using System;
using System.Threading.Tasks;
using Prism.Commands;
using Prism.Mvvm;
using XP.Hardware.PLC.Models;

namespace XP.Hardware.PLC.Sentry.ViewModels
{
    /// <summary>
    /// 单行信号 ViewModel，封装 SignalEntry 并添加运行时状态 | Single signal row ViewModel wrapping SignalEntry with runtime state
    /// </summary>
    public class SignalRowViewModel : BindableBase
    {
        private readonly SignalEntry _signal;
        private string _currentValue = "--";
        private bool _hasReadError;
        private object _writeValue;
        private string _validationError;

        /// <summary>
        /// 构造函数 | Constructor
        /// </summary>
        /// <param name="signal">信号定义条目 | Signal definition entry</param>
        /// <param name="applyAction">队列写入回调 | Queue write callback</param>
        /// <param name="directWriteAction">直接写入回调 | Direct write callback</param>
        /// <param name="canExecuteWrite">写入命令是否可用判断 | Write command can-execute predicate</param>
        public SignalRowViewModel(
            SignalEntry signal,
            Action<SignalRowViewModel> applyAction,
            Action<SignalRowViewModel> directWriteAction,
            Func<bool> canExecuteWrite)
        {
            _signal = signal ?? throw new ArgumentNullException(nameof(signal));

            ApplyCommand = new DelegateCommand(
                () => applyAction?.Invoke(this),
                () => canExecuteWrite?.Invoke() ?? false);

            DirectWriteCommand = new DelegateCommand(
                () => directWriteAction?.Invoke(this),
                () => canExecuteWrite?.Invoke() ?? false);
        }

        // === 信号定义信息（只读）| Signal definition info (read-only) ===

        /// <summary>
        /// 信号名称 | Signal name
        /// </summary>
        public string Name => _signal.Name;

        /// <summary>
        /// 数据类型 | Data type
        /// </summary>
        public string Type => _signal.Type;

        /// <summary>
        /// 起始地址 | Start address
        /// </summary>
        public int StartAddr => _signal.StartAddr;

        /// <summary>
        /// 长度/索引 | Length/Index
        /// </summary>
        public string IndexOrLength => _signal.IndexOrLength;

        /// <summary>
        /// 备注 | Remark
        /// </summary>
        public string Remark => _signal.Remark;

        /// <summary>
        /// DB 块号 | DB block number
        /// </summary>
        public int DBNumber => _signal.DBNumber;

        /// <summary>
        /// 原始信号定义条目 | Original signal definition entry
        /// </summary>
        public SignalEntry Signal => _signal;

        /// <summary>
        /// 格式化的地址显示 | Formatted address display
        /// bool 类型显示位地址（DB{n}.{addr}.{bit}），其他类型显示字节地址（DB{n}.{addr}）
        /// </summary>
        public string AddressDisplay => Type?.ToLowerInvariant() == "bool"
            ? $"DB{DBNumber}.{StartAddr}.{IndexOrLength}"
            : $"DB{DBNumber}.{StartAddr}";

        // === 运行时状态 | Runtime state ===

        /// <summary>
        /// 当前读取值 | Current read value
        /// </summary>
        public string CurrentValue
        {
            get => _currentValue;
            set => SetProperty(ref _currentValue, value ?? "--");
        }

        /// <summary>
        /// 是否存在读取错误 | Whether read error exists
        /// </summary>
        public bool HasReadError
        {
            get => _hasReadError;
            set => SetProperty(ref _hasReadError, value);
        }

        /// <summary>
        /// 写入值 | Write value
        /// </summary>
        public object WriteValue
        {
            get => _writeValue;
            set
            {
                if (SetProperty(ref _writeValue, value))
                {
                    // 写入值变更时清除校验错误 | Clear validation error when write value changes
                    ValidationError = null;
                }
            }
        }

        /// <summary>
        /// 校验错误信息 | Validation error message
        /// </summary>
        public string ValidationError
        {
            get => _validationError;
            set => SetProperty(ref _validationError, value);
        }

        // === 命令 | Commands ===

        /// <summary>
        /// 队列写入命令 | Queue write command
        /// </summary>
        public DelegateCommand ApplyCommand { get; }

        /// <summary>
        /// 直接写入+回读校验命令 | Direct write with verify command
        /// </summary>
        public DelegateCommand DirectWriteCommand { get; }

        /// <summary>
        /// 刷新写入命令可用状态 | Refresh write command can-execute state
        /// </summary>
        public void RefreshCommandState()
        {
            ApplyCommand.RaiseCanExecuteChanged();
            DirectWriteCommand.RaiseCanExecuteChanged();
        }

        /// <summary>
        /// 校验写入值是否符合信号数据类型要求 | Validate write value against signal data type
        /// </summary>
        /// <returns>校验错误信息，null 表示通过 | Validation error message, null means passed</returns>
        public string ValidateWriteValue()
        {
            if (WriteValue == null)
                return "写入值不能为空 | Write value cannot be empty";

            var strValue = WriteValue.ToString();
            if (string.IsNullOrWhiteSpace(strValue))
                return "写入值不能为空 | Write value cannot be empty";

            switch (Type?.ToLowerInvariant())
            {
                case "bool":
                    if (!bool.TryParse(strValue, out _))
                        return "布尔值仅接受 True/False | Bool accepts only True/False";
                    break;
                case "byte":
                    if (!byte.TryParse(strValue, out _))
                        return "字节值超出范围 (0-255) | Byte value out of range (0-255)";
                    break;
                case "short":
                    if (!short.TryParse(strValue, out _))
                        return "短整型值超出范围 | Short value out of range";
                    break;
                case "int":
                    if (!int.TryParse(strValue, out _))
                        return "整型值超出范围 | Int value out of range";
                    break;
                case "single":
                    if (!float.TryParse(strValue, out _))
                        return "浮点数格式错误 | Float format error";
                    break;
                case "double":
                    if (!double.TryParse(strValue, out _))
                        return "双精度浮点数格式错误 | Double format error";
                    break;
                case "string":
                    // 字符串接受任意非空值 | String accepts any non-empty value
                    break;
                default:
                    return $"不支持的类型: {Type} | Unsupported type: {Type}";
            }

            return null;
        }
    }
}