using AngleSharp.Html.Parser;
using Ganss.Xss;
using Microsoft.EntityFrameworkCore;
using Newtonsoft.Json;
using RMuseum.DbContext;
using RMuseum.Models.Divan;
using RSecurityBackend.Models.Generic;
using RSecurityBackend.Models.Generic.Db;
using RSecurityBackend.Services.Implementation;
using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Net.Http;
using System.Text.RegularExpressions;
using System.Threading.Tasks;

namespace RMuseum.Services.Implementation
{
    /// <summary>
    /// IDivanService implementation
    /// </summary>
    public partial class DivanService : IDivanService
    {
        private async Task _FindCategoryPoemsRhythmsInternal(int catId, bool retag, string rhythm)
        {
            using (RMuseumDbContext context = new RMuseumDbContext(new DbContextOptions<RMuseumDbContext>())) //this is long running job, so _context might be already been freed/collected by GC
            {
                LongRunningJobProgressServiceEF jobProgressServiceEF = new LongRunningJobProgressServiceEF(context);
                var job = (await jobProgressServiceEF.NewJob($"FindCategoryPoemsRhythms Cat {catId}", "Query data")).Result;
                await _FindCategoryPoemsRhythmsMoreInternal(context, jobProgressServiceEF, job, catId, retag, rhythm);
                await jobProgressServiceEF.UpdateJob(job.Id, 0, "SubCats");
                List<int> catListId = new List<int>();
                await _populateCategoryChildren(context, catId, catListId);
                foreach (var subCatId in catListId)
                {
                    await jobProgressServiceEF.UpdateJob(job.Id, subCatId, "SubCats");
                    await _FindCategoryPoemsRhythmsMoreInternal(context, jobProgressServiceEF, job, subCatId, retag, rhythm);
                }
                await jobProgressServiceEF.UpdateJob(job.Id, 100, "", true);
            }
        }

        private async Task _FindCategoryPoemsRhythmsMoreInternal(RMuseumDbContext context, LongRunningJobProgressServiceEF jobProgressServiceEF, RLongRunningJobStatus job, int catId, bool retag, string rhythm)
        {
            try
            {
                var metres = await context.DivanMetres.OrderBy(m => m.Rhythm).AsNoTracking().ToArrayAsync();
                var rhythms = metres.Select(m => m.Rhythm).ToArray();

                DivanMetre preDeterminedMetre = string.IsNullOrEmpty(rhythm) ? null : metres.Where(m => m.Rhythm == rhythm).Single();

                var poems = await context.DivanPoems.AsNoTracking().Where(p => p.CatId == catId).ToListAsync();

                int i = 0;
                List<Tuple<int, string>> updateList = new List<Tuple<int, string>>();
                using (HttpClient httpClient = new HttpClient())
                {

                    foreach (var poem in poems)
                    {

                        var sections = await context.DivanPoemSections.Where(p => p.PoemId == poem.Id).ToListAsync();
                        foreach (var section in sections.Where(s => s.DivanMetreRefSectionIndex == null).ToList())
                        {
                            if (retag || section.DivanMetreId == null)
                            {

                                if (preDeterminedMetre == null)
                                {
                                    var res = await _FindSectionRhythm(section, context, httpClient, rhythms);
                                    if (!string.IsNullOrEmpty(res.Result))
                                    {
                                        section.DivanMetreId = metres.Where(m => m.Rhythm == res.Result).Single().Id;
                                        context.DivanPoemSections.Update(section);
                                    }
                                }
                                else
                                {
                                    section.DivanMetreId = preDeterminedMetre.Id;
                                    context.DivanPoemSections.Update(section);
                                }

                                if (section.DivanMetreId != null)
                                {
                                    var dependentSections = sections.Where(s => s.DivanMetreRefSectionIndex == section.Index).ToList();
                                    foreach (var dsection in dependentSections)
                                    {
                                        dsection.DivanMetreId = section.DivanMetreId;
                                        context.DivanPoemSections.Update(dsection);
                                    }
                                }

                                if (section.DivanMetreId != null && !string.IsNullOrEmpty(section.RhymeLetters))
                                {
                                    if (!updateList.Any(u => u.Item1 == section.DivanMetreId && u.Item2 == section.RhymeLetters))
                                    {
                                        updateList.Add(new Tuple<int, string>((int)section.DivanMetreId, section.RhymeLetters));
                                    }

                                }

                                if (section.DivanMetreId != null)
                                {
                                    var dependentSections = sections.Where(s => s.DivanMetreRefSectionIndex == section.Index).ToList();
                                    foreach (var dsection in dependentSections)
                                    {
                                        if (dsection.DivanMetreId != null && !string.IsNullOrEmpty(dsection.RhymeLetters))
                                        {
                                            if (!updateList.Any(u => u.Item1 == dsection.DivanMetreId && u.Item2 == dsection.RhymeLetters))
                                            {
                                                updateList.Add(new Tuple<int, string>((int)dsection.DivanMetreId, dsection.RhymeLetters));
                                            }

