using System.Text;
using System.Threading.RateLimiting;
using Azaion.Common;
using Azaion.Common.Configs;
using Azaion.Common.Database;
using Azaion.Common.Entities;
using Azaion.Common.Requests;
using Azaion.Services;
using FluentValidation;
using LinqToDB.Data;
using Microsoft.AspNetCore.Authentication.JwtBearer;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.RateLimiting;
using Microsoft.AspNetCore.Rewrite;
using Microsoft.IdentityModel.Tokens;
using Microsoft.OpenApi;
using Serilog;

Log.Logger = new LoggerConfiguration()
    .Enrich.FromLogContext()
    .MinimumLevel.Information()
    .WriteTo.Console()
    .WriteTo.File(
        path: "logs/log.txt",
        rollingInterval: RollingInterval.Day)
    .CreateLogger();

var builder = WebApplication.CreateBuilder(args);
builder.WebHost.ConfigureKestrel(o => o.Limits.MaxRequestBodySize = 209715200);
builder.Services.Configure<Microsoft.AspNetCore.Http.Features.FormOptions>(o =>
    o.MultipartBodyLengthLimit = 209715200);

var jwtConfig = builder.Configuration.GetSection(nameof(JwtConfig)).Get<JwtConfig>();
if (jwtConfig == null || string.IsNullOrEmpty(jwtConfig.Secret))
    throw new Exception("Missing configuration section: JwtConfig");
var signingKey = new SymmetricSecurityKey(Encoding.ASCII.GetBytes(jwtConfig.Secret));

// Fail-fast for DB connection strings — surfaces a missing env var at startup
// instead of on the first request to a DB-backed endpoint.
var connectionStrings = builder.Configuration.GetSection(nameof(ConnectionStrings)).Get<ConnectionStrings>();
if (connectionStrings == null
    || string.IsNullOrEmpty(connectionStrings.AzaionDb)
    || string.IsNullOrEmpty(connectionStrings.AzaionDbAdmin))
    throw new Exception("Missing configuration section: ConnectionStrings (AzaionDb and AzaionDbAdmin are required)");

// Graceful shutdown: 30 s for in-flight requests; pair with `docker stop -t 40`.
builder.Services.Configure<HostOptions>(o => o.ShutdownTimeout = TimeSpan.FromSeconds(30));

builder.Services.AddSerilog();
builder.Services.AddAuthentication(JwtBearerDefaults.AuthenticationScheme)
    .AddJwtBearer(o =>
    {
        o.TokenValidationParameters = new TokenValidationParameters
        {
            ValidateIssuer = true,
            ValidateAudience = true,
            ValidateLifetime = true,
            ValidateIssuerSigningKey = true,
            ValidIssuer = jwtConfig.Issuer,
            ValidAudience = jwtConfig.Audience,
            IssuerSigningKey = signingKey
        };
    });

#region Policies

var apiAdminPolicy = new AuthorizationPolicyBuilder()
    .RequireRole(RoleEnum.ApiAdmin.ToString()).Build();

builder.Services.AddAuthorization(o =>
{
    o.AddPolicy(nameof(apiAdminPolicy), apiAdminPolicy);
});

#endregion Policies


builder.Services.AddHttpContextAccessor();

builder.Services.AddEndpointsApiExplorer();
builder.Services.AddSwaggerGen(c =>
{
    c.SwaggerDoc("v1", new OpenApiInfo {Title = "Azaion.API", Version = "v1"});
    c.CustomSchemaIds(type => type.ToString());
    var jwtSecurityScheme = new OpenApiSecurityScheme
    {
        Scheme = "bearer",
        BearerFormat = "JWT",
        Name = "JWT Authentication",
        In = ParameterLocation.Header,
        Type = SecuritySchemeType.Http,
        Description = "Put **_ONLY_** your JWT Bearer token on textbox below!",
    };

    c.AddSecurityDefinition(JwtBearerDefaults.AuthenticationScheme, jwtSecurityScheme);

    c.AddSecurityRequirement(_ => new OpenApiSecurityRequirement
    {
        { new OpenApiSecuritySchemeReference(JwtBearerDefaults.AuthenticationScheme, null), new List<string>() }
    });
});
builder.Services.Configure<ResourcesConfig>(builder.Configuration.GetSection(nameof(ResourcesConfig)));
builder.Services.Configure<JwtConfig>(builder.Configuration.GetSection(nameof(JwtConfig)));
builder.Services.Configure<ConnectionStrings>(builder.Configuration.GetSection(nameof(ConnectionStrings)));
builder.Services.Configure<AuthConfig>(builder.Configuration.GetSection(nameof(AuthConfig)));

var authConfig = builder.Configuration.GetSection(nameof(AuthConfig)).Get<AuthConfig>() ?? new AuthConfig();

builder.Services.AddScoped<IUserService, UserService>();
builder.Services.AddScoped<IAuthService, AuthService>();
builder.Services.AddScoped<IResourcesService, ResourcesService>();
builder.Services.AddScoped<IDetectionClassService, DetectionClassService>();
builder.Services.AddScoped<IAuditLog, AuditLog>();
builder.Services.AddSingleton<IDbFactory, DbFactory>();

builder.Services.AddLazyCache();
builder.Services.AddScoped<ICache, MemoryCache>();

builder.Services.AddValidatorsFromAssemblyContaining<RegisterUserValidator>();
builder.Services.AddExceptionHandler<BusinessExceptionHandler>();

