use canonical_name if it is available; report error when trying to send mail to non-existent players

api.lua

@@ -1,5 +1,7 @@
 -- see: mail.md
 
+local f = string.format
+
 mail.registered_on_receives = {}
 function mail.register_on_receive(func)
 	mail.registered_on_receives[#mail.registered_on_receives + 1] = func
@@ -15,101 +17,96 @@ see: "Mail format" api.md
 
 TODO: refactor this garbage code!
 --]]
-function mail.send(src, dst, subject, body)
+function mail.send(...)
 	-- figure out format
 	local m
-	if dst == nil and subject == nil and body == nil then
+	if #{...} == 1 then
-		-- new format (one object param)
+		-- new format (one table param)
-		m = src
+		m = ...
+		-- populate "to" field
+		m.to = m.to or m.dst
+		-- populate "from" field
+		m.from = m.from or m.src
 	else
 		-- old format
 		m = {}
-		m.from = src
+		m.from, m.to, m.subject, m.body = ...
-		m.to = dst
-		m.subject = subject
-		m.body = body
-	end
-
-	if m.dst and not m.to then
-		-- populate "to" field
-		m.to = m.dst
-	end
-
-	if m.src and not m.from then
-		-- populate "from" field
-		m.from = m.src
 	end
 
 	-- sane default values
 	m.subject = m.subject or ""
 	m.body = m.body or ""
 
-	local cc
+	if m.subject == "" then
-	local bcc
+		m.subject = "(No subject)"
-	local extra
-	-- log mail send action
-	if m.cc or m.bcc then
-		if m.cc then
-			cc = "CC: " .. m.cc
-			if m.bcc then
-				cc = cc .. " - "
 	end
-		else
+	if string.len(m.subject) > 30 then
-			cc = ""
+		m.subject = string.sub(m.subject,1,27) .. "..."
 	end
-		if m.bcc then
-			bcc = "BCC: " .. m.bcc
-		else
-			bcc = ""
-		end
-		extra = " (" .. cc .. bcc .. ")"
-	else
-		extra = ""
-	end
-	minetest.log("action", "[mail] '" .. m.from .. "' sends mail to '" .. m.to .. "'" ..
-		extra .. "' with subject '" .. m.subject .. "' and body: '" .. m.body .. "'")
-
 
 	-- normalize to, cc and bcc while compiling a list of all recipients
 	local recipients = {}
-	m.to = mail.normalize_players_and_add_recipients(m.to, recipients)
+	local undeliverable = {}
+	m.to = mail.normalize_players_and_add_recipients(m.to, recipients, undeliverable)
 	if m.cc then
-		m.cc = mail.normalize_players_and_add_recipients(m.cc, recipients)
+		m.cc = mail.normalize_players_and_add_recipients(m.cc, recipients, undeliverable)
 	end
 	if m.bcc then
-		m.bcc = mail.normalize_players_and_add_recipients(m.bcc, recipients)
+		m.bcc = mail.normalize_players_and_add_recipients(m.bcc, recipients, undeliverable)
 	end
 
+	if next(undeliverable) then -- table is not empty
+		local undeliverable_names = {}
+		for name in pairs(undeliverable) do
+			undeliverable_names[#undeliverable_names + 1] = '"' .. name .. '"'
+		end
+		return f("recipients %s don't exist; cannot send mail.",
+			table.concat(undeliverable_names, ", ")
+		)
+	end
+
+	local extra = {}
+	local extra_log
+	if m.cc then
+		table.insert(extra, "CC: " .. m.cc)
+	end
+	if m.bcc then
+		table.insert(extra, "BCC: " .. m.bcc)
+	end
+	if #extra > 0 then
+		extra_log = f(" (%s)", table.concat(extra, " - "))
+	else
+		extra_log = ""
+	end
+
+	minetest.log("action", f("[mail] %q send mail to %q%s with subject %q and body %q",
+		m.from, m.to, extra_log, m.subject, m.body
+	))
+
 	-- form the actual mail
 	local msg = {
 		unread  = true,
 		sender  = m.from,
 		to      = m.to,
+		cc      = m.cc,
 		subject = m.subject,
 		body    = m.body,
 		time    = os.time(),
 	}
-	if m.cc then
-		msg.cc  = m.cc
-	end
 
