using System;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading;
using xAiModels.Models;
using System.Threading.Tasks;
using xAiApi.Interfaces.Extractors;
using DocumentFormat.OpenXml.Drawing;
using DocumentFormat.OpenXml.Packaging;

namespace xAiApi.Providers.Extractors
{
    /// <summary>
    /// Extracts text content from DOCX files using DocumentFormat.OpenXml ...
    /// </summary>    
    public class XDocxFileContentExtractor : IXDocxFileContentExtractor
    {
        /// <summary>
        /// Supported MIME Types ...
        /// </summary>
        private static readonly string[] SupportedMimeTypes =
        [
            "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
        ];

        /// <summary>
        /// Check if this extractor supports the specified MIME type ...
        /// </summary>
        public bool CanExtract(string mimeType)
        {
            //
            return SupportedMimeTypes.Contains(
                mimeType?.ToLowerInvariant() ?? string.Empty
            );
        }

        /// <summary>
        /// Extract text content from file stream ...
        /// </summary>
        public async Task<string> ExtractAsync(
            Stream fileStream,
            string mimeType,
            CancellationToken cancellationToken = default
        )
        {
            //
            using var memoryStream = new MemoryStream();
            await fileStream.CopyToAsync(memoryStream, cancellationToken);
            memoryStream.Position = 0;

            //
            var stringBuilder = new StringBuilder();

            //
            using (var wordDocument = WordprocessingDocument.Open(memoryStream, false))
            {
                //
                var body = wordDocument.MainDocumentPart?.Document?.Body;
                if (body != null)
                {
                    //
                    var paragraphs = body.Elements<Paragraph>();
                    foreach (var paragraph in paragraphs)
                    {
                        //
                        var text = paragraph.InnerText?.Trim();
                        if (!string.IsNullOrEmpty(text))
                        {
                            stringBuilder.AppendLine(text);
                        }
                    }
                }
            }

            //
            return stringBuilder.ToString();
        }

        /// <summary>
        /// Extract content from stream as Rich Result ...
        /// </summary>
        /// <param name="fileStream"></param>
        /// <param name="fileName"></param>
        /// <param name="mimeType"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        public async Task<XFileExtractionResult> ExtractRichAsync(
            Stream fileStream,
            string fileName,
            string mimeType,
            CancellationToken cancellationToken = default
        )
        {
            //
            var content = await ExtractAsync(
                mimeType: mimeType,
                fileStream: fileStream,
                cancellationToken: cancellationToken
            );

            //
            var result = new XFileExtractionResult
            {
                Text = content,
                FileName = fileName,
                MimeType = mimeType
            };

            //
            return result;
        }
    }
}