using System.Linq;
using System.Net;
using System.Net.Http;
using Microsoft.Azure.WebJobs;
using Microsoft.Azure.WebJobs.Extensions.Http;
using Microsoft.Azure.WebJobs.Host;

using Microsoft.Azure; // Namespace for CloudConfigurationManager
using Microsoft.WindowsAzure.Storage; // Namespace for CloudStorageAccount
using Microsoft.WindowsAzure.Storage.Blob; // Namespace for Blob storage types
using System.IO;
using Newtonsoft.Json.Linq;
using Newtonsoft;
using Newtonsoft.Json;
using System;
using System.Net.Http.Headers;

namespace RemoteConfiguration
{
    public static class GetRemoteConfiguration
    {
        [FunctionName("GetRemoteConfiguration")]

        public static HttpResponseMessage Run([HttpTrigger(AuthorizationLevel.Anonymous, "head", "get", "post", Route = "GetRemoteConfiguration/{farm}/{tenant}/{component}")]HttpRequestMessage req, string farm, string tenant, TraceWriter log, string component)
        {
            log.Info("C# HTTP trigger function processed a request.");

            if (string.IsNullOrEmpty(farm) || string.IsNullOrEmpty(tenant))
            {
                return req.CreateErrorResponse(HttpStatusCode.BadRequest, "you failed to provide a 'farm' and/or 'tenant' parameters");
            }

            var componentName = component?.ToString();

            if (componentName == "defaults") componentName = "";

            // Parse the connection string and return a reference to the storage account.
            CloudStorageAccount storageAccount = CloudStorageAccount.Parse("DefaultEndpointsProtocol=https;AccountName=mtstcc1storage;AccountKey=NWOlKhOzFphjqUwxzMcLtKzv7YfJXHR7eTNsvk6IHdBGW8ZjgEQBpSBCq3chC9Xt64SQf0T8B18hDfIq3xI4Lw==;EndpointSuffix=core.windows.net");

            var client = storageAccount.CreateCloudBlobClient();

            CloudBlobContainer container = null;
            try {
                container = client.GetContainerReference(farm);
            }
            catch
            {
                return req.CreateErrorResponse(HttpStatusCode.BadRequest, "The requested farm container doesn't exist");
            }

            CloudBlockBlob defaultsBlob = container.GetBlockBlobReference(string.Format("m.defaults_{0}.json", tenant));
            CloudBlockBlob mergedFileBlob = null;

            //Merge requested component with the defaults.
            if (!string.IsNullOrEmpty(componentName)) {
                var componentConfiguration = string.Format("m.overrides_{0}_{1}.json", tenant, component);

                CloudBlockBlob overridesBlob = container.GetBlockBlobReference(componentConfiguration);

                mergedFileBlob = container.GetBlockBlobReference(string.Format("merged{0}{1}{2}.json", farm, tenant, component));

                string contentDefaults;
                using (var memoryStream = new MemoryStream())
                {
                    try
                    {
                        defaultsBlob.DownloadToStream(memoryStream);
                    }
                    catch
                    {
                        return req.CreateErrorResponse(HttpStatusCode.BadRequest, "The requested defaults configuration doesn't exist for this farm");
                    }

                    contentDefaults = System.Text.Encoding.UTF8.GetString(memoryStream.ToArray());
                }

                string contentOverrides;
                using (var memoryStream = new MemoryStream())
                {
                    try
                    {
                        overridesBlob.DownloadToStream(memoryStream);
                    }
                    catch
                    {
                        return req.CreateErrorResponse(HttpStatusCode.BadRequest, "The requested defaults configuration doesn't exist for this farm");
                    }

                    contentOverrides = System.Text.Encoding.UTF8.GetString(memoryStream.ToArray());
                }

                JObject defaults = null;
                JObject overrides = null;

                try
                {
                    defaults = JObject.Parse(contentDefaults);
                    overrides = JObject.Parse(contentOverrides);
                }
                catch
                {
                    return req.CreateErrorResponse(HttpStatusCode.BadRequest, "The requested farm configuration couldn't be fetched. Check if it exists");
                }

                var mergeSettings = new JsonMergeSettings
                {
                    MergeArrayHandling = MergeArrayHandling.Union,
                    MergeNullValueHandling = MergeNullValueHandling.Merge
                };

                defaults.Merge(overrides, mergeSettings);

                mergedFileBlob.UploadText(defaults.ToString(Formatting.None));
            }

            var contraints = new SharedAccessBlobPolicy();
            contraints.SharedAccessStartTime = DateTime.UtcNow.AddMinutes(-5);
            contraints.SharedAccessExpiryTime = DateTime.UtcNow.AddMinutes(10);
            contraints.Permissions = SharedAccessBlobPermissions.Read;

            var sasBlobToken = "";
            Stream stream = null;
            if (string.IsNullOrEmpty(componentName)) {
                 sasBlobToken = defaultsBlob.GetSharedAccessSignature(contraints);
                 stream = defaultsBlob.OpenRead();
            } else {
                sasBlobToken = mergedFileBlob.GetSharedAccessSignature(contraints);
                stream = mergedFileBlob.OpenRead();
            }

            HttpResponseMessage response;
            response = req.CreateResponse(HttpStatusCode.OK);
            response.Content = new StreamContent(stream);
            response.Content.Headers.ContentType = new MediaTypeHeaderValue("application/octet-stream");

            return response;
        }
    }
}