extensions/CollectionExtensions.cs

using System;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Chrosey.Extensions
{
    public static class CollectionExtensions
    {
        public static T Get<T>(this Dictionary<string, T> dict, string key) where T : class
        {
            T value;
            if (!dict.TryGetValue(key,out value))
            {
                return null;
            }
            return value;
        }

        
        public static IEnumerable<T> Filter<T>(this IEnumerable<T> collection, NameValueCollection query) where T : class
        {
            var props = typeof(T).GetProperties().Select(p => p.Name.ToLower());
            var commonProps = props.Intersect(query.AllKeys.Select(k => k.ToLower()));

            foreach (var condition in commonProps)
            {
                try
                {
                    var values = query[condition].Split('|');
                    var predicate = PredicateBuilder.False<T>();
                    foreach (var value in values)
                    {
                        if (value.EndsWith("*") && value.StartsWith("*"))
                        {
                            predicate = predicate
                                .Or(m => m
                                    .GetPropertyValue(condition)
                                    .ToString()
                                    .IndexOf(value.Trim('*'), StringComparison.CurrentCultureIgnoreCase) > -1
                                    );
                        }
                        else if (value.EndsWith("*"))
                        {
                            predicate = predicate
                                .Or(m => m
                                     .GetPropertyValue(condition)
                                     .ToString()
                                     .StartsWith(value.Trim('*'), StringComparison.CurrentCultureIgnoreCase)
                                     );
                        }
                        else if (value.StartsWith("*"))
                        {
                            predicate = predicate
                                .Or(m => m
                                     .GetPropertyValue(condition)
                                     .ToString()
                                     .EndsWith(value.Trim('*'), StringComparison.CurrentCultureIgnoreCase)
                                     );
                        }
                        else
                        {
                            predicate = predicate
                                .Or(m => m
                                     .GetPropertyValue(condition)
                                     .ToString()
                                     .Equals(value, StringComparison.CurrentCultureIgnoreCase)
                                     );
                        }
                    }

                    collection = collection.AsQueryable().Where(predicate);
                }
                catch (NotFoundException)
                {
                    
                }
                
            }
            return collection;
        }
        public static IOrderedEnumerable<T> Sort<T>(this IEnumerable<T> collection, NameValueCollection query, string defaultSortProperty = "") where T : class
        {
            
            if (string.IsNullOrEmpty(query["sort"]))
            {
                if (!string.IsNullOrEmpty(defaultSortProperty) && collection.First().HasProperty(defaultSortProperty))
                {
                    return collection.OrderBy(c => c.GetPropertyValue(defaultSortProperty));
                }
                return collection.OrderBy(i => i);
            }

            var order = query["sort"].Split(',');
            var sortProps = order.Select(o => o.Split(' ')[0].ToLower());
            var props = typeof(T).GetProperties().Select(p => p.Name.ToLower());

            IOrderedEnumerable<T> ordered = null;
            foreach (var condition in sortProps.Intersect(props))
            {
                var isDescending = order
                    .Single(c => c.StartsWith(condition, StringComparison.CurrentCultureIgnoreCase))
                    .EndsWith("desc", StringComparison.CurrentCultureIgnoreCase);
                if (ordered == null)
                {
                    ordered = isDescending
                        ? collection.OrderByDescending(i => i.GetPropertyValue(condition))
                        : collection.OrderBy(i => i.GetPropertyValue(condition));
                }
                else
                {
                    ordered = isDescending
                        ? ordered.ThenByDescending(i => i.GetPropertyValue(condition))
                        : ordered.ThenBy(i => i.GetPropertyValue(condition));
                }
            }

            return ordered;
        }
        public static IEnumerable<IGrouping<object, T>> GroupBy<T>(this IEnumerable<T> collection, NameValueCollection query) where T : class
        {
            var props = typeof(T).GetProperties().Select(p => p.Name.ToLower());
            var groupBy = string.IsNullOrEmpty(query["groupby"])? "" : query["groupby"].ToLower();
            var entferneAb = string.IsNullOrEmpty(query["groupbynletters"]) ? 0 : int.Parse(query["groupbynletters"]);

            if (string.IsNullOrEmpty(groupBy) || !props.Contains(groupBy))
            {
                return collection.GroupBy(i => "Alle " + typeof(T).Name);
            }

            return entferneAb > 0
                ? collection.GroupBy(i => i.GetPropertyValue(groupBy).ToString().Remove(Math.Min(entferneAb, i.GetPropertyValue(groupBy).ToString().Length)))
                : collection.GroupBy(i => i.GetPropertyValue(groupBy));
        }

        public static IEnumerable<IGrouping<object, T>> Organize<T>(this IEnumerable<T> collection, NameValueCollection query, string defaultSortProperty = "") where T : class
        {
            return collection.Filter(query).Sort(query, defaultSortProperty).GroupBy(query);
        }
    }
}