Better logging, new preview.lua plugin.

When an exception is caught, info will be printed to the config.log_chat or the console.
/preview will give an "unlinked" preview for the link.
youtube.lua now uses config.google_api_key.
youtube.lua now uses unlinked previews.
lastfm.lua gives more informative error messages.
New utility: handle_exception().

bindings.lua

@@ -105,7 +105,7 @@ sendPhoto = function(chat_id, photo, caption, reply_to_message_id)
 
 	local url = BASE_URL .. '/sendPhoto'
 
-	local curl_command = 'curl "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "photo=@' .. photo .. '"'
+	local curl_command = 'curl -s "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "photo=@' .. photo .. '"'
 
 	if reply_to_message_id then
 		curl_command = curl_command .. ' -F "reply_to_message_id=' .. reply_to_message_id .. '"'
@@ -123,7 +123,7 @@ sendDocument = function(chat_id, document, reply_to_message_id)
 
 	local url = BASE_URL .. '/sendDocument'
 
-	local curl_command = 'curl "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "document=@' .. document .. '"'
+	local curl_command = 'curl -s "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "document=@' .. document .. '"'
 
 	if reply_to_message_id then
 		curl_command = curl_command .. ' -F "reply_to_message_id=' .. reply_to_message_id .. '"'
@@ -137,7 +137,7 @@ sendSticker = function(chat_id, sticker, reply_to_message_id)
 
 	local url = BASE_URL .. '/sendSticker'
 
-	local curl_command = 'curl "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "sticker=@' .. sticker .. '"'
+	local curl_command = 'curl -s "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "sticker=@' .. sticker .. '"'
 
 	if reply_to_message_id then
 		curl_command = curl_command .. ' -F "reply_to_message_id=' .. reply_to_message_id .. '"'
@@ -151,7 +151,7 @@ sendAudio = function(chat_id, audio, reply_to_message_id, duration, performer, t
 
 	local url = BASE_URL .. '/sendAudio'
 
-	local curl_command = 'curl "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "audio=@' .. audio .. '"'
+	local curl_command = 'curl -s "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "audio=@' .. audio .. '"'
 
 	if reply_to_message_id then
 		curl_command = curl_command .. ' -F "reply_to_message_id=' .. reply_to_message_id .. '"'
@@ -177,7 +177,7 @@ sendVideo = function(chat_id, video, reply_to_message_id, duration, performer, t
 
 	local url = BASE_URL .. '/sendVideo'
 
-	local curl_command = 'curl "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "video=@' .. video .. '"'
+	local curl_command = 'curl -s "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "video=@' .. video .. '"'
 
 	if reply_to_message_id then
 		curl_command = curl_command .. ' -F "reply_to_message_id=' .. reply_to_message_id .. '"'
@@ -199,7 +199,7 @@ sendVoice = function(chat_id, voice, reply_to_message_id)
 
 	local url = BASE_URL .. '/sendVoice'
 
-	local curl_command = 'curl "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "voice=@' .. voice .. '"'
+	local curl_command = 'curl -s "' .. url .. '" -F "chat_id=' .. chat_id .. '" -F "voice=@' .. voice .. '"'
 
 	if reply_to_message_id then
 		curl_command = curl_command .. ' -F "reply_to_message_id=' .. reply_to_message_id .. '"'

bot.lua

@@ -61,7 +61,7 @@ on_msg_receive = function(msg) -- The fn run whenever a message is received.
 				end)
 				if not success then
 					sendReply(msg, 'An unexpected error occurred.')
-					print(msg.text, result)
+					handle_exception(result, msg.text)
 					return
 				end
 				-- If the action returns a table, make that table msg.
@@ -95,7 +95,9 @@ while is_started do -- Start a loop while the bot should be running.
 		for i,v in ipairs(plugins) do
 			if v.cron then -- Call each plugin's cron function, if it has one.
 				local res, err = pcall(function() v.cron() end)
-				if not res then print('ERROR: '..err) end
+				if not res then
+					handle_exception(err, 'CRON: ' .. i)
+				end
 			end
 		end
 		last_cron = os.time() -- And finally, update the variable.

config.lua

@@ -12,6 +12,7 @@ return {
 	cli_port = 4567,
 	admin = 00000000,
 	admin_name = 'John Smith',
+	log_chat = nil,
 	about_text = [[
 I am otouto, the plugin-wielding, multi-purpose Telegram bot written by topkecleon.
 

