using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using JD.Kernel.StaticHelpers;
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>
    /// An addin is a plugin that adds or extends some functionality. It can also define extension points for other addins.
    /// </summary>
    public sealed class Addin
    {
        #region Inner Types

        private class ExtensionTypeSetCollection : AddinObjectKeyedCollection<string, ExtensionTypeSet>
        {
            #region Constructor

            internal ExtensionTypeSetCollection(Module owner)
                : base(owner)
            {
            }

            #endregion

            #region Methods

            /// <summary>
            /// Overriden.
            /// </summary>
            /// <param name="item"></param>
            /// <returns></returns>
            protected override string GetKeyForItem(ExtensionTypeSet item)
            {
                if (item == null)
                {
                    throw new ArgumentNullException("item");
                }

                System.Diagnostics.Debug.Assert(!string.IsNullOrEmpty(item.Name));
                return item.Name;
            }

            #endregion
        }

        private class ModuleCollection : Collection<Module>
        {
            #region Variables

            private readonly Addin m_addin;

            #endregion

            #region Constructor

            public ModuleCollection(Addin addin)
            {
                m_addin = addin;
            }

            #endregion

            #region Methods

            protected override void InsertItem(int index, Module item)
            {
                m_addin.ThrowIfLoaded();

                base.InsertItem(index, item);
                item.SetAddin(m_addin);
            }            

            protected override void SetItem(int index, Module item)
            {
                m_addin.ThrowIfLoaded();

                this[index].SetAddin(null);
                base.SetItem(index, item);
                item.SetAddin(m_addin);
            }

            protected override void RemoveItem(int index)
            {
                m_addin.ThrowIfLoaded();

                this[index].SetAddin(null);
                base.RemoveItem(index);
            }

            protected override void ClearItems()
            {
                m_addin.ThrowIfLoaded();

                foreach (Module module in this)
                {
                    module.SetAddin(null);
                }
                base.ClearItems();
            }

            #endregion
        }

        #endregion

        #region Variables

        private readonly AddinManifest m_manifest;
        private readonly Module m_mainModule = new Module();
        private readonly ModuleCollection m_modules;
        private readonly ExtensionPointCollection m_extensionPoints;
        private readonly ExtensionTypeSetCollection m_extensionTypeSets;
        private readonly NodeTypeCollection<ConditionType> m_conditionTypes;

        private FileLocation? m_fileLocation;

        private readonly List<string> m_partialAddinFilenames = new List<string>();

        #endregion

        #region Constructor

        /// <summary>
        /// Constructor.
        /// </summary>
        public Addin()
            : this(null)
        {
        }

        /// <summary>
        /// Constructor.
        /// </summary>
        /// <param name="id"></param>
        public Addin(string id)
        {
            m_manifest = new AddinManifest(this, id);
            m_mainModule.SetAddin(this);
            m_modules = new ModuleCollection(this);
            m_extensionPoints = new ExtensionPointCollection(MainModule);
            m_extensionTypeSets = new ExtensionTypeSetCollection(MainModule);
            m_conditionTypes = new NodeTypeCollection<ConditionType>(MainModule);
        }

        #endregion

        #region Properties

        /// <summary>
        /// Full id of the addin.
        /// </summary>
        public string FullId
        {
            get
            {
                return Manifest.FullId;
            }
        }

        /// <summary>
        /// Returns whether this addin is laoded.
        /// </summary>
        public bool IsLoaded
        {
            get
            {
                return AddinManager.IsAddinLoaded(this);
            }
        }

        /// <summary>
        /// Manifest of this addin.
        /// </summary>
        public AddinManifest Manifest
        {
            get
            {
                return m_manifest;
            }
        }

        /// <summary>
        /// Main module.
        /// </summary>
        public Module MainModule
        {
            get
            {
                return m_mainModule;
            }
        }

        /// <summary>
        /// All modules, including the main module.
        /// </summary>
        public IEnumerable<Module> AllModules
        {
            get
            {
                yield return MainModule;
                foreach (Module module in Modules)
                {
                    yield return module;
                }
            }
        }

        /// <summary>
        /// Optional modules of this addin.
        /// </summary>
        public IList<Module> Modules
        {
            get
            {
                return m_modules;
            }
        }

        /// <summary>
        /// <see cref="ExtensionPoint"/>s defined in this addin.
        /// </summary>
        public KeyedCollection<string, ExtensionPoint> ExtensionPoints
        {
            get
            {
                return m_extensionPoints;
            }
        }

        /// <summary>
        /// The <see cref="ExtensionTypeSet"/>s defined in this addin.
        /// </summary>
        public KeyedCollection<string, ExtensionTypeSet> ExtensionTypeSets
        {
            get
            {
                return m_extensionTypeSets;
            }
        }

        /// <summary>
        /// The <see cref="ConditionType"/>s defined in this addin.
        /// </summary>
        public KeyedCollection<string, ConditionType> ConditionTypes
        {
            get
            {
                return m_conditionTypes;
            }
        }

        /// <summary>
        /// File Location of the addin.
        /// </summary>
        public FileLocation? FileLocation
        {
            get
            {
                return m_fileLocation;
            }
            set
            {
                ThrowIfLoaded();
                m_fileLocation = value;
            }
        }

        /// <summary>
        /// Filenames of the partial addins that contributed to this addin.
        /// </summary>
        public IList<string> PartialAddinFilenames
        {
            get
            {
                return m_partialAddinFilenames.AsReadOnly();
            }
        }

        #endregion

        #region Methods

        internal void AddPartialAddinFilename(string filename)
        {
            m_partialAddinFilenames.Add(filename);
        }

        internal void ThrowIfLoaded()
        {
            Throw.InvalidOperationIf(IsLoaded, "Cannot modify an addin while it is loaded.");
        }

        /// <summary>
        /// Overriden.
        /// </summary>
        /// <returns></returns>
        public override string ToString()
        {
            return
                $"[{Manifest.FullId}{(IsLoaded ? string.Empty : " (not loaded)")}: {Modules.Count} optional modules, {ExtensionPoints.Count} extension points, {ExtensionTypeSets.Count} extension type sets]";
        }

        #endregion
    }
}