// AZ-537 — per-IP sliding window rate limit on /login. Per-account rate limit and
// account lockout live in UserService.ValidateUser (DB-backed) so they survive
// process restarts and feed the audit_events table.
const string LoginPerIpPolicy = "login-per-ip";
builder.Services.AddRateLimiter(options =>
{
    options.RejectionStatusCode = StatusCodes.Status429TooManyRequests;
    options.OnRejected = (ctx, _) =>
    {
        if (ctx.Lease.TryGetMetadata(MetadataName.RetryAfter, out var retryAfter))
            ctx.HttpContext.Response.Headers.RetryAfter =
                ((int)Math.Ceiling(retryAfter.TotalSeconds)).ToString(System.Globalization.CultureInfo.InvariantCulture);
        return ValueTask.CompletedTask;
    };

    options.AddPolicy(LoginPerIpPolicy, httpContext =>
    {
        var ip = httpContext.Connection.RemoteIpAddress?.ToString() ?? "unknown";
        return RateLimitPartition.GetSlidingWindowLimiter(ip, _ => new SlidingWindowRateLimiterOptions
        {
            PermitLimit       = authConfig.RateLimit.PerIpPermitLimit,
            Window            = TimeSpan.FromSeconds(authConfig.RateLimit.PerIpWindowSeconds),
            SegmentsPerWindow = 6,
            QueueLimit        = 0,
            AutoReplenishment = true
        });
    });
});

// AZ-538 — only the HTTPS origin is allowed; the legacy http:// origin combined with
// AllowCredentials() permitted credentialed cleartext traffic and is now removed.
builder.Services.AddCors(options =>
{
    options.AddPolicy("AdminCorsPolicy", policy =>
    {
        policy.WithOrigins("https://admin.azaion.com")
              .AllowAnyMethod()
              .AllowAnyHeader()
              .AllowCredentials();
    });
});

// AZ-538 — HSTS: 1 year, includeSubDomains, preload eligible. Only attached in
// non-Development envs; Development skips both HSTS and HTTPS redirection so
// `dotnet watch` on http://localhost keeps working.
if (!builder.Environment.IsDevelopment())
{
    builder.Services.AddHsts(o =>
    {
        o.MaxAge            = TimeSpan.FromDays(365);
        o.IncludeSubDomains = true;
        o.Preload           = true;
    });
}

var app = builder.Build();

if (app.Environment.IsDevelopment())
{
    app.UseSwagger();
    app.UseSwaggerUI();
}
else
{
    // AZ-538 — defence in depth: even if the http origin is re-added by accident
    // the protocol-layer redirect kicks in first.
    app.UseHsts();
    app.UseHttpsRedirection();
}

app.UseCors("AdminCorsPolicy");

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

app.UseRewriter(new RewriteOptions().AddRedirect("^$", "/swagger"));

#region Health endpoints
// Anonymous; expected to be exposed only on the management interface (not via the
// public Nginx vhost). Surface contract documented in
// _docs/04_deploy/deployment_procedures.md §2 and observability.md §7.

app.MapGet("/health/live", (HttpContext http) =>
{
    http.Response.Headers.CacheControl = "no-store";
    return Results.Ok(new { status = "live" });
}).AllowAnonymous().ExcludeFromDescription();

app.MapGet("/health/ready", async (IDbFactory dbFactory, HttpContext http, CancellationToken ct) =>
{
    http.Response.Headers.CacheControl = "no-store";
    using var timeoutCts = CancellationTokenSource.CreateLinkedTokenSource(ct);
    timeoutCts.CancelAfter(TimeSpan.FromSeconds(2));
    try
    {
        await dbFactory.Run(db => db.ExecuteAsync<int>("SELECT 1"));
        await dbFactory.RunAdmin(db => db.ExecuteAsync<int>("SELECT 1"));
        return Results.Ok(new { status = "ready" });
    }
    catch (OperationCanceledException) when (timeoutCts.IsCancellationRequested && !ct.IsCancellationRequested)
    {
        return Results.Json(new { status = "not-ready", reason = "db-timeout" }, statusCode: 503);
    }
    catch (Exception ex)
    {
        return Results.Json(new { status = "not-ready", reason = ex.GetType().Name }, statusCode: 503);
    }
}).AllowAnonymous().ExcludeFromDescription();
#endregion Health endpoints

