using BMA.EHR.Application.Responses;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Wordprocessing;
using System.Diagnostics;
using System.Reflection;
using System.Runtime.InteropServices;

namespace BMA.EHR.Retirement.Service.Services
{
    public class RetirementReportService
    {
        private readonly IWebHostEnvironment _environment;
        private readonly ILogger<RetirementReportService> _logger;
        private readonly IConfiguration _configuration;

        /// <summary>
        /// Initializes a new instance of the RetirementReportService class.
        /// </summary>
        public RetirementReportService(
            IWebHostEnvironment environment,
            ILogger<RetirementReportService> logger,
            IConfiguration configuration)
        {
            _environment = environment;
            _logger = logger;
            _configuration = configuration;
        }

        #region Public Methods

        /// <summary>
        /// สร้างรายงานจาก Template (.docx)
        /// </summary>
        public async Task<byte[]> GenerateReportAsync(string templateName, dynamic data, string exportType)
        {
            try
            {
                var templatePath = GetTemplatePath(templateName);
                var docxBytes = await ProcessTemplateAsync(templatePath, data);

                return exportType.ToLower() == "pdf"
                    ? await ConvertToPdfAsync(docxBytes)
                    : docxBytes;
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error generating report");
                throw;
            }
        }

        #endregion

        #region Template Processing

        private string GetTemplatePath(string templateName)
        {
            var path = Path.Combine(_environment.ContentRootPath, "Templates", $"{templateName}.docx");
            if (!File.Exists(path))
                throw new FileNotFoundException($"Template not found: {templateName}");
            return path;
        }

        private async Task<byte[]> ProcessTemplateAsync(string templatePath, dynamic data)
        {
            using var templateStream = File.OpenRead(templatePath);
            using var outputStream = new MemoryStream();
            await templateStream.CopyToAsync(outputStream);
            outputStream.Position = 0;

            using (var wordDoc = WordprocessingDocument.Open(outputStream, true))
            {
                var mainPart = wordDoc.MainDocumentPart;
                if (mainPart == null) return Array.Empty<byte>();

                ReplacePlaceholders(mainPart, data);
                wordDoc.Save();
            }

            return outputStream.ToArray();
        }

        private void ReplacePlaceholders(MainDocumentPart mainPart, dynamic data)
        {
            var document = mainPart.Document;
            if (document == null) return;

            var processor = CreateDataProcessor(data);
            processor.Process(document, new Action<Document, System.Collections.IEnumerable>(FillTableRows));
        }

        #endregion

        #region Data Processing Strategy

        private IDataProcessor CreateDataProcessor(dynamic data)
        {
            var dataType = data.GetType();
            var isDictionary = dataType.IsGenericType &&
                             dataType.GetGenericTypeDefinition() == typeof(Dictionary<,>);

            return isDictionary
                ? new DictionaryDataProcessor(data)
                : new ObjectDataProcessor(data);
        }

        #endregion

        #region Table Processing

        private void FillTableRows(Document document, System.Collections.IEnumerable profiles)
        {
            var table = document.Descendants<Table>().FirstOrDefault();
            if (table == null) return;

            var rows = table.Elements<TableRow>().ToList();
            if (rows.Count == 0) return;

            var strategy = CreateTableStrategy(rows);
            strategy.Process(table, rows, profiles);
        }

        private static ITableStrategy CreateTableStrategy(List<TableRow> rows)
        {
            // retire-1 format: 1 row, 1 cell, 1 paragraph
            if (IsSingleParagraphFormat(rows))
                return new SingleParagraphTableStrategy();

            // retire-3 format: 2+ rows (header + template)
            return new MultiRowTableStrategy();
        }

        private static bool IsSingleParagraphFormat(List<TableRow> rows) =>
            rows.Count == 1 &&
            rows[0].Elements<TableCell>().Count() == 1 &&
            rows[0].Elements<TableCell>().First().Elements<Paragraph>().Count() == 1;

