// Copyright 2007, 2010, 2011 The Apache Software Foundation
//
// Licensed 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.

package org.apache.tapestry5.json;

/*
 * Copyright (c) 2002 JSON.org
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 * The Software shall be used for Good, not Evil.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

import java.util.*;

/**
 * A JSONObject is an unordered collection of name/value pairs. Its external form is a string wrapped in curly braces
 * with colons between the names and values, and commas between the values and names. The internal form is an object
 * having <code>get</code> and <code>opt</code> methods for accessing the values by name, and <code>put</code> methods
 * for adding or replacing values by name. The values can be any of these types: <code>Boolean</code>,
 * {@link org.apache.tapestry5.json.JSONArray}, {@link org.apache.tapestry5.json.JSONLiteral}, <code>JSONObject</code>,
 * <code>Number</code>, <code>String</code>, or the <code>JSONObject.NULL</code> object. A JSONObject constructor can be
 * used to convert an external form JSON text into
 * an internal form whose values can be retrieved with the <code>get</code> and <code>opt</code> methods, or to convert
 * values into a JSON text using the <code>put</code> and <code>toString</code> methods. A <code>get</code> method
 * returns a value if one can be found, and throws an exception if one cannot be found. An <code>opt</code> method
 * returns a default value instead of throwing an exception, and so is useful for obtaining optional values.
 * <p/>
 * The generic <code>get()</code> and <code>opt()</code> methods return an object, which you can cast or query for type.
 * There are also typed <code>get</code> and <code>opt</code> methods that do type checking and type coersion for you.
 * <p/>
 * The <code>put</code> methods adds values to an object. For example,
 * <p/>
 * <p/>
 * <pre>
 * myString = new JSONObject().put(&quot;JSON&quot;, &quot;Hello, World!&quot;).toString();
 * </pre>
 * <p/>
 * produces the string <code>{"JSON": "Hello, World"}</code>.
 * <p/>
 * The texts produced by the <code>toString</code> methods strictly conform to the JSON syntax rules. The constructors
 * are more forgiving in the texts they will accept:
 * <ul>
 * <li>An extra <code>,</code>&nbsp;<small>(comma)</small> may appear just before the closing brace.</li>
 * <li>Strings may be quoted with <code>'</code>&nbsp;<small>(single quote)</small>.</li>
 * <li>Strings do not need to be quoted at all if they do not begin with a quote or single quote, and if they do not
 * contain leading or trailing spaces, and if they do not contain any of these characters: <code>{ }
 * [ ] / \ : , = ; #</code> and if they do not look like numbers and if they are not the reserved words
 * <code>true</code>, <code>false</code>, or <code>null</code>.</li>
 * <li>Keys can be followed by <code>=</code> or <code>=></code> as well as by <code>:</code>.</li>
 * <li>Values can be followed by <code>;</code> <small>(semicolon)</small> as well as by <code>,</code>
 * <small>(comma)</small>.</li>
 * <li>Numbers may have the <code>0-</code> <small>(octal)</small> or <code>0x-</code> <small>(hex)</small> prefix.</li>
 * <li>Comments written in the slashshlash, slashstar, and hash conventions will be ignored.</li>
 * </ul>
 * <hr/>
 * <p/>
 * This class, and the other related classes, have been heavily modified from the original source, to fit Tapestry
 * standards and to make use of JDK 1.5 features such as generics. Further, since the interest of Tapestry is primarily
 * constructing JSON (and not parsing it), many of the non-essential methods have been removed (since the original code
 * came with no tests).
 * <p/>
 * Finally, support for the {@link org.apache.tapestry5.json.JSONLiteral} type has been added, which allow the exact
 * output to be controlled; useful when a JSONObject is being used as a configuration object, and must contain values
 * that are not simple data, such as an inline function (technically making the result not JSON).
 *
 * @author JSON.org
 * @version 2
 */
@SuppressWarnings(
        {"CloneDoesntCallSuperClone"})
public final class JSONObject extends JSONCollection
{

    /**
     * JSONObject.NULL is equivalent to the value that JavaScript calls null, whilst Java's null is equivalent to the
     * value that JavaScript calls undefined.
     */
    private static final class Null implements JSONString
    {
        /**
         * A Null object is equal to the null value and to itself.
         *
         * @param object An object to test for nullness.
         * @return true if the object parameter is the JSONObject.NULL object or null.
         */
        @Override
        public boolean equals(Object object)
        {
            return object == null || object == this;
        }

