tooling/camel-util-json/src/main/java/org/apache/camel/util/json/JsonArray.java

/*
 * 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.
 */
package org.apache.camel.util.json;

import java.io.IOException;
import java.io.StringWriter;
import java.io.Writer;
import java.math.BigDecimal;
import java.util.ArrayList;
import java.util.Collection;
import java.util.Iterator;
import java.util.Map;

/**
 * JsonArray is a common non-thread safe data format for a collection of data.
 * The contents of a JsonArray are only validated as JSON values on
 * serialization.
 * 
 * @see Jsoner
 * @since 2.0.0
 */
public class JsonArray extends ArrayList<Object> implements Jsonable {
    /**
     * The serialization version this class is compatible with. This value
     * doesn't need to be incremented if and only if the only changes to occur
     * were updating comments, updating javadocs, adding new fields to the
     * class, changing the fields from static to non-static, or changing the
     * fields from transient to non transient. All other changes require this
     * number be incremented.
     */
    private static final long serialVersionUID = 1L;

    /** Instantiates an empty JsonArray. */
    public JsonArray() {
        super();
    }

    /**
     * Instantiate a new JsonArray using ArrayList's constructor of the same
     * type.
     * 
     * @param collection represents the elements to produce the JsonArray with.
     */
    public JsonArray(final Collection<?> collection) {
        super(collection);
    }

    /**
     * A convenience method that assumes every element of the JsonArray is
     * castable to T before adding it to a collection of Ts.
     * 
     * @param <T> represents the type that all of the elements of the JsonArray
     *            should be cast to and the type the collection will contain.
     * @param destination represents where all of the elements of the JsonArray
     *            are added to after being cast to the generic type provided.
     * @throws ClassCastException if the unchecked cast of an element to T
     *             fails.
     */
    @SuppressWarnings("unchecked")
    public <T> void asCollection(final Collection<T> destination) {
        for (final Object o : this) {
            destination.add((T)o);
        }
    }

    /**
     * A convenience method that assumes there is a BigDecimal, Number, or
     * String at the given index. If a Number or String is there it is used to
     * construct a new BigDecimal.
     * 
     * @param index representing where the value is expected to be at.
     * @return the value stored at the key or the default provided if the key
     *         doesn't exist.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return types.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @throws NumberFormatException if a String isn't a valid representation of
     *             a BigDecimal.
     * @see BigDecimal
     * @see Number#doubleValue()
     */
    public BigDecimal getBigDecimal(final int index) {
        Object returnable = this.get(index);
        if (returnable instanceof BigDecimal) {
            /* Success there was a BigDecimal. */
        } else if (returnable instanceof Number) {
            /* A number can be used to construct a BigDecimal. */
            returnable = new BigDecimal(returnable.toString());
        } else if (returnable instanceof String) {
            /* A number can be used to construct a BigDecimal. */
            returnable = new BigDecimal((String)returnable);
        }
        return (BigDecimal)returnable;
    }

    /**
     * A convenience method that assumes there is a Boolean or String value at
     * the given index.
     * 
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a boolean.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     */
    public Boolean getBoolean(final int index) {
        Object returnable = this.get(index);
        if (returnable instanceof String) {
            returnable = Boolean.valueOf((String)returnable);
        }
        return (Boolean)returnable;
    }

    /**
     * A convenience method that assumes there is a Number or String value at
     * the given index.
     * 
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a byte.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws NumberFormatException if a String isn't a valid representation of
     *             a BigDecimal or if the Number represents the double or float
     *             Infinity or NaN.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @see Number
     */
    public Byte getByte(final int index) {
        Object returnable = this.get(index);
        if (returnable == null) {
            return null;
        }
        if (returnable instanceof String) {
            /* A String can be used to construct a BigDecimal. */
            returnable = new BigDecimal((String)returnable);
        }
        return ((Number)returnable).byteValue();
    }

