using System;
using System.Collections.Generic;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Text.RegularExpressions;

namespace BLL
{
    /// <summary>
    /// PDF 书籍模块 WebAPI 数据服务（移动端 / 第三方系统集成用）。
    /// 对应 PC 页面 HSSE/PDFDOC/PdfBookView.aspx 的完整功能：书籍、多级章节目录、章节正文（富文本 HTML）的
    /// 查询与维护（新增书籍 / 新增·编辑·删除章节 / 保存章节正文），并额外提供章节关键词检索。
    /// 数据表：Sys_PdfBook / Sys_PdfChapter（正文存 [Text] 列，为 UMeditor 生成的 HTML）。
    /// 说明：目录结构用 ParentChapterId + Level(1章 2节 3小节) 表达多级层级，SortNo 控制同级顺序。
    /// </summary>
    public static class APIPdfBookService
    {
        #region 返回模型
        /// <summary>书籍列表项。</summary>
        public class BookItem
        {
            /// <summary>书籍主键。</summary>
            public string BookId { get; set; }
            /// <summary>书名。</summary>
            public string Title { get; set; }
            /// <summary>章节总数。</summary>
            public int ChapterCount { get; set; }
            /// <summary>登记时间。</summary>
            public DateTime? CreateTime { get; set; }
        }

        /// <summary>章节目录树节点（多级嵌套）。</summary>
        public class ChapterTreeNode
        {
            /// <summary>章节主键。</summary>
            public string ChapterId { get; set; }
            /// <summary>章节名称。</summary>
            public string ChapterTitle { get; set; }
            /// <summary>层级：1章 2节 3小节。</summary>
            public int Level { get; set; }
            /// <summary>起始页码（无则为0）。</summary>
            public int PageStart { get; set; }
            /// <summary>结束页码（无则为0）。</summary>
            public int PageEnd { get; set; }
            /// <summary>是否已有正文内容（用于客户端标识可读章节）。</summary>
            public bool HasContent { get; set; }
            /// <summary>子章节列表（叶子章节为空数组）。</summary>
            public List<ChapterTreeNode> Children { get; set; }
        }

        /// <summary>章节正文详情。</summary>
        public class ChapterDetailItem
        {
            /// <summary>章节主键。</summary>
            public string ChapterId { get; set; }
            /// <summary>所属书籍主键。</summary>
            public string BookId { get; set; }
            /// <summary>所属书籍名称。</summary>
            public string BookTitle { get; set; }
            /// <summary>章节名称。</summary>
            public string ChapterTitle { get; set; }
            /// <summary>父章节主键（顶级为 null）。</summary>
            public string ParentChapterId { get; set; }
            /// <summary>层级：1章 2节 3小节。</summary>
            public int Level { get; set; }
            /// <summary>起始页码（无则为0）。</summary>
            public int PageStart { get; set; }
            /// <summary>结束页码（无则为0）。</summary>
            public int PageEnd { get; set; }
            /// <summary>正文（富文本 HTML，可直接用 WebView 渲染）。</summary>
            public string Content { get; set; }
            /// <summary>正文纯文本（去掉 HTML 标签，便于全文展示/搜索）。</summary>
            public string ContentText { get; set; }
        }

        /// <summary>章节关键词检索命中项。</summary>
        public class SearchHitItem
        {
            /// <summary>书籍主键。</summary>
            public string BookId { get; set; }
            /// <summary>书籍名称。</summary>
            public string BookTitle { get; set; }
            /// <summary>章节主键。</summary>
            public string ChapterId { get; set; }
            /// <summary>章节名称。</summary>
            public string ChapterTitle { get; set; }
            /// <summary>起始页码（无则为0）。</summary>
            public int PageStart { get; set; }
            /// <summary>结束页码（无则为0）。</summary>
            public int PageEnd { get; set; }
            /// <summary>命中片段（关键词前后各约40字）。</summary>
            public string Snippet { get; set; }
        }
        #endregion