        /**
         * Get the "null" string value.
         *
         * @return The string "null".
         */
        @Override
        public String toString()
        {
            return "null";
        }

        public String toJSONString()
        {
            return "null";
        }
    }

    /**
     * The map where the JSONObject's properties are kept.
     */
    private final Map<String, Object> properties = new HashMap<String, Object>();

    /**
     * It is sometimes more convenient and less ambiguous to have a <code>NULL</code> object than to use Java's
     * <code>null</code> value. <code>JSONObject.NULL.equals(null)</code> returns <code>true</code>.
     * <code>JSONObject.NULL.toString()</code> returns <code>"null"</code>.
     */
    public static final Object NULL = new Null();

    /**
     * Construct an empty JSONObject.
     */
    public JSONObject()
    {
    }

    /**
     * Constructs a new JSONObject using a series of String keys and values.
     *
     * @since 5.2.0
     */
    public JSONObject(String... keysAndValues)
    {
        int i = 0;

        while (i < keysAndValues.length)
        {
            put(keysAndValues[i++], keysAndValues[i++]);
        }
    }

    /**
     * Construct a JSONObject from a subset of another JSONObject. An array of strings is used to identify the keys that
     * should be copied. Missing keys are ignored.
     *
     * @param source        A JSONObject.
     * @param propertyNames The strings to copy.
     * @throws RuntimeException If a value is a non-finite number.
     */
    public JSONObject(JSONObject source, String... propertyNames)
    {
        for (String name : propertyNames)
        {
            Object value = source.opt(name);

            if (value != null)
                put(name, value);
        }
    }

    /**
     * Construct a JSONObject from a JSONTokener.
     *
     * @param x A JSONTokener object containing the source string. @ If there is a syntax error in the source string.
     */
    JSONObject(JSONTokener x)
    {
        String key;

        if (x.nextClean() != '{')
        {
            throw x.syntaxError("A JSONObject text must begin with '{'");
        }

        while (true)
        {
            char c = x.nextClean();
            switch (c)
            {
                case 0:
                    throw x.syntaxError("A JSONObject text must end with '}'");
                case '}':
                    return;
                default:
                    x.back();
                    key = x.nextValue().toString();
            }

            /*
             * The key is followed by ':'. We will also tolerate '=' or '=>'.
             */

            c = x.nextClean();
            if (c == '=')
            {
                if (x.next() != '>')
                {
                    x.back();
                }
            } else if (c != ':')
            {
                throw x.syntaxError("Expected a ':' after a key");
            }
            put(key, x.nextValue());

            /*
             * Pairs are separated by ','. We will also tolerate ';'.
             */

            switch (x.nextClean())
            {
                case ';':
                case ',':
                    if (x.nextClean() == '}')
                    {
                        return;
                    }
                    x.back();
                    break;
                case '}':
                    return;
                default:
                    throw x.syntaxError("Expected a ',' or '}'");
            }
        }
    }

    /**
     * Construct a JSONObject from a string. This is the most commonly used JSONObject constructor.
     *
     * @param string A string beginning with <code>{</code>&nbsp;<small>(left brace)</small> and ending with <code>}</code>
     *               &nbsp;<small>(right brace)</small>.
     * @throws RuntimeException If there is a syntax error in the source string.
     */
    public JSONObject(String string)
    {
        this(new JSONTokener(string));
    }

    /**
     * Accumulate values under a key. It is similar to the put method except that if there is already an object stored
     * under the key then a JSONArray is stored under the key to hold all of the accumulated values. If there is already
     * a JSONArray, then the new value is appended to it. In contrast, the put method replaces the previous value.
     *
     * @param key   A key string.
     * @param value An object to be accumulated under the key.
     * @return this.
     * @throws {@link RuntimeException} If the value is an invalid number or if the key is null.
     */
    public JSONObject accumulate(String key, Object value)
    {
        testValidity(value);

        Object existing = opt(key);

        if (existing == null)
        {
            // Note that the original implementation of this method contradicited the method
            // documentation.
            put(key, value);
            return this;
        }

        if (existing instanceof JSONArray)
        {
            ((JSONArray) existing).put(value);
            return this;
        }

        // Replace the existing value, of any type, with an array that includes both the
        // existing and the new value.

