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// *  http://www.apache.org/licenses/LICENSE-2.0                                                                             *
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package org.apache.juneau;

import java.util.*;

import org.apache.juneau.annotation.*;
import org.apache.juneau.internal.*;
import org.apache.juneau.json.*;

/**
 * A reusable stateless thread-safe read-only configuration, typically used for creating one-time use {@link Session}
 * objects.
 *
 * <p>
 * Contexts are created through the {@link ContextBuilder#build()} method (and subclasses of {@link ContextBuilder}).
 *
 * <p>
 * Subclasses MUST implement the following constructor:
 *
 * <p class='bcode w800'>
 * 	<jk>public</jk> T(PropertyStore);
 * </p>
 *
 * <p>
 * Besides that restriction, a context object can do anything you desire.
 * <br>However, it MUST be thread-safe and all fields should be declared final to prevent modification.
 * <br>It should NOT be used for storing temporary or state information.
 *
 * @see PropertyStore
 */
public abstract class Context {

	private final PropertyStore propertyStore;
	private final int identityCode;

	/**
	 * Constructor for this class.
	 *
	 * <p>
	 * Subclasses MUST implement the same public constructor.
	 *
	 * @param ps The read-only configuration for this context object.
	 * @param allowReuse If <jk>true</jk>, subclasses that share the same property store values can be reused.
	 */
	public Context(PropertyStore ps, boolean allowReuse) {
		this.propertyStore = ps == null ? PropertyStore.DEFAULT : ps;
		this.identityCode = allowReuse ? new HashCode().add(getClass().getName()).add(ps).get() : System.identityHashCode(this);
	}

	/**
	 * Returns the raw property value with the specified name.
	 *
	 * @param key The property name.
	 * @return The property value, or <jk>null</jk> if it doesn't exist.
	 */
	public Object getProperty(String key) {
		return propertyStore.getProperty(key);
	}

	/**
	 * Returns the property value with the specified name.
	 *
	 * @param key The property name.
	 * @param c The class to cast or convert the value to.
	 * @param def The default value.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final <T> T getProperty(String key, Class<T> c, T def) {
		return propertyStore.getProperty(key, c, def);
	}

	/**
	 * Shortcut for calling <code>getProperty(key, Boolean.<jk>class</jk>, def)</code>.
	 *
	 * @param key The property name.
	 * @param def The default value.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final Boolean getBooleanProperty(String key, Boolean def) {
		return getProperty(key, Boolean.class, def);
	}

	/**
	 * Shortcut for calling <code>getProperty(key, Integer.<jk>class</jk>, def)</code>.
	 *
	 * @param key The property name.
	 * @param def The default value.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final Integer getIntegerProperty(String key, Integer def) {
		return getProperty(key, Integer.class, def);
	}

	/**
	 * Shortcut for calling <code>getProperty(key, Long.<jk>class</jk>, def)</code>.
	 *
	 * @param key The property name.
	 * @param def The default value.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final Long getLongProperty(String key, Long def) {
		return getProperty(key, Long.class, def);
	}

	/**
	 * Shortcut for calling <code>getProperty(key, String.<jk>class</jk>, def)</code>.
	 *
	 * @param key The property name.
	 * @param def The default value.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final String getStringProperty(String key, String def) {
		return getProperty(key, String.class, def);
	}

	/**
	 * Returns a property as a parsed comma-delimited list of strings.
	 *
	 * @param key The property name.
	 * @param def The default value.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final String[] getCdlProperty(String key, String def) {
		return StringUtils.split(StringUtils.emptyIfNull(getProperty(key, String.class, def)));
	}

	/**
	 * Same as {@link #getStringProperty(String, String)} but returns a blank instead of the default value if it resolves to <js>"NONE"</js>.
	 *
	 * @param key The property name.
	 * @param def The default value.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final String getStringPropertyWithNone(String key, String def) {
		String s = getProperty(key, String.class, def);
		return "NONE".equalsIgnoreCase(s) ? "" : s;
	}