        #endregion

        #region PDF Conversion

        private async Task<byte[]> ConvertToPdfAsync(byte[] docxBytes)
        {
            var tempDocx = Path.Combine(Path.GetTempPath(), $"{Guid.NewGuid()}.docx");
            var tempPdf = Path.ChangeExtension(tempDocx, ".pdf");

            try
            {
                await File.WriteAllBytesAsync(tempDocx, docxBytes);
                await ConvertToPdfInternalAsync(tempDocx, tempPdf);
                return await File.ReadAllBytesAsync(tempPdf);
            }
            finally
            {
                if (File.Exists(tempDocx)) File.Delete(tempDocx);
                if (File.Exists(tempPdf)) File.Delete(tempPdf);
            }
        }

        private async Task ConvertToPdfInternalAsync(string docxPath, string pdfPath)
        {
            try
            {
                var useDocker = _configuration.GetValue<bool>("LibreOffice:UseDocker", false);
                var timeout = _configuration.GetValue<int>("LibreOffice:Timeout", 180000);

                if (useDocker)
                {
                    await ConvertToPdfViaDockerAsync(docxPath, pdfPath, timeout);
                }
                else
                {
                    // // PROD: Disabled local LibreOffice conversion
                    // await ConvertToPdfLocallyAsync(docxPath, pdfPath, timeout);
                    throw new NotSupportedException("LibreOffice conversion is disabled.");
                }
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "Error converting to PDF");
                throw;
            }
        }

        private async Task ConvertToPdfViaDockerAsync(string docxPath, string pdfPath, int timeout)
        {
            var inputDir = _configuration["LibreOffice:InputDirectory"] ?? "/app/libreoffice/input";
            var outputDir = _configuration["LibreOffice:OutputDirectory"] ?? "/app/libreoffice/output";
            var fileName = Path.GetFileName(docxPath);
            var pdfName = Path.ChangeExtension(fileName, ".pdf");

            // Ensure directories exist
            Directory.CreateDirectory(inputDir);
            Directory.CreateDirectory(outputDir);

            // Copy file to input folder (LibreOffice watcher will pick it up)
            var inputPath = Path.Combine(inputDir, fileName).Replace('\\', '/');
            var outputPath = Path.Combine(outputDir, pdfName).Replace('\\', '/');

            _logger.LogInformation("📤 Sending file to LibreOffice: {FileName}", fileName);
            await File.WriteAllBytesAsync(inputPath, await File.ReadAllBytesAsync(docxPath));

            // Wait for LibreOffice to convert (file watcher handles it)
            var stopwatch = System.Diagnostics.Stopwatch.StartNew();
            var pollInterval = TimeSpan.FromMilliseconds(500);

            while (stopwatch.ElapsedMilliseconds < timeout)
            {
                if (File.Exists(outputPath))
                {
                    _logger.LogInformation("✅ PDF received: {PdfName} (took {ElapsedMs}ms)", pdfName, stopwatch.ElapsedMilliseconds);

                    await File.WriteAllBytesAsync(pdfPath, await File.ReadAllBytesAsync(outputPath));

                    // Cleanup
                    try
                    {
                        if (File.Exists(outputPath)) File.Delete(outputPath);
                        _logger.LogDebug("🗑️ Cleaned up output file: {PdfName}", pdfName);
                    }
                    catch (Exception ex)
                    {
                        _logger.LogWarning(ex, "Failed to cleanup output file");
                    }

                    return;
                }

                await Task.Delay(pollInterval);
            }

            throw new TimeoutException($"LibreOffice conversion timed out after {timeout}ms. File not found: {outputPath}");
        }