        put(key, new JSONArray().put(existing).put(value));

        return this;
    }

    /**
     * Append values to the array under a key. If the key does not exist in the JSONObject, then the key is put in the
     * JSONObject with its value being a JSONArray containing the value parameter. If the key was already associated
     * with a JSONArray, then the value parameter is appended to it.
     *
     * @param key   A key string.
     * @param value An object to be accumulated under the key.
     * @return this. @ If the key is null or if the current value associated with the key is not a JSONArray.
     */
    public JSONObject append(String key, Object value)
    {
        testValidity(value);
        Object o = opt(key);
        if (o == null)
        {
            put(key, new JSONArray().put(value));
        } else if (o instanceof JSONArray)
        {
            put(key, ((JSONArray) o).put(value));
        } else
        {
            throw new RuntimeException("JSONObject[" + quote(key) + "] is not a JSONArray.");
        }

        return this;
    }

    /**
     * Produce a string from a double. The string "null" will be returned if the number is not finite.
     *
     * @param d A double.
     * @return A String.
     */
    static String doubleToString(double d)
    {
        if (Double.isInfinite(d) || Double.isNaN(d))
        {
            return "null";
        }

        // Shave off trailing zeros and decimal point, if possible.

        String s = Double.toString(d);
        if (s.indexOf('.') > 0 && s.indexOf('e') < 0 && s.indexOf('E') < 0)
        {
            while (s.endsWith("0"))
            {
                s = s.substring(0, s.length() - 1);
            }
            if (s.endsWith("."))
            {
                s = s.substring(0, s.length() - 1);
            }
        }
        return s;
    }

    /**
     * Get the value object associated with a key.
     *
     * @param key A key string.
     * @return The object associated with the key.
     * @throws RuntimeException if the key is not found.
     * @see #opt(String)
     */
    public Object get(String key)
    {
        Object o = opt(key);
        if (o == null)
        {
            throw new RuntimeException("JSONObject[" + quote(key) + "] not found.");
        }

        return o;
    }

    /**
     * Get the boolean value associated with a key.
     *
     * @param key A key string.
     * @return The truth.
     * @throws RuntimeException if the value does not exist, is not a Boolean or the String "true" or "false".
     */
    public boolean getBoolean(String key)
    {
        Object o = get(key);

        if (o instanceof Boolean)
            return o.equals(Boolean.TRUE);

        if (o instanceof String)
        {
            String value = (String) o;

            if (value.equalsIgnoreCase("true"))
                return true;

            if (value.equalsIgnoreCase("false"))
                return false;
        }

        throw new RuntimeException("JSONObject[" + quote(key) + "] is not a Boolean.");
    }

    /**
     * Get the double value associated with a key.
     *
     * @param key A key string.
     * @return The numeric value. @throws RuntimeException if the key is not found or if the value is not a Number object and cannot be
     *         converted to a number.
     */
    public double getDouble(String key)
    {
        Object value = get(key);

        try
        {
            if (value instanceof Number)
                return ((Number) value).doubleValue();

            // This is a bit sloppy for the case where value is not a string.

            return Double.valueOf((String) value);
        } catch (Exception e)
        {
            throw new RuntimeException("JSONObject[" + quote(key) + "] is not a number.");
        }
    }

    /**
     * Get the int value associated with a key. If the number value is too large for an int, it will be clipped.
     *
     * @param key A key string.
     * @return The integer value.
     * @throws RuntimeException if the key is not found or if the value cannot be converted to an integer.
     */
    public int getInt(String key)
    {
        Object value = get(key);

        if (value instanceof Number)
            return ((Number) value).intValue();

        // Very inefficient way to do this!
        return (int) getDouble(key);
    }

    /**
     * Get the JSONArray value associated with a key.
     *
     * @param key A key string.
     * @return A JSONArray which is the value.
     * @throws RuntimeException if the key is not found or if the value is not a JSONArray.
     */
    public JSONArray getJSONArray(String key)
    {
        Object o = get(key);
        if (o instanceof JSONArray)
        {
            return (JSONArray) o;
        }

        throw new RuntimeException("JSONObject[" + quote(key) + "] is not a JSONArray.");
    }

    /**
     * Get the JSONObject value associated with a key.
     *
     * @param key A key string.
     * @return A JSONObject which is the value.
     * @throws RuntimeException if the key is not found or if the value is not a JSONObject.
     */
    public JSONObject getJSONObject(String key)
    {
        Object o = get(key);
        if (o instanceof JSONObject)
        {
            return (JSONObject) o;
        }

        throw new RuntimeException("JSONObject[" + quote(key) + "] is not a JSONObject.");
    }

