using System;
using Microsoft.Extensions.Logging;
using YunDa.Server.ISMSTcp.Models;
using YunDa.Server.ISMSTcp.Interfaces;

namespace YunDa.Server.ISMSTcp.Services
{
    /// <summary>
    /// 命令状态机实现
    /// </summary>
    public class CommandStateMachine : ICommandStateMachine
    {
        private readonly ILogger<CommandStateMachine> _logger;
        private readonly object _lock = new object();
        private CommandState _currentCommand;

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

        /// <summary>
        /// 当前命令状态
        /// </summary>
        public CommandState CurrentCommand
        {
            get
            {
                lock (_lock)
                {
                    return _currentCommand;
                }
            }
        }

        /// <summary>
        /// 是否有命令正在执行
        /// </summary>
        public bool HasPendingCommand
        {
            get
            {
                lock (_lock)
                {
                    return _currentCommand != null && _currentCommand.State == CommandExecutionState.WaitingForResponse;
                }
            }
        }

        /// <summary>
        /// 开始执行命令
        /// </summary>
        /// <param name="commandName">命令名称</param>
        /// <param name="fullMessage">完整消息</param>
        /// <param name="timeoutSeconds">超时时间（秒）</param>
        /// <returns>是否成功开始执行</returns>
        public bool StartCommand(string commandName, string fullMessage, int timeoutSeconds = 180)
        {
            if (string.IsNullOrWhiteSpace(commandName))
            {
                _logger.LogWarning("Cannot start command with empty name");
                return false;
            }

            lock (_lock)
            {
                // 检查是否有命令正在执行
                if (_currentCommand != null && _currentCommand.State == CommandExecutionState.WaitingForResponse)
                {
                    if (_currentCommand.IsTimeout)
                    {
                        _logger.LogWarning("Previous command '{PreviousCommand}' timed out, starting new command '{NewCommand}'", 
                            _currentCommand.CommandName, commandName);
                        _currentCommand.State = CommandExecutionState.Timeout;
                    }
                    else
                    {
                        _logger.LogWarning("Command '{CurrentCommand}' is still pending (remaining: {RemainingTime:F1}s), cannot start new command '{NewCommand}'",
                            _currentCommand.CommandName, _currentCommand.RemainingTimeoutSeconds, commandName);
                        return false;
                    }
                }

                // 创建新的命令状态
                _currentCommand = new CommandState
                {
                    CommandName = commandName,
                    FullMessage = fullMessage,
                    State = CommandExecutionState.WaitingForResponse,
                    SentTime = DateTime.Now,
                    TimeoutSeconds = timeoutSeconds
                };

                _logger.LogInformation("Started command '{CommandName}' with timeout {TimeoutSeconds}s", 
                    commandName, timeoutSeconds);
                return true;
            }
        }

        /// <summary>
        /// 完成当前命令
        /// </summary>
        /// <param name="commandName">响应的命令名称（用于验证）</param>
        /// <returns>是否成功完成</returns>
        public bool CompleteCommand(string commandName = null)
        {
            lock (_lock)
            {
                if (_currentCommand == null || _currentCommand.State != CommandExecutionState.WaitingForResponse)
                {
                    _logger.LogWarning("No pending command to complete");
                    return false;
                }

                // 如果提供了命令名称，验证是否匹配
                if (!string.IsNullOrEmpty(commandName) && 
                    !string.Equals(_currentCommand.CommandName, commandName, StringComparison.OrdinalIgnoreCase))
                {
                    _logger.LogWarning("Command name mismatch: expected '{Expected}', got '{Actual}'", 
                        _currentCommand.CommandName, commandName);
                    return false;
                }

                var executionTime = DateTime.Now.Subtract(_currentCommand.SentTime).TotalSeconds;
                _currentCommand.State = CommandExecutionState.Completed;

                _logger.LogInformation("Completed command '{CommandName}' in {ExecutionTime:F2}s", 
                    _currentCommand.CommandName, executionTime);
                return true;
            }
        }

        /// <summary>
        /// 设置命令超时
        /// </summary>
        /// <returns>是否有命令被设置为超时</returns>
        public bool TimeoutCommand()
        {
            lock (_lock)
            {
                if (_currentCommand != null && _currentCommand.State == CommandExecutionState.WaitingForResponse)
                {
                    _currentCommand.State = CommandExecutionState.Timeout;
                    _logger.LogWarning("Command '{CommandName}' timed out after {TimeoutSeconds}s", 
                        _currentCommand.CommandName, _currentCommand.TimeoutSeconds);
                    return true;
                }
                return false;
            }
        }

        /// <summary>
        /// 检查并处理超时
        /// </summary>
        /// <returns>是否有命令超时</returns>
        public bool CheckAndHandleTimeout()
        {
            lock (_lock)
            {
                if (_currentCommand != null && _currentCommand.IsTimeout == true)
                {
                    return TimeoutCommand();
                }
                return false;
            }
        }

        /// <summary>
        /// 处理OK响应，解锁命令状态
        /// </summary>
        /// <returns>是否成功处理OK响应</returns>
        public bool HandleOkResponse()
        {
            lock (_lock)
            {
                if (_currentCommand != null && _currentCommand.State == CommandExecutionState.WaitingForResponse)
                {
                    var executionTime = DateTime.Now.Subtract(_currentCommand.SentTime).TotalSeconds;
                    _currentCommand.State = CommandExecutionState.Completed;

                    _logger.LogInformation("Command '{CommandName}' completed with OK response in {ExecutionTime:F2}s",
                        _currentCommand.CommandName, executionTime);
                    return true;
                }
                else if (_currentCommand != null)
                {
                    _logger.LogWarning("Received OK response but command '{CommandName}' is in state: {State}",
                        _currentCommand.CommandName, _currentCommand.State);
                }
                else
                {
                    _logger.LogDebug("Received OK response but no command is currently pending");
                }
                return false;
            }
        }

        /// <summary>
        /// 重置状态机
        /// </summary>
        public void Reset()
        {
            lock (_lock)
            {
                if (_currentCommand != null)
                {
                    _logger.LogInformation("Resetting command state machine, current command: '{CommandName}' in state: {State}",
                        _currentCommand.CommandName, _currentCommand.State);
                }
                _currentCommand = null;
            }
        }
    }
}