        // // PROD: Disabled local LibreOffice conversion
        // private async Task ConvertToPdfLocallyAsync(string docxPath, string pdfPath, int timeout)
        // {
        //     var libreOfficePath = _configuration["LibreOffice:Path"] ?? GetDefaultLibreOfficePath();
        //     var arguments = _configuration["LibreOffice:Arguments"] ?? "--headless --convert-to pdf --nologo --norestore";
        //     var outputDir = Path.GetDirectoryName(pdfPath);
        
        //     if (string.IsNullOrEmpty(outputDir))
        //     {
        //         throw new DirectoryNotFoundException("Output directory cannot be determined");
        //     }
        
        //     var psi = new ProcessStartInfo
        //     {
        //         FileName = libreOfficePath,
        //         Arguments = $"{arguments} --outdir \"{outputDir}\" \"{docxPath}\"",
        //         UseShellExecute = false,
        //         RedirectStandardOutput = true,
        //         RedirectStandardError = true,
        //         CreateNoWindow = true
        //     };
        
        //     using var process = Process.Start(psi);
        //     var exited = process.WaitForExit(timeout);
        
        //     if (!exited)
        //     {
        //         process.Kill(entireProcessTree: true);
        //         throw new TimeoutException($"LibreOffice conversion timed out after {timeout}ms");
        //     }
        
        //     if (process.ExitCode != 0)
        //     {
        //         var error = await process.StandardError.ReadToEndAsync();
        //         throw new Exception($"LibreOffice conversion failed: {error}");
        //     }
        // }

        // // PROD: Disabled local LibreOffice path detection
        // private static string GetDefaultLibreOfficePath()
        // {
        //     if (RuntimeInformation.IsOSPlatform(OSPlatform.Windows))
        //     {
        //         var possiblePaths = new[]
        //         {
        //             @"C:\Program Files\LibreOffice\program\soffice.exe",
        //             @"C:\Program Files (x86)\LibreOffice\program\soffice.exe",
        //             @"C:\Program Files\LibreOffice\program\soffice.com"
        //         };
        
        //         return possiblePaths.FirstOrDefault(File.Exists)
        //             ?? throw new FileNotFoundException("LibreOffice not found. Please install LibreOffice or configure the path in appsettings.json");
        //     }
        
        //     // Linux/Docker: use default path
        //     return "libreoffice";
        // }

        #endregion
    }

    #region Data Processor Interfaces & Implementations

    internal interface IDataProcessor
    {
        void Process(Document document, Action<Document, System.Collections.IEnumerable> tableFiller);
    }

    internal class DictionaryDataProcessor : IDataProcessor
    {
        private readonly dynamic _data;

        public DictionaryDataProcessor(dynamic data)
        {
            _data = data;
        }

        public void Process(Document document, Action<Document, System.Collections.IEnumerable> tableFiller)
        {
            var keys = _data.Keys as System.Collections.ICollection;
            if (keys == null) return;

            System.Collections.IEnumerable? profiles = null;

            foreach (string key in keys)
            {
                if (key.Equals("profiles", StringComparison.OrdinalIgnoreCase))
                {
                    profiles = _data[key] as System.Collections.IEnumerable;
                    continue;
                }

                var valueObj = _data[key];
                if (valueObj != null && typeof(System.Collections.IEnumerable).IsAssignableFrom(valueObj.GetType()) &&
                    valueObj.GetType() != typeof(string))
                {
                    continue;
                }

                var value = valueObj?.ToString() ?? string.Empty;
                var placeholder = $"{{{{{key}}}}}";
                TextReplacer.ReplaceAll(document, placeholder, value);
            }

            if (profiles != null)
            {
                tableFiller(document, profiles);
            }
        }
    }

    internal class ObjectDataProcessor : IDataProcessor
    {
        private readonly dynamic _data;

        public ObjectDataProcessor(dynamic data)
        {
            _data = data;
        }

        public void Process(Document document, Action<Document, System.Collections.IEnumerable> tableFiller)
        {
            var dataType = _data.GetType();
            var allProps = dataType.GetProperties();
            var validProps = new List<PropertyInfo>();

            foreach (var p in allProps)
            {
                if (p.GetIndexParameters().Length == 0)
                {
                    validProps.Add(p);
                }
            }