plugins/lastfm.lua

@@ -69,7 +69,7 @@ local action = function(msg)
 
 	local jdat = JSON.decode(jstr)
 	if jdat.error then
-		sendReply(msg, config.errors.results)
+		sendReply(msg, 'Please specify your last.fm username or set it with /fmset.')
 		return
 	end
 

plugins/preview.lua

@@ -0,0 +1,47 @@
+local command = 'preview <link>'
+local doc = [[```
+/preview <link>
+Returns a full-message, "unlinked" preview.
+```]]
+
+local triggers = {
+	'^/preview'
+}
+
+local action = function(msg)
+
+	local input = msg.text:input()
+
+	if not input then
+		sendMessage(msg.chat.id, doc, true, nil, true)
+		return
+	end
+
+	input = get_word(input, 1)
+	if not input:match('^https?://.+') then
+		input = 'http://' .. input
+	end
+
+	local res = HTTP.request(input)
+	if not res then
+		sendReply(msg, 'Please provide a valid link.')
+		return
+	end
+
+	if res:len() == 0 then
+		sendReply(msg, 'Sorry, the link you provided is not letting us make a preview.')
+		return
+	end
+
+	-- Invisible zero-width, non-joiner.
+	local output = '[​](' .. input .. ')'
+	sendMessage(msg.chat.id, output, false, nil, true)
+
+end
+
+return {
+	action = action,
+	triggers = triggers,
+	doc = doc,
+	command = command
+}

plugins/wikipedia.lua

@@ -42,7 +42,7 @@ local action = function(msg)
 		sendReply(msg, config.errors.results)
 		return
 	end
-
+--
 	local url = jdat.responseData.results[1].url
 	local title = jdat.responseData.results[1].titleNoFormatting:gsub(' %- Wikipedia, the free encyclopedia', '')
 
@@ -79,6 +79,13 @@ local action = function(msg)
 	end
 
 	sendMessage(msg.chat.id, output, true, nil, true)
+--
+--[[ Comment the previous block and uncomment this one for full-message,
+ -- "unlinked" link previews.
+	-- Invisible zero-width, non-joiner.
+	local output = '[​](' .. jdat.responseData.results[1].url .. ')'
+	sendMessage(msg.chat.id, output, false, nil, true)
+]]--
 
 end
 

plugins/youtube.lua

@@ -1,5 +1,11 @@
  -- Thanks to @TiagoDanin for writing the original plugin.
 
+if not config.google_api_key then
+	print('Missing config value: google_api_key.')
+	print('youtube.lua will not be enabled.')
+	return
+end
+
 local command = 'youtube <query>'
 local doc = [[```
 /youtube <query>
@@ -25,7 +31,7 @@ local action = function(msg)
 		end
 	end
 
-	local url = 'https://www.googleapis.com/youtube/v3/search?key=AIzaSyAfe7SI8kwQqaoouvAmevBfKumaLf-3HzI&type=video&part=snippet&maxResults=1&q=' .. URL.escape(input)
+	local url = 'https://www.googleapis.com/youtube/v3/search?key=' .. config.google_api_key .. '&type=video&part=snippet&maxResults=1&q=' .. URL.escape(input)
 
 	local jstr, res = HTTPS.request(url)
 	if res ~= 200 then
@@ -35,9 +41,9 @@ local action = function(msg)
 
 	local jdat = JSON.decode(jstr)
 
-	local message = 'https://www.youtube.com/watch?v=' .. jdat.items[1].id.videoId
+	local output = '[​](https://www.youtube.com/watch?v=' .. jdat.items[1].id.videoId .. ')'
 
-	sendMessage(msg.chat.id, message, false, msg.message_id)
+	sendMessage(msg.chat.id, output, false, nil, true)
 
 end
 

utilities.lua

@@ -140,3 +140,16 @@ resolve_username = function(target)
 	end
 
 end
+
+handle_exception = function(err, message)
+
+	local output = '\n[' .. os.date('%F %T', os.time()) .. ']\n' .. bot.username .. ': ' .. err .. '\n' .. message .. '\n'
+
+	if config.log_chat then
+		output = '```' .. output .. '```'
+		sendMessage(config.log_chat, output, true, nil, true)
+	else
+		print(output)
+	end
+
+end