DP44/DataPRO/CanFDApiProxy/RESTWrapper.cs

using CANFDApiProxy.Messages;
using Newtonsoft.Json;
using System;
using System.CodeDom;
using System.ComponentModel;
using System.IO;
using System.Net.Http;
using System.Reflection;
using System.Text;
using System.Threading;
using System.Threading.Tasks;

namespace CANFDApiProxy
{
    internal static class RESTWrapper
    {
        /// <summary>
        /// Get the description part of the enum
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <param name="source"></param>
        /// <returns></returns>
        private static string DescriptionAttr<T>(this T source)
        {
            FieldInfo fi = source.GetType().GetField(source.ToString());

            DescriptionAttribute[] attributes = (DescriptionAttribute[])fi.GetCustomAttributes(
                typeof(DescriptionAttribute), false);

            if (attributes != null && attributes.Length > 0) return attributes[0].Description;
            else return source.ToString();
        }

        public static int Port { get; set; } = 5000;
        private static readonly TimeSpan TIMEOUT_DEFAULT = TimeSpan.FromSeconds(30);
        public static TimeSpan Timeout { get; set; } = TIMEOUT_DEFAULT;

        public static Protocol Protocol { get; set; } = Protocol.http;

        /// <summary>
        /// 
        /// </summary>
        /// <param name="host">device ip address or host name</param>
        /// <param name="command"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        /// <exception cref="ArgumentNullException"></exception>
        public static async Task<string> GetResourceAsync(string host, CommandName command, CancellationToken cancellationToken)
        {
            VerifyHost(host);

            try
            {
                var httpClient = HttpClientFactory.CreateHttpClient();

                httpClient.Timeout = Timeout;

                var commandString = command.DescriptionAttr();
                string requestUri = $"{Protocol.ToString()}://{host}:{Port}/{commandString}";

                var response = await httpClient.GetAsync(requestUri, cancellationToken);

                if (!response.IsSuccessStatusCode)
                {
                    if (response.StatusCode == System.Net.HttpStatusCode.InternalServerError)
                    {
                        var errorJson = await response.Content.ReadAsStringAsync();
                        var res = JsonConvert.DeserializeObject<ErrorMessage>(errorJson);

                        throw new CanApiException(res.Error, 500);
                    }

                    response.EnsureSuccessStatusCode();
                }

                return await response.Content.ReadAsStringAsync();
            }
            catch (TaskCanceledException ex)
            {
                throw new CanApiException("An API call was cancelled or timedout", ex);
            }
        }

        public static async Task<string> PostResourceAsync<T>(string host, CommandName command, T request, CancellationToken cancellationToken)
        {
            VerifyHost(host);

            try
            {
                HttpResponseMessage response = await PostAsJsonAsync(host, command, request, Timeout, cancellationToken);
                return await response.Content.ReadAsStringAsync();
            }
            catch (TaskCanceledException ex)
            {
                throw new CanApiException("An API call was cancelled or timedout", ex);
            }
        }

        public static async Task<Stream> SendResourceReadAsStreamAsync<T>(string host, CommandName command, T request, TimeSpan timeOut, CancellationToken cancellationToken)
        {
            VerifyHost(host);
            return await SendResourceReadAsStreamProcess(host, command, request, timeOut, cancellationToken);
        }

        private static async Task<Stream> SendResourceReadAsStreamProcess<T>(string host, CommandName command, T request, TimeSpan timeOut, CancellationToken cancellationToken)
        {
            try
            {
                HttpResponseMessage response = await SendAsync(host, command, request, timeOut, cancellationToken);
                return await response.Content.ReadAsStreamAsync();
            }
            catch (TaskCanceledException ex)
            {
                throw new CanApiException("An API call was cancelled or timedout", ex);
            }
        }

        private static void VerifyHost(string host)
        {
            if (string.IsNullOrEmpty(host)) { throw new ArgumentNullException("host", "host cannot be empty"); }
        }

        public static async Task<string> PostResourceReadAsStringAsync(string host, CommandName command, MultipartFormDataContent multipart, TimeSpan timeOut, CancellationToken cancellationToken)
        {
            VerifyHost(host);

