using System.IdentityModel.Tokens.Jwt;
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.Extensions.Logging;
using Microsoft.Extensions.Options;
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.Issuer) || string.IsNullOrEmpty(jwtConfig.Audience))
    throw new Exception("Missing configuration section: JwtConfig (Issuer + Audience required)");

// AZ-532 — load ES256 signing keys eagerly so JwtBearer can resolve issuer signing
// keys via the same provider DI registers below for AuthService.
var signingKeyLoggerFactory = LoggerFactory.Create(c => c.AddSerilog(Log.Logger));
var jwtSigningKeyProvider = new JwtSigningKeyProvider(
    Options.Create(jwtConfig),
    signingKeyLoggerFactory.CreateLogger<JwtSigningKeyProvider>());

// 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,
            // AZ-532 AC-5 — pin algorithms so a token forged with alg=HS256 using the
            // public key as the HMAC secret cannot pass validation.
            ValidAlgorithms          = [SecurityAlgorithms.EcdsaSha256],
            IssuerSigningKeyResolver = (_, _, kid, _) =>
            {
                if (string.IsNullOrEmpty(kid))
                    return jwtSigningKeyProvider.All.Select(k => (SecurityKey)k.SecurityKey);
                var hit = jwtSigningKeyProvider.All.FirstOrDefault(k => k.Kid == kid);
                return hit != null ? [hit.SecurityKey] : [];
            }
        };
    });

#region Policies

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

// AZ-535 — verifiers (satellite-provider, gps-denied, ui) authenticate as
// service-role identities and are the only callers (besides ApiAdmin) allowed
// to read the global revocation snapshot.
var revocationReaderPolicy = new AuthorizationPolicyBuilder()
    .RequireRole(RoleEnum.Service.ToString(), RoleEnum.ApiAdmin.ToString()).Build();

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

#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)));
builder.Services.Configure<SessionConfig>(builder.Configuration.GetSection(nameof(SessionConfig)));

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

// AZ-532 — share the eagerly-built provider so JwtBearer and AuthService both
// hold the same set of loaded keys.
builder.Services.AddSingleton<IJwtSigningKeyProvider>(jwtSigningKeyProvider);
builder.Services.AddScoped<IUserService, UserService>();
builder.Services.AddScoped<IAuthService, AuthService>();
builder.Services.AddScoped<IRefreshTokenService, RefreshTokenService>();
builder.Services.AddScoped<ISessionService, SessionService>();
builder.Services.AddScoped<IMissionTokenService, MissionTokenService>();
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,
           IRefreshTokenService refreshTokens,
           ISessionService sessionService,
           CancellationToken cancellationToken) =>
    {
        var user = await userService.ValidateUser(request, ct: cancellationToken);
        var (refreshToken, session) = await refreshTokens.IssueForNewLogin(user.Id, cancellationToken);
        var access = authService.CreateToken(user, sessionId: session.Id, jti: Guid.NewGuid());

        // AZ-533 AC-4 — post-flight reconnect: if the just-authenticated user is an
        // aircraft (CompanionPC), kill any open mission session bound to it.
        if (user.Role == RoleEnum.CompanionPC)
            await sessionService.RevokeMissionsForAircraft(user.Id, cancellationToken);

        return Results.Ok(new LoginResponse
        {
            AccessToken  = access.Jwt,
            AccessExp    = access.ExpiresAt,
            RefreshToken = refreshToken,
            RefreshExp   = session.ExpiresAt,
        });
    })
    .RequireRateLimiting(LoginPerIpPolicy)
    .WithSummary("Login (returns access + refresh token)");

// AZ-531 — refresh-token rotation. Anonymous: clients pass the opaque refresh
// in the request body so an expired access token doesn't block the refresh.
app.MapPost("/token/refresh",
    async (RefreshTokenRequest request,
           IRefreshTokenService refreshTokens,
           IUserService userService,
           IAuthService authService,
           ISessionService sessionService,
           CancellationToken cancellationToken) =>
    {
        var (newRefresh, session) = await refreshTokens.Rotate(request.RefreshToken, cancellationToken);
        var user = await userService.GetById(session.UserId, cancellationToken);
        if (user == null) throw new BusinessException(ExceptionEnum.InvalidRefreshToken);
        var access = authService.CreateToken(user, sessionId: session.Id, jti: Guid.NewGuid());

        // AZ-533 AC-4 — same auto-revoke trigger as /login.
        if (user.Role == RoleEnum.CompanionPC)
            await sessionService.RevokeMissionsForAircraft(user.Id, cancellationToken);

        return Results.Ok(new LoginResponse
        {
            AccessToken  = access.Jwt,
            AccessExp    = access.ExpiresAt,
            RefreshToken = newRefresh,
            RefreshExp   = session.ExpiresAt,
        });
    })
    .AllowAnonymous()
    .WithSummary("Rotate a refresh token; returns a fresh access + refresh pair");