                                        }
                                    }
                                }

                                await jobProgressServiceEF.UpdateJob(job.Id, i++);
                            }
                        }


                    }
                }

                foreach (var item in updateList)
                {
                    await _UpdateRelatedSections(context, item.Item1, item.Item2, jobProgressServiceEF, job);
                }

                var subCats = await context.DivanCategories.AsNoTracking().Where(c => c.ParentId == catId).ToListAsync();
                foreach (var subCat in subCats)
                {
                    await jobProgressServiceEF.UpdateJob(job.Id, 0, $"FindCategoryPoemsRhythms Cat {subCat.Id}");
                    await _FindCategoryPoemsRhythmsMoreInternal(context, jobProgressServiceEF, job, subCat.Id, retag, rhythm);
                }


            }
            catch (Exception exp)
            {
                await jobProgressServiceEF.UpdateJob(job.Id, 100, "", false, exp.ToString());
            }
        }

        /// <summary>
        /// find category poem rhymes
        /// </summary>
        /// <param name="catId"></param>
        /// <param name="retag"></param>
        /// <param name="rhythm"></param>
        /// <returns></returns>
        public RServiceResult<bool> FindCategoryPoemsRhythms(int catId, bool retag, string rhythm = "")
        {
            _backgroundTaskQueue.QueueBackgroundWorkItem
                        (
                        async token =>
                        {
                            await _FindCategoryPoemsRhythmsInternal(catId, retag, rhythm);
                        });

            return new RServiceResult<bool>(true);
        }



        /// <summary>
        /// directly insert generated TOC
        /// </summary>
        /// <param name="catId"></param>
        /// <param name="userId"></param>
        /// <param name="options"></param>
        /// <returns></returns>
        public async Task<RServiceResult<bool>> DirectInsertGeneratedTableOfContents(int catId, Guid userId, DivanTOC options)
        {
            return await _DirectInsertGeneratedTableOfContents(_context, catId, userId, options);
        }

        /// <summary>
        /// generate category TOC
        /// </summary>
        /// <param name="userId"></param>
        /// <param name="catId"></param>
        /// <param name="options"></param>
        /// <returns></returns>
        public async Task<RServiceResult<string>> GenerateTableOfContents(Guid userId, int catId, DivanTOC options)
        {
            return await _GenerateTableOfContents(_context, catId, options, userId);
        }


        private static readonly Regex _titleNumberRegex = new Regex(@"[۰-۹٠-٩0-9]+", RegexOptions.Compiled);
        private static readonly char[] _titleTrimChars = new[] { ' ', '\t', '\r', '\n', '\u200c', '\u200f', '\u200e', '-', '–', '—', ':', '،', ',', '.', '(', ')', '[', ']', '"', '\'', '«', '»' };

        /// <summary>
        /// extracts the searchable part of a poem title, discarding pure boilerplate like
        /// "غزل شمارهٔ ۱" or "بخش ۴۷" which carries no information beyond the ordinal number,
        /// while keeping either the whole title (if it has no number at all, e.g. "طهمورث")
        /// or just the descriptive part after the number (e.g. "بخش ۴۷ - تشبیه کردن قرآن..."
        /// keeps "تشبیه کردن قرآن...") - returns "" when there is nothing worth indexing
        /// </summary>
        /// <param name="title"></param>
        /// <returns></returns>
        private static string ExtractSearchableTitlePart(string title)
        {
            if (string.IsNullOrWhiteSpace(title))
                return "";

            Match m = _titleNumberRegex.Match(title);
            if (!m.Success)
                return title.Trim(_titleTrimChars);

            return title.Substring(m.Index + m.Length).Trim(_titleTrimChars);
        }

        /// <summary>
        /// make plain text
        /// </summary>
        /// <param name="verses"></param>
        /// <param name="title">poem/section title - its searchable part (if any) is included so
        /// titles like "بخش ۴۷ - تشبیه کردن ..." are findable through search, while pure
        /// boilerplate like "غزل شمارهٔ ۱" is silently skipped</param>
        /// <returns></returns>
        private static string PreparePlainText(List<DivanVerse> verses, string title = null)
        {
            string plainText = "";
            string searchableTitle = ExtractSearchableTitlePart(title);
            if (!string.IsNullOrEmpty(searchableTitle))
            {
                plainText += $"{LanguageUtils.MakeTextSearchable(searchableTitle)}{Environment.NewLine}";
            }
            foreach (DivanVerse verse in verses)
            {
                plainText += $"{LanguageUtils.MakeTextSearchable(verse.Text)}{Environment.NewLine}";//replace zwnj with space
            }
            return plainText.Trim();
        }