            try
            {
                var response = await PostWithMultipartFormAsync(host, command, multipart, timeOut, cancellationToken);
                return await response.Content.ReadAsStringAsync();
            }
            catch (TaskCanceledException ex)
            {
                throw new CanApiException("An API call was cancelled or timedout", ex);
            }
        }

        private static async Task<HttpResponseMessage> PostAsJsonAsync<T>(string host, CommandName command, T request, TimeSpan timeOut, CancellationToken cancellationToken)
        {
            var httpClient = HttpClientFactory.CreateHttpClient();
            httpClient.Timeout = timeOut;
            var commandString = command.DescriptionAttr();

            string requestUri = $"{Protocol.ToString()}://{host}:{Port}/{commandString}";

            var response = await httpClient.PostAsJsonAsync(requestUri, request, cancellationToken);

            await ValidateResponse(response);

            return response;
        }

        private static async Task<HttpResponseMessage> PostWithMultipartFormAsync(string host, CommandName command, MultipartFormDataContent multipart, TimeSpan timeOut, CancellationToken cancellationToken)
        {
            var httpClient = HttpClientFactory.CreateHttpClient();
            httpClient.Timeout = timeOut;
            var commandString = command.DescriptionAttr();
            string requestUri = $"{Protocol.ToString()}://{host}:{Port}/{commandString}";

            var response = await httpClient.PostAsync(requestUri, multipart, cancellationToken);

            await ValidateResponse(response);

            return response;
        }

        private static async Task<HttpResponseMessage> SendAsync<T>(string host, CommandName command, T request, TimeSpan timeOut, CancellationToken cancellationToken)
        {
            var httpClient = HttpClientFactory.CreateHttpClient();
            httpClient.Timeout = timeOut;
            var commandString = command.DescriptionAttr();
            string requestUri = $"{Protocol.ToString()}://{host}:{Port}/{commandString}";
            HttpRequestMessage httpRequestMessage = new HttpRequestMessage(HttpMethod.Post, requestUri);
            var json = JsonConvert.SerializeObject(request);
            var content = new StringContent(json, Encoding.UTF8, "application/json");
            httpRequestMessage.Content = content;
            var response = await httpClient.SendAsync(httpRequestMessage, HttpCompletionOption.ResponseHeadersRead, cancellationToken);

            await ValidateResponse(response);

            return response;
        }

        private static async Task<ErrorMessage> BuildErrorMessage(HttpResponseMessage response)
        {
            var errorJson = await response.Content.ReadAsStringAsync();
            var res = JsonConvert.DeserializeObject<ErrorMessage>(errorJson);
            return res;
        }

        private static async Task ValidateResponse(HttpResponseMessage response)
        {
            if (!response.IsSuccessStatusCode)
            {
                switch (response.StatusCode)
                {
                    case System.Net.HttpStatusCode.BadRequest:
                        throw new CanApiException((await BuildErrorMessage(response)).Error, 400);
                    case System.Net.HttpStatusCode.Forbidden:
                        throw new CanApiException((await BuildErrorMessage(response)).Error, 403);
                    case System.Net.HttpStatusCode.NotFound:
                        throw new CanApiException((await BuildErrorMessage(response)).Error, 404);

                    case System.Net.HttpStatusCode.InternalServerError:
                        throw new CanApiException((await BuildErrorMessage(response)).Error, 500);
                    case System.Net.HttpStatusCode.ServiceUnavailable:
                        throw new CanApiException((await BuildErrorMessage(response)).Error, 503);
                }
                response.EnsureSuccessStatusCode();
            }
        }

        public static async Task WriteStreamToFileAsync(Stream inputStream, string filePath)
        {
            if (inputStream.CanSeek)
            {
                inputStream.Position = 0;
            }

            using (FileStream fileStream = new FileStream(filePath, FileMode.Create, FileAccess.Write))
            {
                await inputStream.CopyToAsync(fileStream);
            }
        }
    }
}