            System.Collections.IEnumerable? profiles = null;

            foreach (var prop in validProps)
            {
                var propType = prop.PropertyType;
                bool isEnumerable = typeof(System.Collections.IEnumerable).IsAssignableFrom(propType);
                bool isString = propType == typeof(string);

                if (isEnumerable && !isString)
                {
                    if (prop.Name.Equals("profiles", StringComparison.OrdinalIgnoreCase))
                    {
                        profiles = prop.GetValue(_data) as System.Collections.IEnumerable;
                    }
                    continue;
                }

                var value = prop.GetValue(_data)?.ToString() ?? string.Empty;
                var placeholder = $"{{{{{prop.Name}}}}}";
                TextReplacer.ReplaceAll(document, placeholder, value);
            }

            if (profiles != null)
            {
                tableFiller(document, profiles);
            }
        }
    }

    #endregion

    #region Text Replacer

    internal static class TextReplacer
    {
        public static void ReplaceAll(Document document, string oldValue, string newValue)
        {
            bool found = false;

            // Method 1: Check within single Run
            foreach (var run in document.Descendants<Run>())
            {
                var textElements = run.Elements<Text>().ToList();
                if (textElements.Count == 0) continue;

                var combinedText = string.Concat(textElements.Select(t => t.Text));
                if (combinedText.Contains(oldValue))
                {
                    found = true;
                    var replacedText = combinedText.Replace(oldValue, newValue);
                    textElements[0].Text = replacedText;
                    for (int i = 1; i < textElements.Count; i++)
                    {
                        textElements[i].Text = string.Empty;
                    }
                }
            }

            // Method 2: Check across all Runs in Paragraph
            foreach (var para in document.Descendants<Paragraph>())
            {
                var allRuns = para.Elements<Run>().ToList();
                if (allRuns.Count == 0) continue;

                var combinedParaText = string.Concat(allRuns.SelectMany(r => r.Elements<Text>().Select(t => t.Text)));
                if (combinedParaText.Contains(oldValue))
                {
                    found = true;
                    var replacedText = combinedParaText.Replace(oldValue, newValue);

                    var firstRunTexts = allRuns[0].Elements<Text>().ToList();
                    if (firstRunTexts.Count > 0)
                    {
                        firstRunTexts[0].Text = replacedText;
                        for (int i = 1; i < firstRunTexts.Count; i++)
                        {
                            firstRunTexts[i].Text = string.Empty;
                        }
                    }

                    for (int i = 1; i < allRuns.Count; i++)
                    {
                        foreach (var t in allRuns[i].Elements<Text>())
                        {
                            t.Text = string.Empty;
                        }
                    }
                }
            }

            // Fallback: Check individual Text elements
            if (!found)
            {
                foreach (var text in document.Descendants<Text>())
                {
                    if (!string.IsNullOrEmpty(text.Text) && text.Text.Contains(oldValue))
                    {
                        found = true;
                        text.Text = text.Text.Replace(oldValue, newValue);
                    }
                }
            }
        }

        public static void ReplaceInRow(TableRow row, string oldValue, string newValue)
        {
            bool found = false;

            foreach (var cell in row.Descendants<TableCell>())
            {
                foreach (var para in cell.Elements<Paragraph>())
                {
                    found = ReplaceInParagraph(para, oldValue, newValue) || found;
                }
            }