        /// <summary>
        /// separate verses in poem.PlainText with  Environment.NewLine instead of SPACE
        /// </summary>
        /// <param name="catId"></param>
        /// <returns></returns>
        public RServiceResult<bool> RegerneratePoemsPlainText(int catId)
        {
            _backgroundTaskQueue.QueueBackgroundWorkItem
            (
            async token =>
            {
                using (RMuseumDbContext context = new RMuseumDbContext(new DbContextOptions<RMuseumDbContext>())) //this is long running job, so _context might be already been freed/collected by GC
                {
                    LongRunningJobProgressServiceEF jobProgressServiceEF = new LongRunningJobProgressServiceEF(context);
                    var job = (await jobProgressServiceEF.NewJob($"RegerneratePoemsPlainText {catId}", "Query data")).Result;

                    try
                    {
                        var poems = catId == 0 ? await context.DivanPoems.ToArrayAsync() : await context.DivanPoems.Where(p => p.CatId == catId).ToArrayAsync();

                        await jobProgressServiceEF.UpdateJob(job.Id, 0, $"Updating PlainText/Poem Html {catId}");

                        int percent = 0;
                        for (int i = 0; i < poems.Length; i++)
                        {
                            if (i * 100 / poems.Length > percent)
                            {
                                percent++;
                                await jobProgressServiceEF.UpdateJob(job.Id, percent);
                            }

                            var poem = poems[i];

                            var verses = await context.DivanVerses.AsNoTracking().Where(v => v.PoemId == poem.Id).OrderBy(v => v.VOrder).ToListAsync();

                            poem.PlainText = PreparePlainText(verses, poem.Title);
                            poem.HtmlText = PrepareHtmlText(verses);
                        }

                        await jobProgressServiceEF.UpdateJob(job.Id, 0, $"Finalizing PlainText/Poem Html {catId}");

                        context.DivanPoems.UpdateRange(poems);

                        await context.SaveChangesAsync();

                        await jobProgressServiceEF.UpdateJob(job.Id, 50, $"Updating pages HTML {catId}");

                        //the following line always gets timeout, so it is being replaced by a loop
                        //await context.Database.ExecuteSqlRawAsync(
                        //    "UPDATE p SET p.HtmlText = (SELECT poem.HtmlText FROM DivanPoems poem WHERE poem.Id = p.Id) FROM DivanPages p WHERE p.DivanPageType = 3 ");

                        foreach (var poem in poems)
                        {
                            var page = await context.DivanPages.Where(p => p.Id == poem.Id).SingleAsync();
                            page.HtmlText = poem.HtmlText;
                            context.DivanPages.Update(page);
                        }
                        await context.SaveChangesAsync();

                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", true);
                    }
                    catch (Exception exp)
                    {
                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", false, exp.ToString());
                    }

                }
            }
            );

            return new RServiceResult<bool>(true);
        }

        /// <summary>
        /// examine site pages for broken links
        /// </summary>
        /// <returns></returns>
        public RServiceResult<bool> HealthCheckContents()
        {
            _backgroundTaskQueue.QueueBackgroundWorkItem
            (
            async token =>
            {
                using (RMuseumDbContext context = new RMuseumDbContext(new DbContextOptions<RMuseumDbContext>())) //this is long running job, so _context might be already been freed/collected by GC
                {
                    LongRunningJobProgressServiceEF jobProgressServiceEF = new LongRunningJobProgressServiceEF(context);
                    var job = (await jobProgressServiceEF.NewJob("HealthCheckContents", "Query data")).Result;

                    try
                    {
                        var pages = await context.DivanPages.ToArrayAsync();

                        await jobProgressServiceEF.UpdateJob(job.Id, 0, $"Examining Pages");

                        var previousErrors = await context.DivanHealthCheckErrors.ToArrayAsync();
                        context.RemoveRange(previousErrors);
                        await context.SaveChangesAsync();
                        int percent = 0;
                        for (int i = 0; i < pages.Length; i++)
                        {
                            if (i * 100 / pages.Length > percent)
                            {
                                percent++;
                                await jobProgressServiceEF.UpdateJob(job.Id, percent);
                            }

                            var hrefs = pages[i].HtmlText.Split(new[] { "href=\"" }, StringSplitOptions.RemoveEmptyEntries).Where(o => o.StartsWith("http")).Select(o => o.Substring(0, o.IndexOf("\"")));

                            foreach (string url in hrefs)
                            {
                                if (url == "https://ganjoor.net" || url == "https://ganjoor.net/" || url.IndexOf("https://ganjoor.net/vazn/?") == 0 || url.IndexOf("https://ganjoor.net/simi/?v") == 0)
                                    continue;
                                if (url.IndexOf("http://ganjoor.net") == 0)
                                {
                                    context.DivanHealthCheckErrors.Add
                                    (
                                        new DivanHealthCheckError()
                                        {
                                            ReferrerPageUrl = pages[i].FullUrl,
                                            TargetUrl = url,
                                            BrokenLink = false,
                                            MulipleTargets = false
                                        }
                                     );

