From a9b6964c74b5882ad01e5b8975e61e40412ef1f4 Mon Sep 17 00:00:00 2001
From: Lars Mueller <appgurulars@gmx.de>
Date: Sun, 29 Aug 2021 11:31:45 +0200
Subject: [PATCH] Add experimental modlib.minetest.get_mod_load_order

---
 minetest.lua      |  3 ++-
 minetest/misc.lua | 34 ++++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/minetest.lua b/minetest.lua
index 9ffecb9..768fc04 100644
--- a/minetest.lua
+++ b/minetest.lua
@@ -27,7 +27,8 @@ for filename, comps in pairs{
 		"playerdata",
 		"connected_players",
 		"register_on_leaveplayer",
-		"get_mod_info"
+		"get_mod_info",
+		"get_mod_load_order"
 	},
 	liquid = {
 		"liquid_level_max",
diff --git a/minetest/misc.lua b/minetest/misc.lua
index 003716b..14bf949 100644
--- a/minetest/misc.lua
+++ b/minetest/misc.lua
@@ -298,3 +298,37 @@ function get_mod_info()
 	return mod_info
 end
 
+--! experimental
+function get_mod_load_order()
+	local mod_info = get_mod_info()
+	local mod_load_order = {}
+	-- If there are circular soft dependencies, it is possible that a mod is loaded, but not in the right order
+	-- TODO somehow maximize the number of soft dependencies fulfilled in case of circular soft dependencies
+	local function load(mod)
+		if mod.status == "loaded" then
+			return true
+		end
+		if mod.status == "loading" then
+			return false
+		end
+		-- TODO soft/vs hard loading status, reset?
+		mod.status = "loading"
+		-- Try hard dependencies first. These must be fulfilled.
+		for depend in pairs(mod.depends) do
+			if not load(mod_info[depend]) then
+				return false
+			end
+		end
+		-- Now, try soft dependencies.
+		for depend in pairs(mod.optional_depends) do
+			load(mod_info[depend])
+		end
+		mod.status = "loaded"
+		table.insert(mod_load_order, mod)
+		return true
+	end
+	for _, mod in pairs(mod_info) do
+		assert(load(mod))
+	end
+	return mod_load_order
+end