using GB5Shared.DTO.ReportOrchestration;
using GB5Shared.Enums.ReportOrchestration;
using Microsoft.Extensions.Logging;

namespace FrameworkBLL.ReportOrchestration
{
    /// <summary>
    /// Determines whether a report request should execute synchronously or
    /// be submitted as a SysJob, based on AsyncMode and date-range threshold.
    /// PolicyBased mode falls back to Auto until MREPORTPOLICY is implemented.
    /// </summary>
    public sealed class AsyncDecisionEngine : IAsyncDecisionEngine
    {
        private readonly ILogger<AsyncDecisionEngine> _logger;

        public AsyncDecisionEngine(ILogger<AsyncDecisionEngine> logger)
        {
            _logger = logger;
        }

        public Task<bool> ShouldRunAsyncAsync(
            ReportExecutionContext context,
            CancellationToken cancellationToken = default)
        {
            if (context.ReportConfig is null)
            {
                // No config loaded — default to sync (safe)
                return Task.FromResult(false);
            }

            bool isAsync = context.ReportConfig.AsyncMode switch
            {
                AsyncMode.AlwaysAsync  => true,
                AsyncMode.AlwaysSync   => false,
                AsyncMode.PolicyBased  => EvaluateAutoThreshold(context),  // Policy not yet implemented; falls back to Auto
                AsyncMode.Auto         => EvaluateAutoThreshold(context),
                _                      => false
            };

            if (isAsync)
                _logger.LogDebug(
                    "AsyncDecision=Async for ReportId={ReportId} AsyncMode={Mode} DateRangeDays={Days}",
                    context.ReportId, context.ReportConfig.AsyncMode, context.DateRangeDays);

            return Task.FromResult(isAsync);
        }

        private bool EvaluateAutoThreshold(ReportExecutionContext context)
            => context.DateRangeDays > context.ReportConfig!.AsyncThresholdDays;
    }
}