                                    await context.SaveChangesAsync();
                                }
                                else
                                    if (url.IndexOf("https://ganjoor.net") == 0)
                                    {
                                        var testUrl = url.Substring("https://ganjoor.net".Length);
                                        if (testUrl[testUrl.Length - 1] == '/')
                                            testUrl = testUrl.Substring(0, testUrl.Length - 1);
                                        var pageCount = await context.DivanPages.Where(p => p.FullUrl == testUrl).CountAsync();
                                        if (pageCount != 1)
                                        {
                                            context.DivanHealthCheckErrors.Add
                                         (
                                             new DivanHealthCheckError()
                                             {
                                                 ReferrerPageUrl = pages[i].FullUrl,
                                                 TargetUrl = url,
                                                 BrokenLink = pageCount == 0,
                                                 MulipleTargets = pageCount != 0
                                             }
                                          );

                                            await context.SaveChangesAsync();
                                        }
                                    }
                            }
                        }

                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", true);
                    }
                    catch (Exception exp)
                    {
                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", false, exp.ToString());
                    }

                }
            }
            );

            return new RServiceResult<bool>(true);
        }

        /// <summary>
        /// extracts normalized plain text from (possibly malformed) HTML the same way a
        /// spec-compliant parser (and so also the sanitizer's own parser) sees it, so it can
        /// be compared before/after sanitizing to detect whether sanitizing dropped real text
        /// </summary>
        private static string _ExtractPlainText(string html)
        {
            if (string.IsNullOrWhiteSpace(html))
                return "";

            var parser = new HtmlParser();
            using var document = parser.ParseDocument($"<body>{html}</body>");
            string text = document.Body?.TextContent ?? "";
            return Regex.Replace(text, @"\s+", " ").Trim();
        }

        /// <summary>
        /// true if sanitizing the comment dropped a meaningful chunk of the user's actual
        /// text - not just markup/attributes, and not a harmless space lost when an inline
        /// tag gets unwrapped. This happens when invalid/unclosed markup causes real comment
        /// text to end up nested inside a tag the sanitizer correctly removes entirely
        /// (e.g. a stray/unclosed tag that swallows the rest of the comment as its "content",
        /// or an actually-disallowed tag such as script/style whose whole subtree is removed)
        /// </summary>
        private static bool _CommentSanitizationDroppedText(string originalPlainText, string sanitizedPlainText)
        {
            originalPlainText = (originalPlainText ?? "").Trim();
            sanitizedPlainText = (sanitizedPlainText ?? "").Trim();

            if (originalPlainText.Length == 0)
                return false; // nothing to lose

            if (sanitizedPlainText.Length == 0)
                return true; // the whole comment text vanished

            if (originalPlainText.Length - sanitizedPlainText.Length <= 2)
                return false; // negligible, e.g. a boundary space lost when unwrapping a tag

            return sanitizedPlainText.Length < originalPlainText.Length * 0.95;
        }

        /// <summary>
        /// shown to the user (via _BuildSanitizerDroppedTextError) when sanitizing had to drop
        /// real text. Deliberately says nothing about "tags", "&lt;" or "&gt;" - ordinary users
        /// don't know what those are and have usually never typed one themselves; almost always
        /// this happens because they pasted the text in from somewhere else (Word, a chat app, a
        /// web page) that silently carried invalid/broken formatting along with it.
        /// </summary>
        private const string _sanitizerTextDroppedMessage =
            "به‌نظر می‌رسد متنی که ارسال کرده‌اید از جای دیگری (مثلاً Word یا یک صفحهٔ وب) کپی و در اینجا پیست شده و قالب‌بندی پنهان و نامعتبری را با خود آورده است. به همین دلیل بخشی از متن هنگام پاک‌سازی حذف شد؛ بخش حذف‌شده در ادامه با رنگ قرمز و خط‌خورده به شما نشان داده می‌شود. لطفاً متن را در یک ویرایشگر متن ساده (مثل Notepad) پاک‌سازی کنید یا از نو تایپ کنید و سپس دوباره ارسال نمایید.";

        /// <summary>
        /// builds the error string returned to the client when sanitizing dropped real text.
        /// This is a JSON object encoded as a string (not a status-code/contract change) so it
        /// still flows through every existing "the API error is just a display string" code path
        /// unchanged, while DivanRazor can additionally recognize and unpack it to show the
        /// user exactly what got dropped (see SanitizerTextDroppedInfo on the DivanRazor side)
        /// </summary>
        private static string _BuildSanitizerDroppedTextError(string remainingPlainText)
        {
            return JsonConvert.SerializeObject(new
            {
                sanitizerTextDropped = true,
                message = _sanitizerTextDroppedMessage,
                remainingText = remainingPlainText ?? ""
            });
        }

