using Newtonsoft.Json.Linq;
using System;
using System.IO;
using System.Net.Http;
using System.Net.Http.Headers;
using System.Threading.Tasks;

namespace CSHttpClientSample
{
    static class Program
    {
        // Add your Computer Vision key and base endpoint.
        static string key = "PASTE_YOUR_COMPUTER_VISION_KEY_HERE";
        static string endpoint = "PASTE_YOUR_COMPUTER_VISION_ENDPOINT_HERE";
        
        // the Analyze method endpoint
        static string uriBase = endpoint + "vision/v3.1/analyze";

        // Image you want analyzed (add to your bin/debug/netcoreappX.X folder)
        // For sample images, download one from here (png or jpg):
        // https://github.com/Azure-Samples/cognitive-services-sample-data-files/tree/master/ComputerVision/Images
        static string imageFilePath = @"my-sample-image";

        public static void Main()
        {
            // Call the API
            MakeAnalysisRequest(imageFilePath).Wait();

            Console.WriteLine("\nPress Enter to exit...");
            Console.ReadLine();
        }

        /// <summary>
        /// Gets the analysis of the specified image file by using
        /// the Computer Vision REST API.
        /// </summary>
        /// <param name="imageFilePath">The image file to analyze.</param>
        static async Task MakeAnalysisRequest(string imageFilePath)
        {
            try
            {
                HttpClient client = new HttpClient();

                // Request headers.
                client.DefaultRequestHeaders.Add(
                    "Ocp-Apim-Subscription-Key", key);

                // Request parameters. A third optional parameter is "details".
                // The Analyze Image method returns information about the following
                // visual features:
                // Categories:  categorizes image content according to a
                //              taxonomy defined in documentation.
                // Description: describes the image content with a complete
                //              sentence in supported languages.
                // Color:       determines the accent color, dominant color, 
                //              and whether an image is black & white.
                string requestParameters =
                    "visualFeatures=Categories,Description,Color";

                // Assemble the URI for the REST API method.
                string uri = uriBase + "?" + requestParameters;

                HttpResponseMessage response;

                // Read the contents of the specified local image
                // into a byte array.
                byte[] byteData = GetImageAsByteArray(imageFilePath);

                // Add the byte array as an octet stream to the request body.
                using (ByteArrayContent content = new ByteArrayContent(byteData))
                {
                    // This example uses the "application/octet-stream" content type.
                    // The other content types you can use are "application/json"
                    // and "multipart/form-data".
                    content.Headers.ContentType =
                        new MediaTypeHeaderValue("application/octet-stream");

                    // Asynchronously call the REST API method.
                    response = await client.PostAsync(uri, content);
                }

                // Asynchronously get the JSON response.
                string contentString = await response.Content.ReadAsStringAsync();

                // Display the JSON response.
                Console.WriteLine("\nResponse:\n\n{0}\n",
                    JToken.Parse(contentString).ToString());
            }
            catch (Exception e)
            {
                Console.WriteLine("\n" + e.Message);
            }
        }

        /// <summary>
        /// Returns the contents of the specified file as a byte array.
        /// </summary>
        /// <param name="imageFilePath">The image file to read.</param>
        /// <returns>The byte array of the image data.</returns>
        static byte[] GetImageAsByteArray(string imageFilePath)
        {
            // Open a read-only file stream for the specified file.
            using (FileStream fileStream =
                new FileStream(imageFilePath, FileMode.Open, FileAccess.Read))
            {
                // Read the file's contents into a byte array.
                BinaryReader binaryReader = new BinaryReader(fileStream);
                return binaryReader.ReadBytes((int)fileStream.Length);
            }
        }
    }
}