        #region 查询：书籍列表
        /// <summary>
        /// 获取全部书籍（按登记时间升序，与页面下拉一致）。
        /// </summary>
        public static List<BookItem> GetBooks()
        {
            var list = new List<BookItem>();
            DataTable dt = SQLHelper.GetDataTableRunText(
                "SELECT b.BookId, b.Title, b.CreateTime, " +
                "(SELECT COUNT(*) FROM dbo.Sys_PdfChapter c WHERE c.BookId = b.BookId) AS ChapterCount " +
                "FROM dbo.Sys_PdfBook b ORDER BY b.CreateTime", new SqlParameter[] { });
            if (dt == null)
                return list;
            foreach (DataRow r in dt.Rows)
            {
                list.Add(new BookItem
                {
                    BookId = r["BookId"] == null ? "" : r["BookId"].ToString(),
                    Title = r["Title"] == null ? "" : r["Title"].ToString(),
                    ChapterCount = r["ChapterCount"] == DBNull.Value ? 0 : Convert.ToInt32(r["ChapterCount"]),
                    CreateTime = r["CreateTime"] == DBNull.Value ? (DateTime?)null : Convert.ToDateTime(r["CreateTime"])
                });
            }
            return list;
        }
        #endregion

        #region 查询：多级章节目录树
        /// <summary>
        /// 获取某本书的多级章节目录树（嵌套 Children，顶级为根的数组；按 SortNo 排序）。
        /// </summary>
        public static List<ChapterTreeNode> GetChapterTree(string bookId)
        {
            if (string.IsNullOrWhiteSpace(bookId))
                throw new Exception("bookId 不能为空");

            var chapters = PdfBookService.GetChapters(bookId);
            var result = new List<ChapterTreeNode>();
            if (chapters == null || chapters.Count == 0)
                return result;

            // 有正文标记（一次查询）
            var hasContentSet = new HashSet<string>();
            DataTable dt = SQLHelper.GetDataTableRunText(
                "SELECT ChapterId FROM dbo.Sys_PdfChapter " +
                "WHERE BookId = @BookId AND [Text] IS NOT NULL AND LTRIM(RTRIM([Text])) <> N''",
                new[] { new SqlParameter("@BookId", bookId) });
            if (dt != null)
                foreach (DataRow r in dt.Rows)
                    hasContentSet.Add(r["ChapterId"] == null ? "" : r["ChapterId"].ToString());

            // 1) 先为每个章节建节点
            var nodeMap = new Dictionary<string, ChapterTreeNode>();
            foreach (PdfChapter c in chapters)
            {
                nodeMap[c.ChapterId] = new ChapterTreeNode
                {
                    ChapterId = c.ChapterId,
                    ChapterTitle = c.Title,
                    Level = c.Level,
                    PageStart = c.PageStart,
                    PageEnd = c.PageEnd,
                    HasContent = hasContentSet.Contains(c.ChapterId),
                    Children = new List<ChapterTreeNode>()
                };
            }

            // 2) 按父章节挂接（父不在列表中的作为顶级）
            foreach (PdfChapter c in chapters)
            {
                var node = nodeMap[c.ChapterId];
                if (!string.IsNullOrWhiteSpace(c.ParentChapterId) && nodeMap.ContainsKey(c.ParentChapterId))
                    nodeMap[c.ParentChapterId].Children.Add(node);
                else
                    result.Add(node);
            }
            return result;
        }
        #endregion

        #region 查询：章节正文
        /// <summary>
        /// 获取章节正文详情（含 HTML 与纯文本）；章节不存在返回 null。
        /// </summary>
        public static ChapterDetailItem GetChapterDetail(string chapterId)
        {
            if (string.IsNullOrWhiteSpace(chapterId))
                throw new Exception("chapterId 不能为空");

            DataTable dt = SQLHelper.GetDataTableRunText(
                "SELECT c.ChapterId, c.BookId, b.Title AS BookTitle, c.ParentChapterId, c.[Level], " +
                "c.ChapterTitle, c.PageStart, c.PageEnd, c.[Text] " +
                "FROM dbo.Sys_PdfChapter c INNER JOIN dbo.Sys_PdfBook b ON c.BookId = b.BookId " +
                "WHERE c.ChapterId = @ChapterId",
                new[] { new SqlParameter("@ChapterId", chapterId) });
            if (dt == null || dt.Rows.Count == 0)
                return null;