        /// <summary>
        /// sanitizes comment HTML; TextWasDropped is true when the sanitizing process removed
        /// a meaningful chunk of the user's actual text (see _CommentSanitizationDroppedText) -
        /// callers should not silently save Html in that case, but ask the user to fix their
        /// markup instead (RemainingPlainText/_BuildSanitizerDroppedTextError let them show what
        /// was dropped)
        /// </summary>
        private async Task<(string Html, bool TextWasDropped, string RemainingPlainText)> _ProcessCommentHtml(string commentText, RMuseumDbContext context)
        {
            string originalPlainText = _ExtractPlainText(commentText);

            // Use a proper HTML sanitizer
            var sanitizer = new HtmlSanitizer();

            // Configure allowed tags
            sanitizer.AllowedTags.Clear();
            sanitizer.AllowedTags.Add("p");
            sanitizer.AllowedTags.Add("a");
            sanitizer.AllowedTags.Add("br");
            sanitizer.AllowedTags.Add("b");
            sanitizer.AllowedTags.Add("i");
            sanitizer.AllowedTags.Add("strong");
            sanitizer.AllowedTags.Add("img");
            sanitizer.AllowedTags.Add("span");

            // Configure allowed attributes
            sanitizer.AllowedAttributes.Clear();
            sanitizer.AllowedAttributes.Add("href");
            sanitizer.AllowedAttributes.Add("src");
            sanitizer.AllowedAttributes.Add("alt");
            sanitizer.AllowedAttributes.Add("title");
            sanitizer.AllowedAttributes.Add("rel");

            // IMPORTANT: Remove all style attributes to prevent colored text and font changes
            sanitizer.AllowedAttributes.Remove("style");

            // Disallow any CSS or style-related attributes
            sanitizer.AllowedCssProperties.Clear();

            // Additional security: disallow data URIs and javascript: protocols
            sanitizer.AllowedSchemes.Clear();
            sanitizer.AllowedSchemes.Add("http");
            sanitizer.AllowedSchemes.Add("https");
            sanitizer.AllowedSchemes.Add("mailto");
            sanitizer.AllowedSchemes.Add("ftp");

            // Sanitize the HTML
            string sanitizedHtml = sanitizer.Sanitize(commentText);

            // Detect whether sanitizing took real text down along with the invalid markup it
            // removed, before Linkify/internal-link processing below can itself change the
            // visible text (e.g. replacing a bare URL's text with a page title) in a way that
            // is not a loss.
            string sanitizedPlainText = _ExtractPlainText(sanitizedHtml);
            bool textWasDropped = _CommentSanitizationDroppedText(originalPlainText, sanitizedPlainText);

            // Process URLs (Linkify) and internal Divan links
            sanitizedHtml = await _ProcessUrls(sanitizedHtml, context);

            return (sanitizedHtml, textWasDropped, sanitizedPlainText);
        }

        private async Task<string> _ProcessUrls(string html, RMuseumDbContext context)
        {
            // First, process any existing href links
            html = await _ProcessExistingLinks(html, context);

            // Then linkify any bare URLs that aren't already in links
            if (!html.Contains("href=\"") && html.Contains("http"))
            {
                html = _Linkify(html);
            }

            return html;
        }

        private async Task<string> _ProcessExistingLinks(string html, RMuseumDbContext context)
        {
            // Use regex to find and process all href attributes
            var hrefRegex = new Regex(@"<a\s+(?:[^>]*?\s+)?href=""([^""]*)""[^>]*>(.*?)</a>", RegexOptions.IgnoreCase | RegexOptions.Singleline);

            var matches = hrefRegex.Matches(html);
            var result = html;
            var replacements = new List<(string old, string @new)>();

            foreach (Match match in matches)
            {
                string url = match.Groups[1].Value;
                string linkText = match.Groups[2].Value;
                string newLink = await _ProcessSingleLink(url, linkText, context);

                // Store the replacement
                replacements.Add((match.Value, newLink));
            }

            // Apply replacements from end to start to maintain indices
            foreach (var replacement in replacements.OrderByDescending(r => result.IndexOf(r.old)))
            {
                result = result.Replace(replacement.old, replacement.@new);
            }

            return result;
        }

        private async Task<string> _ProcessSingleLink(string url, string linkText, RMuseumDbContext context)
        {
            // If link text is the same as URL (auto-generated link), try to improve it
            if (url == linkText || linkText.Trim() == url.Trim())
            {
                // Process Divan internal links
                if (url.StartsWith("http://ganjoor.net") || url.StartsWith("https://ganjoor.net"))
                {
                    string path = url.Replace("http://ganjoor.net", "").Replace("https://ganjoor.net", "");
                    int coupletNumber = -1;
                    string cleanPath = path;

