```

Refactor transaction handling on startup

Changed the config option for handling transactions on startup from a simple boolean (clear transactions) to an enum ('keep', 'delete', 'rollback') for more granular control. Implemented the 'rollback' logic to revert transactions on startup. Added validation and error logging for the new config value.
```

settingtypes.txt

@@ -2,4 +2,4 @@ worldedit_bigschems_max_lengths (Max sizes of chuncks) String { x: 256, y: 256,
 worldedit_bigschems_failfast (fail fast tests) bool false
 worldedit_bigschems_stop_server (stop test server after tests) bool true
 worldedit_bigschems_max_undo (max undo length) int 10
-worldedit_bigschems_clear_transactions (Clear existing transactions on startup) bool true
+worldedit_bigschems_transactions_on_start (indicates what to do with lingering transactions on start : 'keep', keep them, 'delete": delete them, 'rollback': rollback transactions)  enum rollback delete,keep,rollback

worldedit_bigschems_undo/init.lua

@@ -12,13 +12,34 @@ local transactions_path = worldedit_bigschems.transactions_path
 local undo = dofile(worldedit_bigschems.modpath.worldedit_bigschems_undo .. "/undo.lua")
 worldedit_bigschems.undo = undo
 
-local clear_transactions = minetest.settings:get_bool("worldedit_bigschems_clear_transactions", true)
+local transactions_on_start = minetest.settings:get("worldedit_bigschems_transactions_on_start")
+if transactions_on_start == nil then
+	transactions_on_start = 'rollback'
+end
 
+if not string.find("|keep|delete|rollback|", transactions_on_start) then
+	minetest.log('error', "the value of worldedit_bigschems_transactions_on_start ('"..transactions_on_start.."') is not in keep,delete,rollback. Set it to the default value 'rollback'.")
+	transactions_on_start = 'rollback'
+end
 --TODO check path exists
 minetest.mkdir(transactions_path)
 
-if clear_transactions then
+if transactions_on_start == 'delete' then
 	undo.clearTransactions()
+elseif transactions_on_start == 'rollback' then
+	local transactionList = {}
+	for _,t in ipairs(undo.state.transactions) do
+		table.insert(transactionList, t)
+	end
+	for i=#transactionList,1,-1 do
+		local t = transactionList[i]
+		local transIndex = undo.findTransaction(t)
+		if transIndex ~= nil then
+			undo.removeTransaction(transIndex)
+			local trans = undo.Transaction.new(t)
+			trans:rollback()
+		end
+	end
 end
 
 dofile(worldedit_bigschems.modpath.worldedit_bigschems_undo .. "/commands.lua")

worldedit_bigschems_undo/undo.lua

@@ -227,4 +227,20 @@ function undo.getTransaction(cmd)
 	return Transaction:new { command = cmd }
 end
 
+-- t is a table
+function undo.findTransaction(t)
+	local self_index = nil
+	for i, v in ipairs(undo.state.transactions) do
+		if v.folder_name == t.folder_name then
+			self_index = i
+			break
+		end
+	end
+	return self_index
+end
+
+function undo.removeTransaction(i)
+	return table.remove(undo.state.transactions, i)
+end
+
 return undo