using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Xml;
using System.Xml.Linq;
using XP.Hardware.PLC.Abstractions;
using XP.Hardware.PLC.Models;

namespace XP.Hardware.PLC.Helpers
{
    /// <summary>
    /// XML 信号地址定义解析/序列化器 | XML signal address definition parser/serializer
    /// 负责 PlcAddrDfn.xml 的读写操作 | Responsible for reading/writing PlcAddrDfn.xml
    /// </summary>
    public class XmlSignalParser : IXmlSignalParser
    {
        /// <summary>
        /// 从文件加载信号分组列表 | Load signal group list from file
        /// </summary>
        /// <param name="filePath">XML 文件路径 | XML file path</param>
        /// <returns>信号分组列表 | Signal group list</returns>
        /// <exception cref="FileNotFoundException">文件不存在 | File not found</exception>
        /// <exception cref="XmlException">XML 格式错误或 Group 缺少必要属性 | XML format error or Group missing required attributes</exception>
        public List<SignalGroup> LoadFromFile(string filePath)
        {
            // 文件不存在时抛出异常 | Throw exception if file does not exist
            if (!File.Exists(filePath))
            {
                throw new FileNotFoundException($"XML 配置文件不存在 | XML config file not found: {filePath}", filePath);
            }

            XDocument doc;
            try
            {
                doc = XDocument.Load(filePath, LoadOptions.SetLineInfo);
            }
            catch (XmlException ex)
            {
                throw new XmlException($"XML 格式错误 | XML format error: {ex.Message}", ex);
            }

            var groups = new List<SignalGroup>();

            // 遍历 <Config> 下所有 <Group> 子节点 | Iterate all <Group> child nodes under <Config>
            var groupElements = doc.Root?.Elements("Group") ?? Enumerable.Empty<XElement>();
            foreach (var groupElement in groupElements)
            {
                // 验证 Group 必须包含 ID 属性 | Validate Group must have ID attribute
                var idAttr = groupElement.Attribute("ID");
                if (idAttr == null)
                {
                    var lineInfo = (IXmlLineInfo)groupElement;
                    throw new XmlException(
                        $"Group 节点缺少 ID 属性 | Group node missing ID attribute. " +
                        $"位置 | Position: Line {lineInfo.LineNumber}");
                }

                // 验证 Group 必须包含 DBNumber 属性 | Validate Group must have DBNumber attribute
                var dbNumberAttr = groupElement.Attribute("DBNumber");
                if (dbNumberAttr == null)
                {
                    var lineInfo = (IXmlLineInfo)groupElement;
                    throw new XmlException(
                        $"Group 节点缺少 DBNumber 属性 | Group node missing DBNumber attribute. " +
                        $"Group ID: {idAttr.Value}, " +
                        $"位置 | Position: Line {lineInfo.LineNumber}");
                }

                // 解析 DBNumber 为整数 | Parse DBNumber as integer
                if (!int.TryParse(dbNumberAttr.Value, out int dbNumber))
                {
                    var lineInfo = (IXmlLineInfo)groupElement;
                    throw new XmlException(
                        $"Group 节点 DBNumber 属性值无效（非整数）| Group node DBNumber attribute value is invalid (not an integer). " +
                        $"Group ID: {idAttr.Value}, DBNumber: {dbNumberAttr.Value}, " +
                        $"位置 | Position: Line {lineInfo.LineNumber}");
                }

                string groupId = idAttr.Value;

                // 解析该 Group 下所有 Signal 子节点 | Parse all Signal child nodes under this Group
                var signals = new System.Collections.ObjectModel.ObservableCollection<SignalEntry>();
                foreach (var signalElement in groupElement.Elements("Signal"))
                {
                    var signal = new SignalEntry
                    {
                        // 使用 Name 属性作为信号名称 | Use Name attribute as signal name
                        Name = signalElement.Attribute("Name")?.Value ?? string.Empty,
                        Type = signalElement.Attribute("Type")?.Value ?? string.Empty,
                        StartAddr = int.TryParse(signalElement.Attribute("StartAddr")?.Value, out var addr) ? addr : 0,
                        IndexOrLength = (signalElement.Attribute("IndexOrLength")?.Value ?? string.Empty).Trim(),
                        Remark = signalElement.Attribute("Remark")?.Value ?? string.Empty,
                        // 将 Group 的 ID 和 DBNumber 赋值到 SignalEntry | Assign Group's ID and DBNumber to SignalEntry
                        GroupId = groupId,
                        DBNumber = dbNumber
                    };
                    signals.Add(signal);
                }

                groups.Add(new SignalGroup
                {
                    GroupId = groupId,
                    DBNumber = dbNumber,
                    Signals = signals
                });
            }

            return groups;
        }

        /// <summary>
        /// 按 SignalGroup 结构保存信号配置到文件 | Save signal configuration to file by SignalGroup structure
        /// </summary>
        /// <param name="filePath">XML 文件路径 | XML file path</param>
        /// <param name="groups">信号分组列表 | Signal group list</param>
        public void SaveToFile(string filePath, List<SignalGroup> groups)
        {
            var doc = new XDocument(
                new XDeclaration("1.0", "utf-8", "yes"),
                new XElement("Config",
                    groups.Select(group => new XElement("Group",
                        new XAttribute("ID", group.GroupId ?? string.Empty),
                        new XAttribute("DBNumber", group.DBNumber),
                        group.Signals.Select(signal => new XElement("Signal",
                            new XAttribute("Name", signal.Name ?? string.Empty),
                            new XAttribute("Type", signal.Type ?? string.Empty),
                            new XAttribute("StartAddr", signal.StartAddr.ToString()),
                            new XAttribute("IndexOrLength", signal.IndexOrLength ?? string.Empty),
                            new XAttribute("Remark", signal.Remark ?? string.Empty)
                        ))
                    ))
                )
            );

            doc.Save(filePath);
        }
    }
}