﻿/*

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#  #  #########     _______ _     _  ______ _     _
##  ######## @ ##   |______ |     | |  ____ |     |
##################  |       |_____| |_____| |_____|
##  #############      f  r  a  m  e  w  o  r  k
#  #  #########
         ###

(c) 2015 - 2017 FUGU framework project

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

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 "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

*/

using System;
using System.Collections.Generic;
using System.Linq;
using System.Reflection;

namespace Fugu.EntityFrameworkCore.Internal
{
    internal static class IndexResolver
    {
        private static readonly IDictionary<Type, IEnumerable<IndexResolverResultItem>> _cache = new Dictionary<Type, IEnumerable<IndexResolverResultItem>>();

        public static IEnumerable<IndexResolverResultItem> ResolveType(Type entityType)
        {
            if (_cache.ContainsKey(entityType))
            {
                return _cache[entityType];
            }

            var result = new List<IndexResolverResultItem>();

            var indexedProperties = entityType
                .GetProperties()
                .Where(pi => pi.IsDefined(typeof(IndexAttribute), false) || pi.IsDefined(typeof(UniqueAttribute), false))
                .ToDictionary(pi => pi, pi => pi.GetCustomAttributes(typeof(IndexAttribute), false));

            foreach (var indexedProperty in indexedProperties)
            {
                foreach (IndexAttribute indexAttribute in indexedProperty.Value)
                {
                    var resultItem = result.SingleOrDefault(ri => ri.Name == indexAttribute.Name);
                    if (resultItem == null)
                    {
                        resultItem = new IndexResolverResultItem
                        {
                            Name = indexAttribute.Name,
                            Properties = new string[8]
                        };

                        result.Add(resultItem);
                    }

                    if (indexAttribute.Order > resultItem.Properties.Length - 1)
                    {
                        var arrayToResize = resultItem.Properties;
                        Array.Resize(ref arrayToResize, indexAttribute.Order);
                        resultItem.Properties = arrayToResize;
                    }

                    resultItem.Properties[indexAttribute.Order] = indexedProperty.Key.Name;
                    resultItem.IsUnique = indexAttribute.IsUnique;
                    resultItem.IsDescending = indexAttribute.IsDescending;
                }
            }

            foreach (var resultItem in result)
            {
                resultItem.Properties = resultItem.Properties.Where(s => !string.IsNullOrWhiteSpace(s)).ToArray();
            }

            _cache.Add(entityType, result);

            return result;
        }
    }
}