add contacts dir, leave mail files as is

- restructured storage.lua so reading/writing json is not duplicated
- when a player joins and has no contacts file yet, automatically add all players he wrote to

storage.lua

@@ -1,32 +1,70 @@
 
 -- TODO: maybe local cache?
 
-function getMailFile(playername)
+function mail.getMailFile(playername)
 	local saneplayername = string.gsub(playername, "[.|/]", "")
 	return mail.maildir .. "/" .. saneplayername .. ".json"
 end
 
+function mail.getContactsFile(playername)
+	local saneplayername = string.gsub(playername, "[.|/]", "")
+	return mail.maildir .. "/contacts/" .. saneplayername .. ".json"
+end
+
+
 mail.getMessages = function(playername)
-	local file = io.open(getMailFile(playername), "r")
-	local messages = {}
-	if file then
-		local json = file:read("*a")
-		messages = minetest.parse_json(json or "[]") or {}
+	local messages = mail.read_json_file(mail.getMailFile(playername))
+	if messages then
 		mail.hud_update(playername, messages)
-		file:close()
 	end
 
 	return messages
 end
 
 mail.setMessages = function(playername, messages)
-	local file = io.open(getMailFile(playername),"w")
-	local json = minetest.write_json(messages)
-	if file and file:write(json) and file:close() then
+	if mail.write_json_file(mail.getMailFile(playername), messages) then
 		mail.hud_update(playername, messages)
 		return true
 	else
-		minetest.log("error","[mail] Save failed - messages may be lost!")
+		minetest.log("error","[mail] Save failed - messages may be lost! ("..playername..")")
+		return false
+	end
+end
+
+
+mail.getContacts = function(playername)
+	return mail.read_json_file(mail.getContactsFile(playername))
+end
+
+mail.setContacts = function(playername, contacts)
+	if mail.write_json_file(mail.getContactsFile(playername), contacts) then
+		return true
+	else
+		minetest.log("error","[mail] Save failed - contacts may be lost! ("..playername..")")
+		return false
+	end
+end
+
+
+function mail.read_json_file(path)
+	local file = io.open(path, "r")
+	local content = {}
+	if file then
+		local json = file:read("*a")
+		print(string.format('read from %s:  %s', path, json))
+		content = minetest.parse_json(json or "[]") or {}
+		file:close()
+	end
+	return content
+end
+
+function mail.write_json_file(path, content)
+	local file = io.open(path,"w")
+	local json = minetest.write_json(content)
+	print(string.format('writing to %s:  %s', path, json))
+	if file and file:write(json) and file:close() then
+		return true
+	else
 		return false
 	end
 end