"Rework" the csv parsing to cook metatable for header access instead of whatever the fuck I was doing

processor/luahelper-test.lua

@@ -520,4 +520,57 @@ phoenix_brigade	30	0.1	shielding_basic battle_physicist_basic reinforced_battery
 	assert(rows2.Headers[1] == rows.Headers[1], "First header should match")
 end)
 
+-- Test metatable: row[1] and row.foobar return same value
+test("metatable row[1] equals row.header", function()
+	local csv = "Id	Name	Value\n1	Test	100"
+	local rows, err = fromCSV(csv, { delimiter = "\t", hasheader = true })
+	if err then error("fromCSV error: " .. err) end
+	assert(rows[1][1] == rows[1].Id, "row[1] should equal row.Id")
+	assert(rows[1][2] == rows[1].Name, "row[2] should equal row.Name")
+	assert(rows[1][3] == rows[1].Value, "row[3] should equal row.Value")
+	assert(rows[1].Id == "1", "row.Id should be '1'")
+	assert(rows[1][1] == "1", "row[1] should be '1'")
+end)
+
+-- Test metatable: setting via header name updates numeric index
+test("metatable set via header name", function()
+	local csv = "Id	Name	Value\n1	Test	100"
+	local rows, err = fromCSV(csv, { delimiter = "\t", hasheader = true })
+	if err then error("fromCSV error: " .. err) end
+	rows[1].Id = "999"
+	assert(rows[1][1] == "999", "Setting row.Id should update row[1]")
+	assert(rows[1].Id == "999", "row.Id should be '999'")
+end)
+
+-- Test metatable: error on unknown header assignment
+test("metatable error on unknown header", function()
+	local csv = "Id	Name	Value\n1	Test	100"
+	local rows, err = fromCSV(csv, { delimiter = "\t", hasheader = true })
+	if err then error("fromCSV error: " .. err) end
+	local ok, errMsg = pcall(function()
+		rows[1].UnknownHeader = "test"
+	end)
+	assert(ok == false, "Should error on unknown header")
+	assert(string.find(errMsg, "unknown header"), "Error should mention unknown header")
+end)
+
+-- Test metatable: numeric indices still work
+test("metatable numeric indices work", function()
+	local csv = "Id	Name	Value\n1	Test	100"
+	local rows, err = fromCSV(csv, { delimiter = "\t", hasheader = true })
+	if err then error("fromCSV error: " .. err) end
+	rows[1][1] = "999"
+	assert(rows[1].Id == "999", "Setting row[1] should update row.Id")
+	assert(rows[1][1] == "999", "row[1] should be '999'")
+end)
+
+-- Test metatable: numeric keys work normally
+test("metatable numeric keys work", function()
+	local csv = "Id	Name	Value\n1	Test	100"
+	local rows, err = fromCSV(csv, { delimiter = "\t", hasheader = true })
+	if err then error("fromCSV error: " .. err) end
+	rows[1][100] = "hundred"
+	assert(rows[1][100] == "hundred", "Numeric keys should work")
+end)
+
 print("\nAll tests completed!")

processor/luahelper.lua

@@ -209,17 +209,45 @@ function fromCSV(csv, options)
 
 	if hasheader and #allRows > 0 then
 		local headers = allRows[1]
+		local headerMap = {}
+		for j = 1, #headers do
+			if headers[j] ~= nil and headers[j] ~= "" then
+				local headerName = trim(headers[j])
+				headerMap[headerName] = j
+			end
+		end
+
+		local header_mt = {
+			headers = headerMap,
+			__index = function(t, key)
+				local mt = getmetatable(t)
+				if type(key) == "string" and mt.headers and mt.headers[key] then
+					return rawget(t, mt.headers[key])
+				end
+				return rawget(t, key)
+			end,
+			__newindex = function(t, key, value)
+				local mt = getmetatable(t)
+				if type(key) == "string" and mt.headers then
+					if mt.headers[key] then
+						rawset(t, mt.headers[key], value)
+					else
+						error("unknown header: " .. tostring(key))
+					end
+				else
+					rawset(t, key, value)
+				end
+			end
+		}
+
 		local rows = {}
 		for ii = 2, #allRows do
 			local row = {}
 			local dataRow = allRows[ii]
 			for j = 1, #dataRow do
 				row[j] = dataRow[j]
-				if headers[j] ~= nil and headers[j] ~= "" then
-					local headerName = trim(headers[j])
-					row[headerName] = dataRow[j]
-				end
 			end
+			setmetatable(row, header_mt)
 			table.insert(rows, row)
 		end
 		rows.Headers = headers