using System;
using System.Collections.Generic;
using JD.Collections.Extensions;
using JD.Collections.Interfaces;
using JD.Kernel.Structs;
using JD.TeaBoxAddinSystem.Addins.Description;
using JD.TeaBoxAddinSystem.Addins.Description.Conditions;
using JD.TeaBoxAddinSystem.Addins.Internal;

namespace JD.TeaBoxAddinSystem.Addins
{
    /// <summary>
    /// Extension Nodes are the objects that are created and placed in the extension tree.
    /// </summary>
    public class ExtensionNode : Node
    {
        #region Inner Types

        private class ExtensionNodeCollection : System.Collections.ObjectModel.ReadOnlyCollection<ExtensionNode>, IKeyedList<string, ExtensionNode>
        {
            #region Constructor

            internal ExtensionNodeCollection(IList<ExtensionNode> list)
                : base(list)
            {
            }

            #endregion

            #region Properties

            public ExtensionNode this[string key]
            {
                get
                {
                    foreach (ExtensionNode node in this)
                    {
                        if (node.Id == key)
                        {
                            return node;
                        }
                    }

                    return null;
                }
            }

            #endregion

            #region Methods

            public bool ContainsKey(string key)
            {
                return (this[key] != null);
            }

            public bool Remove(string key)
            {
                throw new NotSupportedException();
            }

            public bool TryGetValue(string key, out ExtensionNode value)
            {
                value = this[key];
                return value != null;
            }

            #endregion
        }

        #endregion

        #region Variables

        private object m_cachedInstance;

        // Set through Initialize
        private TreeNode m_node;

        // Lazy-constructed
        private List<ExtensionNode> m_childNodes;

        private object m_lock = new object();

        #endregion

        #region Properties

        /// <summary>
        /// Gets the file location of the extension node.
        /// </summary>
        /// <returns></returns>
        public override sealed FileLocation FileLocation
        {
            get
            {
                if (m_node != null)
                {
                    return m_node.ExtensionNodeDescription.FileLocation.GetValueOrDefault();
                }

                return FileLocation.Empty;
            }
        }

        /// <summary>
        /// Type of this extension node.
        /// </summary>
        public new ExtensionType Type
        {
            get
            {
                return (ExtensionType)base.Type;
            }
        }

        /// <summary>
        /// Id of the extension node.
        /// </summary>
        public string Id
        {
            get
            {
                return m_node.Id;
            }
        }

        /// <summary>
        /// Gets whether the <see cref="Id"/> of this <see cref="ExtensionNode"/> was defined by the user or automatically generated.
        /// </summary>
        public bool HasIdDefined
        {
            get
            {
                return m_node.HasIdDefined;
            }
        }

        /// <summary>
        /// Full path of the extension node.
        /// </summary>
        public string FullPath
        {
            get
            {
                return m_node.FullPath;
            }
        }

        /// <summary>
        /// Child nodes of this extension node.
        /// </summary>
        public IKeyedList<string, ExtensionNode> ChildNodes
        {
            get
            {
                if (m_childNodes == null)
                {
                    lock (m_lock)
                    {
                        if (m_childNodes == null)
                        {
                            List<ExtensionNode> nodes = new List<ExtensionNode>(m_node.ChildNodes.Count);

                            foreach (TreeNode childNode in m_node.ChildNodes)
                            {
                                ExtensionNode childExtensionNode = childNode.ExtensionNode;

                                if (childExtensionNode != null)
                                {
                                    nodes.Add(childExtensionNode);
                                }
                            }

                            m_childNodes = nodes;
                        }
                    }
                }

                System.Diagnostics.Debug.Assert(m_childNodes != null);
                return new ExtensionNodeCollection(m_childNodes);
            }
        }

        /// <summary>
        /// Extension Object of this node.
        /// </summary>
        /// <remarks>
        /// This method is only valid on <see cref="TypeExtensionNode"/>s
        /// </remarks>
        /// <exception cref="InvalidOperationException">The node is not a <see cref="TypeExtensionNode"/>.</exception>
        public virtual object ExtensionObject
        {
            get
            {
                if (m_cachedInstance == null)
                {
                    m_cachedInstance = CreateExtensionObject();
                }

                return m_cachedInstance;
            }
        }

        #endregion

        #region Methods

        /// <summary>
        /// Creates an extension object for this node.
        /// </summary>
        /// <remarks>
        /// This method is only valid on certain extension node types like <see cref="TypeExtensionNode"/>.
        /// </remarks>
        /// <returns></returns>
        /// <exception cref="InvalidOperationException">This extension node doesn't support extension objects.</exception>
        public virtual object CreateExtensionObject()
        {
            throw new InvalidOperationException("ExtensionObjects are only available on TypeExtensionNodes");
        }

        /// <summary>
        /// Gets a collection of extension objects contained in this extension node.
        /// </summary>
        /// <remarks>
        /// All objects created by child nodes MUST be of type <typeparamref name="T"/>.
        /// </remarks>
        /// <typeparam name="T"></typeparam>
        /// <returns></returns>
        public IList<T> GetExtensionObjects<T>()
        {
            return ChildNodes.Project(node => (T)node.ExtensionObject);
        }

        internal T GetExtensionObject<T>()
        {
            return (T)ExtensionObject;
        }

        /// <summary>
        /// Called by a <see cref="TreeNode"/> when its collection of child nodes is modified.
        /// </summary>
        internal void NotifyChildNodesChanged(ExtensionNodeChangedEventArgs e)
        {
            // This will trigger a recreation of the nodes on demand.
            m_childNodes = null;
            OnChanged(e);
        }

        internal bool Initialize(TreeNode node, Module module, ExtensionNodeDescription description, ExtensionType type)
        {
            System.Diagnostics.Debug.Assert(node != null);
            m_node = node;

            if (!base.Initialize(module, description, type))
            {
                return false;
            }

            // Validate conditional targets
            if (description != null) // Description can be null in case of extension point's fake extension nodes.
            {
                foreach (ConditionInfo conditionInfo in description.Conditions)
                {
                    if (!string.IsNullOrEmpty(conditionInfo.Target) && !type.ConditionAttributes.Contains(conditionInfo.Target))
                    {
                        description.LogWarning("Cannot apply condition {0} on target {1} of node {2} because it is not supported on extension nodes of type {3}",
                                               conditionInfo.Condition,
                                               conditionInfo.Target,
                                               description.DisplayId,
                                               type.Name);
                    }
                }
            }

            return true;
        }

        #endregion

        #region Events

        /// <summary>
        /// Triggered when this extension node changes.
        /// </summary>
        public event EventHandler<ExtensionNodeChangedEventArgs> Changed
        {
            add
            {
                AddinManager.SessionService.AddExtensionChangedHandler(FullPath, value);
            }
            remove
            {
                AddinManager.SessionService.RemoveExtensionChangedHandler(FullPath, value);
            }
        }

        /// <summary>
        /// Triggers a <see cref="Changed"/> event.
        /// </summary>
        /// <param name="e">Event Args.</param>
        protected virtual void OnChanged(ExtensionNodeChangedEventArgs e)
        {
            AddinManager.SessionService.ChangedHandlerManager.OnChanged(e);
        }

        #endregion
    }
}