// ***************************************************************************************************************************
// * Licensed to the Apache Software Foundation (ASF) under one or more contributor license agreements.  See the NOTICE file *
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// * to you under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance            *
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// *  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  *
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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
 */
@ConfigurableContext
public abstract class Context {

   static final String PREFIX = "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)
         );
   }
}