using System.Globalization;
using System.Net;
using Microsoft.AspNetCore.Authentication;
using Microsoft.AspNetCore.Authorization;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Options;
using OpenTelemetry.Instrumentation.AspNetCore;
using OpenTelemetry.Instrumentation.Runtime;
using OpenTelemetry.Metrics;
using OpenTelemetry.Trace;

using Serilog;
using Serilog.Events;
using StellaOps.AirGap.Policy;
using StellaOps.Auth.Abstractions;
using StellaOps.Auth.ServerIntegration;
using StellaOps.Configuration;
using StellaOps.Telemetry.Core;
using StellaOps.Registry.TokenService;
using StellaOps.Registry.TokenService.Admin;
using StellaOps.Registry.TokenService.Observability;

var builder = WebApplication.CreateBuilder(args);

builder.Configuration.AddStellaOpsDefaults(options =>
{
    options.BasePath = builder.Environment.ContentRootPath;
    options.EnvironmentPrefix = "REGISTRY_TOKEN_";
    options.ConfigureBuilder = configurationBuilder =>
    {
        configurationBuilder.AddYamlFile("../etc/registry-token.yaml", optional: true, reloadOnChange: true);
    };
});

var bootstrapOptions = builder.Configuration.BindOptions<RegistryTokenServiceOptions>(
    RegistryTokenServiceOptions.SectionName,
    (opts, _) => opts.Validate());

builder.Host.UseSerilog((context, services, loggerConfiguration) =>
{
    loggerConfiguration
        .MinimumLevel.Information()
        .MinimumLevel.Override("Microsoft.AspNetCore", LogEventLevel.Warning)
        .Enrich.FromLogContext()
        .WriteTo.Console();
});

builder.Services.AddOptions<RegistryTokenServiceOptions>()
    .Bind(builder.Configuration.GetSection(RegistryTokenServiceOptions.SectionName))
    .PostConfigure(options => options.Validate())
    .ValidateOnStart();

builder.Services.AddSingleton(TimeProvider.System);
builder.Services.AddSingleton<RegistryTokenMetrics>();
builder.Services.AddSingleton<PlanRegistry>(sp =>
{
    var options = sp.GetRequiredService<IOptions<RegistryTokenServiceOptions>>().Value;
    return new PlanRegistry(options);
});
builder.Services.AddSingleton<RegistryTokenIssuer>();

// Plan Admin API dependencies
builder.Services.AddSingleton<IPlanRuleStore, InMemoryPlanRuleStore>();
builder.Services.AddSingleton<PlanValidator>();

builder.Services.AddHealthChecks().AddCheck("self", () => Microsoft.Extensions.Diagnostics.HealthChecks.HealthCheckResult.Healthy());

builder.Services.AddAirGapEgressPolicy(builder.Configuration);
builder.Services.AddStellaOpsTelemetry(
    builder.Configuration,
    serviceName: "StellaOps.Registry.TokenService",
    configureMetrics: metricsBuilder =>
    {
        metricsBuilder.AddRuntimeInstrumentation();
        metricsBuilder.AddMeter(RegistryTokenMetrics.MeterName);
    },
    configureTracing: tracerBuilder =>
    {
        tracerBuilder.AddAspNetCoreInstrumentation();
        tracerBuilder.AddHttpClientInstrumentation();
    });

builder.Services.AddStellaOpsResourceServerAuthentication(
    builder.Configuration,
    configurationSection: null,
    configure: resourceOptions =>
    {
        resourceOptions.Authority = bootstrapOptions.Authority.Issuer;
        resourceOptions.RequireHttpsMetadata = bootstrapOptions.Authority.RequireHttpsMetadata;
        resourceOptions.MetadataAddress = bootstrapOptions.Authority.MetadataAddress;

        resourceOptions.Audiences.Clear();
        foreach (var audience in bootstrapOptions.Authority.Audiences)
        {
            resourceOptions.Audiences.Add(audience);
        }
    });

builder.Services.AddAuthorization(options =>
{
    var scopes = bootstrapOptions.Authority.RequiredScopes.Count == 0
        ? new[] { "registry.token.issue" }
        : bootstrapOptions.Authority.RequiredScopes.ToArray();

    options.AddPolicy("registry.token.issue", policy =>
    {
        policy.RequireAuthenticatedUser();
        policy.Requirements.Add(new StellaOpsScopeRequirement(scopes));
        policy.AddAuthenticationSchemes(StellaOpsAuthenticationDefaults.AuthenticationScheme);
    });

    // Admin policy for plan management
    options.AddPolicy("registry.admin", policy =>
    {
        policy.RequireAuthenticatedUser();
        policy.Requirements.Add(new StellaOpsScopeRequirement(["registry.admin"]));
        policy.AddAuthenticationSchemes(StellaOpsAuthenticationDefaults.AuthenticationScheme);
    });
});

var app = builder.Build();

app.UseSerilogRequestLogging();
app.UseAuthentication();
app.UseAuthorization();

app.MapHealthChecks("/healthz");

// Plan Admin API endpoints
app.MapPlanAdminEndpoints();

app.MapGet("/token", (
    HttpContext context,
    [FromServices] IOptions<RegistryTokenServiceOptions> options,
    [FromServices] RegistryTokenIssuer issuer) =>
{
    var serviceOptions = options.Value;

    var service = context.Request.Query["service"].FirstOrDefault()?.Trim();
    if (string.IsNullOrWhiteSpace(service))
    {
        return Results.Problem(
            detail: "The 'service' query parameter is required.",
            statusCode: StatusCodes.Status400BadRequest);
    }

    if (serviceOptions.Registry.AllowedServices.Count > 0 &&
        !serviceOptions.Registry.AllowedServices.Contains(service, StringComparer.OrdinalIgnoreCase))
    {
        return Results.Problem(
            detail: "The requested registry service is not permitted for this installation.",
            statusCode: StatusCodes.Status403Forbidden);
    }

    IReadOnlyList<RegistryAccessRequest> accessRequests;
    try
    {
        accessRequests = RegistryScopeParser.Parse(context.Request.Query);
    }
    catch (InvalidScopeException ex)
    {
        return Results.Problem(
            detail: ex.Message,
            statusCode: StatusCodes.Status400BadRequest);
    }

    if (accessRequests.Count == 0)
    {
        return Results.Problem(
            detail: "At least one scope must be requested.",
            statusCode: StatusCodes.Status400BadRequest);
    }

    try
    {
        var response = issuer.IssueToken(context.User, service, accessRequests);

        return Results.Json(new
        {
            token = response.Token,
            expires_in = response.ExpiresIn,
            issued_at = response.IssuedAt.UtcDateTime.ToString("O", CultureInfo.InvariantCulture),
            issued_token_type = "urn:ietf:params:oauth:token-type:access_token"
        });
    }
    catch (RegistryTokenException ex)
    {
        return Results.Problem(
            detail: ex.Message,
            statusCode: StatusCodes.Status403Forbidden);
    }
})
.WithName("GetRegistryToken")
.RequireAuthorization("registry.token.issue")
.Produces(StatusCodes.Status200OK)
.ProducesProblem(StatusCodes.Status400BadRequest)
.ProducesProblem(StatusCodes.Status403Forbidden);

app.Run();