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 string GetValue(this Dictionary<string,string> dict,string key)
        {
            string value;
            if (!dict.TryGetValue(key,out value))
            {
                return string.Empty;
            }
            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 value = query[condition].ToString();
                    if (value.EndsWith("*") && value.StartsWith("*"))
                    {
                        collection = collection
                            .Where(m => m
                                .GetPropertyValue(condition)
                                .ToString()
                                .IndexOf(value.Trim('*'), StringComparison.CurrentCultureIgnoreCase) > -1);
                    }
                    else if (value.EndsWith("*"))
                    {
                        collection = collection
                             .Where(m => m
                                 .GetPropertyValue(condition)
                                 .ToString()
                                 .StartsWith(value.Trim('*'), StringComparison.CurrentCultureIgnoreCase));
                    }
                    else if (value.StartsWith("*"))
                    {
                        collection = collection
                             .Where(m => m
                                 .GetPropertyValue(condition)
                                 .ToString()
                                 .EndsWith(value.Trim('*'), StringComparison.CurrentCultureIgnoreCase));
                    }
                    else
                    {
                        collection = collection
                             .Where(m => m
                                 .GetPropertyValue(condition)
                                 .ToString()
                                 .Equals(value, StringComparison.CurrentCultureIgnoreCase));
                    }
                }
                catch (NotFoundException)
                {
                    
                }
                
            }
            return collection;
        }
        public static IOrderedEnumerable<T> Sort<T>(this IEnumerable<T> collection, NameValueCollection query) where T : class
        {
            
            if (string.IsNullOrEmpty(query["sort"]))
            {
                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).ToString());
            }

            var grouped = entferneAb > 0
                ? collection.GroupBy(i => i.GetPropertyValue(groupBy).ToString().Remove(entferneAb))
                : collection.GroupBy(i => i.GetPropertyValue(groupBy));

            return grouped; 
        }

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