From c2c397c2a50ae0a01f8043ee4ee4ed7041199306 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Ga=C3=ABl=20C?= <gael-de-sailly@netc.eu>
Date: Sat, 24 Jul 2021 13:21:06 +0200
Subject: [PATCH] Added compatibility script to update parameter values coming
 from older versions

---
 compatibility.lua | 34 ++++++++++++++++++++++++++++++++++
 settings.lua      | 19 +++++++++++++++++++
 2 files changed, 53 insertions(+)
 create mode 100644 compatibility.lua

diff --git a/compatibility.lua b/compatibility.lua
new file mode 100644
index 0000000..18e22bf
--- /dev/null
+++ b/compatibility.lua
@@ -0,0 +1,34 @@
+local function fix_min_catchment(settings, is_global)
+    local prefix = is_global and "mapgen_rivers_" or ""
+
+    local min_catchment = settings:get(prefix.."min_catchment")
+    if min_catchment then
+        min_catchment = tonumber(min_catchment)
+        local blocksize = tonumber(settings:get(prefix.."blocksize") or 15)
+        settings:set(prefix.."min_catchment", tonumber(min_catchment) * blocksize*blocksize)
+        local max_catchment = settings:get(prefix.."max_catchment")
+        if max_catchment then
+            max_catchment = tonumber(max_catchment)
+            local wpower = math.log(2*blocksize)/math.log(max_catchment/min_catchment)
+            settings:set(prefix.."river_widening_power", wpower)
+        end
+    end
+end
+
+local function fix_compatibility_minetest(settings)
+    local previous_version = settings:get("mapgen_rivers_version") or "0.0"
+
+    if previous_version == "0.0" then
+        fix_min_catchment(settings, true)
+    end
+end
+
+local function fix_compatibility_mapgen_rivers(settings)
+    local previous_version = settings:get("version") or "0.0"
+
+    if previous_version == "0.0" then
+        fix_min_catchment(settings, false)
+    end
+end
+
+return fix_compatibility_minetest, fix_compatibility_mapgen_rivers
diff --git a/settings.lua b/settings.lua
index 4ad6582..18e9710 100644
--- a/settings.lua
+++ b/settings.lua
@@ -1,5 +1,24 @@
 local mtsettings = minetest.settings
 local mgrsettings = Settings(minetest.get_worldpath() .. '/mapgen_rivers.conf')
+
+mapgen_rivers.version = "1.0"
+
+local previous_version_mt = mtsettings:get("mapgen_rivers_version") or "0.0"
+local previous_version_mgr = mgrsettings:get("version") or "0.0"
+
+if mapgen_rivers.version ~= previous_version_mt or mapgen_rivers.version ~= previous_version_mgr then
+    local compat_mt, compat_mgr = dofile(minetest.get_modpath(minetest.get_current_modname()) .. "/compatibility.lua")
+    if mapgen_rivers.version ~= previous_version_mt then
+        compat_mt(mtsettings)
+    end
+    if mapgen_rivers.version ~= previous_version_mgr then
+        compat_mgr(mgrsettings)
+    end
+end
+
+mtsettings:set("mapgen_rivers_version", mapgen_rivers.version)
+mgrsettings:set("version", mapgen_rivers.version)
+
 function mapgen_rivers.define_setting(name, dtype, default)
 	if dtype == "number" or dtype == "string" then
 		local v = mgrsettings:get(name)