using OrpaonVision.Core.Results;
using OrpaonVision.SiteApp.Runtime.Contracts;
using OrpaonVision.SiteApp.Runtime.Options;

namespace OrpaonVision.SiteApp.Runtime.Services
{
    /// <summary>
    /// 运行状态机简化实现（MVP 阶段）。
    /// </summary>
    public sealed class SimpleRuntimeStateMachineService : IRuntimeStateMachineService
    {
        private readonly RuntimeOptions _options;

        private int _currentLayer;

        /// <summary>
        /// 构造函数。
        /// </summary>
        public SimpleRuntimeStateMachineService(RuntimeOptions options)
        {
            _options = options;
            _currentLayer = 1;
        }

        /// <inheritdoc />
        public RuntimeStateSnapshotDto GetSnapshot()
        {
            return new RuntimeStateSnapshotDto
            {
                CurrentLayer = _currentLayer,
                TotalLayers = _options.TotalLayers,
                StateText = _currentLayer > _options.TotalLayers ? "工位完成" : "运行中"
            };
        }

        /// <inheritdoc />
        public RuntimeState GetCurrentState()
        {
            return _currentLayer > _options.TotalLayers ? RuntimeState.Completed : RuntimeState.Running;
        }

        /// <inheritdoc />
        public int GetCurrentLayer()
        {
            return _currentLayer;
        }

        /// <inheritdoc />
        public bool CanExecuteOperation(StateTrigger trigger)
        {
            _ = trigger;
            return true;
        }

        /// <inheritdoc />
        public Result<StateTransitionEvent> TriggerTransition(StateTrigger trigger, string? reason = null, object? parameters = null)
        {
            _ = reason;
            _ = parameters;

            // 简化实现：对某些触发器映射到已有操作
            if (trigger == StateTrigger.MoveToNextLayer)
            {
                var move = MoveToNextLayer();
                if (!move.Succeeded)
                {
                    return Result<StateTransitionEvent>.Fail(move.Code, move.Message);
                }
            }
            else if (trigger == StateTrigger.Reset)
            {
                Reset();
            }

            var ev = new StateTransitionEvent
            {
                EventType = StateTransitionEventType.Error,
                PreviousState = RuntimeState.Running,
                NewState = GetCurrentState(),
                PreviousLayer = _currentLayer,
                NewLayer = _currentLayer,
                Timestamp = DateTime.UtcNow,
                Reason = reason ?? string.Empty,
                Trigger = trigger,
                GuardResult = "Simple"
            };

            return Result<StateTransitionEvent>.Success(ev);
        }

        /// <inheritdoc />
        public Result MoveToNextLayer()
        {
            if (_currentLayer >= _options.TotalLayers)
            {
                return Result.Fail("STATE_MACHINE_FINISHED", "当前已到最后一层，无法继续切层。");
            }

            _currentLayer += 1;
            return Result.Success("STATE_MACHINE_MOVED", $"已切换到第 {_currentLayer} 层。");
        }

        /// <inheritdoc />
        public void Reset()
        {
            _currentLayer = 1;
        }
    }
}