = chars[i];
            
            if ((c >= 'a' && c <= 'z')
                    || (c >= 'A' && c <= 'Z')
                    || (c >= '0' && c <= '9')
                    || noQuoteExtras.indexOf(c) >= 0) {
                continue;
            }

            shouldQuote = true;
        }

		str = escapeString(str);
		return (shouldQuote) ? '\"' + str + '\"' : str;
	}
}