	/**
	 * Returns the class property with the specified name.
	 *
	 * @param key The property name.
	 * @param type The class type of the property.
	 * @param def The default value.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final <T> Class<? extends T> getClassProperty(String key, Class<T> type, Class<? extends T> def) {
		return propertyStore.getClassProperty(key, type, def);
	}

	/**
	 * Returns the array property value with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final <T> T[] getArrayProperty(String key, Class<T> eType) {
		return propertyStore.getArrayProperty(key, eType);
	}

	/**
	 * Returns the array property value with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @param def The default value.
	 * @return The property value, or the default value if it doesn't exist.
	 */
	public final <T> T[] getArrayProperty(String key, Class<T> eType, T[] def) {
		return propertyStore.getArrayProperty(key, eType, def);
	}

	/**
	 * Returns the class array property with the specified name.
	 *
	 * @param key The property name.
	 * @return The property value, or an empty array if it doesn't exist.
	 */
	public final Class<?>[] getClassArrayProperty(String key) {
		return propertyStore.getClassArrayProperty(key);
	}

	/**
	 * Returns the class array property with the specified name.
	 *
	 * @param key The property name.
	 * @param def The default value.
	 * @return The property value, or an empty array if it doesn't exist.
	 */
	public final Class<?>[] getClassArrayProperty(String key, Class<?>[] def) {
		return propertyStore.getClassArrayProperty(key, def);
	}

	/**
	 * Returns the class array property with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @return The property value, or an empty array if it doesn't exist.
	 */
	public final <T> Class<T>[] getClassArrayProperty(String key, Class<T> eType) {
		return propertyStore.getClassArrayProperty(key, eType);
	}

	/**
	 * Returns the set property with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @return The property value as an unmodifiable <c>LinkedHashSet</c>, or an empty set if it doesn't exist.
	 */
	public final <T> Set<T> getSetProperty(String key, Class<T> eType) {
		return propertyStore.getSetProperty(key, eType);
	}

	/**
	 * Returns the set property with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @param def The default value if the property doesn't exist or is empty.
	 * @return The property value as an unmodifiable <c>LinkedHashSet</c>, or the default value if it doesn't exist or is empty.
	 */
	public final <T> Set<T> getSetProperty(String key, Class<T> eType, Set<T> def) {
		return propertyStore.getSetProperty(key, eType, def);
	}

	/**
	 * Returns the class set property with the specified name.
	 *
	 * @param key The property name.
	 * @return The property value as an unmodifiable <c>LinkedHashSet</c>, or an empty set if it doesn't exist.
	 */
	public final Set<Class<?>> getClassSetProperty(String key) {
		return propertyStore.getClassSetProperty(key);
	}

	/**
	 * Returns the class set property with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @return The property value as an unmodifiable <c>LinkedHashSet</c>, or an empty set if it doesn't exist.
	 */
	public final <T> Set<Class<T>> getClassSetProperty(String key, Class<T> eType) {
		return propertyStore.getClassSetProperty(key, eType);
	}

	/**
	 * Returns the list property with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @return The property value as an unmodifiable <c>ArrayList</c>, or an empty list if it doesn't exist.
	 */
	public final <T> List<T> getListProperty(String key, Class<T> eType) {
		return propertyStore.getListProperty(key, eType);
	}

	/**
	 * Returns the list property with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @param def The default value if the property doesn't exist or is empty.
	 * @return The property value as an unmodifiable <c>ArrayList</c>, or the default value if it doesn't exist or is empty.
	 */
	public final <T> List<T> getListProperty(String key, Class<T> eType, List<T> def) {
		return propertyStore.getListProperty(key, eType, def);
	}

	/**
	 * Returns the class list property with the specified name.
	 *
	 * @param key The property name.
	 * @return The property value as an unmodifiable <c>ArrayList</c>, or an empty list if it doesn't exist.
	 */
	public final List<Class<?>> getClassListProperty(String key) {
		return propertyStore.getClassListProperty(key);
	}

	/**
	 * Returns the class list property with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @return The property value as an unmodifiable <c>ArrayList</c>, or an empty list if it doesn't exist.
	 */
	public final <T> List<Class<T>> getClassListProperty(String key, Class<T> eType) {
		return propertyStore.getClassListProperty(key, eType);
	}

