using System.Text;
using System.Threading.RateLimiting;
using FluentValidation;
using FluentValidation.AspNetCore;
using MealPlan.Api.Data;
using MealPlan.Api.Middleware;
using MealPlan.Api.Models;
using MealPlan.Api.Services;
using MealPlan.Api.Validators;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.HttpOverrides;
using Microsoft.AspNetCore.Identity;
using Microsoft.AspNetCore.RateLimiting;
using Microsoft.EntityFrameworkCore;
using Microsoft.IdentityModel.Tokens;
using Serilog;

var builder = WebApplication.CreateBuilder(args);

// Optional local overrides (connection string, secrets) — not committed; see appsettings.Local.json.example.
builder.Configuration.AddJsonFile("appsettings.Local.json", optional: true, reloadOnChange: true);

// ---------------------------------------------------------------------------
// Serilog: structured logging to console + rolling daily file.
// ---------------------------------------------------------------------------
builder.Host.UseSerilog((context, services, configuration) => configuration
    .ReadFrom.Configuration(context.Configuration)
    .ReadFrom.Services(services)
    .Enrich.FromLogContext()
    .WriteTo.Console()
    .WriteTo.File(
        path: "logs/mealplan-.log",
        rollingInterval: RollingInterval.Day,
        retainedFileCountLimit: 14,
        shared: true));

// ---------------------------------------------------------------------------
// Configuration / options
// ---------------------------------------------------------------------------
var connectionString = builder.Configuration.GetConnectionString("DefaultConnection")
    ?? throw new InvalidOperationException(
        "ConnectionStrings__DefaultConnection is not configured.");

builder.Services.Configure<JwtOptions>(builder.Configuration.GetSection(JwtOptions.SectionName));
var jwtOptions = builder.Configuration.GetSection(JwtOptions.SectionName).Get<JwtOptions>()
    ?? throw new InvalidOperationException("Jwt configuration section is missing.");

if (string.IsNullOrWhiteSpace(jwtOptions.Secret) || jwtOptions.Secret.Length < 32)
{
    throw new InvalidOperationException(
        "Jwt__Secret must be configured and at least 32 characters long.");
}

var allowedOrigin = builder.Configuration["CORS:AllowedOrigin"];

// ---------------------------------------------------------------------------
// EF Core (PostgreSQL, database-first — no migrations)
// ---------------------------------------------------------------------------
builder.Services.AddDbContext<AppDbContext>(options =>
    options.UseNpgsql(connectionString, npgsql => npgsql.EnableRetryOnFailure()));

// ---------------------------------------------------------------------------
// Application services
// ---------------------------------------------------------------------------
builder.Services.AddSingleton<IRefreshTokenStore, DbRefreshTokenStore>();
builder.Services.AddHostedService<RefreshTokenCleanupService>();
builder.Services.AddSingleton<IPasswordHasher<ApplicationUser>, PasswordHasher<ApplicationUser>>();
builder.Services.AddScoped<ITokenService, TokenService>();
builder.Services.AddScoped<IAuthService, AuthService>();
builder.Services.AddScoped<IRecipeService, RecipeService>();
builder.Services.AddScoped<IRecipeManagementService, RecipeManagementService>();
builder.Services.AddScoped<IRecipeExcelService, RecipeExcelService>();
builder.Services.AddScoped<IDietTrackingService, DietTrackingService>();
builder.Services.AddScoped<IIngredientCatalogService, IngredientCatalogService>();
builder.Services.AddScoped<IMealPlanService, MealPlanService>();
builder.Services.Configure<MealPlan.Api.Services.AI.OpenAiOptions>(
    builder.Configuration.GetSection(MealPlan.Api.Services.AI.OpenAiOptions.SectionName));
builder.Services.AddHttpClient<MealPlan.Api.Services.AI.IOpenAiChatService, MealPlan.Api.Services.AI.OpenAiChatService>();
builder.Services.AddScoped<MealPlan.Api.Services.Generators.ICatalogMatchingService, MealPlan.Api.Services.Generators.CatalogMatchingService>();
builder.Services.AddScoped<MealPlan.Api.Services.Generators.IDietGeneratorService, MealPlan.Api.Services.Generators.DietGeneratorService>();
builder.Services.AddScoped<MealPlan.Api.Services.Generators.IRecipeGeneratorService, MealPlan.Api.Services.Generators.RecipeGeneratorService>();

// ---------------------------------------------------------------------------
// Authentication / authorization (JWT bearer)
// ---------------------------------------------------------------------------
builder.Services
    .AddAuthentication(options =>
    {
        options.DefaultAuthenticateScheme = JwtBearerDefaults.AuthenticationScheme;
        options.DefaultChallengeScheme = JwtBearerDefaults.AuthenticationScheme;
    })
    .AddJwtBearer(options =>
    {
        options.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateLifetime = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = jwtOptions.Issuer,
            ValidAudience = jwtOptions.Audience,
            IssuerSigningKey = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(jwtOptions.Secret)),
            ClockSkew = TimeSpan.Zero,
        };
    });

builder.Services.AddAuthorization();