    /**
     * A convenience method that assumes there is a Collection value at the
     * given index.
     * 
     * @param <T> the kind of collection to expect at the index. Note unless
     *            manually added, collection values will be a JsonArray.
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a Collection.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @see Collection
     */
    @SuppressWarnings("unchecked")
    public <T extends Collection<?>> T getCollection(final int index) {
        /*
         * The unchecked warning is suppressed because there is no way of
         * guaranteeing at compile time the cast will work.
         */
        return (T)this.get(index);
    }

    /**
     * A convenience method that assumes there is a Number or String value at
     * the given index.
     * 
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a double.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws NumberFormatException if a String isn't a valid representation of
     *             a BigDecimal or if the Number represents the double or float
     *             Infinity or NaN.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @see Number
     */
    public Double getDouble(final int index) {
        Object returnable = this.get(index);
        if (returnable == null) {
            return null;
        }
        if (returnable instanceof String) {
            /* A String can be used to construct a BigDecimal. */
            returnable = new BigDecimal((String)returnable);
        }
        return ((Number)returnable).doubleValue();
    }

    /**
     * A convenience method that assumes there is a String value at the given
     * index representing a fully qualified name in dot notation of an enum.
     * 
     * @param index representing where the value is expected to be at.
     * @param <T> the Enum type the value at the index is expected to belong to.
     * @return the enum based on the string found at the index, or null if the
     *         value at the index was null.
     * @throws ClassNotFoundException if the element was a String but the
     *             declaring enum type couldn't be determined with it.
     * @throws ClassCastException if the element at the index was not a String
     *             or if the fully qualified enum name is of the wrong type.
     * @throws IllegalArgumentException if an enum type was dynamically
     *             determined but it doesn't define an enum with the dynamically
     *             determined name.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @see Enum#valueOf(Class, String)
     */
    @SuppressWarnings("unchecked")
    public <T extends Enum<T>> T getEnum(final int index) throws ClassNotFoundException {
        /*
         * Supressing the unchecked warning because the returnType is
         * dynamically identified and could lead to a ClassCastException when
         * returnType is cast to Class<T>, which is expected by the method's
         * contract.
         */
        T returnable;
        final String element;
        final String[] splitValues;
        final int numberOfValues;
        final StringBuilder returnTypeName;
        final StringBuilder enumName;
        final Class<T> returnType;
        /* Make sure the element at the index is a String. */
        element = this.getString(index);
        if (element == null) {
            return null;
        }
        /* Get the package, class, and enum names. */
        splitValues = element.split("\\.");
        numberOfValues = splitValues.length;
        returnTypeName = new StringBuilder();
        enumName = new StringBuilder();
        for (int i = 0; i < numberOfValues; i++) {
            if (i == (numberOfValues - 1)) {
                /*
                 * If it is the last split value then it should be the name of
                 * the Enum since dots are not allowed in enum names.
                 */
                enumName.append(splitValues[i]);
            } else if (i == (numberOfValues - 2)) {
                /*
                 * If it is the penultimate split value then it should be the
                 * end of the package/enum type and not need a dot appended to
                 * it.
                 */
                returnTypeName.append(splitValues[i]);
            } else {
                /*
                 * Must be part of the package/enum type and will need a dot
                 * appended to it since they got removed in the split.
                 */
                returnTypeName.append(splitValues[i]);
                returnTypeName.append(".");
            }
        }
        /* Use the package/class and enum names to get the Enum<T>. */
        returnType = (Class<T>)Class.forName(returnTypeName.toString());
        returnable = Enum.valueOf(returnType, enumName.toString());
        return returnable;
    }

    /**
     * A convenience method that assumes there is a Number or String value at
     * the given index.
     * 
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a float.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws NumberFormatException if a String isn't a valid representation of
     *             a BigDecimal or if the Number represents the double or float
     *             Infinity or NaN.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @see Number
     */
    public Float getFloat(final int index) {
        Object returnable = this.get(index);
        if (returnable == null) {
            return null;
        }
        if (returnable instanceof String) {
            /* A String can be used to construct a BigDecimal. */
            returnable = new BigDecimal((String)returnable);
        }
        return ((Number)returnable).floatValue();
    }

