using System.Security.Cryptography;
using System.Text;
using Api.SeaHavenIndustries.Options;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Mvc.Filters;
using Microsoft.Extensions.Options;

namespace Api.SeaHavenIndustries.Filters
{
    /// <summary>Validates X-Ingest-Key for POST /api/workorders/ingest.</summary>
    public class IngestApiKeyFilter : IAsyncActionFilter
    {
        private readonly WorkOrderIngestOptions _options;

        public IngestApiKeyFilter(IOptions<WorkOrderIngestOptions> options)
        {
            _options = options.Value;
        }

        public async Task OnActionExecutionAsync(ActionExecutingContext context, ActionExecutionDelegate next)
        {
            if (!_options.Enabled)
            {
                context.Result = new ObjectResult(new { message = "Work order ingest is disabled." })
                {
                    StatusCode = StatusCodes.Status503ServiceUnavailable
                };
                return;
            }

            if (string.IsNullOrWhiteSpace(_options.ApiKey)
                || _options.ApiKey.Contains("${", StringComparison.Ordinal))
            {
                context.Result = new ObjectResult(new { message = "Ingest API key is not configured." })
                {
                    StatusCode = StatusCodes.Status503ServiceUnavailable
                };
                return;
            }

            if (!context.HttpContext.Request.Headers.TryGetValue("X-Ingest-Key", out var provided)
                || !FixedTimeEquals(provided.ToString(), _options.ApiKey))
            {
                context.Result = new UnauthorizedObjectResult(new { message = "Invalid or missing X-Ingest-Key." });
                return;
            }

            await next();
        }

        private static bool FixedTimeEquals(string provided, string expected)
        {
            var providedBytes = Encoding.UTF8.GetBytes(provided);
            var expectedBytes = Encoding.UTF8.GetBytes(expected);
            return providedBytes.Length == expectedBytes.Length
                && CryptographicOperations.FixedTimeEquals(providedBytes, expectedBytes);
        }
    }

    [AttributeUsage(AttributeTargets.Class | AttributeTargets.Method)]
    public sealed class IngestApiKeyAttribute : ServiceFilterAttribute
    {
        public IngestApiKeyAttribute() : base(typeof(IngestApiKeyFilter))
        {
        }
    }
}