fix: sniff csv delimiters outside quotes (#4055)

src/renderer/src/components/editor/csv-parse.test.ts

@@ -83,4 +83,14 @@ describe('detectCsvDelimiter', () => {
   it('strips a leading BOM before sniffing', () => {
     expect(detectCsvDelimiter('x.csv', '\uFEFFa\tb\tc')).toBe('\t')
   })
+
+  it('ignores delimiters inside quoted fields when sniffing', () => {
+    const content = '"Doe, Jane"\tAge\n"Roe, John"\t42\n'
+
+    expect(detectCsvDelimiter('contacts.csv', content)).toBe('\t')
+    expect(parseCsv(content, detectCsvDelimiter('contacts.csv', content)).rows).toEqual([
+      ['Doe, Jane', 'Age'],
+      ['Roe, John', '42']
+    ])
+  })
 })

src/renderer/src/components/editor/csv-parse.ts

@@ -122,7 +122,27 @@ export function detectCsvDelimiter(filePath: string, content: string): string {
       break
     }
   }
-  const tabs = (firstLine.match(/\t/g) ?? []).length
-  const commas = (firstLine.match(/,/g) ?? []).length
+  const tabs = countDelimiterOutsideQuotes(firstLine, '\t')
+  const commas = countDelimiterOutsideQuotes(firstLine, ',')
   return tabs > commas ? '\t' : ','
 }
+
+function countDelimiterOutsideQuotes(line: string, delimiter: string): number {
+  let count = 0
+  let inQuotes = false
+  for (let i = 0; i < line.length; i += 1) {
+    const ch = line[i]
+    if (ch === '"') {
+      if (inQuotes && line[i + 1] === '"') {
+        i += 1
+      } else {
+        inQuotes = !inQuotes
+      }
+      continue
+    }
+    if (!inQuotes && ch === delimiter) {
+      count += 1
+    }
+  }
+  return count
+}