fix: adds Excel export support for SEP list data

app/lib/download.ts

@@ -6,16 +6,14 @@
  * @param filename - optional file name to use for downloaded file
  * @param delimiter - csv delimiter (default is comma)
  * @param addBOM - add UTF-8 BOM to the file to make Excel detect UTF-8 correctly
+ * Usage examples:
+ * 1) With headers and array of objects
+ * downloadCsv(['name', 'age'], [{name: 'Alice', age: 25}, {name: 'Bob', age: 30}], 'people.csv');
+ * 2) Without headers (automatically uses object keys)
+ * downloadCsv(null, [{name: 'Alice', age: 25}, {name: 'Bob', age: 30}], 'people.csv');
+ * 3) With array-of-arrays
+ * downloadCsv(['col1', 'col2'], [['a', 'b'], ['c', 'd']], 'matrix.csv');
  */
-/*
-	Usage examples:
-	// 1) With headers and array of objects
-	// downloadCsv(['name', 'age'], [{name: 'Alice', age: 25}, {name: 'Bob', age: 30}], 'people.csv');
-	// 2) Without headers (automatically uses object keys)
-	// downloadCsv(null, [{name: 'Alice', age: 25}, {name: 'Bob', age: 30}], 'people.csv');
-	// 3) With array-of-arrays
-	// downloadCsv(['col1', 'col2'], [['a', 'b'], ['c', 'd']], 'matrix.csv');
-  */
 export function downloadCsv(
   headers: string[] | null,
   data: Array<Record<string, any> | any[]>,
@@ -79,3 +77,74 @@ export function downloadCsv(
   link.click()
   document.body.removeChild(link)
 }
+
+/**
+ * Download data as XLS (Excel) file using xlsx library.
+ *
+ * @param headers - Array of header names. If omitted and data is array of objects, keys will be taken from first object.
+ * @param data - Array of rows. Each row can be either an object (key -> value) or an array of values.
+ * @param filename - optional file name to use for downloaded file (default: 'data.xlsx')
+ * @param sheetName - optional sheet name in workbook (default: 'Sheet1')
+ * Usage examples:
+ * 1) With headers and array of objects
+ * await downloadXls(['name', 'age'], [{name: 'Alice', age: 25}, {name: 'Bob', age: 30}], 'people.xlsx');
+ * 2) Without headers (automatically uses object keys)
+ * await downloadXls(null, [{name: 'Alice', age: 25}, {name: 'Bob', age: 30}], 'people.xlsx');
+ * 3) With custom sheet name
+ * await downloadXls(['col1', 'col2'], [['a', 'b'], ['c', 'd']], 'matrix.xlsx', 'MyData');
+ */
+export async function downloadXls(
+  headers: string[] | null,
+  data: Array<Record<string, any> | any[]>,
+  filename = 'data.xlsx',
+  sheetName = 'Sheet1',
+) {
+  // Dynamically import xlsx to avoid server-side issues
+  const { utils, write } = await import('xlsx')
+  const { saveAs } = await import('file-saver')
+
+  if (!Array.isArray(data) || data.length === 0) {
+    // Create empty sheet with headers only
+    const ws = utils.aoa_to_sheet(headers ? [headers] : [[]])
+    const wb = utils.book_new()
+    utils.book_append_sheet(wb, ws, sheetName)
+    const wbout = write(wb, { bookType: 'xlsx', type: 'array' })
+    saveAs(new Blob([wbout], { type: 'application/octet-stream' }), filename)
+    return
+  }
+
+  // if headers not provided and rows are objects, take keys from first object
+  let _headers: string[] | null = headers
+  if (!_headers) {
+    const firstRow = data[0]
+    if (typeof firstRow === 'object' && !Array.isArray(firstRow)) {
+      _headers = Object.keys(firstRow)
+    } else if (Array.isArray(firstRow)) {
+      _headers = null
+    }
+  }
+
+  // Convert data rows to 2D array
+  const rows: any[][] = data.map((row) => {
+    if (Array.isArray(row)) {
+      return row
+    }
+    // object row - map using headers if available, otherwise use object values
+    if (_headers && Array.isArray(_headers)) {
+      return _headers.map((h) => (row as Record<string, any>)[h] ?? '')
+    }
+    return Object.values(row)
+  })
+
+  // Combine headers and rows for sheet
+  const sheetData = _headers ? [_headers, ...rows] : rows
+
+  // Create worksheet and workbook
+  const ws = utils.aoa_to_sheet(sheetData)
+  const wb = utils.book_new()
+  utils.book_append_sheet(wb, ws, sheetName)
+
+  // Write and save file
+  const wbout = write(wb, { bookType: 'xlsx', type: 'array' })
+  saveAs(new Blob([wbout], { type: 'application/octet-stream' }), filename)
+}