vgquotes/Src/VideoGameQuotes.Web/Models/ApiModel.cs

using System;
using System.Collections.Generic;
using System.Web.Mvc;
using Portoa.Web;

namespace VideoGameQuotes.Web.Models {
	public class ApiModel {
		public ApiModel() {
			Criteria = new Dictionary<string, IEnumerable<object>>();
		}

		public bool FetchAll { get; set; }
		public int Id { get; set; }
		public SortMethod SortMethod { get; set; }
		public SortOrder SortOrder { get; set; }
		public IDictionary<string, IEnumerable<object>> Criteria { get; set; }
	}

	public class ApiModelBinder : IModelBinder {
		public object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext) {
			var model = new ApiModel {
				SortMethod = SortMethod.None,
				SortOrder = SortOrder.Ascending
			};

			ParseId(controllerContext, model);
			ParseSort(controllerContext, model);
			ParseCriteria(controllerContext, model);

			return model;
		}

		private static void ParseCriteria(ControllerContext controllerContext, ApiModel model) {
			var criteria = (controllerContext.RouteData.Values["criteria"] ?? string.Empty).ToString().Split(new[] { '/' }, StringSplitOptions.RemoveEmptyEntries);

			for (var i = 0; i < criteria.Length; i++) {
				switch (criteria[i]) {
					case "system":
						if (i < criteria.Length - 1) {
							model.Criteria["system"] = ParseCommaSeparatedCriterion(criteria[i + 1]);
							i++;
						} else {
							controllerContext.AddModelError("criteria", "Unable to parse criteria for key \"system\"");
						}

						break;
					default:
						controllerContext.AddModelError("criteria", string.Format("Unable to parse criteria for key \"{0}\"", criteria[i]));
						break;
				}
			}

		}

		private static IEnumerable<object> ParseCommaSeparatedCriterion(string csv) {
			var values = csv.Split(',');
			foreach (var value in values) {
				int result;
				if (int.TryParse(value, out result)) {
					yield return result;
				} else {
					yield return value;
				}
			}
		}

		private static void ParseSort(ControllerContext controllerContext, ApiModel model) {
			var sortValue = controllerContext.HttpContext.Request.QueryString["sort"];
			if (string.IsNullOrWhiteSpace(sortValue)) {
				return;
			}

			var sortValues = sortValue.Split('|');
			try {
				model.SortMethod = (SortMethod)Enum.Parse(typeof(SortMethod), sortValues[0], ignoreCase: true);
			} catch {
				controllerContext.AddModelError("sort", string.Format("The sort method \"{0}\" is invalid", sortValues[0]));
			}
			if (sortValues.Length > 1) {
				try {
					model.SortOrder = (SortOrder)Enum.Parse(typeof(SortOrder), sortValues[1], ignoreCase: true);
				} catch {
					controllerContext.AddModelError("sort", string.Format("The sort order \"{0}\" is invalid", sortValues[1]));
				}
			}
		}

		private static void ParseId(ControllerContext controllerContext, ApiModel model) {
			var idValue = (controllerContext.RouteData.Values["id"] ?? string.Empty).ToString();
			int id;
			if (int.TryParse(idValue, out id)) {
				if (id <= 0) {
					controllerContext.AddModelError("id", "Invalid value for id");
				} else {
					model.Id = id;
				}
			} else {
				model.FetchAll = idValue == "all";
			}
		}
	}
}