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

namespace Ips.Library.Basic
{
    public static class ListExtensions
    {
        public static void InsertRange<T>(this IList<T> source, int index, IEnumerable<T> items)
        {
            foreach (var item in items)
            {
                source.Insert(index++, item);
            }
        }

        public static int FindIndex<T>(this IList<T> source, Predicate<T> selector)
        {
            for (var i = 0; i < source.Count; ++i)
            {
                if (selector(source[i]))
                {
                    return i;
                }
            }

            return -1;
        }

        public static void AddFirst<T>(this IList<T> source, T item)
        {
            source.Insert(0, item);
        }

        public static void AddLast<T>(this IList<T> source, T item)
        {
            source.Insert(source.Count, item);
        }

        public static void InsertAfter<T>(this IList<T> source, T existingItem, T item)
        {
            var index = source.IndexOf(existingItem);
            if (index < 0)
            {
                source.AddFirst(item);
                return;
            }

            source.Insert(index + 1, item);
        }

        public static void InsertAfter<T>(this IList<T> source, Predicate<T> selector, T item)
        {
            var index = source.FindIndex(selector);
            if (index < 0)
            {
                source.AddFirst(item);
                return;
            }

            source.Insert(index + 1, item);
        }

        public static void InsertBefore<T>(this IList<T> source, T existingItem, T item)
        {
            var index = source.IndexOf(existingItem);
            if (index < 0)
            {
                source.AddLast(item);
                return;
            }

            source.Insert(index, item);
        }

        public static void InsertBefore<T>(this IList<T> source, Predicate<T> selector, T item)
        {
            var index = source.FindIndex(selector);
            if (index < 0)
            {
                source.AddLast(item);
                return;
            }

            source.Insert(index, item);
        }

        public static void ReplaceWhile<T>(this IList<T> source, Predicate<T> selector, T item)
        {
            for (int i = 0; i < source.Count; i++)
            {
                if (selector(source[i]))
                {
                    source[i] = item;
                }
            }
        }

        public static void ReplaceWhile<T>(this IList<T> source, Predicate<T> selector, Func<T, T> itemFactory)
        {
            for (int i = 0; i < source.Count; i++)
            {
                var item = source[i];
                if (selector(item))
                {
                    source[i] = itemFactory(item);
                }
            }
        }

        public static void ReplaceOne<T>(this IList<T> source, Predicate<T> selector, T item)
        {
            for (int i = 0; i < source.Count; i++)
            {
                if (selector(source[i]))
                {
                    source[i] = item;
                    return;
                }
            }
        }

        public static void ReplaceOne<T>(this IList<T> source, Predicate<T> selector, Func<T, T> itemFactory)
        {
            for (int i = 0; i < source.Count; i++)
            {
                var item = source[i];
                if (selector(item))
                {
                    source[i] = itemFactory(item);
                    return;
                }
            }
        }

        public static void ReplaceOne<T>(this IList<T> source, T item, T replaceWith)
        {
            for (int i = 0; i < source.Count; i++)
            {
                if (Comparer<T>.Default.Compare(source[i], item) == 0)
                {
                    source[i] = replaceWith;
                    return;
                }
            }
        }

        public static void MoveItem<T>(this List<T> source, Predicate<T> selector, int targetIndex)
        {
            var currentIndex = source.FindIndex(0, selector);
            if (currentIndex == targetIndex)
            {
                return;
            }

            var item = source[currentIndex];
            source.RemoveAt(currentIndex);
            source.Insert(targetIndex, item);
        }

        public static T GetOrAdd<T>(this IList<T> source, Func<T, bool> selector, Func<T> factory)
        {

            var item = source.FirstOrDefault(selector);

            if (item == null)
            {
                item = factory();
                source.Add(item);
            }

            return item;
        }

        public static List<T> SortByDependencies<T>(
            this IEnumerable<T> source,
            Func<T, IEnumerable<T>> getDependencies,
            IEqualityComparer<T> comparer = null)
        {
            var sorted = new List<T>();
            var visited = new Dictionary<T, bool>(comparer);

            foreach (var item in source)
            {
                SortByDependenciesVisit(item, getDependencies, sorted, visited);
            }

            return sorted;
        }

        private static void SortByDependenciesVisit<T>(T item, Func<T, IEnumerable<T>> getDependencies, List<T> sorted,
            Dictionary<T, bool> visited)
        {
            bool inProcess;
            var alreadyVisited = visited.TryGetValue(item, out inProcess);

            if (alreadyVisited)
            {
                if (inProcess)
                {
                    throw new ArgumentException("Cyclic dependency found! Item: " + item);
                }
            }
            else
            {
                visited[item] = true;

                var dependencies = getDependencies(item);
                if (dependencies != null)
                {
                    foreach (var dependency in dependencies)
                    {
                        SortByDependenciesVisit(dependency, getDependencies, sorted, visited);
                    }
                }

                visited[item] = false;
                sorted.Add(item);
            }
        }
    }
}