From 2ccdb14999f336b5db1e7d14a749cfc47d65d670 Mon Sep 17 00:00:00 2001
From: riefive <rie.five@gmail.com>
Date: Tue, 18 Nov 2025 14:43:14 +0700
Subject: [PATCH] fix: add comments

---
 app/lib/download.ts | 119 ++++++++++++++++++++++++--------------------
 1 file changed, 64 insertions(+), 55 deletions(-)

diff --git a/app/lib/download.ts b/app/lib/download.ts
index d5df2dcd..03757d75 100644
--- a/app/lib/download.ts
+++ b/app/lib/download.ts
@@ -7,66 +7,75 @@
  * @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');
+  */
 export function downloadCsv(
-	headers: string[] | null,
-	data: Array<Record<string, any> | any[]>,
-	filename = 'data.csv',
-	delimiter = ',',
-	addBOM = true,
+  headers: string[] | null,
+  data: Array<Record<string, any> | any[]>,
+  filename = 'data.csv',
+  delimiter = ',',
+  addBOM = true,
 ) {
-	if (!Array.isArray(data) || data.length === 0) {
-		// still create an empty CSV containing only headers
-		const csvHeader = headers ? headers.join(delimiter) : '';
-		const csvString = addBOM ? '\uFEFF' + csvHeader : csvHeader;
-		const blob = new Blob([csvString], { type: 'text/csv;charset=utf-8;' });
-		const link = document.createElement('a');
-		link.href = URL.createObjectURL(blob);
-		link.setAttribute('download', filename);
-		document.body.appendChild(link);
-		link.click();
-		document.body.removeChild(link);
-		return;
-	}
+  if (!Array.isArray(data) || data.length === 0) {
+    // still create an empty CSV containing only headers
+    const csvHeader = headers ? headers.join(delimiter) : ''
+    const csvString = addBOM ? '\uFEFF' + csvHeader : csvHeader
+    const blob = new Blob([csvString], { type: 'text/csv;charset=utf-8;' })
+    const link = document.createElement('a')
+    link.href = URL.createObjectURL(blob)
+    link.setAttribute('download', filename)
+    document.body.appendChild(link)
+    link.click()
+    document.body.removeChild(link)
+    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)) {
-			// if rows are arrays and no headers provided, we won't add header row
-			_headers = null;
-		}
-	}
+  // 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)) {
+      // if rows are arrays and no headers provided, we won't add header row
+      _headers = null
+    }
+  }
 
-	const escape = (val: unknown) => {
-		if (val === null || typeof val === 'undefined') return '';
-		const str = String(val);
-		const needsQuoting = str.includes(delimiter) || str.includes('\n') || str.includes('\r') || str.includes('"');
-		if (!needsQuoting) return str;
-		return '"' + str.replace(/"/g, '""') + '"';
-	};
+  const escape = (val: unknown) => {
+    if (val === null || typeof val === 'undefined') return ''
+    const str = String(val)
+    const needsQuoting = str.includes(delimiter) || str.includes('\n') || str.includes('\r') || str.includes('"')
+    if (!needsQuoting) return str
+    return '"' + str.replace(/"/g, '""') + '"'
+  }
 
-	const rows: string[] = data.map((row) => {
-		if (Array.isArray(row)) {
-			return row.map(escape).join(delimiter);
-		}
-		// object row - map using headers if available, otherwise use object values
-		if (_headers && Array.isArray(_headers)) {
-			return _headers.map(h => escape((row as Record<string, any>)[h])).join(delimiter);
-		}
-		return Object.values(row).map(escape).join(delimiter);
-	});
+  const rows: string[] = data.map((row) => {
+    if (Array.isArray(row)) {
+      return row.map(escape).join(delimiter)
+    }
+    // object row - map using headers if available, otherwise use object values
+    if (_headers && Array.isArray(_headers)) {
+      return _headers.map((h) => escape((row as Record<string, any>)[h])).join(delimiter)
+    }
+    return Object.values(row).map(escape).join(delimiter)
+  })
 
-	const headerRow = _headers ? _headers.join(delimiter) : null;
-	const csvString = (addBOM ? '\uFEFF' : '') + [headerRow, ...rows].filter(Boolean).join('\r\n');
+  const headerRow = _headers ? _headers.join(delimiter) : null
+  const csvString = (addBOM ? '\uFEFF' : '') + [headerRow, ...rows].filter(Boolean).join('\r\n')
 
-	const blob = new Blob([csvString], { type: 'text/csv;charset=utf-8;' });
-	const link = document.createElement('a');
-	link.href = URL.createObjectURL(blob);
-	link.setAttribute('download', filename);
-	document.body.appendChild(link);
-	link.click();
-	document.body.removeChild(link);
+  const blob = new Blob([csvString], { type: 'text/csv;charset=utf-8;' })
+  const link = document.createElement('a')
+  link.href = URL.createObjectURL(blob)
+  link.setAttribute('download', filename)
+  document.body.appendChild(link)
+  link.click()
+  document.body.removeChild(link)
 }