Implement non-player recipients

[y5nw]

This PR allows sending mail to non-player recipients.

There are some potential usecases for this PR:

• Interaction with automated systems (e.g. remote control)
• Mailing lists; in particular, it could allow (for example) sending messages to all members of a beerchat channel, which can be useful for (for public channels) announcements or (for private channels) internal communication without having to keep track of the members.

Checklist:

• Implement recipient handlers
• Properly handle sending mail to the sender:
  • The sender should not receive mail addressed to a list if the sender is not otherwise listed as a recipient.
  • The sender may send mail to an alias (and should also receive it)
• Add a callback for a player receiving mail (as opposed to a mail being sent)
• Add tests

(I hope I did not miss anything important.)

Advtrains

For people into Advtrains, I put together a simple patch for Advtrains as a proof-of-concept for what can be done with this PR. The patch below allows

• sending ATC commands to a train (note the protection code - the mail is rejected if the sender does not have permission to control the train)
• sending mail to subscribers of a LuaATC environment, which can be useful for communicating certain changes to the code.

diff --git a/advtrains/init.lua b/advtrains/init.lua
index a7e5764..d1a605c 100644
--- a/advtrains/init.lua
+++ b/advtrains/init.lua
@@ -222,6 +222,7 @@ dofile(advtrains.modpath.."/craft_items.lua")
 
 dofile(advtrains.modpath.."/log.lua")
 dofile(advtrains.modpath.."/passive.lua")
+dofile(advtrains.modpath.."/mail.lua")
 if mesecon then
 	dofile(advtrains.modpath.."/p_mesecon_iface.lua")
 end
diff --git a/advtrains/mail.lua b/advtrains/mail.lua
new file mode 100644
index 0000000..6c0c48b
--- /dev/null
+++ b/advtrains/mail.lua
@@ -0,0 +1,19 @@
+if mail and mail.register_recipient_handler then
+	mail.register_recipient_handler(function(sender, recipient)
+		local tid = string.match(recipient, "^advtrains/train/(.+)$")
+		if tid and advtrains.trains[tid] then
+			local train = advtrains.trains[tid]
+			for _, wid in ipairs(train.trainparts) do
+				local wagon = advtrains.wagons[wid]
+				if not advtrains.check_driving_couple_protection(sender, wagon.owner, wagon.whitelist) then
+					return false, attrans("You do not have permission to operate the train @1", tid)
+				end
+			end
+			return true, function(msg)
+				if msg.subject == "ATC" then
+					advtrains.atc.train_set_command(train, msg.body)
+				end
+			end
+		end
+	end)
+end
diff --git a/advtrains/mod.conf b/advtrains/mod.conf
index 5808d1a..34c5fad 100644
--- a/advtrains/mod.conf
+++ b/advtrains/mod.conf
@@ -4,4 +4,4 @@ description=Core system for realistic trains in Minetest
 author=orwell96
 
 depends=serialize_lib
-optional_depends=mesecons,mesecons_switch,digtron
+optional_depends=mesecons,mesecons_switch,digtron,mail
diff --git a/advtrains_luaautomation/environment.lua b/advtrains_luaautomation/environment.lua
index d85bedc..c1685df 100644
--- a/advtrains_luaautomation/environment.lua
+++ b/advtrains_luaautomation/environment.lua
@@ -376,6 +376,12 @@ function atlatc.run_initcode()
 	end
 end
 
-
-
-
+--- mail interface
+if mail and mail.register_recipient_handler then
+	mail.register_recipient_handler(function(_, pname)
+		local envname = string.match(pname, "atlatc/subscribers/(.+)")
+		if envname and atlatc.envs[envname] then
+			return true, atlatc.envs[envname].subscribers
+		end
+	end)
+end
diff --git a/advtrains_luaautomation/mod.conf b/advtrains_luaautomation/mod.conf
index a737603..2fc210d 100644
--- a/advtrains_luaautomation/mod.conf
+++ b/advtrains_luaautomation/mod.conf
@@ -4,4 +4,4 @@ description=Lua control interface to Advanced Trains
 author=orwell96
 
 depends=advtrains
-optional_depends=advtrains_interlocking,advtrains_line_automation,mesecons_switch
+optional_depends=advtrains_interlocking,advtrains_line_automation,mesecons_switch,mail

[Athozus]

This PR allows sending mail to non-player recipients.

There are some potential usecases for this PR:

* Interaction with automated systems (e.g. remote control)

* Mailing lists; in particular, it could allow (for example) sending messages to all members of a beerchat channel, which can be useful for (for public channels) announcements or (for private channels) internal communication without having to keep track of the members.

Advtrains

Hi,

First, thanks for this PR and giving interest to mail. However, I have some problems with that PR. The concept itself is good, but some are already active, and some are planning for the upcoming version (release blockers PR have to be merged first) :

• Non-player recipients : playerfactions support #1, and already private mailing lists
• Mailing lists : private are implemented, planning more in Mailing lists & Contacts compatibility #40 and Public mailing lists #41

Waiting for my "colleagues", but it has at my first impression to be reworked a bit.

[BuckarooBanzay]

Waiting for my "colleagues", but it has at my first impression to be reworked a bit.

base concept sounds good to me (haven't tested the code though)

i like the idea of the recipient handler, this might be useful for some other automated mods/things 😏

release blockers PR have to be merged first

feel free to ping me up if you need help (might take a few days but i'll try) the other PR's have all approvals on it btw 😉

[Athozus]

Show your changes since the last comment, and it actually looks good to me. I'll test it in few days, but it seems to be good. It offers new perspective for mail mod.

[Athozus]

I'll wait for #128 merged, to have more likely merging conflicts, if you agree. Anyway will be rebased soon for the next release.

[Athozus]

All merges are now done, I'm gonna test a last time tonight.

Would you like I squash or I rebase (or I squash only some commits) ?