using System.Security.Claims;
using Microsoft.AspNetCore.Authorization;
using StellaOps.AirGap.Controller.Endpoints.Contracts;
using StellaOps.AirGap.Controller.Services;
using StellaOps.AirGap.Time.Models;
using StellaOps.AirGap.Time.Services;

namespace StellaOps.AirGap.Controller.Endpoints;

internal static class AirGapEndpoints
{
    private const string StatusScope = "airgap:status:read";
    private const string SealScope = "airgap:seal";

    public static RouteGroupBuilder MapAirGapEndpoints(this IEndpointRouteBuilder app)
    {
        var group = app.MapGroup("/system/airgap")
            .RequireAuthorization();

        group.MapGet("/status", HandleStatus)
            .RequireScope(StatusScope)
            .WithName("AirGapStatus");

        group.MapPost("/seal", HandleSeal)
            .RequireScope(SealScope)
            .WithName("AirGapSeal");

        group.MapPost("/unseal", HandleUnseal)
            .RequireScope(SealScope)
            .WithName("AirGapUnseal");

        return group;
    }

    private static async Task<IResult> HandleStatus(
        ClaimsPrincipal user,
        AirGapStateService service,
        TimeProvider timeProvider,
        HttpContext httpContext,
        CancellationToken cancellationToken)
    {
        var tenantId = ResolveTenant(httpContext);
        var status = await service.GetStatusAsync(tenantId, timeProvider.GetUtcNow(), cancellationToken);
        return Results.Ok(AirGapStatusResponse.FromStatus(status));
    }

    private static async Task<IResult> HandleSeal(
        SealRequest request,
        ClaimsPrincipal user,
        AirGapStateService service,
        StalenessCalculator stalenessCalculator,
        TimeProvider timeProvider,
        HttpContext httpContext,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(request.PolicyHash))
        {
            return Results.BadRequest(new { error = "policy_hash_required" });
        }

        var tenantId = ResolveTenant(httpContext);
        var anchor = request.TimeAnchor ?? TimeAnchor.Unknown;
        var budget = request.StalenessBudget ?? StalenessBudget.Default;

        var now = timeProvider.GetUtcNow();
        var state = await service.SealAsync(tenantId, request.PolicyHash!, anchor, budget, now, cancellationToken);
        var status = new AirGapStatus(state, stalenessCalculator.Evaluate(anchor, budget, now), now);
        return Results.Ok(AirGapStatusResponse.FromStatus(status));
    }

    private static async Task<IResult> HandleUnseal(
        ClaimsPrincipal user,
        AirGapStateService service,
        TimeProvider timeProvider,
        HttpContext httpContext,
        CancellationToken cancellationToken)
    {
        var tenantId = ResolveTenant(httpContext);
        var state = await service.UnsealAsync(tenantId, timeProvider.GetUtcNow(), cancellationToken);
        var status = new AirGapStatus(state, StalenessEvaluation.Unknown, timeProvider.GetUtcNow());
        return Results.Ok(AirGapStatusResponse.FromStatus(status));
    }

    private static string ResolveTenant(HttpContext httpContext)
    {
        if (httpContext.Request.Headers.TryGetValue("x-tenant-id", out var tenantHeader) && !string.IsNullOrWhiteSpace(tenantHeader))
        {
            return tenantHeader.ToString();
        }
        return "default";
    }
}

internal static class AuthorizationExtensions
{
    public static RouteHandlerBuilder RequireScope(this RouteHandlerBuilder builder, string requiredScope)
    {
        return builder.RequireAuthorization(policy =>
        {
            policy.RequireAssertion(ctx =>
            {
                var scopes = ctx.User.FindFirstValue("scope") ?? ctx.User.FindFirstValue("scp") ?? string.Empty;
                return scopes.Split(' ', StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries)
                    .Contains(requiredScope, StringComparer.OrdinalIgnoreCase);
            });
        });
    }
}