public static IEnumerable <Post> FilterBy(this IEnumerable <Post> posts, FilterOptions options)
{
if (options == null)
{
return(posts);
}
var filters = options.GetKeyValuePairs()
.Where(filter =>
{
var validFilterProperties = new string[] { "pricePerUnit", "price" };
if (!validFilterProperties.Contains(filter.Key))
{
return(false);
}
var filterType = filter.Value.Substring(0, 3);
var validFilterTypes = new string[] { "$lt", "$gt", "$eq" };
if (!validFilterTypes.Contains(filterType))
{
return(false);
}
return(true);
});
return(filters.Count() <= 0
? posts
: posts.Where(post =>
{
var result = false;
foreach (var filter in filters)
{
var filterType = filter.Value.Substring(0, 3);
var filterValue = filter.Value.Replace(filterType, string.Empty);
if (filter.Key == "pricePerUnit")
{
var value = decimal.Parse(filterValue, CultureInfo.InvariantCulture);
if (filterType == "$gt")
{
return post.PricePerUnit > value;
}
if (filterType == "$lt")
{
return post.PricePerUnit < value;
}
if (filterType == "$eq")
{
return post.PricePerUnit == value;
}
return false;
}
if (filter.Key == "price")
{
var value = decimal.Parse(filterValue, CultureInfo.InvariantCulture);
if (filterType == "$gt")
{
return post.Article.Price > value;
}
if (filterType == "$lt")
{
return post.Article.Price < value;
}
if (filterType == "$eq")
{
return post.Article.Price == value;
}
return false;
}
}
return result;
}));
}