            DataRow r = dt.Rows[0];
            string html = r["Text"] == DBNull.Value ? "" : r["Text"].ToString();
            var item = new ChapterDetailItem
            {
                ChapterId = r["ChapterId"] == null ? "" : r["ChapterId"].ToString(),
                BookId = r["BookId"] == null ? "" : r["BookId"].ToString(),
                BookTitle = r["BookTitle"] == null ? "" : r["BookTitle"].ToString(),
                ParentChapterId = r["ParentChapterId"] == DBNull.Value ? null : r["ParentChapterId"].ToString(),
                Level = r["Level"] == DBNull.Value ? 1 : Convert.ToInt32(r["Level"]),
                ChapterTitle = r["ChapterTitle"] == null ? "" : r["ChapterTitle"].ToString(),
                PageStart = r["PageStart"] == DBNull.Value ? 0 : Convert.ToInt32(r["PageStart"]),
                PageEnd = r["PageEnd"] == DBNull.Value ? 0 : Convert.ToInt32(r["PageEnd"]),
                Content = html,
                ContentText = HtmlToPlainText(html)
            };
            return item;
        }
        #endregion

        #region 查询：章节关键词检索
        /// <summary>
        /// 章节关键词检索：在章节正文中按关键词做字面匹配（正文为 HTML，匹配前先剔除标签）。
        /// bookId 可空：不传则全库检索。
        /// </summary>
        public static List<SearchHitItem> SearchChapter(string keyword, string bookId)
        {
            if (string.IsNullOrWhiteSpace(keyword))
                throw new Exception("keyword 不能为空");

            // LIKE 通配符转义（ESCAPE 字符为反斜杠）
            string esc = keyword.Replace("\\", "\\\\").Replace("%", "\\%").Replace("_", "\\_");
            var ps = new List<SqlParameter>
            {
                new SqlParameter("@Keyword", "%" + esc + "%")
            };
            string where = "c.[Text] LIKE @Keyword ESCAPE '\\'";
            if (!string.IsNullOrWhiteSpace(bookId))
            {
                where += " AND c.BookId = @BookId";
                ps.Add(new SqlParameter("@BookId", bookId));
            }

            DataTable dt = SQLHelper.GetDataTableRunText(
                "SELECT c.ChapterId, c.ChapterTitle, c.BookId, b.Title AS BookTitle, " +
                "c.PageStart, c.PageEnd, c.[Text] " +
                "FROM dbo.Sys_PdfChapter c INNER JOIN dbo.Sys_PdfBook b ON c.BookId = b.BookId " +
                "WHERE " + where + " ORDER BY b.Title, c.SortNo", ps.ToArray());

            var list = new List<SearchHitItem>();
            if (dt == null)
                return list;
            foreach (DataRow r in dt.Rows)
            {
                string html = r["Text"] == DBNull.Value ? "" : r["Text"].ToString();
                string plain = HtmlToPlainText(html);
                list.Add(new SearchHitItem
                {
                    BookId = r["BookId"] == null ? "" : r["BookId"].ToString(),
                    BookTitle = r["BookTitle"] == null ? "" : r["BookTitle"].ToString(),
                    ChapterId = r["ChapterId"] == null ? "" : r["ChapterId"].ToString(),
                    ChapterTitle = r["ChapterTitle"] == null ? "" : r["ChapterTitle"].ToString(),
                    PageStart = r["PageStart"] == DBNull.Value ? 0 : Convert.ToInt32(r["PageStart"]),
                    PageEnd = r["PageEnd"] == DBNull.Value ? 0 : Convert.ToInt32(r["PageEnd"]),
                    Snippet = BuildSnippet(plain, keyword)
                });
            }
            return list;
        }

