--
-- slack.lua: try to fix up UX when using the Slack IRC gateway
--
-- Copyright (c) 2017, Přemysl Janouch <p.janouch@gmail.com>
--
-- Permission to use, copy, modify, and/or distribute this software for any
-- purpose with or without fee is hereby granted, provided that the above
-- copyright notice and this permission notice appear in all copies.
--
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
-- WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
-- MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
-- SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
-- WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
-- OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
-- CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
--

local servers = {}
local read_servers = function (v)
	servers = {}
	for name in v:lower ():gmatch "[^,]+" do
		servers[name] = true
	end
end

degesch.setup_config {
	servers = {
		type = "string_array",
		default = "\"\"",
		comment = "list of server names that are Slack IRC gateways",
		on_change = read_servers
	}
}

-- We can handle external messages about what we've supposedly sent just fine,
-- so let's get rid of that "[username] some message sent from the web UI" crap
degesch.hook_irc (function (hook, server, line)
	local msg, us = degesch.parse (line), server.user
	if not servers[server.name] or msg.command ~= "PRIVMSG" or not us
		or msg.params[1]:lower () ~= us.nickname:lower () then return line end

	-- Taking a shortcut to avoid lengthy message reassembly
	local quoted_nick = us.nickname:gsub ("[%^%$%(%)%%%.%[%]%*%+%-%?]", "%%%0")
	local text = line:match ("^.- PRIVMSG .- :%[" .. quoted_nick .. "%] (.*)$")
	if not text then return line end
	return ":" .. us.nickname .. "!" .. server.irc_user_host .. " PRIVMSG "
		.. msg.prefix:match "^[^!@]*" .. " :" .. text
end)

degesch.hook_completion (function (hook, data, word)
	local chan = degesch.current_buffer.channel
	local server = degesch.current_buffer.server
	if not chan or not servers[server.name] then return end

	-- In /commands there is typically no desire at all to add the at sign
	if data.location == 1 and data.words[1]:match "^/" then return end

	-- Handle both when the at sign is already there and when it is not
	local needle = word:gsub ("^@", ""):lower ()

	local t = {}
	for i, chan_user in ipairs (chan.users) do
		local nick = chan_user.user.nickname
		if data.location == 0 then nick = nick .. ":" end
		if nick:sub (1, #needle):lower () == needle then
			table.insert (t, "@" .. nick)
		end
	end
	return t
end)