using System;
using System.Collections.Generic;
using Umbraco.Core.Models.Entities;
using Umbraco.Core.Scoping;

namespace Umbraco.Core.Cache
{
    /// <summary>
    /// A base class for repository cache policies.
    /// </summary>
    /// <typeparam name="TEntity">The type of the entity.</typeparam>
    /// <typeparam name="TId">The type of the identifier.</typeparam>
    internal abstract class RepositoryCachePolicyBase<TEntity, TId> : IRepositoryCachePolicy<TEntity, TId>
        where TEntity : class, IEntity
    {
        private readonly IAppPolicyCache _globalCache;
        private readonly IScopeAccessor _scopeAccessor;

        protected RepositoryCachePolicyBase(IAppPolicyCache globalCache, IScopeAccessor scopeAccessor)
        {
            _globalCache = globalCache ?? throw new ArgumentNullException(nameof(globalCache));
            _scopeAccessor = scopeAccessor ?? throw new ArgumentNullException(nameof(scopeAccessor));
        }

        protected IAppPolicyCache Cache
        {
            get
            {
                var ambientScope = _scopeAccessor.AmbientScope;
                switch (ambientScope.RepositoryCacheMode)
                {
                    case RepositoryCacheMode.Default:
                        return _globalCache;
                    case RepositoryCacheMode.Scoped:
                        return ambientScope.IsolatedCaches.GetOrCreate<TEntity>();
                    case RepositoryCacheMode.None:
                        return NoAppCache.Instance;
                    default:
                        throw new NotSupportedException($"Repository cache mode {ambientScope.RepositoryCacheMode} is not supported.");
                }
            }
        }

        /// <inheritdoc />
        public abstract TEntity Get(TId id, Func<TId, TEntity> performGet, Func<TId[], IEnumerable<TEntity>> performGetAll);

        /// <inheritdoc />
        public abstract TEntity GetCached(TId id);

        /// <inheritdoc />
        public abstract bool Exists(TId id, Func<TId, bool> performExists, Func<TId[], IEnumerable<TEntity>> performGetAll);

        /// <inheritdoc />
        public abstract void Create(TEntity entity, Action<TEntity> persistNew);

        /// <inheritdoc />
        public abstract void Update(TEntity entity, Action<TEntity> persistUpdated);

        /// <inheritdoc />
        public abstract void Delete(TEntity entity, Action<TEntity> persistDeleted);

        /// <inheritdoc />
        public abstract TEntity[] GetAll(TId[] ids, Func<TId[], IEnumerable<TEntity>> performGetAll);

        /// <inheritdoc />
        public abstract void ClearAll();
    }
}