// ---------------------------------------------------------------------------
// Rate limiting: max 5 login attempts per minute per client IP.
// ---------------------------------------------------------------------------
builder.Services.AddRateLimiter(options =>
{
    options.RejectionStatusCode = StatusCodes.Status429TooManyRequests;

    options.AddPolicy("login", httpContext =>
    {
        var clientIp = httpContext.Connection.RemoteIpAddress?.ToString() ?? "unknown";
        return RateLimitPartition.GetFixedWindowLimiter(clientIp, _ => new FixedWindowRateLimiterOptions
        {
            PermitLimit = 5,
            Window = TimeSpan.FromMinutes(1),
            QueueLimit = 0,
            QueueProcessingOrder = QueueProcessingOrder.OldestFirst,
        });
    });
});

// ---------------------------------------------------------------------------
// CORS: restricted to the configured frontend origin only.
// ---------------------------------------------------------------------------
const string corsPolicy = "frontend";
builder.Services.AddCors(options =>
{
    options.AddPolicy(corsPolicy, policy =>
    {
        if (builder.Environment.IsDevelopment())
        {
            // Vite may use 5173, 5174, 5175, etc. when ports are busy.
            policy.SetIsOriginAllowed(origin =>
                    !string.IsNullOrEmpty(origin) &&
                    Uri.TryCreate(origin, UriKind.Absolute, out var uri) &&
                    (uri.Host.Equals("localhost", StringComparison.OrdinalIgnoreCase) ||
                     uri.Host.Equals("127.0.0.1", StringComparison.OrdinalIgnoreCase)))
                .AllowAnyHeader()
                .AllowAnyMethod();
        }
        else if (!string.IsNullOrWhiteSpace(allowedOrigin))
        {
            policy.WithOrigins(allowedOrigin)
                .AllowAnyHeader()
                .AllowAnyMethod();
        }
    });
});

// Forwarded headers so the app honors the original scheme/IP behind the nginx proxy.
builder.Services.Configure<ForwardedHeadersOptions>(options =>
{
    options.ForwardedHeaders = ForwardedHeaders.XForwardedFor | ForwardedHeaders.XForwardedProto;
    options.KnownNetworks.Clear();
    options.KnownProxies.Clear();
});

builder.Services.AddControllers();
builder.Services.AddFluentValidationAutoValidation();
builder.Services.AddFluentValidationClientsideAdapters();
builder.Services.AddValidatorsFromAssemblyContaining<LoginRequestValidator>();
builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen();

// Kestrel listens on 5000 (HTTP) inside the container; TLS is terminated at nginx.
builder.WebHost.ConfigureKestrel(options => options.AddServerHeader = false);

var app = builder.Build();

if (args.Contains("--fix-sequences", StringComparer.OrdinalIgnoreCase))
{
    await using var scope = app.Services.CreateAsyncScope();
    var db = scope.ServiceProvider.GetRequiredService<AppDbContext>();
    var messages = await SequenceMaintenance.ResyncIdentitySequencesAsync(db);
    foreach (var message in messages)
    {
        Console.WriteLine(message);
    }

    return;
}

// ---------------------------------------------------------------------------
// HTTP request pipeline
// ---------------------------------------------------------------------------
app.UseForwardedHeaders();
app.UseSerilogRequestLogging();
app.UseExceptionMiddleware();

// Security headers on every response.
app.Use(async (context, next) =>
{
    var headers = context.Response.Headers;
    headers["X-Frame-Options"] = "DENY";
    headers["X-Content-Type-Options"] = "nosniff";
    headers["Referrer-Policy"] = "no-referrer";
    headers["Content-Security-Policy"] =
        "default-src 'self'; frame-ancestors 'none'; base-uri 'self'; object-src 'none'";
    headers["X-Permitted-Cross-Domain-Policies"] = "none";
    await next();
});

// Behind nginx, X-Forwarded-Proto makes HTTPS redirection work for the public URL.
app.UseHttpsRedirection();

if (app.Environment.IsProduction())
{
    app.UseHsts();
}
else
{
    app.UseSwagger();
    app.UseSwaggerUI();
}

app.UseCors(corsPolicy);
app.UseRateLimiter();
app.UseAuthentication();
app.UseAuthorization();

app.MapControllers();
app.MapGet("/health", () => Results.Ok(new { status = "ok" })).AllowAnonymous();

try
{
    Log.Information("Starting MealPlan API");
    if (app.Environment.IsDevelopment())
    {
        var authEndpoints = app.Services.GetRequiredService<Microsoft.AspNetCore.Routing.EndpointDataSource>()
            .Endpoints
            .OfType<Microsoft.AspNetCore.Routing.RouteEndpoint>()
            .Where(e => e.RoutePattern.RawText?.Contains("auth", StringComparison.OrdinalIgnoreCase) == true)
            .Select(e => e.RoutePattern.RawText)
            .Distinct()
            .OrderBy(x => x);
        Log.Information("Auth endpoints: {Endpoints}", string.Join(", ", authEndpoints));
    }

    app.Run();
}
catch (Exception ex)
{
    Log.Fatal(ex, "MealPlan API terminated unexpectedly");
}
finally
{
    Log.CloseAndFlush();
}