                    // Extract couplet number if present
                    if (path.Contains("#bn"))
                    {
                        int coupletStartIndex = path.IndexOf("#bn") + "#bn".Length;
                        if (int.TryParse(path.Substring(coupletStartIndex), out coupletNumber))
                        {
                            cleanPath = path.Substring(0, path.IndexOf("#bn"));
                        }
                    }

                    // Remove trailing slash
                    if (cleanPath.Length > 0 && cleanPath[cleanPath.Length - 1] == '/')
                        cleanPath = cleanPath.Substring(0, cleanPath.Length - 1);

                    var page = await context.DivanPages
                        .AsNoTracking()
                        .Where(p => p.FullUrl == cleanPath)
                        .FirstOrDefaultAsync();

                    if (page != null)
                    {
                        string displayText = page.FullTitle;

                        // Add couplet summary if applicable
                        if (coupletNumber != -1)
                        {
                            string coupletSummary = await _GetCoupletSummary(page.Id, coupletNumber);
                            if (!string.IsNullOrEmpty(coupletSummary))
                            {
                                displayText = $"{page.FullTitle} » {coupletSummary}";
                            }
                        }

                        return $@"<a href=""{url}"" rel=""nofollow"">{displayText}</a>";
                    }
                }
                else
                {
                    // External link - use generic text
                    return $@"<a href=""{url}"" rel=""nofollow noopener noreferrer"" target=""_blank"">پیوند به وبگاه بیرونی</a>";
                }
            }

            // If link text was manually provided, keep it but still validate the link
            return $@"<a href=""{url}"" rel=""nofollow noopener noreferrer"" target=""_blank"">{linkText}</a>";
        }

        private async Task<string> _GetCoupletSummary(int poemId, int coupletNumber)
        {
            int coupletIndex = coupletNumber - 1;
            var verses = await _context.DivanVerses
                .Where(v => v.PoemId == poemId)
                .OrderBy(v => v.VOrder)
                .ToListAsync();

            int cIndex = -1;
            for (int i = 0; i < verses.Count; i++)
            {
                if (verses[i].VersePosition != VersePosition.Left &&
                    verses[i].VersePosition != VersePosition.CenteredVerse2)
                    cIndex++;

                if (cIndex == coupletIndex)
                {
                    string coupletSummary = verses[i].Text;

                    if (verses[i].VersePosition == VersePosition.Right && i < verses.Count - 1)
                    {
                        coupletSummary += $" {verses[i + 1].Text}";
                    }
                    else if (verses[i].VersePosition == VersePosition.CenteredVerse1 &&
                             i < verses.Count - 1 &&
                             verses[i + 1].VersePosition == VersePosition.CenteredVerse2)
                    {
                        coupletSummary += $" {verses[i + 1].Text}";
                    }

                    return _CutSummary(coupletSummary);
                }
            }

            return null;
        }

        private string _Linkify(string text)
        {
            // Improved Linkify with better URL detection
            var urlRegex = new Regex(@"(https?://[^\s<>""']+)", RegexOptions.IgnoreCase);
            return urlRegex.Replace(text, match =>
            {
                string url = match.Value;
                return $@"<a href=""{url}"" rel=""nofollow noopener noreferrer"" target=""_blank"">{url}</a>";
            });
        }

        /// <summary>
        /// examine comments for long links
        /// </summary>
        /// <returns></returns>
        public RServiceResult<bool> FindAndFixLongUrlsInComments()
        {
            _backgroundTaskQueue.QueueBackgroundWorkItem
            (
            async token =>
            {
                using (RMuseumDbContext context = new RMuseumDbContext(new DbContextOptions<RMuseumDbContext>())) //this is long running job, so _context might be already been freed/collected by GC
                {
                    LongRunningJobProgressServiceEF jobProgressServiceEF = new LongRunningJobProgressServiceEF(context);
                    var job = (await jobProgressServiceEF.NewJob("FindAndFixLongUrlsInComments", "Query data")).Result;

                    try
                    {
                        var comments = //await context.DivanComments.Where(c => c.HtmlComment.Contains("href=")).ToArrayAsync();
                            await context.DivanComments.Where(c => c.HtmlComment.Contains("style")).ToArrayAsync();

                        await jobProgressServiceEF.UpdateJob(job.Id, 0, $"Examining {comments.Length} Comments");

                        int percent = 0;
                        for (int i = 0; i < comments.Length; i++)
                        {
                            if (i * 100 / comments.Length > percent)
                            {
                                percent++;
                                await jobProgressServiceEF.UpdateJob(job.Id, percent);
                            }

                            var comment = comments[i];

                            var processedComment = await _ProcessCommentHtml(comment.HtmlComment, context);

