using System;
using System.IO;
using System.Reflection;

using Autofac;

using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Diagnostics;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Versioning;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;
using Microsoft.OpenApi.Models;

using Newtonsoft.Json;

using Serilog;

using PluralKit.Core;

namespace PluralKit.API
{
    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.AddCors();
            services.AddAuthentication("SystemToken")
                .AddScheme<SystemTokenAuthenticationHandler.Opts, SystemTokenAuthenticationHandler>("SystemToken", null);

            services.AddAuthorization(options =>
            {
                options.AddPolicy("EditSystem", p => p.RequireAuthenticatedUser().AddRequirements(new OwnSystemRequirement()));
                options.AddPolicy("EditMember", p => p.RequireAuthenticatedUser().AddRequirements(new OwnSystemRequirement()));

                options.AddPolicy("ViewMembers", p => p.AddRequirements(new PrivacyRequirement<PKSystem>(s => s.MemberListPrivacy)));
                options.AddPolicy("ViewFront", p => p.AddRequirements(new PrivacyRequirement<PKSystem>(s => s.FrontPrivacy)));
                options.AddPolicy("ViewFrontHistory", p => p.AddRequirements(new PrivacyRequirement<PKSystem>(s => s.FrontHistoryPrivacy)));
            });
            services.AddSingleton<IAuthenticationHandler, SystemTokenAuthenticationHandler>();
            services.AddSingleton<IAuthorizationHandler, MemberOwnerHandler>();
            services.AddSingleton<IAuthorizationHandler, SystemOwnerHandler>();
            services.AddSingleton<IAuthorizationHandler, SystemPrivacyHandler>();

            services.AddControllers()
                .SetCompatibilityVersion(CompatibilityVersion.Latest)
                // sorry MS, this just does *more*
                .AddNewtonsoftJson((opts) =>
                {
                    // ... though by default it messes up timestamps in JSON
                    opts.SerializerSettings.DateParseHandling = DateParseHandling.None;
                })
                .ConfigureApiBehaviorOptions(options =>
                    options.InvalidModelStateResponseFactory = (context) =>
                        throw Errors.GenericBadRequest
                );

            services.AddApiVersioning();

            services.AddVersionedApiExplorer(c =>
            {
                c.GroupNameFormat = "'v'VV";
                c.ApiVersionParameterSource = new UrlSegmentApiVersionReader();
                c.SubstituteApiVersionInUrl = true;
            });

            services.AddSwaggerGen(c =>
            {
                c.SwaggerDoc("v1.0", new OpenApiInfo { Title = "PluralKit", Version = "1.0" });

                c.EnableAnnotations();
                c.AddSecurityDefinition("TokenAuth",
                    new OpenApiSecurityScheme { Name = "Authorization", Type = SecuritySchemeType.ApiKey });

                // Exclude routes without a version, then fall back to group name matching (default behavior)
                c.DocInclusionPredicate((docName, apiDesc) =>
                {
                    if (!apiDesc.RelativePath.StartsWith("v1/")) return false;
                    return apiDesc.GroupName == docName;
                });

                // Set the comments path for the Swagger JSON and UI.
                // https://docs.microsoft.com/en-us/aspnet/core/tutorials/getting-started-with-swashbuckle?view=aspnetcore-3.1&tabs=visual-studio#customize-and-extend
                var xmlFile = $"{Assembly.GetExecutingAssembly().GetName().Name}.xml";
                var xmlPath = Path.Combine(AppContext.BaseDirectory, xmlFile);
                c.IncludeXmlComments(xmlPath);
            });
            services.AddSwaggerGenNewtonsoftSupport();
        }

        public void ConfigureContainer(ContainerBuilder builder)
        {
            builder.RegisterInstance(InitUtils.BuildConfiguration(Environment.GetCommandLineArgs()).Build())
                .As<IConfiguration>();
            builder.RegisterModule(new ConfigModule<ApiConfig>("API"));
            builder.RegisterModule(new LoggingModule("api", cfg: new LoggerConfiguration().Filter.ByExcluding(exc => exc.Exception is PKError)));
            builder.RegisterModule(new MetricsModule("API"));
            builder.RegisterModule<DataStoreModule>();
            builder.RegisterModule<APIModule>();
        }

        // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
        public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();

                // Only enable Swagger stuff when ASPNETCORE_ENVIRONMENT=Development (for now)
                app.UseSwagger();
                app.UseSwaggerUI(c =>
                {
                    c.SwaggerEndpoint("/swagger/v1.0/swagger.json", "PluralKit (v1)");
                });
            }
            else
            {
                // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
                //app.UseHsts();
            }

            // add X-PluralKit-Version header
            app.Use((ctx, next) =>
            {
                ctx.Response.Headers.Add("X-PluralKit-Version", BuildInfoService.Version);
                return next();
            });

            app.UseExceptionHandler(handler => handler.Run(async ctx =>
            {
                var exc = ctx.Features.Get<IExceptionHandlerPathFeature>();

                // handle common ISEs that are generated by invalid user input
                if (exc.Error.IsUserError())
                {
                    ctx.Response.StatusCode = 400;
                    await ctx.Response.WriteAsync("{\"message\":\"400: Bad Request\",\"code\":0}");
                }

                else if (exc.Error is not PKError)
                {
                    ctx.Response.StatusCode = 500;
                    await ctx.Response.WriteAsync("{\"message\":\"500: Internal Server Error\",\"code\":0}");
                }

                // for some reason, if we don't specifically cast to ModelParseError, it uses the base's ToJson method
                else if (exc.Error is ModelParseError fe)
                {
                    ctx.Response.StatusCode = fe.ResponseCode;
                    await ctx.Response.WriteAsync(JsonConvert.SerializeObject(fe.ToJson()));
                }

                else
                {
                    var err = (PKError)exc.Error;
                    ctx.Response.StatusCode = err.ResponseCode;

                    var json = JsonConvert.SerializeObject(err.ToJson());
                    await ctx.Response.WriteAsync(json);
                }

                await ctx.Response.CompleteAsync();
            }));

            app.UseMiddleware<AuthorizationTokenHandlerMiddleware>();

            //app.UseHttpsRedirection();
            app.UseCors(opts => opts.AllowAnyMethod().AllowAnyOrigin().WithHeaders("Content-Type", "Authorization"));

            app.UseRouting();
            app.UseAuthentication();
            app.UseAuthorization();
            app.UseEndpoints(endpoints => endpoints.MapControllers());
        }
    }
}