	/**
	 * Returns the map property with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @return The property value as an unmodifiable <c>LinkedHashMap</c>, or an empty map if it doesn't exist.
	 */
	public final <T> Map<String,T> getMapProperty(String key, Class<T> eType) {
		return propertyStore.getMapProperty(key, eType);
	}

	/**
	 * Returns the class map property with the specified name.
	 *
	 * @param key The property name.
	 * @return The property value as an unmodifiable <c>LinkedHashMap</c>, or an empty map if it doesn't exist.
	 */
	public final Map<String,Class<?>> getClassMapProperty(String key) {
		return propertyStore.getClassMapProperty(key);
	}

	/**
	 * Returns the class map property with the specified name.
	 *
	 * @param key The property name.
	 * @param eType The class type of the elements in the property.
	 * @return The property value as an unmodifiable <c>LinkedHashMap</c>, or an empty map if it doesn't exist.
	 */
	public final <T> Map<String,Class<T>> getClassMapProperty(String key, Class<T> eType) {
		return propertyStore.getClassMapProperty(key, eType);
	}

	/**
	 * Returns an instance of the specified class, string, or object property.
	 *
	 * <p>
	 * If instantiating a class, assumes the class has a no-arg constructor.
	 * Otherwise, throws a runtime exception.
	 *
	 * @param key The property name.
	 * @param type The class type of the property.
	 * @param def
	 * 	The default value if the property doesn't exist.
	 * 	<br>Can either be an instance of <c>T</c>, or a <code>Class&lt;? <jk>extends</jk> T&gt;</code>, or <jk>null</jk>.
	 * @return A new property instance.
	 */
	public <T> T getInstanceProperty(String key, Class<T> type, Object def) {
		return propertyStore.getInstanceProperty(key, type, def);
	}

	/**
	 * Returns an instance of the specified class, string, or object property.
	 *
	 * @param key The property name.
	 * @param type The class type of the property.
	 * @param def
	 * 	The default value if the property doesn't exist.
	 * 	<br>Can either be an instance of <c>T</c>, or a <code>Class&lt;? <jk>extends</jk> T&gt;</code>.
	 * @param resolver
	 * 	The resolver to use for instantiating objects.
	 * @param args
	 * 	Arguments to pass to the constructor.
	 * 	Constructors matching the arguments are always used before no-arg constructors.
	 * @return A new property instance.
	 */
	public <T> T getInstanceProperty(String key, Class<T> type, Object def, ResourceResolver resolver, Object...args) {
		return propertyStore.getInstanceProperty(key, type, def, resolver, args);
	}

	/**
	 * Returns an instance of the specified class, string, or object property.
	 *
	 * @param key The property name.
	 * @param outer The outer object if the class we're instantiating is an inner class.
	 * @param type The class type of the property.
	 * @param def
	 * 	The default value if the property doesn't exist.
	 * 	<br>Can either be an instance of <c>T</c>, or a <code>Class&lt;? <jk>extends</jk> T&gt;</code>.
	 * @param resolver
	 * 	The resolver to use for instantiating objects.
	 * @param args
	 * 	Arguments to pass to the constructor.
	 * 	Constructors matching the arguments are always used before no-arg constructors.
	 * @return A new property instance.
	 */
	public <T> T getInstanceProperty(String key, Object outer, Class<T> type, Object def, ResourceResolver resolver, Object...args) {
		return propertyStore.getInstanceProperty(key, outer, type, def, resolver, args);
	}

	/**
	 * Returns the specified property as an array of instantiated objects.
	 *
	 * @param key The property name.
	 * @param type The class type of the property.
	 * @param def The default object to return if the property doesn't exist.
	 * @return A new property instance.
	 */
	public <T> T[] getInstanceArrayProperty(String key, Class<T> type, T[] def) {
		return propertyStore.getInstanceArrayProperty(key, type, def);
	}

