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Providers/Extractors/XExcelFileContentExtractor.cs

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+using System;
+using System.IO;
+using System.Data;
+using System.Linq;
+using System.Text;
+using ExcelDataReader;
+using System.Threading;
+using System.Threading.Tasks;
+using xAiApi.Interfaces.Extractors;
+
+namespace xAiApi.Providers.Extractors
+{
+    public class XExcelFileContentExtractor : IXExcelFileContentExtractor
+    {
+        /// <summary>
+        /// Supported MIME Types ...
+        /// </summary>
+        private static readonly string[] SupportedMimeTypes =
+        [
+            "application/vnd.openxmlformats-officedocument.spreadsheetml.sheet", // .xlsx
+            "application/vnd.ms-excel" // .xls        
+        ];
+
+        /// <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
+        )
+        {
+            //
+            Encoding.RegisterProvider(CodePagesEncodingProvider.Instance);
+
+            //
+            using var memoryStream = new MemoryStream();
+            await fileStream.CopyToAsync(memoryStream, cancellationToken);
+            memoryStream.Position = 0;
+
+            //
+            var stringBuilder = new StringBuilder();
+
+            //
+            using (var reader = ExcelReaderFactory.CreateReader(memoryStream))
+            {
+                //
+                var result = reader.AsDataSet();
+                foreach (DataTable table in result.Tables)
+                {
+                    //
+                    stringBuilder.AppendLine($"--- Sheet: {table.TableName} ---");
+
+                    //
+                    var headers = new string[table.Columns.Count];
+                    for (int i = 0; i < table.Columns.Count; i++)
+                    {
+                        headers[i] = table.Columns[i].ColumnName;
+                    }
+                    stringBuilder.AppendLine(string.Join(" | ", headers));
+                    stringBuilder.AppendLine(new string('-', 50));
+
+                    //
+                    foreach (DataRow row in table.Rows)
+                    {
+                        //
+                        var rowValues = new string[row.ItemArray.Length];
+                        for (int i = 0; i < row.ItemArray.Length; i++)
+                        {
+                            rowValues[i] = row.ItemArray[i]?.ToString()?.Trim() ?? string.Empty;
+                        }
+                        stringBuilder.AppendLine(string.Join(" | ", rowValues));
+                    }
+                    stringBuilder.AppendLine();
+                }
+            }
+
+            //
+            return stringBuilder.ToString();
+        }
+    }
+}