using System.Collections.Generic;
using System.Diagnostics;
using JD.Collections;
using JD.TeaBoxAddinSystem.Addins.Description;

namespace JD.TeaBoxAddinSystem.Addins.Internal
{
    /// <summary>
    /// Dependency manager.
    /// </summary>
    internal class DependencyManager
    {
        #region Variables

        private readonly MultiDictionary<string, Module> m_dependencies = new MultiDictionary<string, Module>();

        #endregion

        #region Methods

        internal void RegisterModule(Module module)
        {
            foreach (AddinReference reference in module.Dependencies)
            {
                AddDependency(module, reference.Name);
            }
        }

        /// <summary>
        /// Adds a dependency of <paramref name="module"/> towards the given <paramref name="addinId"/>.
        /// </summary>
        /// <param name="module"></param>
        /// <param name="addinId"></param>
        private void AddDependency(Module module, string addinId)
        {
            Debug.Assert(module != null);
            Debug.Assert(!string.IsNullOrEmpty(addinId));
            Debug.Assert(!m_dependencies.Contains(addinId, module));
            m_dependencies.Add(addinId, module);
        }

        internal void UnregisterModule(Module module)
        {
            foreach (AddinReference reference in module.Dependencies)
            {
                RemoveDependency(module, reference.Name);
            }
        }

        /// <summary>
        /// Removes a dependency of <paramref name="module"/> towards the given <paramref name="addinId"/>.
        /// </summary>
        /// <param name="module"></param>
        /// <param name="addinId"></param>
        private void RemoveDependency(Module module, string addinId)
        {
            Debug.Assert(module != null);
            Debug.Assert(!string.IsNullOrEmpty(addinId));
            Debug.Assert(m_dependencies.Contains(addinId, module));
            m_dependencies.Remove(addinId, module);
        }

        /// <summary>
        /// Clears all dependency info.
        /// </summary>
        internal void Clear()
        {
            m_dependencies.Clear();
        }

        /// <summary>
        /// Gets all the dependencies (weak and strong) on the given <paramref name="addinId"/>.
        /// </summary>
        /// <param name="addinId"></param>
        /// <returns></returns>
        public IEnumerable<Module> GetDependencies(string addinId)
        {
            Debug.Assert(!string.IsNullOrEmpty(addinId));
            return m_dependencies[addinId];
        }

        /// <summary>
        /// Gets the modules that depend weakly on the given <paramref name="addinId"/>.
        /// </summary>
        /// <param name="addinId"></param>
        /// <returns></returns>
        public IEnumerable<Module> GetWeakDependencies(string addinId)
        {
            foreach (Module module in GetDependencies(addinId))
            {
                if (!module.IsMainModule)
                {
                    yield return module;
                }
            }
        }

        /// <summary>
        /// Gets the modules that depend strongly on the given <paramref name="addinId"/>.
        /// </summary>
        /// <param name="addinId"></param>
        /// <returns></returns>
        public IEnumerable<Module> GetStrongDependencies(string addinId)
        {
            foreach (Module module in GetDependencies(addinId))
            {
                if (module.IsMainModule)
                {
                    yield return module;
                }
            }
        }

        /// <summary>
        /// Gets whether there is an addin that depends on the given <paramref name="addinId"/>.
        /// </summary>
        /// <param name="addinId"></param>
        /// <returns></returns>
        public bool HasStrongDependencies(string addinId)
        {
            foreach (Module module in GetStrongDependencies(addinId))
            {
                return true;
            }

            return false;
        }

        #endregion
    }
}