using FastEndpoints;
using FluentValidation.Results;
using GB5Shared.DTO.ReportOrchestration;
using Microsoft.AspNetCore.Http;

namespace FrameworkSL.ReportOrchestration
{
    /// <summary>
    /// Extension methods to convert a ReportExecutionResult into an appropriate
    /// HTTP response from a FastEndpoints endpoint.
    /// Call from ExecuteAsync: await result.SendResponseAsync(HttpContext, ct);
    /// </summary>
    public static class ReportResultExtensions
    {
        public static async Task SendResponseAsync(
            this ReportExecutionResult result,
            HttpContext httpContext,
            CancellationToken ct = default)
        {
            switch (result.ResultType)
            {
                case ReportResultType.SyncCompleted when result.ExportStream is not null:
                    result.ExportStream.Seek(0, SeekOrigin.Begin);
                    await httpContext.Response
                        .SendStreamAsync(
                            result.ExportStream,
                            result.ContentType ?? "application/octet-stream",
                            result.ExportStream.Length,
                            result.FileName,
                            cancellation: ct)
                        .ConfigureAwait(false);
                    break;

                case ReportResultType.SyncCompleted:
                    await httpContext.Response
                        .SendOkAsync(new
                        {
                            Data          = result.GridData,
                            TotalRows     = result.TotalRows,
                            IsFromCache   = result.IsFromCache,
                            DataSource    = result.DataSourceUsed.ToString(),
                            CorrelationId = result.CorrelationId,
                            ElapsedMs     = (long)result.ElapsedTime.TotalMilliseconds
                        }, cancellation: ct)
                        .ConfigureAwait(false);
                    break;

                case ReportResultType.AsyncSubmitted:
                    await httpContext.Response
                        .SendOkAsync(new
                        {
                            SysJobId      = result.SysJobId,
                            Message       = result.AsyncMessage,
                            CorrelationId = result.CorrelationId,
                            ElapsedMs     = (long)result.ElapsedTime.TotalMilliseconds
                        }, cancellation: ct)
                        .ConfigureAwait(false);
                    break;

                case ReportResultType.Failed:
                default:
                    await httpContext.Response
                        .SendErrorsAsync(
                            new List<ValidationFailure>
                            {
                                new(string.Empty,
                                    result.ErrorMessage ?? "An unexpected error occurred.")
                            },
                            statusCode: 500,
                            cancellation: ct)
                        .ConfigureAwait(false);
                    break;
            }
        }
    }
}