add highscore persistence util

forms/highscore_configure.lua

@@ -17,7 +17,9 @@ function epic_score.form_highscore_configure(pos, playername)
   )
 end
 
-minetest.register_on_player_receive_fields(function(_, formname, fields)
+minetest.register_on_player_receive_fields(function(player, formname, fields)
+  local playername = player:get_player_name()
+
 	local parts = formname:split(";")
 	local name = parts[1]
 	if name ~= FORMNAME then
@@ -26,6 +28,11 @@ minetest.register_on_player_receive_fields(function(_, formname, fields)
 
 	local pos = minetest.string_to_pos(parts[2])
 
+  if fields.show then
+    -- show highscore
+    epic_score.form_highscore_view(pos, playername)
+  end
+
 	if fields.save then
     print(pos) -- TODO
 	end

init.lua

@@ -3,11 +3,18 @@ epic_score = {}
 
 local MP = minetest.get_modpath("epic_score")
 
+-- utils
+dofile(MP.."/persistence.lua")
+
+-- blocks
 dofile(MP.."/add_score.lua")
 dofile(MP.."/set_score.lua")
 dofile(MP.."/highscore.lua")
 dofile(MP.."/highscore_commit.lua")
+
+-- items
 dofile(MP.."/items.lua")
 
+-- forms
 dofile(MP.."/forms/highscore_view.lua")
 dofile(MP.."/forms/highscore_configure.lua")

persistence.lua

@@ -0,0 +1,91 @@
+
+--[[
+
+File: <worlddir>/epic_score/<topic>.json
+
+Content:
+[{
+  playername: "",
+  score: 0
+},{
+  ...
+}]
+
+--]]
+
+local basedir = minetest.get_worldpath() .. "/epic_score"
+
+local function get_score_file(topic)
+	local sane_filename = string.gsub(topic, "[.|/]", "")
+	return basedir .. "/" .. sane_filename .. ".json"
+end
+
+local function load_score(topic)
+  local file = io.open(get_score_file(topic), "r")
+  local score = nil
+
+  if file then
+    local json = file:read("*a")
+    score = minetest.parse_json(json or "")
+  end
+
+  return score or {}
+end
+
+local function save_score(topic, score)
+  local file = io.open(get_score_file(topic),"w")
+  local json = minetest.write_json(score)
+  if file and file:write(json) and file:close() then
+    return
+  else
+    minetest.log("error","[epic_score] save score failed - data may be lost!")
+    return
+  end
+end
+
+-- updates a player score if it is higher than before
+function epic_score.update_score(topic, playername, score)
+  local score_table = load_score(topic)
+  local found = false
+
+
+  -- existing entry
+  for _, entry in ipairs(score_table) do
+    if entry.playername == playername then
+      if score > entry.score then
+        -- only update if higher
+        entry.score = score
+      end
+      found = true
+      break
+    end
+  end
+
+  -- new entry
+  if not found then
+    table.insert(score_table, {
+      playername = playername,
+      score = score
+    })
+  end
+
+  -- sort by score desc
+  table.sort(score_table, function(a,b)
+    return a.score > b.score
+  end)
+
+  -- create new score table with limited entries
+  local new_score = {}
+  for i, entry in ipairs(score_table) do
+    if i > 20 then
+      break
+    end
+    table.insert(new_score, entry)
+  end
+
+  save_score(score_table, new_score)
+end
+
+function epic_score.get_score(topic)
+  return load_score(topic)
+end