// AZ-535 — logout: revoke the caller's current session (the sid claim on their
// access token). Idempotent.
app.MapPost("/logout",
    async (HttpContext http, ISessionService sessions, CancellationToken ct) =>
    {
        var sid     = ParseSidClaim(http.User);
        var caller  = ParseUserIdClaim(http.User);
        var alreadyRevoked = await sessions.RevokeBySid(sid, caller, SessionRevokedReasons.LoggedOut, ct);
        return Results.Ok(new { alreadyRevoked });
    })
    .RequireAuthorization()
    .WithSummary("AZ-535 — revoke the caller's current session");

// AZ-535 AC-2 — sign out everywhere: revoke every active session for the caller.
app.MapPost("/logout/all",
    async (HttpContext http, ISessionService sessions, CancellationToken ct) =>
    {
        var caller  = ParseUserIdClaim(http.User);
        var revoked = await sessions.RevokeAllForUser(caller, caller, SessionRevokedReasons.LoggedOutAll, ct);
        return Results.Ok(new { revoked });
    })
    .RequireAuthorization()
    .WithSummary("AZ-535 — revoke every session for the caller's user");

// AZ-535 AC-3 — admin-only revoke-by-sid.
app.MapPost("/sessions/{sid:guid}/revoke",
    async (Guid sid, HttpContext http, ISessionService sessions, CancellationToken ct) =>
    {
        var admin = ParseUserIdClaim(http.User);
        var alreadyRevoked = await sessions.RevokeBySid(sid, admin, SessionRevokedReasons.AdminRevoked, ct);
        return Results.Ok(new { alreadyRevoked });
    })
    .RequireAuthorization(apiAdminPolicy)
    .WithSummary("AZ-535 — admin revoke-by-session-id");

// AZ-535 AC-4 — verifier-poll snapshot of revoked-but-not-yet-expired sessions.
app.MapGet("/sessions/revoked",
    async (DateTime? since, HttpContext http, ISessionService sessions, CancellationToken ct) =>
    {
        // Cap "since" to the longest plausible token TTL (12 h, matches mission cap)
        // so a buggy verifier asking for "everything since 1970" doesn't cost us a
        // multi-million-row table scan.
        var floor = DateTime.UtcNow.AddHours(-12);
        var effective = since.HasValue && since.Value > floor ? since.Value : floor;

        var rows = await sessions.GetRevokedSince(effective, ct);
        http.Response.Headers.CacheControl = "no-cache";
        return Results.Ok(rows.Select(r => new
        {
            sid    = r.Sid,
            exp    = r.Exp,
            revokedAt = r.RevokedAt,
            reason = r.Reason
        }));
    })
    .RequireAuthorization(revocationReaderPolicy)
    .WithSummary("AZ-535 — verifier snapshot of revoked sessions still within their TTL");

// AZ-533 — mission token issuance for offline UAV ops. Pilot calls with their
// interactive access token; admin returns a long-lived no-refresh token bound
// to one aircraft + one mission.
app.MapPost("/sessions/mission",
    async (MissionSessionRequest request, HttpContext http, IMissionTokenService missions, CancellationToken ct) =>
    {
        var pilot = ParseUserIdClaim(http.User);
        // TODO (AZ-534): require amr=["pwd","mfa"]; until MFA ships this is a code
        // comment per the AZ-533 spec, not an enforced gate.
        var resp = await missions.Issue(pilot, request, ct);
        return Results.Ok(resp);
    })
    .RequireAuthorization()
    .WithSummary("AZ-533 — issue a long-lived mission token for one UAV flight");

static Guid ParseSidClaim(System.Security.Claims.ClaimsPrincipal user) =>
    Guid.TryParse(user.FindFirst(JwtRegisteredClaimNames.Sid)?.Value, out var s)
        ? s
        : throw new BusinessException(ExceptionEnum.InvalidRefreshToken);

static Guid ParseUserIdClaim(System.Security.Claims.ClaimsPrincipal user) =>
    Guid.TryParse(user.FindFirst(System.Security.Claims.ClaimTypes.NameIdentifier)?.Value, out var u)
        ? u
        : throw new BusinessException(ExceptionEnum.InvalidRefreshToken);

// AZ-532 — JWKS endpoint. Verifiers cache for 1 h (Cache-Control: public, max-age=3600).
app.MapGet("/.well-known/jwks.json",
    (IJwtSigningKeyProvider keys, HttpContext http) =>
    {
        http.Response.Headers.CacheControl = "public, max-age=3600";
        var jwks = new
        {
            keys = keys.All.Select(k =>
            {
                var p = k.Ecdsa.ExportParameters(includePrivateParameters: false);
                return new
                {
                    kty = "EC",
                    crv = "P-256",
                    kid = k.Kid,
                    use = "sig",
                    alg = "ES256",
                    x   = Microsoft.IdentityModel.Tokens.Base64UrlEncoder.Encode(p.Q.X!),
                    y   = Microsoft.IdentityModel.Tokens.Base64UrlEncoder.Encode(p.Q.Y!)
                };
            }).ToArray()
        };
        return Results.Json(jwks);
    })
    .AllowAnonymous()
    .ExcludeFromDescription()
    .WithSummary("JWKS — public verification keys");

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();