        /// <summary>取关键词命中片段（前后各约40字）。</summary>
        private static string BuildSnippet(string plain, string keyword)
        {
            if (string.IsNullOrEmpty(plain))
                return "";
            int idx = plain.IndexOf(keyword, StringComparison.OrdinalIgnoreCase);
            if (idx < 0)
                return plain.Length > 120 ? plain.Substring(0, 120) + "……" : plain;
            int start = Math.Max(0, idx - 40);
            int len = Math.Min(plain.Length - start, keyword.Length + 80);
            return (start > 0 ? "……" : "") + plain.Substring(start, len) + (start + len < plain.Length ? "……" : "");
        }

        /// <summary>HTML 转纯文本（去标签、解码实体、压缩空白）。</summary>
        private static string HtmlToPlainText(string html)
        {
            if (string.IsNullOrEmpty(html))
                return "";
            string s = Regex.Replace(html, "(?i)<(br|/p|/div|/li|/tr|/h[1-6])[^>]*>", "\n");
            s = Regex.Replace(s, "<[^>]+>", "");
            s = System.Net.WebUtility.HtmlDecode(s);
            s = Regex.Replace(s, "[\r\n]+", "\n");
            s = Regex.Replace(s, "[ \t]+", " ");
            return s.Trim();
        }
        #endregion

        #region 维护：书籍
        /// <summary>
        /// 新增书籍（仅书名；FilePath/TotalPages/IndexStatus 与页面一致：NULL/0/2）。
        /// </summary>
        public static string AddBook(string title, string createUser)
        {
            if (string.IsNullOrWhiteSpace(title))
                throw new Exception("书名不能为空");
            if (string.IsNullOrWhiteSpace(createUser))
                createUser = "api";

            string bookId = NewId("PB");
            SQLHelper.ExecutSql(
                "INSERT INTO dbo.Sys_PdfBook (BookId, Title, FilePath, TotalPages, IndexStatus, CreateUser, CreateTime) VALUES ('"
                + SqlEsc(bookId) + "',N'" + SqlEsc(title.Trim()) + "',NULL,0,2,N'"
                + SqlEsc(createUser) + "',GETDATE())");
            return bookId;
        }
        #endregion

        #region 维护：章节（新增 / 改名 / 删除 / 保存正文）
        /// <summary>
        /// 新增章节：parentChapterId 为空则为顶级章节，否则挂到指定父章节下（层级=父级+1）。
        /// SortNo 取全书当前最大值+1（与页面逻辑一致）。
        /// </summary>
        public static string AddChapter(string bookId, string parentChapterId, string chapterTitle, string createUser)
        {
            if (string.IsNullOrWhiteSpace(bookId))
                throw new Exception("bookId 不能为空");
            if (string.IsNullOrWhiteSpace(chapterTitle))
                throw new Exception("章节名称不能为空");

            int level = 1;
            if (!string.IsNullOrWhiteSpace(parentChapterId))
            {
                int parentLevel = GetInt(
                    "SELECT ISNULL([Level],1) FROM dbo.Sys_PdfChapter WHERE ChapterId='" + SqlEsc(parentChapterId) + "'");
                if (parentLevel <= 0)
                    throw new Exception("父章节不存在：" + parentChapterId);
                level = parentLevel + 1;
            }
            int sort = GetInt(
                "SELECT ISNULL(MAX(SortNo),0) FROM dbo.Sys_PdfChapter WHERE BookId='" + SqlEsc(bookId) + "'") + 1;

            string chapterId = NewId("CH");
            SQLHelper.ExecutSql(
                "INSERT INTO dbo.Sys_PdfChapter (ChapterId, BookId, ParentChapterId, [Level], ChapterTitle, PageStart, PageEnd, [Text], SortNo) VALUES ('"
                + SqlEsc(chapterId) + "','" + SqlEsc(bookId) + "',"
                + (string.IsNullOrWhiteSpace(parentChapterId) ? "NULL" : "'" + SqlEsc(parentChapterId) + "'")
                + "," + level + ",N'" + SqlEsc(chapterTitle.Trim()) + "',NULL,NULL,N''," + sort + ")");
            return chapterId;
        }