    /**
     * Get the long value associated with a key. If the number value is too long for a long, it will be clipped.
     *
     * @param key A key string.
     * @return The long value.
     * @throws RuntimeException if the key is not found or if the value cannot be converted to a long.
     */
    public long getLong(String key)
    {
        Object o = get(key);
        return o instanceof Number ? ((Number) o).longValue() : (long) getDouble(key);
    }

    /**
     * Get the string associated with a key.
     *
     * @param key A key string.
     * @return A string which is the value.
     * @throws RuntimeException if the key is not found.
     */
    public String getString(String key)
    {
        return get(key).toString();
    }

    /**
     * Determine if the JSONObject contains a specific key.
     *
     * @param key A key string.
     * @return true if the key exists in the JSONObject.
     */
    public boolean has(String key)
    {
        return properties.containsKey(key);
    }

    /**
     * Determine if the value associated with the key is null or if there is no value.
     *
     * @param key A key string.
     * @return true if there is no value associated with the key or if the value is the JSONObject.NULL object.
     */
    public boolean isNull(String key)
    {
        return JSONObject.NULL.equals(opt(key));
    }

    /**
     * Get an enumeration of the keys of the JSONObject. Caution: the set should not be modified.
     *
     * @return An iterator of the keys.
     */
    public Set<String> keys()
    {
        return properties.keySet();
    }

    /**
     * Get the number of keys stored in the JSONObject.
     *
     * @return The number of keys in the JSONObject.
     */
    public int length()
    {
        return properties.size();
    }

    /**
     * Produce a JSONArray containing the names of the elements of this JSONObject.
     *
     * @return A JSONArray containing the key strings, or null if the JSONObject is empty.
     */
    public JSONArray names()
    {
        JSONArray ja = new JSONArray();

        for (String key : keys())
        {
            ja.put(key);
        }

        return ja.length() == 0 ? null : ja;
    }

    /**
     * Produce a string from a Number.
     *
     * @param n A Number
     * @return A String. @ If n is a non-finite number.
     */
    static String numberToString(Number n)
    {
        assert n != null;

        testValidity(n);

        // Shave off trailing zeros and decimal point, if possible.

        String s = n.toString();
        if (s.indexOf('.') > 0 && s.indexOf('e') < 0 && s.indexOf('E') < 0)
        {
            while (s.endsWith("0"))
            {
                s = s.substring(0, s.length() - 1);
            }
            if (s.endsWith("."))
            {
                s = s.substring(0, s.length() - 1);
            }
        }
        return s;
    }

    /**
     * Get an optional value associated with a key.
     *
     * @param key A key string.
     * @return An object which is the value, or null if there is no value.
     * @see #get(String)
     */
    public Object opt(String key)
    {
        return properties.get(key);
    }

    /**
     * Put a key/value pair in the JSONObject. If the value is null, then the key will be removed from the JSONObject if
     * it is present.
     *
     * @param key   A key string.
     * @param value An object which is the value. It should be of one of these types: Boolean, Double, Integer,
     *              JSONArray, JSONObject, JSONLiteral, Long, String, or the JSONObject.NULL object.
     * @return this.
     * @throws RuntimeException If the value is non-finite number or if the key is null.
     */
    public JSONObject put(String key, Object value)
    {
        assert key != null;

        if (value != null)
        {
            testValidity(value);
            properties.put(key, value);
        } else
        {
            remove(key);
        }

        return this;
    }

    /**
     * Produce a string in double quotes with backslash sequences in all the right places. A backslash will be inserted
     * within </, allowing JSON text to be delivered in HTML. In JSON text, a string cannot contain a control character
     * or an unescaped quote or backslash.
     *
     * @param string A String
     * @return A String correctly formatted for insertion in a JSON text.
     */
    public static String quote(String string)
    {
        if (string == null || string.length() == 0)
        {
            return "\"\"";
        }

        char b;
        char c = 0;
        int i;
        int len = string.length();
        StringBuilder buffer = new StringBuilder(len + 4);
        String t;

        buffer.append('"');
        for (i = 0; i < len; i += 1)
        {
            b = c;
            c = string.charAt(i);
            switch (c)
            {
                case '\\':
                case '"':
                    buffer.append('\\');
                    buffer.append(c);
                    break;
                case '/':
                    if (b == '<')
                    {
                        buffer.append('\\');
                    }
                    buffer.append(c);
                    break;
                case '\b':
                    buffer.append("\\b");
                    break;
                case '\t':
                    buffer.append("\\t");
                    break;
                case '\n':
                    buffer.append("\\n");
                    break;
                case '\f':
                    buffer.append("\\f");
                    break;
                case '\r':
                    buffer.append("\\r");
                    break;
                default:
                    if (c < ' ' || (c >= '\u0080' && c < '\u00a0') || (c >= '\u2000' && c < '\u2100'))
                    {
                        t = "000" + Integer.toHexString(c);
                        buffer.append("\\u").append(t.substring(t.length() - 4));
                    } else
                    {
                        buffer.append(c);
                    }
            }
        }
        buffer.append('"');
        return buffer.toString();
    }