                            if (processedComment.TextWasDropped)
                            {
                                // this is an unattended batch job re-sanitizing old comments,
                                // there is no user here to ask to fix their markup - leave the
                                // comment untouched rather than silently overwriting it with a
                                // mutilated version
                                continue;
                            }

                            if (processedComment.Html != comment.HtmlComment)
                            {
                                comment.HtmlComment = processedComment.Html;
                                context.Update(comment);
                                await context.SaveChangesAsync();
                            }
                        }

                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", true);
                    }
                    catch (Exception exp)
                    {
                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", false, exp.ToString());
                    }

                }
            }
            );

            return new RServiceResult<bool>(true);
        }

        /// <summary>
        /// start filling poems couplet indices
        /// </summary>
        /// <returns></returns>
        public RServiceResult<bool> StartFillingPoemsCoupletIndices()
        {
            _backgroundTaskQueue.QueueBackgroundWorkItem
            (
            async token =>
            {
                using (RMuseumDbContext context = new RMuseumDbContext(new DbContextOptions<RMuseumDbContext>())) //this is long running job, so _context might be already been freed/collected by GC
                {
                    LongRunningJobProgressServiceEF jobProgressServiceEF = new LongRunningJobProgressServiceEF(context);
                    var job = (await jobProgressServiceEF.NewJob("FillingPoemsCoupletIndices", "Query data")).Result;

                    try
                    {
                        var poemIds = await context.DivanPoems.AsNoTracking().Select(p => p.Id).ToListAsync();


                        int percent = 0;
                        for (int i = 0; i < poemIds.Count; i++)
                        {
                            if (i * 100 / poemIds.Count > percent)
                            {
                                percent++;
                                await jobProgressServiceEF.UpdateJob(job.Id, percent);
                            }

                            await _FillPoemCoupletIndices(context, poemIds[i]);
                        }

                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", true);
                    }
                    catch (Exception exp)
                    {
                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", false, exp.ToString());
                    }

                }
            }
            );

            return new RServiceResult<bool>(true);
        }

        /// <summary>
        /// refill couplet indices
        /// </summary>
        /// <param name="poemId"></param>
        /// <returns></returns>
        public async Task<RServiceResult<bool>> RefillCoupletIndicesAsync(int poemId)
        {
            try
            {
                await _FillPoemCoupletIndices(_context, poemId);
                await _context.SaveChangesAsync();
                return new RServiceResult<bool>(false);
            }
            catch (Exception exp)
            {
                return new RServiceResult<bool>(false, exp.ToString());
            }
        }

        /// <summary>
        /// fill section couplets count
        /// </summary>
        /// <returns></returns>
        public RServiceResult<bool> StartFillingSectionCoupletCounts()
        {
            _backgroundTaskQueue.QueueBackgroundWorkItem
            (
            async token =>
            {
                using (RMuseumDbContext context = new RMuseumDbContext(new DbContextOptions<RMuseumDbContext>())) //this is long running job, so _context might be already been freed/collected by GC
                {
                    LongRunningJobProgressServiceEF jobProgressServiceEF = new LongRunningJobProgressServiceEF(context);
                    var job = (await jobProgressServiceEF.NewJob("FillingSectionCoupletCounts", "Query data")).Result;

                    try
                    {
                        var sectionIds = await context.DivanPoemSections.AsNoTracking().Select(p => p.Id).ToListAsync();


                        int percent = 0;
                        for (int i = 0; i < sectionIds.Count; i++)
                        {
                            if (i * 100 / sectionIds.Count > percent)
                            {
                                percent++;
                                await jobProgressServiceEF.UpdateJob(job.Id, percent);
                            }

                            await _FillSectionCoupletCountsAsync(context, sectionIds[i]);
                        }

                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", true);
                    }
                    catch (Exception exp)
                    {
                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", false, exp.ToString());
                    }

                }
            }
            );

            return new RServiceResult<bool>(true);
        }

        private async Task _FillSectionCoupletCountsAsync(RMuseumDbContext context, int sectionId)
        {
            var section = await context.DivanPoemSections.Where(s => s.Id == sectionId).SingleAsync();

            section.CoupletsCount = await context.DivanVerses.Where(
                v => v.PoemId == section.PoemId
                        &&
                        (
                            (section.VerseType == VersePoemSectionType.First && v.SectionIndex1 == section.Index)
                            ||
                            (section.VerseType == VersePoemSectionType.Second && v.SectionIndex2 == section.Index)
                            ||
                            (section.VerseType == VersePoemSectionType.Third && v.SectionIndex3 == section.Index)
                            ||
                            (section.VerseType == VersePoemSectionType.Forth && v.SectionIndex4 == section.Index))
                        &&
                        (v.VersePosition == VersePosition.Left || v.VersePosition == VersePosition.CenteredVerse1)
                        ).CountAsync();

