From ff994a34f2dd072b16f0550bbdbde2a97ca0d90d Mon Sep 17 00:00:00 2001
From: luk3yx <luk3yx@users.noreply.github.com>
Date: Mon, 7 Jan 2019 21:45:41 +1300
Subject: [PATCH] Add JSON-based export string format.

---
 README.md |  2 +-
 init.lua  | 24 +++++++++++++++++++-----
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index efd20ed..26c4a7f 100644
--- a/README.md
+++ b/README.md
@@ -12,7 +12,7 @@ create HUDs on their own.
 
  - `.mrkr`: Opens a formspec allowing you to display or delete markers.
  - `.add_mrkr`: Adds markers. You can use `.add_mrkr x,y,z Marker name` to add markers. Markers are (currently) cross-server, and adding a marker with (exactly) the same name as another will overwrite the original marker. If you replace `x,y,z` with `here`, the marker will be set to your current position, and replacing it with `there` will set the marker to the last `.coords` position.
- - `.mrkr_export`: Exports your markers to an advmarkers string. Remember to not modify the text before copying it.
+ - `.mrkr_export`: Exports your markers to an advmarkers string. Remember to not modify the text before copying it. You can use `.mrkr_export old` if you want an export string compatible with older versions of advmarkers (it should start with `M` instead of `J`). The old format will probably not work nicely with the planned server-side mod, however.
  - `.mrkr_import`: Imports your markers from an advmarkers string (`.mrkr_import <advmarkers string>`). Any markers with the same name will not be overwritten, and if they do not have the same co-ordinates, `_` will be appended to the imported one.
  - `.mrkrthere`: Sets a marker at the last `.coords` position.
 
diff --git a/init.lua b/init.lua
index 49ff805..77377aa 100644
--- a/init.lua
+++ b/init.lua
@@ -76,9 +76,12 @@ end
 -- Export markers
 function advmarkers.export(raw)
     local s = storage:to_table().fields
-    if not raw then
+    if raw == 'M' then
         s = minetest.compress(minetest.serialize(s))
         s = 'M' .. minetest.encode_base64(s)
+    elseif not raw then
+        s = minetest.compress(minetest.write_json(s))
+        s = 'J' .. minetest.encode_base64(s)
     end
     return s
 end
@@ -86,11 +89,16 @@ end
 -- Import markers
 function advmarkers.import(s)
     if type(s) ~= 'table' then
-        if s:sub(1, 1) ~= 'M' then return false, 'No M' end
+        local ver = s:sub(1, 1)
+        if ver ~= 'M' and ver ~= 'J' then return end
         s = minetest.decode_base64(s:sub(2))
         local success, msg = pcall(minetest.decompress, s)
         if not success then return end
-        s = minetest.deserialize(msg)
+        if ver == 'M' then
+            s = minetest.deserialize(msg)
+        else
+            s = minetest.parse_json(msg)
+        end
     end
 
     -- Iterate over markers to preserve existing ones and check for errors.
@@ -327,12 +335,18 @@ end)
 
 -- Allow string exporting
 minetest.register_chatcommand('mrkr_export', {
-    params      = '',
+    params      = '[old]',
     description = 'Exports an advmarkers string containing all your markers.',
     func = function(param)
+        local export
+        if param == 'old' then
+            export = advmarkers.export('M')
+        else
+            export = advmarkers.export()
+        end
         minetest.show_formspec('advmarkers-ignore',
             'field[_;Your marker export string;' ..
-            minetest.formspec_escape(advmarkers.export()) .. ']')
+            minetest.formspec_escape(export) .. ']')
     end
 })