    /**
     * A convenience method that assumes there is a Number or String value at
     * the given index.
     * 
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a int.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws NumberFormatException if a String isn't a valid representation of
     *             a BigDecimal or if the Number represents the double or float
     *             Infinity or NaN.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @see Number
     */
    public Integer getInteger(final int index) {
        Object returnable = this.get(index);
        if (returnable == null) {
            return null;
        }
        if (returnable instanceof String) {
            /* A String can be used to construct a BigDecimal. */
            returnable = new BigDecimal((String)returnable);
        }
        return ((Number)returnable).intValue();
    }

    /**
     * A convenience method that assumes there is a Number or String value at
     * the given index.
     * 
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a long.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws NumberFormatException if a String isn't a valid representation of
     *             a BigDecimal or if the Number represents the double or float
     *             Infinity or NaN.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @see Number
     */
    public Long getLong(final int index) {
        Object returnable = this.get(index);
        if (returnable == null) {
            return null;
        }
        if (returnable instanceof String) {
            /* A String can be used to construct a BigDecimal. */
            returnable = new BigDecimal((String)returnable);
        }
        return ((Number)returnable).longValue();
    }

    /**
     * A convenience method that assumes there is a Map value at the given
     * index.
     * 
     * @param <T> the kind of map to expect at the index. Note unless manually
     *            added, Map values will be a JsonObject.
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a Map.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @see Map
     */
    @SuppressWarnings("unchecked")
    public <T extends Map<?, ?>> T getMap(final int index) {
        /*
         * The unchecked warning is suppressed because there is no way of
         * guaranteeing at compile time the cast will work.
         */
        return (T)this.get(index);
    }

    /**
     * A convenience method that assumes there is a Number or String value at
     * the given index.
     * 
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a short.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws NumberFormatException if a String isn't a valid representation of
     *             a BigDecimal or if the Number represents the double or float
     *             Infinity or NaN.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     * @see Number
     */
    public Short getShort(final int index) {
        Object returnable = this.get(index);
        if (returnable == null) {
            return null;
        }
        if (returnable instanceof String) {
            /* A String can be used to construct a BigDecimal. */
            returnable = new BigDecimal((String)returnable);
        }
        return ((Number)returnable).shortValue();
    }

    /**
     * A convenience method that assumes there is a Boolean, Number, or String
     * value at the given index.
     * 
     * @param index represents where the value is expected to be at.
     * @return the value at the index provided cast to a String.
     * @throws ClassCastException if there was a value but didn't match the
     *             assumed return type.
     * @throws IndexOutOfBoundsException if the index is outside of the range of
     *             element indexes in the JsonArray.
     */
    public String getString(final int index) {
        Object returnable = this.get(index);
        if (returnable instanceof Boolean) {
            returnable = returnable.toString();
        } else if (returnable instanceof Number) {
            returnable = returnable.toString();
        }
        return (String)returnable;
    }

    /*
     * (non-Javadoc)
     * @see org.apache.camel.util.json.Jsonable#asJsonString()
     */
    @Override
    public String toJson() {
        final StringWriter writable = new StringWriter();
        try {
            this.toJson(writable);
        } catch (final IOException caught) {
            /* See java.io.StringWriter. */
        }
        return writable.toString();
    }

    /*
     * (non-Javadoc)
     * @see org.apache.camel.util.json.Jsonable#toJsonString(java.io.Writer)
     */
    @Override
    public void toJson(final Writer writable) throws IOException {
        boolean isFirstElement = true;
        final Iterator<Object> elements = this.iterator();
        writable.write('[');
        while (elements.hasNext()) {
            if (isFirstElement) {
                isFirstElement = false;
            } else {
                writable.write(',');
            }
            writable.write(Jsoner.serialize(elements.next()));
        }
        writable.write(']');
    }
}