        /// <summary>
        /// 编辑章节：仅修改章节名称。
        /// </summary>
        public static void EditChapter(string chapterId, string chapterTitle)
        {
            if (string.IsNullOrWhiteSpace(chapterId))
                throw new Exception("chapterId 不能为空");
            if (string.IsNullOrWhiteSpace(chapterTitle))
                throw new Exception("章节名称不能为空");
            if (GetInt("SELECT COUNT(*) FROM dbo.Sys_PdfChapter WHERE ChapterId='" + SqlEsc(chapterId) + "'") == 0)
                throw new Exception("章节不存在：" + chapterId);

            SQLHelper.ExecutSql("UPDATE dbo.Sys_PdfChapter SET ChapterTitle=N'" + SqlEsc(chapterTitle.Trim())
                + "' WHERE ChapterId='" + SqlEsc(chapterId) + "'");
        }

        /// <summary>
        /// 删除章节及其全部子章节（递归收集自身+后代后一次性删除）。
        /// </summary>
        public static int DeleteChapter(string chapterId)
        {
            if (string.IsNullOrWhiteSpace(chapterId))
                throw new Exception("chapterId 不能为空");

            DataTable dt = SQLHelper.GetDataTableRunText(
                "SELECT BookId FROM dbo.Sys_PdfChapter WHERE ChapterId=@ChapterId",
                new[] { new SqlParameter("@ChapterId", chapterId) });
            if (dt == null || dt.Rows.Count == 0)
                throw new Exception("章节不存在：" + chapterId);
            string bookId = dt.Rows[0]["BookId"].ToString();

            var all = PdfBookService.GetChapters(bookId);
            var ids = new List<string> { chapterId };
            bool changed = true;
            while (changed)
            {
                changed = false;
                foreach (PdfChapter c in all)
                {
                    if (!ids.Contains(c.ChapterId) && ids.Contains(c.ParentChapterId ?? ""))
                    {
                        ids.Add(c.ChapterId);
                        changed = true;
                    }
                }
            }

            var sb = new StringBuilder();
            foreach (string id in ids)
            {
                if (sb.Length > 0)
                    sb.Append(",");
                sb.Append("'").Append(id.Replace("'", "''")).Append("'");
            }
            SQLHelper.ExecutSql("DELETE FROM dbo.Sys_PdfChapter WHERE ChapterId IN (" + sb + ")");
            return ids.Count;
        }

        /// <summary>
        /// 保存章节正文（富文本 HTML，与页面"保存内容"一致）。
        /// </summary>
        public static void SaveContent(string chapterId, string content)
        {
            if (string.IsNullOrWhiteSpace(chapterId))
                throw new Exception("chapterId 不能为空");
            if (GetInt("SELECT COUNT(*) FROM dbo.Sys_PdfChapter WHERE ChapterId='" + SqlEsc(chapterId) + "'") == 0)
                throw new Exception("章节不存在：" + chapterId);

            SQLHelper.ExecutSql("UPDATE dbo.Sys_PdfChapter SET [Text]=N'" + SqlEsc(content ?? "")
                + "' WHERE ChapterId='" + SqlEsc(chapterId) + "'");
        }
        #endregion

        #region 工具
        /// <summary>SQL 字符串转义。</summary>
        private static string SqlEsc(string s)
        {
            return (s ?? "").Replace("'", "''");
        }

        /// <summary>执行 SELECT 首行首列并转 int（查无返回0）。</summary>
        private static int GetInt(string sql)
        {
            DataTable dt = SQLHelper.GetDataTableRunText(sql, new SqlParameter[] { });
            if (dt == null || dt.Rows.Count == 0)
                return 0;
            object v = dt.Rows[0][0];
            return v == DBNull.Value || v == null ? 0 : Convert.ToInt32(v);
        }

        /// <summary>生成业务主键（前缀+时间+随机，与页面一致）。</summary>
        private static string NewId(string prefix)
        {
            return prefix + DateTime.Now.ToString("yyyyMMddHHmmss")
                + Guid.NewGuid().ToString("N").Substring(0, 4);
        }
        #endregion
    }
}