    /**
     * Remove a name and its value, if present.
     *
     * @param key The name to be removed.
     * @return The value that was associated with the name, or null if there was no value.
     */
    public Object remove(String key)
    {
        return properties.remove(key);
    }

    private static final Class[] ALLOWED = new Class[]
            {String.class, Boolean.class, Number.class, JSONObject.class, JSONArray.class, JSONString.class,
                    JSONLiteral.class, Null.class};

    /**
     * Throw an exception if the object is an NaN or infinite number, or not a type which may be stored.
     *
     * @param value The object to test. @ If o is a non-finite number.
     */
    @SuppressWarnings("unchecked")
    static void testValidity(Object value)
    {
        if (value == null)
            return;

        boolean found = false;
        Class actual = value.getClass();

        for (Class allowed : ALLOWED)
        {
            if (allowed.isAssignableFrom(actual))
            {
                found = true;
                break;
            }
        }

        if (!found)
        {
            List<String> typeNames = new ArrayList<String>();

            for (Class c : ALLOWED)
            {
                String name = c.getName();

                if (name.startsWith("java.lang."))
                    name = name.substring(10);

                typeNames.add(name);
            }

            Collections.sort(typeNames);

            StringBuilder joined = new StringBuilder();
            String sep = "";

            for (String name : typeNames)
            {
                joined.append(sep);
                joined.append(name);

                sep = ", ";
            }

            String message = String.format("JSONObject properties may be one of %s. Type %s is not allowed.",
                    joined.toString(), actual.getName());

            throw new RuntimeException(message);
        }

        if (value instanceof Double)
        {
            Double asDouble = (Double) value;

            if (asDouble.isInfinite() || asDouble.isNaN())
            {
                throw new RuntimeException(
                        "JSON does not allow non-finite numbers.");
            }

            return;
        }

        if (value instanceof Float)
        {
            Float asFloat = (Float) value;

            if (asFloat.isInfinite() || asFloat.isNaN())
            {
                throw new RuntimeException(
                        "JSON does not allow non-finite numbers.");
            }

        }

    }

    /**
     * Prints the JSONObject using the session.
     *
     * @since 5.2.0
     */
    void print(JSONPrintSession session)
    {
        session.printSymbol('{');

        session.indent();

        boolean comma = false;

        for (String key : keys())
        {
            if (comma)
                session.printSymbol(',');

            session.newline();

            session.printQuoted(key);

            session.printSymbol(':');

            printValue(session, properties.get(key));

            comma = true;
        }

        session.outdent();

        if (comma)
            session.newline();

        session.printSymbol('}');
    }

    /**
     * Prints a value (a JSONArray or JSONObject, or a value stored in an array or object) using
     * the session.
     *
     * @since 5.2.0
     */
    static void printValue(JSONPrintSession session, Object value)
    {
        if (value instanceof JSONObject)
        {
            ((JSONObject) value).print(session);
            return;
        }

        if (value instanceof JSONArray)
        {
            ((JSONArray) value).print(session);
            return;
        }

        if (value instanceof JSONString)
        {
            String printValue = ((JSONString) value).toJSONString();

            session.print(printValue);

            return;
        }

        if (value instanceof Number)
        {
            String printValue = numberToString((Number) value);
            session.print(printValue);
            return;
        }

        if (value instanceof Boolean)
        {
            session.print(value.toString());

            return;
        }

        // Otherwise it really should just be a string. Nothing else can go in.
        session.printQuoted(value.toString());
    }

    /**
     * Returns true if the other object is a JSONObject and its set of properties matches this object's properties.
     */
    @Override
    public boolean equals(Object obj)
    {
        if (obj == null)
            return false;

        if (!(obj instanceof JSONObject))
            return false;

        JSONObject other = (JSONObject) obj;

        return properties.equals(other.properties);
    }
}