 	-- send the mail to all recipients
-	for _, recipient in pairs(recipients) do
+	for recipient in pairs(recipients) do
 		local messages = mail.getMessages(recipient)
 		table.insert(messages, 1, msg)
 		mail.setMessages(recipient, messages)
 	end
 
 	-- notify recipients that happen to be online
+	local mail_alert = f(mail.receive_mail_message, m.from, m.subject)
 	for _, player in ipairs(minetest.get_connected_players()) do
 		local name = player:get_player_name()
-		if recipients[string.lower(name)] ~= nil then
+		if recipients[name] then
-			if m.subject == "" then m.subject = "(No subject)" end
+			minetest.chat_send_player(name, mail_alert)
-			if string.len(m.subject) > 30 then
-				m.subject = string.sub(m.subject,1,27) .. "..."
-			end
-			minetest.chat_send_player(name,
-					string.format(mail.receive_mail_message, m.from, m.subject))
 		end
 	end
 

api.md

@@ -35,12 +35,13 @@ mail = {
 ## Sending mail
 Old variant (pre-1.1)
 ```lua
-mail.send("source name", "destination name", "subject line", "mail body")
+local error = mail.send("source name", "destination name", "subject line", "mail body")
+-- error will contain an error message if mail couldn't be delivered, otherwise nil
 ```
 
 New variant (1.1+)
 ```lua
-mail.send({
+local error = mail.send({
 	from = "sender name",
 	to = "destination name",
 	cc = "carbon copy",
@@ -48,6 +49,7 @@ mail.send({
 	subject = "subject line",
 	body = "mail body"
 })
+-- error will contain an error message if mail couldn't be delivered, otherwise nil
 ```
 
 # Hooks

gui.lua

@@ -464,7 +464,7 @@ function mail.handle_receivefields(player, formname, fields)
 	elseif formname == "mail:compose" then
 		local name = player:get_player_name()
 		if fields.send then
-			mail.send({
+			local error = mail.send({
 				from = name,
 				to = fields.to,
 				cc = fields.cc,
@@ -472,6 +472,11 @@ function mail.handle_receivefields(player, formname, fields)
 				subject = fields.subject,
 				body = fields.body,
 			})
+			if error then
+				minetest.chat_send_player(name, error)
+				return
+			end
+
 			local contacts = mail.getContacts(name)
 			local recipients = mail.parse_player_list(fields.to)
 			local changed = false

mod.conf

@@ -1,3 +1,3 @@
 name = mail
 description = ingame mail-system
-optional_depends = unified_inventory,default,mtt
+optional_depends = canonical_name,default,mtt,unified_inventory

util/normalize.lua

@@ -1,18 +1,21 @@
+local has_canonical_name = minetest.get_modpath("canonical_name")
+
 --[[
 return the field normalized (comma separated, single space)
 and add individual player names to recipient list
 --]]
-function mail.normalize_players_and_add_recipients(field, recipients)
+function mail.normalize_players_and_add_recipients(field, recipients, undeliverable)
     local order = mail.parse_player_list(field)
-    for _, c in ipairs(order) do
+    for _, player_name in ipairs(order) do
-        if recipients[string.lower(c)] == nil then
+        if not minetest.player_exists(player_name) then
-            recipients[string.lower(c)] = c
+            undeliverable[player_name] = true
+        else
+            recipients[player_name] = true
         end
     end
     return mail.concat_player_list(order)
 end
 
-
 function mail.parse_player_list(field)
     if not field then
         return {}
@@ -24,10 +27,15 @@ function mail.parse_player_list(field)
     -- get individual players
     local player_set = {}
     local order = {}
-    field:gsub(pattern, function(c)
+    field:gsub(pattern, function(player_name)
-        if player_set[string.lower(c)] == nil then
+        local lower = string.lower(player_name)
-            player_set[string.lower(c)] = c
+        if not player_set[lower] then
-            order[#order+1] = c
+            if has_canonical_name then
+                player_name = canonical_name.get(player_name) or player_name
+            end
+
+            player_set[lower] = player_name
+            order[#order+1] = player_name
         end
     end)
 
@@ -44,15 +52,14 @@ function mail.player_in_list(name, list)
     if type(list) == "string" then
         list = mail.parse_player_list(list)
     end
-    for _, c in pairs(list) do
+    for _, player_name in pairs(list) do
-        if name == c then
+        if name == player_name then
             return true
         end
     end
     return false
 end
 
-
 function mail.ensure_new_format(message, name)
     if message.to == nil then
         message.to = name