	/**
	 * Returns the specified property as an array of instantiated objects.
	 *
	 * @param key The property name.
	 * @param type The class type of the property.
	 * @param def The default object to return if the property doesn't exist.
	 * @param resolver
	 * 	The resolver to use for instantiating objects.
	 * @param args
	 * 	Arguments to pass to the constructor.
	 * 	Constructors matching the arguments are always used before no-arg constructors.
	 * @return A new property instance.
	 */
	public <T> T[] getInstanceArrayProperty(String key, Class<T> type, T[] def, ResourceResolver resolver, Object...args) {
		return propertyStore.getInstanceArrayProperty(key, type, def, resolver, args);
	}

	/**
	 * Returns the specified property as an array of instantiated objects.
	 *
	 * @param key The property name.
	 * @param outer The outer object if the class we're instantiating is an inner class.
	 * @param type The class type of the property.
	 * @param def The default object to return if the property doesn't exist.
	 * @param resolver
	 * 	The resolver to use for instantiating objects.
	 * @param args
	 * 	Arguments to pass to the constructor.
	 * 	Constructors matching the arguments are always used before no-arg constructors.
	 * @return A new property instance.
	 */
	public <T> T[] getInstanceArrayProperty(String key, Object outer, Class<T> type, T[] def, ResourceResolver resolver, Object...args) {
		return propertyStore.getInstanceArrayProperty(key, outer, type, def, resolver, args);
	}

	/**
	 * Returns the keys found in the specified property group.
	 *
	 * <p>
	 * The keys are NOT prefixed with group names.
	 *
	 * @param group The group name.
	 * @return The set of property keys, or an empty set if the group was not found.
	 */
	public Set<String> getPropertyKeys(String group) {
		return propertyStore.getPropertyKeys(group);
	}

	/**
	 * Returns the property store associated with this context.
	 *
	 * @return The property store associated with this context.
	 */
	@BeanIgnore
	public final PropertyStore getPropertyStore() {
		return propertyStore;
	}

	/**
	 * Creates a builder from this context object.
	 *
	 * <p>
	 * Builders are used to define new contexts (e.g. serializers, parsers) based on existing configurations.
	 *
	 * @return A new ContextBuilder object.
	 */
	public ContextBuilder builder() {
		return null;
	}

	/**
	 * Create a new bean session based on the properties defined on this context.
	 *
	 * <p>
	 * Use this method for creating sessions if you don't need to override any
	 * properties or locale/timezone currently set on this context.
	 *
	 * @return A new session object.
	 */
	public Session createSession() {
		return createSession(createDefaultSessionArgs());
	}

	/**
	 * Create a new session based on the properties defined on this context combined with the specified
	 * runtime args.
	 *
	 * <p>
	 * Use this method for creating sessions if you don't need to override any
	 * properties or locale/timezone currently set on this context.
	 *
	 * @param args
	 * 	The session arguments.
	 * @return A new session object.
	 */
	public abstract Session createSession(SessionArgs args);

	/**
	 * Defines default session arguments used when calling the {@link #createSession()} method.
	 *
	 * @return A SessionArgs object, possibly a read-only reusable instance.
	 */
	public abstract SessionArgs createDefaultSessionArgs();

	@Override /* Object */
	public int hashCode() {
		return identityCode;
	}

	/**
	 * Returns a uniqueness identity code for this context.
	 *
	 * @return A uniqueness identity code.
	 */
	public int identityCode() {
		return identityCode;
	}

	@Override /* Object */
	public boolean equals(Object o) {
		// Context objects are considered equal if they're the same class and have the same set of properties.
		if (o == null)
			return false;
		if (o.getClass() != this.getClass())
			return false;
		Context c = (Context)o;
		return (c.propertyStore.equals(propertyStore));
	}

	//-----------------------------------------------------------------------------------------------------------------
	// Other methods
	//-----------------------------------------------------------------------------------------------------------------

	@Override /* Object */
	public String toString() {
		return SimpleJsonSerializer.DEFAULT_READABLE.toString(toMap());
	}

	/**
	 * Returns the properties defined on this bean context as a simple map for debugging purposes.
	 *
	 * @return A new map containing the properties defined on this context.
	 */
	public ObjectMap toMap() {
		return new DefaultFilteringObjectMap()
			.append("Context", new DefaultFilteringObjectMap()
				.append("identityCode", identityCode)
				.append("propertyStore", propertyStore)
			);
	}
}