From e0085ecb6fe7bc37e5053acfb201dfd2b4b811de Mon Sep 17 00:00:00 2001
From: ztimson <zaktimson@gmail.com>
Date: Mon, 24 Mar 2025 21:28:51 -0400
Subject: [PATCH] Better CSV handling

---
 package.json |  2 +-
 src/csv.ts   | 63 +++++++++++++++++++++++++++++++++-------------------
 2 files changed, 41 insertions(+), 24 deletions(-)

diff --git a/package.json b/package.json
index 098ed24..6815e5c 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
 	"name": "@ztimson/utils",
-	"version": "0.23.15",
+	"version": "0.23.16",
 	"description": "Utility library",
 	"author": "Zak Timson",
 	"license": "MIT",
diff --git a/src/csv.ts b/src/csv.ts
index 3e38218..dfc85b8 100644
--- a/src/csv.ts
+++ b/src/csv.ts
@@ -1,27 +1,40 @@
+import {makeArray} from './array.ts';
 import {ASet} from './aset.ts';
 import {dotNotation, flattenObj, JSONSanitize} from './objects.ts';
 import {LETTER_LIST} from './string.ts';
 
+/**
+ * Parse a CSV string into an array of objects
+ *
+ * @param csv String with CSV
+ * @param hasHeaders First line of CSV contains headers
+ * @return {T[]} Array of parsed objects
+ */
 export function fromCsv<T = any>(csv: string, hasHeaders=true): T[] {
-	const row = csv.split('\n');
-	let headers: any = hasHeaders ? row.splice(0, 1)[0] : null;
-	if(headers) headers = headers.match(/(?:[^,"']+|"[^"]*"|'[^']*')+/g);
-	return <T[]>row.map(r => {
-		function parseLine(line: string): (string | null)[] {
-			const parts = line.split(','), columns: string[] = [];
-			let quoted = false;
-			for(const p of parts) {
-				if(quoted) columns[columns.length - 1] = columns.at(-1) + ',' + p;
-				else columns.push(p);
-				if(/[^"]"$/g.test(p)) {
-					quoted = false;
-				} else if(/^"[^"]/g.test(p)) {
-					quoted = true;
-				}
-			}
-			return columns;
+	function parseLine(line: string): (string | null)[] {
+		const columns: string[] = [];
+		let current = '', inQuotes = false;
+		for(let i = 0; i < line.length; i++) {
+			const char = line[i];
+			const nextChar = line[i + 1];
+			if (char === '"') {
+				if (inQuotes && nextChar === '"') {
+					current += '"';
+					i++;
+				} else inQuotes = !inQuotes;
+			} else if (char === ',' && !inQuotes) {
+				columns.push(current);
+				current = '';
+			} else current += char;
 		}
+		columns.push(current);
+		return columns.map(col => col.replace(/^"|"$/g, '').replace(/""/g, '"'));
+	}
 
+	const row = csv.split(/\r?\n/);
+	let headers: any = hasHeaders ? row.splice(0, 1)[0] : null;
+	if(headers) headers = headers.match(/(?:[^,"']+|"(?:[^"]|"")*"|'(?:[^']|'')*')+/g);
+	return <T[]>row.map(r => {
 		const props = parseLine(r);
 		const h = headers || (Array(props.length).fill(null).map((r, i) => {
 			let letter = '';
@@ -34,23 +47,27 @@ export function fromCsv<T = any>(csv: string, hasHeaders=true): T[] {
 			dotNotation(acc, h, props[i]);
 			return acc;
 		}, {});
-	})
+	});
 }
 
 /**
- * Convert an object to a CSV string
+ * Convert an array of objects to a CSV string
  *
  * @param {any[]} target Array of objects to create CSV from
  * @param {boolean} flatten Should nested object be flattened or treated as values
  * @return {string} CSV string
  */
-export function toCsv(target: any[], flatten=true) {
-	const headers = new ASet(target.reduce((acc, row) => [...acc, ...Object.keys(flatten ? flattenObj(row) : row)], []));
+export function toCsv(target: any, flatten=true) {
+	const t = makeArray(target);
+	const headers = new ASet(t.reduce((acc, row) => [...acc, ...Object.keys(flatten ? flattenObj(row) : row)], []));
 	return [
 		headers.join(','),
-		...target.map(row => headers.map((h: string) => {
+		...t.map(row => headers.map((h: string) => {
 			const value = dotNotation<any>(row, h);
-			return (typeof value == 'object' && value != null) ? '"' + JSONSanitize(value).replaceAll('"', '""') + '"' : value;
+			if(value == null) return '';
+			if(typeof value == 'object') return `"${JSONSanitize(value).replaceAll('`', '""')}"`;
+			if(typeof value == 'string' &&  /[\n"]/g.test(value)) return `"${value.replaceAll('"', '""')}"`;
+			return value;
 		}).join(','))
 	].join('\n');
 }