From 11fa43f0a49abcab762bc15613e1d74ce4d5869b Mon Sep 17 00:00:00 2001
From: Fabian Dill <Berserker66@users.noreply.github.com>
Date: Thu, 20 Feb 2025 00:17:19 +0100
Subject: [PATCH] Factorio: prevent players from getting stuck from Teleport
 Traps (#4537)

---
 worlds/factorio/Options.py                    |  3 +-
 worlds/factorio/data/mod/lib.lua              | 67 +++++++++++++++++++
 worlds/factorio/data/mod_template/control.lua | 13 ++--
 3 files changed, 77 insertions(+), 6 deletions(-)

diff --git a/worlds/factorio/Options.py b/worlds/factorio/Options.py
index fe72d386..481ed009 100644
--- a/worlds/factorio/Options.py
+++ b/worlds/factorio/Options.py
@@ -263,7 +263,8 @@ class AttackTrapCount(TrapCount):
 
 
 class TeleportTrapCount(TrapCount):
-    """Trap items that when received trigger a random teleport."""
+    """Trap items that when received trigger a random teleport.
+    It is ensured the player can walk back to where they got teleported from."""
     display_name = "Teleport Traps"
 
 
diff --git a/worlds/factorio/data/mod/lib.lua b/worlds/factorio/data/mod/lib.lua
index edec5b7a..aa50b926 100644
--- a/worlds/factorio/data/mod/lib.lua
+++ b/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
diff --git a/worlds/factorio/data/mod_template/control.lua b/worlds/factorio/data/mod_template/control.lua
index 07fd4c04..cd0c00e9 100644
--- a/worlds/factorio/data/mod_template/control.lua
+++ b/worlds/factorio/data/mod_template/control.lua
@@ -134,6 +134,9 @@ end
 
 script.on_event(defines.events.on_player_changed_position, on_player_changed_position)
 {% endif %}
+-- Handle the pathfinding result of teleport traps
+script.on_event(defines.events.on_script_path_request_finished, handle_teleport_attempt)
+
 function count_energy_bridges()
     local count = 0
     for i, bridge in pairs(storage.energy_link_bridges) do
@@ -143,9 +146,11 @@ function count_energy_bridges()
     end
     return count
 end
+
 function get_energy_increment(bridge)
     return ENERGY_INCREMENT + (ENERGY_INCREMENT * 0.3 * bridge.quality.level)
 end
+
 function on_check_energy_link(event)
     --- assuming 1 MJ increment and 5MJ battery:
     --- first 2 MJ request fill, last 2 MJ push energy, middle 1 MJ does nothing
@@ -722,12 +727,10 @@ end,
     game.forces["enemy"].set_evolution_factor(new_factor, "nauvis")
     game.print({"", "New evolution factor:", new_factor})
 end,
-["Teleport Trap"] = function ()
+["Teleport Trap"] = function()
     for _, player in ipairs(game.forces["player"].players) do
-        current_character = player.character
-        if current_character ~= nil then
-            current_character.teleport(current_character.surface.find_non_colliding_position(
-                current_character.prototype.name, random_offset_position(current_character.position, 1024), 0, 1))
+        if player.character then
+            attempt_teleport_player(player, 1)
         end
     end
 end,