From 16fb3129aeed88fa22fdc0cf7161b1a7294f1359 Mon Sep 17 00:00:00 2001
From: BuckarooBanzay <BuckarooBanzay@users.noreply.github.com>
Date: Thu, 10 Nov 2022 10:58:50 +0100
Subject: [PATCH] events

---
 build.lua       |  2 +-
 events.lua      | 18 ++++++++++++++++++
 events.spec.lua | 16 ++++++++++++++++
 init.lua        |  2 ++
 readme.md       |  9 +++++++++
 remove.lua      |  3 ++-
 6 files changed, 48 insertions(+), 2 deletions(-)
 create mode 100644 events.lua
 create mode 100644 events.spec.lua

diff --git a/build.lua b/build.lua
index 31c4d4f..078f72c 100644
--- a/build.lua
+++ b/build.lua
@@ -151,7 +151,7 @@ function building_lib.build(mapblock_pos, playername, building_name, rotation, c
 	end)
 
 	placement.place(placement, mapblock_pos, building_def, rotation, callback)
-
+	building_lib.fire_event("placed", mapblock_pos, playername, building_def, rotation)
 	return true
 end
 
diff --git a/events.lua b/events.lua
new file mode 100644
index 0000000..34b4f7c
--- /dev/null
+++ b/events.lua
@@ -0,0 +1,18 @@
+
+-- name -> list<fn>
+local events = {}
+
+function building_lib.fire_event(name, ...)
+    for _, fn in ipairs(events[name] or {}) do
+        fn(...)
+    end
+end
+
+function building_lib.register_on(name, fn)
+    local list = events[name]
+    if not list then
+        list = {}
+        events[name] = list
+    end
+    table.insert(list, fn)
+end
\ No newline at end of file
diff --git a/events.spec.lua b/events.spec.lua
new file mode 100644
index 0000000..0042ed6
--- /dev/null
+++ b/events.spec.lua
@@ -0,0 +1,16 @@
+
+mtt.register("events", function(callback)
+
+    local success = false
+
+    building_lib.register_on("my_event", function(x,y)
+        if x == 1 and y == 2 then
+            success = true
+        end
+    end)
+
+    building_lib.fire_event("my_event", 1, 2)
+
+    assert(success)
+    callback()
+end)
\ No newline at end of file
diff --git a/init.lua b/init.lua
index b87fd92..a51ed64 100644
--- a/init.lua
+++ b/init.lua
@@ -19,9 +19,11 @@ dofile(MP .. "/build.lua")
 dofile(MP .. "/remove.lua")
 dofile(MP .. "/chat.lua")
 dofile(MP .. "/tools.lua")
+dofile(MP .. "/events.lua")
 dofile(MP .. "/mapgen.lua")
 
 if minetest.get_modpath("mtt") and mtt.enabled then
+	dofile(MP .. "/events.spec.lua")
 	dofile(MP .. "/conditions.spec.lua")
 	dofile(MP .. "/build.spec.lua")
 end
diff --git a/readme.md b/readme.md
index eeccc81..e8153f3 100644
--- a/readme.md
+++ b/readme.md
@@ -84,10 +84,19 @@ building_lib.register_condition("on_flat_surface", {
 })
 ```
 
+## Conditions
+
 Built-in conditions:
 * `group=<groupname>` checks if there is already a building with the specified groupname
 * `on_group=<groupname>` checks if there is a building with the specified groupname below
 
+## Events
+
+```lua
+building_lib.register_on("placed", function(mapblock_pos, playername, building_def, rotation) end)
+building_lib.register_on("removed", function(mapblock_pos, playername, building_info) end)
+```
+
 ## Chat commands
 
 * `/building_info`
diff --git a/remove.lua b/remove.lua
index 23db67b..46b6fc8 100644
--- a/remove.lua
+++ b/remove.lua
@@ -13,7 +13,7 @@ function building_lib.can_remove(mapblock_pos)
     return true
 end
 
-function building_lib.remove(mapblock_pos)
+function building_lib.remove(mapblock_pos, playername)
     local success, err = building_lib.can_remove(mapblock_pos)
     if not success then
         return success ,err
@@ -34,5 +34,6 @@ function building_lib.remove(mapblock_pos)
         end
     end
 
+    building_lib.fire_event("removed", mapblock_pos, playername, building_info)
     return true
 end
\ No newline at end of file