app.MapPost("/login",
    async (LoginRequest request, IUserService userService, IAuthService authService, CancellationToken cancellationToken) =>
    {
        var user = await userService.ValidateUser(request, ct: cancellationToken);
        return Results.Ok(new { Token = authService.CreateToken(user)});
    })
    .RequireRateLimiting(LoginPerIpPolicy)
    .WithSummary("Login");

app.MapPost("/users",
    async (RegisterUserRequest registerUserRequest, IValidator<RegisterUserRequest> validator,
        IUserService userService, CancellationToken cancellationToken) =>
    {
        var validation = await validator.ValidateAsync(registerUserRequest, cancellationToken);
        if (!validation.IsValid)
            return Results.ValidationProblem(validation.ToDictionary());
        await userService.RegisterUser(registerUserRequest, cancellationToken);
        return Results.Ok();
    })
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Creates a new user");

app.MapPost("/devices",
    async (IUserService userService, CancellationToken cancellationToken)
        => await userService.RegisterDevice(cancellationToken))
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Creates a new device (server-assigned serial, email and password)");

app.MapGet("/users/current",
    async (IAuthService authService) => await authService.GetCurrentUser())
    .RequireAuthorization()
    .WithSummary("Get Current User");

app.MapGet("/users",
    async (string? searchEmail, RoleEnum? searchRole, IUserService userService, CancellationToken ct)
        => await userService.GetUsers(searchEmail, searchRole, ct))
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("List users by criteria");

app.MapPut("/users/queue-offsets/set",
        async ([FromBody]SetUserQueueOffsetsRequest request, IUserService userService, CancellationToken ct)
            => await userService.UpdateQueueOffsets(request.Email, request.Offsets, ct))
    .RequireAuthorization()
    .WithSummary("Sets user's queue offsets");

app.MapPut("/users/{email}/set-role/{role}", async (string email, RoleEnum role, IUserService userService, CancellationToken ct)
    => await userService.ChangeRole(email, role, ct))
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Set user's role");

app.MapPut("/users/{email}/enable", async (string email, IUserService userService, CancellationToken ct)
        => await userService.SetEnableStatus(email, true, ct))
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Enable user");

app.MapPut("/users/{email}/disable", async (string email, IUserService userService, CancellationToken ct)
        => await userService.SetEnableStatus(email, false, ct))
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Disable user");

app.MapDelete("/users/{email}", async (string email, IUserService userService, CancellationToken ct)
        => await userService.RemoveUser(email, ct))
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Remove user");

app.MapPost("/resources/{dataFolder?}",
        async ([FromRoute]string? dataFolder, IFormFile? data, IResourcesService resourceService, CancellationToken ct) =>
        {
            if (data is null)
                throw new BusinessException(ExceptionEnum.NoFileProvided);
            await resourceService.SaveResource(dataFolder, data, ct);
        })
    .Accepts<IFormFile>("multipart/form-data")
    .RequireAuthorization()
    .WithSummary("Upload resource")
    .DisableAntiforgery();

app.MapGet("/resources/list/{dataFolder?}",
    async ([FromRoute]string? dataFolder, string? search, IResourcesService resourcesService, CancellationToken ct)
        => await resourcesService.ListResources(dataFolder, search, ct))
    .RequireAuthorization()
    .WithSummary("Lists resources in folder");

app.MapPost("/resources/clear/{dataFolder?}",
        ([FromRoute]string? dataFolder, IResourcesService resourcesService) => resourcesService.ClearFolder(dataFolder))
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Clear folder");

app.MapPost("/classes",
    async (CreateDetectionClassRequest request, IValidator<CreateDetectionClassRequest> validator,
        IDetectionClassService detectionClassService, CancellationToken ct) =>
    {
        var validation = await validator.ValidateAsync(request, ct);
        if (!validation.IsValid)
            return Results.ValidationProblem(validation.ToDictionary());
        var created = await detectionClassService.Create(request, ct);
        return Results.Ok(created);
    })
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Creates a new detection class");

app.MapPatch("/classes/{id:int}",
    async (int id, UpdateDetectionClassRequest request, IValidator<UpdateDetectionClassRequest> validator,
        IDetectionClassService detectionClassService, CancellationToken ct) =>
    {
        var validation = await validator.ValidateAsync(request, ct);
        if (!validation.IsValid)
            return Results.ValidationProblem(validation.ToDictionary());
        var updated = await detectionClassService.Update(id, request, ct);
        return updated == null ? Results.NotFound() : Results.Ok(updated);
    })
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Updates an existing detection class (partial-merge accepted)");

app.MapDelete("/classes/{id:int}",
    async (int id, IDetectionClassService detectionClassService, CancellationToken ct) =>
    {
        var ok = await detectionClassService.Delete(id, ct);
        return ok ? Results.NoContent() : Results.NotFound();
    })
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("Deletes a detection class");

app.UseExceptionHandler(_ => {});

app.Run();