            // Fallback: Check individual Text elements
            if (!found)
            {
                foreach (var text in row.Descendants<Text>())
                {
                    if (!string.IsNullOrEmpty(text.Text) && text.Text.Contains(oldValue))
                    {
                        found = true;
                        text.Text = text.Text.Replace(oldValue, newValue);
                    }
                }
            }
        }

        public static bool ReplaceInParagraph(Paragraph paragraph, string oldValue, string newValue)
        {
            bool found = false;

            var allTexts = paragraph.Descendants<Text>().ToList();
            if (allTexts.Count == 0) return false;

            var combinedParaText = string.Concat(allTexts.Select(t => t.Text));

            if (combinedParaText.Contains(oldValue))
            {
                found = true;
                var replacedText = combinedParaText.Replace(oldValue, newValue);
                allTexts[0].Text = replacedText;

                for (int i = 1; i < allTexts.Count; i++)
                {
                    allTexts[i].Text = string.Empty;
                }
            }

            // Fallback: Check individual Text elements
            if (!found)
            {
                foreach (var text in allTexts)
                {
                    if (!string.IsNullOrEmpty(text.Text) && text.Text.Contains(oldValue))
                    {
                        found = true;
                        text.Text = text.Text.Replace(oldValue, newValue);
                    }
                }
            }

            return found;
        }
    }

    #endregion

    #region Table Strategy Interfaces & Implementations

    internal interface ITableStrategy
    {
        void Process(Table table, List<TableRow> rows, System.Collections.IEnumerable profiles);
    }

    internal class SingleParagraphTableStrategy : ITableStrategy
    {
        public void Process(Table table, List<TableRow> rows, System.Collections.IEnumerable profiles)
        {
            var cell = rows[0].Elements<TableCell>().First();
            var templatePara = cell.Elements<Paragraph>().First();

            var profileList = profiles.Cast<object>().ToList();

            foreach (var profile in profileList)
            {
                var props = profile.GetType()
                    .GetProperties()
                    .Where(p => p.GetIndexParameters().Length == 0)
                    .ToList();

                var newPara = (Paragraph)templatePara.CloneNode(true);

                foreach (var prop in props)
                {
                    var value = prop.GetValue(profile)?.ToString() ?? string.Empty;
                    var placeholder = $"{{{{{prop.Name}}}}}";
                    TextReplacer.ReplaceInParagraph(newPara, placeholder, value);
                }

                cell.Append(newPara);
            }

            templatePara.Remove();
        }
    }

    internal class MultiRowTableStrategy : ITableStrategy
    {
        public void Process(Table table, List<TableRow> rows, System.Collections.IEnumerable profiles)
        {
            var templateRowIndex = rows.Count >= 2 ? 1 : 0;
            var templateRow = rows[templateRowIndex];
            templateRow.Remove();

            var profileList = profiles.Cast<object>().ToList();

            // Process header row if exists
            if (rows.Count >= 2)
            {
                ProcessHeaderRow(rows[0], profileList);
            }

            // Process template rows
            foreach (var profile in profileList)
            {
                var newRow = (TableRow)templateRow.CloneNode(true);
                var props = profile.GetType()
                    .GetProperties()
                    .Where(p => p.GetIndexParameters().Length == 0)
                    .ToList();

                foreach (var prop in props)
                {
                    var value = prop.GetValue(profile)?.ToString() ?? string.Empty;
                    var placeholder = $"{{{{{prop.Name}}}}}";
                    TextReplacer.ReplaceInRow(newRow, placeholder, value);
                }

                table.AppendChild(newRow);
            }
        }

        private static void ProcessHeaderRow(TableRow headerRow, List<object> profileList)
        {
            var firstProfile = profileList.FirstOrDefault();
            if (firstProfile == null) return;

            var props = firstProfile.GetType()
                .GetProperties()
                .Where(p => p.GetIndexParameters().Length == 0)
                .ToList();

            foreach (var prop in props)
            {
                var value = prop.GetValue(firstProfile)?.ToString() ?? string.Empty;
                var placeholder = $"{{{{{prop.Name}}}}}";

                if (!string.IsNullOrWhiteSpace(value))
                {
                    TextReplacer.ReplaceInRow(headerRow, placeholder, value);
                }
            }
        }
    }

    #endregion
}