using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text.RegularExpressions;
using Prism.Mvvm;

namespace XP.Hardware.PLC.Models
{
    /// <summary>
    /// PLC 信号地址定义条目 | PLC signal address definition entry
    /// </summary>
    public class SignalEntry : BindableBase
    {
        /// <summary>
        /// 支持的数据类型列表 | Supported data types
        /// </summary>
        public static readonly string[] SupportedTypes = { "bool", "byte", "short", "int", "single", "double", "string" };

        /// <summary>
        /// 固定长度类型（不可编辑 IndexOrLength）| Fixed-length types (IndexOrLength not editable)
        /// </summary>
        private static readonly HashSet<string> FixedLengthTypes = new(StringComparer.OrdinalIgnoreCase)
        {
            "byte", "short", "int", "single", "double"
        };

        /// <summary>
        /// 合法 XML 元素名称正则 | Valid XML element name regex
        /// 以字母或下划线开头，后续为字母、数字、下划线、连字符、点号
        /// </summary>
        private static readonly Regex ValidXmlNameRegex = new(@"^[a-zA-Z_][\w\.\-]*$", RegexOptions.Compiled);

        private string _name = string.Empty;
        private string _type = "byte";
        private int _startAddr;
        private string _indexOrLength = string.Empty;
        private string _remark = string.Empty;

        /// <summary>
        /// 信号名称（XML 元素标签名）| Signal name (XML element tag name)
        /// </summary>
        public string Name
        {
            get => _name;
            set
            {
                var oldName = _name;
                if (SetProperty(ref _name, value ?? string.Empty))
                {
                    RaisePropertyChanged(nameof(ValidationError));
                    // 通知同集合中与旧名或新名相同的条目刷新验证 | Notify siblings with old/new name to refresh validation
                    NotifySiblingsValidation(oldName);
                    NotifySiblingsValidation(_name);
                }
            }
        }

        /// <summary>
        /// 数据类型 | Data type
        /// </summary>
        public string Type
        {
            get => _type;
            set
            {
                if (SetProperty(ref _type, value ?? "byte"))
                {
                    // 固定长度类型自动清空 IndexOrLength | Auto-clear IndexOrLength for fixed-length types
                    if (FixedLengthTypes.Contains(_type))
                    {
                        IndexOrLength = string.Empty;
                    }

                    RaisePropertyChanged(nameof(IsLengthEditable));
                    RaisePropertyChanged(nameof(IsLengthReadOnly));
                    RaisePropertyChanged(nameof(ValidationError));
                }
            }
        }

        /// <summary>
        /// 起始地址 | Start address
        /// </summary>
        public int StartAddr
        {
            get => _startAddr;
            set
            {
                if (SetProperty(ref _startAddr, value))
                {
                    RaisePropertyChanged(nameof(ValidationError));
                }
            }
        }

        /// <summary>
        /// 长度/索引（string 类型时为长度，bool 类型时为位索引）| Length/Index
        /// </summary>
        public string IndexOrLength
        {
            get => _indexOrLength;
            set
            {
                if (SetProperty(ref _indexOrLength, value ?? string.Empty))
                {
                    RaisePropertyChanged(nameof(ValidationError));
                }
            }
        }

        /// <summary>
        /// 备注 | Remark
        /// </summary>
        public string Remark
        {
            get => _remark;
            set => SetProperty(ref _remark, value ?? string.Empty);
        }

        private string _groupId = string.Empty;
        private int _dbNumber;

        /// <summary>
        /// 所属 Group ID，由解析器赋值，不参与 XML Signal 节点序列化
        /// Group ID this signal belongs to, assigned by parser, not serialized to XML Signal node
        /// </summary>
        public string GroupId
        {
            get => _groupId;
            set => SetProperty(ref _groupId, value ?? string.Empty);
        }

        /// <summary>
        /// 所属 DB 块号，由解析器赋值，不参与 XML Signal 节点序列化
        /// DB block number this signal belongs to, assigned by parser, not serialized to XML Signal node
        /// </summary>
        public int DBNumber
        {
            get => _dbNumber;
            set => SetProperty(ref _dbNumber, value);
        }

        /// <summary>
        /// 所属信号集合引用，用于名称重复检测 | Owner collection reference for duplicate name detection
        /// </summary>
        public ObservableCollection<SignalEntry> OwnerCollection { get; set; }

        /// <summary>
        /// 长度字段是否可编辑 | Whether length field is editable
        /// bool 和 string 类型可编辑，其余固定长度类型不可编辑
        /// </summary>
        public bool IsLengthEditable =>
            string.Equals(_type, "bool", StringComparison.OrdinalIgnoreCase) ||
            string.Equals(_type, "string", StringComparison.OrdinalIgnoreCase);

        /// <summary>
        /// 长度字段是否只读（IsLengthEditable 的反转，供 RadGridView IsReadOnlyBinding 使用）
        /// Whether length field is read-only (inverse of IsLengthEditable, for RadGridView IsReadOnlyBinding)
        /// </summary>
        public bool IsLengthReadOnly => !IsLengthEditable;

        /// <summary>
        /// 验证错误信息，返回第一个错误或 null | Validation error message, returns first error or null
        /// </summary>
        public string ValidationError
        {
            get
            {
                // 验证信号名称非空 | Validate name is not empty
                if (string.IsNullOrWhiteSpace(_name))
                    return "信号名称不能为空";

                // 验证信号名称为合法 XML 元素名称字符 | Validate name contains valid XML element name chars
                if (!ValidXmlNameRegex.IsMatch(_name))
                    return "信号名称包含非法字符";

                // 验证同一分区内名称不重复 | Validate name uniqueness within the same collection
                if (OwnerCollection != null && OwnerCollection.Count(s => string.Equals(s.Name, _name, StringComparison.Ordinal)) > 1)
                    return "信号名称重复";

                // 验证起始地址非负 | Validate start address is non-negative
                if (_startAddr < 0)
                    return "起始地址必须为非负整数";

                // 验证 string 类型长度为正整数 | Validate string type length is positive integer
                if (string.Equals(_type, "string", StringComparison.OrdinalIgnoreCase))
                {
                    if (!int.TryParse(_indexOrLength, out int length) || length <= 0)
                        return "字符串长度必须为正整数";
                }

                // 验证 bool 类型位索引在 0-7 之间 | Validate bool type bit index is 0-7
                if (string.Equals(_type, "bool", StringComparison.OrdinalIgnoreCase))
                {
                    if (!string.IsNullOrWhiteSpace(_indexOrLength))
                    {
                        if (!int.TryParse(_indexOrLength, out int bitIndex) || bitIndex < 0 || bitIndex > 7)
                            return "位索引必须在 0-7 之间";
                    }
                }

                return null;
            }
        }

        /// <summary>
        /// 通知同集合中同名条目刷新验证状态 | Notify siblings with same name to refresh validation
        /// </summary>
        private void NotifySiblingsValidation(string name)
        {
            if (OwnerCollection == null || string.IsNullOrWhiteSpace(name))
                return;

            foreach (var sibling in OwnerCollection)
            {
                if (sibling != this && string.Equals(sibling.Name, name, StringComparison.Ordinal))
                {
                    sibling.RaisePropertyChanged(nameof(ValidationError));
                }
            }
        }
    }
}