using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Wordprocessing;
using Furion.DependencyInjection;

namespace YD_Event.Core.Certificate
{
    /// <summary>
    /// DOCX模板解析器
    /// </summary>
    public class DocxTemplateParser : ITransient
    {
        private const string PlaceholderPattern = @"\{\{([^}]+)\}\}";

        /// <summary>
        /// 从DOCX文件中提取占位符
        /// </summary>
        /// <param name="docxStream">DOCX文件流</param>
        /// <returns>占位符列表</returns>
        public List<string> ExtractPlaceholders(Stream docxStream)
        {
            var placeholders = new HashSet<string>();
            
            using (var document = WordprocessingDocument.Open(docxStream, false))
            {
                var body = document.MainDocumentPart?.Document?.Body;
                if (body == null) return new List<string>();

                // 解析段落中的占位符
                foreach (var paragraph in body.Elements<Paragraph>())
                {
                    var text = ExtractTextFromParagraph(paragraph);
                    var foundPlaceholders = ExtractPlaceholdersFromText(text);
                    foreach (var placeholder in foundPlaceholders)
                    {
                        placeholders.Add(placeholder);
                    }
                }

                // 解析表格中的占位符
                foreach (var table in body.Elements<Table>())
                {
                    var tablePlaceholders = ExtractPlaceholdersFromTable(table);
                    foreach (var placeholder in tablePlaceholders)
                    {
                        placeholders.Add(placeholder);
                    }
                }

                // 解析页眉页脚中的占位符
                ExtractPlaceholdersFromHeaderFooter(document, placeholders);
            }

            return placeholders.OrderBy(x => x).ToList();
        }

        /// <summary>
        /// 从文本中提取占位符
        /// </summary>
        /// <param name="text">文本内容</param>
        /// <returns>占位符列表</returns>
        private List<string> ExtractPlaceholdersFromText(string text)
        {
            var placeholders = new List<string>();
            var matches = Regex.Matches(text, PlaceholderPattern);

            foreach (Match match in matches)
            {
                var placeholder = match.Groups[1].Value.Trim();
                if (!string.IsNullOrWhiteSpace(placeholder))
                {
                    placeholders.Add(placeholder);
                }
            }

            return placeholders;
        }

        /// <summary>
        /// 从段落中提取文本
        /// </summary>
        /// <param name="paragraph">段落元素</param>
        /// <returns>文本内容</returns>
        private string ExtractTextFromParagraph(Paragraph paragraph)
        {
            return string.Join("", paragraph.Elements<Run>().Select(run => 
                string.Join("", run.Elements<Text>().Select(text => text.Text))));
        }

        /// <summary>
        /// 从表格中提取占位符
        /// </summary>
        /// <param name="table">表格元素</param>
        /// <returns>占位符列表</returns>
        private List<string> ExtractPlaceholdersFromTable(Table table)
        {
            var placeholders = new HashSet<string>();

            foreach (var row in table.Elements<TableRow>())
            {
                foreach (var cell in row.Elements<TableCell>())
                {
                    foreach (var paragraph in cell.Elements<Paragraph>())
                    {
                        var text = ExtractTextFromParagraph(paragraph);
                        var cellPlaceholders = ExtractPlaceholdersFromText(text);
                        foreach (var placeholder in cellPlaceholders)
                        {
                            placeholders.Add(placeholder);
                        }
                    }
                }
            }

            return placeholders.ToList();
        }

        /// <summary>
        /// 从页眉页脚中提取占位符
        /// </summary>
        /// <param name="document">Word文档对象</param>
        /// <param name="placeholders">占位符集合</param>
        private void ExtractPlaceholdersFromHeaderFooter(WordprocessingDocument document, HashSet<string> placeholders)
        {
            // 暂时跳过页眉页脚处理，因为API兼容性问题
            // 实际项目中需要根据具体的DocumentFormat.OpenXml版本调整
        }

        /// <summary>
        /// 验证占位符格式
        /// </summary>
        /// <param name="placeholder">占位符</param>
        /// <returns>是否有效</returns>
        public bool IsValidPlaceholder(string placeholder)
        {
            return !string.IsNullOrWhiteSpace(placeholder) && 
                   Regex.IsMatch(placeholder, @"^[a-zA-Z_][a-zA-Z0-9_]*$");
        }

        /// <summary>
        /// 获取占位符类型
        /// </summary>
        /// <param name="placeholder">占位符</param>
        /// <returns>占位符类型</returns>
        public string GetPlaceholderType(string placeholder)
        {
            if (string.IsNullOrWhiteSpace(placeholder))
                return "Text";

            var lowerPlaceholder = placeholder.ToLowerInvariant();
            
            if (lowerPlaceholder.Contains("date") || lowerPlaceholder.Contains("time"))
                return "Date";
            
            if (lowerPlaceholder.Contains("qr") || lowerPlaceholder.Contains("qrcode"))
                return "QRCode";
            
            if (lowerPlaceholder.Contains("image") || lowerPlaceholder.Contains("img") || lowerPlaceholder.Contains("photo"))
                return "Image";

            return "Text";
        }
    }
}