using System;
using System.IO;
using System.Net;
using AllocsFixes.JSON;

namespace Webserver.WebAPI {
	public abstract class AbsRestApi : AbsWebAPI {
		private static readonly UnityEngine.Profiling.CustomSampler jsonDeserializeSampler = UnityEngine.Profiling.CustomSampler.Create ("JSON_Deserialize");

		public sealed override void HandleRequest (RequestContext _context) {
			JsonNode jsonBody = null;

			if (_context.Request.HasEntityBody) {
				string body = new StreamReader (_context.Request.InputStream).ReadToEnd ();

				if (!string.IsNullOrEmpty (body)) {
					try {
						jsonDeserializeSampler.Begin ();
						jsonBody = Parser.Parse (body);
						jsonDeserializeSampler.End ();
					} catch (Exception e) {
						jsonDeserializeSampler.End ();

						SendEnvelopedResult (_context, null, HttpStatusCode.BadRequest, null, "INVALID_BODY", e);
						return;
					}
				}
			}

			try {
				switch (_context.Request.HttpMethod) {
					case "GET":
						if (jsonBody != null) {
							SendEnvelopedResult (_context, null, HttpStatusCode.BadRequest, jsonBody, "GET_WITH_BODY");
							return;
						}

						HandleRestGet (_context);
						return;
					case "POST":
						if (!string.IsNullOrEmpty (_context.RequestPath)) {
							SendEnvelopedResult (_context, null, HttpStatusCode.BadRequest, jsonBody, "POST_WITH_ID");
							return;
						}

						if (jsonBody == null) {
							SendEnvelopedResult (_context, null, HttpStatusCode.BadRequest, null, "POST_WITHOUT_BODY");
							return;
						}

						HandleRestPost (_context, jsonBody);
						return;
					case "PUT":
						if (string.IsNullOrEmpty (_context.RequestPath)) {
							SendEnvelopedResult (_context, null, HttpStatusCode.BadRequest, jsonBody, "PUT_WITHOUT_ID");
							return;
						}

						if (jsonBody == null) {
							SendEnvelopedResult (_context, null, HttpStatusCode.BadRequest, null, "PUT_WITHOUT_BODY");
							return;
						}

						HandleRestPut (_context, jsonBody);
						return;
					case "DELETE":
						if (string.IsNullOrEmpty (_context.RequestPath)) {
							SendEnvelopedResult (_context, null, HttpStatusCode.BadRequest, jsonBody, "DELETE_WITHOUT_ID");
							return;
						}

						if (jsonBody != null) {
							SendEnvelopedResult (_context, null, HttpStatusCode.BadRequest, null, "DELETE_WITH_BODY");
							return;
						}

						HandleRestDelete (_context);
						return;
					default:
						SendEnvelopedResult (_context, null, HttpStatusCode.BadRequest, null, "INVALID_METHOD");
						return;
				}
			} catch (Exception e) {
				SendEnvelopedResult (_context, null, HttpStatusCode.InternalServerError, jsonBody, "ERROR_PROCESSING", e);
			}
		}

		private static readonly JsonArray emptyData = new JsonArray ();

		protected void SendEnvelopedResult (RequestContext _context, JsonNode _resultData, HttpStatusCode _statusCode = HttpStatusCode.OK,
			JsonNode _jsonInputBody = null, string _errorCode = null, Exception _exception = null) {
			JsonObject meta = new JsonObject ();

			meta.Add ("serverTime", new JsonString (DateTime.Now.ToString ("o")));
			if (!string.IsNullOrEmpty (_errorCode)) {
				meta.Add ("requestMethod", new JsonString (_context.Request.HttpMethod));
				meta.Add ("requestSubpath", new JsonString (_context.RequestPath));
				meta.Add ("requestBody", new JsonString (_jsonInputBody?.ToString () ?? "-empty-"));
				meta.Add ("errorCode", new JsonString (_errorCode));
				if (_exception != null) {
					meta.Add ("exceptionMessage", new JsonString (_exception.Message));
					meta.Add ("exceptionTrace", new JsonString (_exception.StackTrace));
				}
			}

			JsonObject envelope = new JsonObject ();
			envelope.Add ("meta", meta);
			envelope.Add ("data", _resultData ?? emptyData);

			WebUtils.WriteJson (_context.Response, envelope, _statusCode);
		}

		protected bool TryGetJsonField (JsonObject _jsonObject, string _fieldName, out int _value) {
			_value = default;
			
			if (!_jsonObject.TryGetValue (_fieldName, out JsonNode fieldNode)) {
				return false;
			}

			if (!(fieldNode is JsonValue valueField)) {
				return false;
			}

			try {
				_value = valueField.AsInt;
				return true;
			} catch (Exception) {
				return false;
			}
		}

		protected bool TryGetJsonField (JsonObject _jsonObject, string _fieldName, out double _value) {
			_value = default;
			
			if (!_jsonObject.TryGetValue (_fieldName, out JsonNode fieldNode)) {
				return false;
			}

			if (!(fieldNode is JsonValue valueField)) {
				return false;
			}

			try {
				_value = valueField.AsDouble;
				return true;
			} catch (Exception) {
				return false;
			}
		}

		protected bool TryGetJsonField (JsonObject _jsonObject, string _fieldName, out string _value) {
			_value = default;
			
			if (!_jsonObject.TryGetValue (_fieldName, out JsonNode fieldNode)) {
				return false;
			}

			if (!(fieldNode is JsonValue valueField)) {
				return false;
			}

			try {
				_value = valueField.AsString;
				return true;
			} catch (Exception) {
				return false;
			}
		}

		protected abstract void HandleRestGet (RequestContext _context);

		protected abstract void HandleRestPost (RequestContext _context, JsonNode _jsonBody);

		protected abstract void HandleRestPut (RequestContext _context, JsonNode _jsonBody);

		protected abstract void HandleRestDelete (RequestContext _context);
	}
}