From 5a49998c2ceaa229d69d39bad55ababc16f5dbde Mon Sep 17 00:00:00 2001
From: PhatPhuckDave <david.majdandzic@hotmail.com>
Date: Mon, 3 Nov 2025 19:27:27 +0100
Subject: [PATCH] Add a toCSV to go along with the fromCSV

---
 processor/processor.go | 44 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 42 insertions(+), 2 deletions(-)

diff --git a/processor/processor.go b/processor/processor.go
index d284e36..33f4f3f 100644
--- a/processor/processor.go
+++ b/processor/processor.go
@@ -223,7 +223,7 @@ end
 ---
 --- Returns:
 --- - A table (array) of rows; each row is a table (array) of string fields.
-function parseCSV(csv)
+function fromCSV(csv)
 	local rows = {}
 	local fields = {}
 	local field = {}
@@ -305,6 +305,45 @@ function parseCSV(csv)
 	return rows
 end
 
+--- Converts a table of rows back to CSV text format (RFC 4180 compliant).
+---
+--- Requirements:
+--- - Input is a table (array) of rows, where each row is a table (array) of field values.
+--- - Field values are converted to strings using tostring().
+--- - Fields are quoted if they contain commas, newlines, or double quotes.
+--- - Double quotes inside quoted fields are doubled ("").
+--- - Fields are joined with commas; rows are joined with newlines.
+---
+--- @param rows table Array of rows, where each row is an array of field values.
+--- @return string CSV-formatted text.
+function toCSV(rows)
+	local rowStrings = {}
+
+	for _, row in ipairs(rows) do
+		local fieldStrings = {}
+
+		for _, field in ipairs(row) do
+			local fieldStr = tostring(field)
+			local needsQuoting = false
+
+			if fieldStr:find(',') or fieldStr:find('\n') or fieldStr:find('\r') or fieldStr:find('"') then
+				needsQuoting = true
+			end
+
+			if needsQuoting then
+				fieldStr = fieldStr:gsub('"', '""')
+				fieldStr = '"' .. fieldStr .. '"'
+			end
+
+			table.insert(fieldStrings, fieldStr)
+		end
+
+		table.insert(rowStrings, table.concat(fieldStrings, ','))
+	end
+
+	return table.concat(rowStrings, '\n')
+end
+
 -- String to number conversion helper
 function num(str)
     return tonumber(str) or 0
@@ -629,7 +668,8 @@ STRING FUNCTIONS:
   format(s, ...)          - Formats string using Lua string.format
   trim(s)                 - Removes leading/trailing whitespace
   strsplit(inputstr, sep) - Splits string by separator (default: whitespace)
-  parseCSV(csv)           - Parses CSV text into rows of fields
+  fromCSV(csv)            - Parses CSV text into rows of fields
+  toCSV(rows)             - Converts table of rows to CSV text format
   num(str)                - Converts string to number (returns 0 if invalid)
   str(num)                - Converts number to string
   is_number(str)          - Returns true if string is numeric