Factorio: prevent players from getting stuck from Teleport Traps (#4537)

worlds/factorio/data/mod/lib.lua

@@ -49,6 +49,73 @@ function fire_entity_at_entities(entity_name, entities, speed)
     end
 end
 
+local teleport_requests = {}
+local teleport_attempts = {}
+local max_attempts = 100
+
+function attempt_teleport_player(player, attempt)
+    -- global attempt storage as metadata can't be stored
+    if attempt == nil then
+        attempt = teleport_attempts[player.index]
+    else
+        teleport_attempts[player.index] = attempt
+    end
+
+    if attempt > max_attempts then
+        player.print("Teleport failed: No valid position found after " .. max_attempts .. " attempts!")
+        teleport_attempts[player.index] = 0
+        return
+    end
+
+    local surface = player.character.surface
+    local prototype_name = player.character.prototype.name
+    local original_position = player.character.position
+    local candidate_position = random_offset_position(original_position, 1024)
+
+    local non_colliding_position = surface.find_non_colliding_position(
+        prototype_name, candidate_position, 0, 1
+    )
+
+    if non_colliding_position then
+        -- Request pathfinding asynchronously
+        local path_id = surface.request_path{
+            bounding_box = player.character.prototype.collision_box,
+            collision_mask = { layers = { ["player"] = true } },
+            start = original_position,
+            goal = non_colliding_position,
+            force = player.force.name,
+            radius = 1,
+            pathfind_flags = {cache = true, low_priority = true, allow_paths_through_own_entities = true},
+        }
+
+        -- Store the request with the player index as the key
+        teleport_requests[player.index] = path_id
+    else
+        attempt_teleport_player(player, attempt + 1)
+    end
+end
+
+function handle_teleport_attempt(event)
+    for player_index, path_id in pairs(teleport_requests) do
+        -- Check if the event matches the stored path_id
+        if path_id == event.id then
+            local player = game.players[player_index]
+
+            if event.path then
+                if player.character then
+                    player.character.teleport(event.path[#event.path].position)  -- Teleport to the last point in the path
+                    -- Clear the attempts for this player
+                    teleport_attempts[player_index] = 0
+                    return
+                end
+                return
+            end
+
+            attempt_teleport_player(player, nil)
+            break
+        end
+    end
+end
 function spill_character_inventory(character)
     if not (character and character.valid) then
         return false