// Copyright (c) 2019 Google LLC.
// 
// Licensed under the Apache License, Version 2.0 (the "License"); you may not
// use this file except in compliance with the License. You may obtain a copy of
// the License at
// 
// http://www.apache.org/licenses/LICENSE-2.0
// 
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
// WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
// License for the specific language governing permissions and limitations under
// the License.

using Google.Apis.Auth.OAuth2;
using Google.Cloud.Firestore;
using Google.Cloud.PubSub.V1;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using System;
using System.Net.Http;

namespace TranslateUI
{
    public class Startup
    {
        public Startup(IConfiguration configuration)
        {
            Configuration = configuration;
        }

        public IConfiguration Configuration { get; }

        // This method gets called by the runtime. Use this method to add services to the container.
        public void ConfigureServices(IServiceCollection services)
        {
            services.AddSingleton<FirestoreDb>(
                provider => FirestoreDb.Create(GetFirestoreProjectId()));
            services.AddSingleton<PublisherClient>(
                provider => PublisherClient.CreateAsync(new TopicName(
                    GetProjectId(), GetTopicName())).Result);
            services.AddMvc(options => options.EnableEndpointRouting = false)
                .SetCompatibilityVersion(CompatibilityVersion.Version_2_1);
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            else
            {
                app.UseExceptionHandler("/Home/Error");
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                app.UseHsts();
            }

            app.UseHttpsRedirection();
            app.UseStaticFiles();
            app.UseCookiePolicy();

            app.UseMvc(routes =>
            {
                routes.MapRoute(
                    name: "default",
                    template: "{controller=Home}/{action=Index}/{id?}");
            });
        }


        public static string GetProjectId()
        {
            GoogleCredential googleCredential = Google.Apis.Auth.OAuth2
                .GoogleCredential.GetApplicationDefault();
            if (googleCredential != null)
            {
                ICredential credential = googleCredential.UnderlyingCredential;
                ServiceAccountCredential serviceAccountCredential =
                    credential as ServiceAccountCredential;
                if (serviceAccountCredential != null)
                {
                    return serviceAccountCredential.ProjectId;
                }
            }
            try
            {
                // Query the metadata server.
                HttpClient http = new HttpClient();
                http.DefaultRequestHeaders.Add("Metadata-Flavor", "Google");
                http.BaseAddress = new Uri(
                    @"http://metadata.google.internal/computeMetadata/v1/project/");
                return http.GetStringAsync("project-id").Result;
            }
            catch (AggregateException e)
            when (e.InnerException is HttpRequestException)
            {
                throw new Exception("Could not find Google project id.  " +
                    "Run this application in Google Cloud or follow these " +
                    "instructions to run locally: " +
                    "https://cloud.google.com/docs/authentication/getting-started",
                    e.InnerException);
            }
        }

        // Would normally be the same as the regular project id.  But in
        // our test environment, we need a different one.
        public string GetFirestoreProjectId() =>
            Configuration["FIRESTORE_PROJECT_ID"] ?? GetProjectId();

        public string GetTopicName() =>
            Configuration["TranslateRequestsTopicName"] ?? "translate-requests";
    }
}