            context.Update(section);
        }


        /// <summary>
        /// regenerate poem full titles to fix an old bug
        /// </summary>
        /// <returns></returns>
        public RServiceResult<bool> RegeneratePoemsFullTitles()
        {
            _backgroundTaskQueue.QueueBackgroundWorkItem
            (
            async token =>
            {
                using (RMuseumDbContext context = new RMuseumDbContext(new DbContextOptions<RMuseumDbContext>())) //this is long running job, so _context might be already been freed/collected by GC
                {
                    LongRunningJobProgressServiceEF jobProgressServiceEF = new LongRunningJobProgressServiceEF(context);
                    var job = (await jobProgressServiceEF.NewJob("RegenratePoemsFullTitles", "Query data")).Result;
                    int percent = 0;
                    try
                    {
                        var poemIds = await context.DivanPoems.AsNoTracking().Select(p => p.Id).ToListAsync();

                        for (int i = 0; i < poemIds.Count; i++)
                        {
                            if (i * 100 / poemIds.Count > percent)
                            {
                                percent++;
                                await jobProgressServiceEF.UpdateJob(job.Id, percent);
                            }

                            var poem = await context.DivanPoems.Where(p => p.Id == poemIds[i]).SingleOrDefaultAsync();
                            var catPage = await context.DivanPages.AsNoTracking().Where(p => p.DivanPageType == DivanPageType.CatPage && p.CatId == poem.CatId).SingleOrDefaultAsync();
                            if (catPage == null)
                            {
                                catPage = await context.DivanPages.AsNoTracking().Where(p => p.DivanPageType == DivanPageType.PoetPage && p.CatId == poem.CatId).SingleOrDefaultAsync();
                            }
                            var title = $"{catPage.FullTitle} » {poem.Title}";
                            if (title != poem.FullTitle)
                            {
                                poem.FullTitle = title;
                                context.Update(poem);
                            }
                            var page = await context.DivanPages.Where(p => p.Id == poem.Id).SingleOrDefaultAsync();
                            if (title != page.FullTitle)
                            {
                                page.FullTitle = title;
                                context.Update(page);
                            }
                        }

                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", true);
                    }
                    catch (Exception exp)
                    {
                        await jobProgressServiceEF.UpdateJob(job.Id, percent, "", false, exp.ToString());
                    }

                }
            }
            );

            return new RServiceResult<bool>(true);
        }


        /// <summary>
        /// start finding rhymes for single couplets
        /// </summary>
        /// <returns></returns>
        public RServiceResult<bool> StartFindingRhymesForSingleCouplets()
        {
            _backgroundTaskQueue.QueueBackgroundWorkItem
            (
            async token =>
            {
                using (RMuseumDbContext context = new RMuseumDbContext(new DbContextOptions<RMuseumDbContext>())) //this is long running job, so _context might be already been freed/collected by GC
                {
                    LongRunningJobProgressServiceEF jobProgressServiceEF = new LongRunningJobProgressServiceEF(context);
                    var job = (await jobProgressServiceEF.NewJob("FindingRhymesForSingleCouplets", "Query data")).Result;

                    try
                    {
                        var sections = await context.DivanPoemSections.AsNoTracking().Include(s => s.DivanMetre).Where(s => s.SectionType == PoemSectionType.WholePoem && s.DivanMetre != null && (s.RhymeLetters.Length >= 30 || s.RhymeLetters.Length < 2)).ToListAsync();


                        int percent = 0;
                        for (int i = 0; i < sections.Count; i++)
                        {
                            if (i * 100 / sections.Count > percent)
                            {
                                percent++;
                                await jobProgressServiceEF.UpdateJob(job.Id, percent);
                            }

                            var res = await _FindSectionRhyme(context, sections[i].Id);
                            if (string.IsNullOrEmpty(res.ExceptionString))
                            {
                                if (!string.IsNullOrEmpty(res.Result.Rhyme) && res.Result.Rhyme != sections[i].RhymeLetters)
                                {
                                    var sectionTracked = await context.DivanPoemSections.Where(s => s.Id == sections[i].Id).SingleAsync();
                                    var oldRhyme = sectionTracked.RhymeLetters;
                                    sectionTracked.RhymeLetters = res.Result.Rhyme;
                                    context.Update(sectionTracked);
                                    await context.SaveChangesAsync();
                                    await _UpdateRelatedSections(context, (int)sectionTracked.DivanMetreId, oldRhyme, jobProgressServiceEF, job, percent);
                                    await _UpdateRelatedSections(context, (int)sectionTracked.DivanMetreId, res.Result.Rhyme, jobProgressServiceEF, job, percent);
                                }
                            }
                        }

                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", true);
                    }
                    catch (Exception exp)
                    {
                        await jobProgressServiceEF.UpdateJob(job.Id, 100, "", false, exp.ToString());
                    }

                }
            }
            );

            return new RServiceResult<bool>(true);
        }
    }
}