telegram

#!/usr/bin/env bash
TOKEN=""
CHATS=()

IMAGE_FILE=""
DOCUMENT_FILE=""
URL="https://api.telegram.org/bot"
METHOD="sendMessage"
FILE_URL="https://api.telegram.org/file/bot"
CURL_OPTIONS="-s"
HAS_JQ=false
hash jq >/dev/null 2>&1 && HAS_JQ=true

DEBUG=false
DRY_RUN=false

function help() {
	echo "Usage: $0 [options] [message]"
	echo
	echo "OPTIONS are:"
	echo "    -t <TOKEN>       Telegram bot token to use. See ENVIRONMENT for more information."
	echo "    -c <CHAT_ID>     Chat to use as recipient. Can be given more than once. See ENVIRONMENT for more information."
	echo "    -f <FILE>        Sends file."
	echo "    -i <FILE>        Sends file as image. This will fail if the file isn't an actual image file."
	echo "    -M               Enables Markdown processing at telegram."
	echo "    -H               Enables HTML processing at telegram."
	echo "    -l               Fetch known chat_ids."
	echo "    -R               Receive a file sent via telegram."
	echo "    -D               Sets disable_web_page_preview parameter to, well, disable the preview for links to webpages."
	echo "                     Can also be set in config as TELEGRAM_DISABLE_WEB_PAGE_PREVIEW=true (see ENVIRONMENT)"
	echo "                     This feature is only supported for text messages, not when sending files or images (-f, -i)."
	echo "    -N               Disbles notifications on clients. Users will receive a notification with no sound."
	echo "                     Can also be set in config as TELEGRAM_DISABLE_NOTIFICATION=true (see ENVIRONMENT)"
	echo
	echo "DEBUGGING OPTIONS are:"
	echo "    -v               Display lots of more or less useful information."
	echo "    -j               Pretend you don't have JQ installed."
	echo "    -n               Dry-run - don't send messages, only print them on screen."
	echo
	echo "Message can be '-', in that case STDIN will be used."
	echo
	echo "ENVIRONMENT"
	echo "    TOKEN and CHAT_ID are required. You can set them in four different ways:"
	echo "      1) globally in /etc/telegram.sh.conf"
	echo "      2) user-local in ~/.telegram.sh"
	echo "      3) via environment variables TELEGRAM_TOKEN and TELEGRAM_CHAT"
	echo "      4) via options -t and -c"
	echo "    Later methods overwrite earlier settings, so you can easily override global settings."
	echo "    Please be aware that you shuld keep your telegram token secret!"
	echo
	exit
}

function list_chats() {
	log "$URL$TOKEN"
	response=$(curl "$CURL_OPTIONS" "$URL$TOKEN"/getUpdates)
	log "$response"

	if [ "$HAS_JQ" = true ]; then
		echo "These are the available chats that I can find right now. The ID is the number at the front."
		echo "If there are no chats or the chat you are looking for isn't there, run this command again"
		echo "after sending a message to your bot via telegram."
		echo
		jq -r '.result | .[].message.chat | "\(.id|tostring) - \(.first_name) \(.last_name) (@\(.username))"' 2>/dev/null <<<"$response" || {
			echo "Could not parse reponse from Telegram."
			echo "Response was: $response"
			exit 1
		}
	else
		echo "You don't have jq installed. I'm afraid I can't parse the JSON from telegram without it."
		echo "So I'll have you do it. ;-)"
		echo
		echo "Please look for your chat_id in this output by yourself."
		echo 'Look for something like "chat":{"id":<CHAT_ID> and verify that first_name, last_name and'
		echo "username match your expected chat."
		echo
		echo "If there are no chats listed or the chat you are looking for isn't there, try again after"
		echo "sending a message to your bot via telegram."
		echo
		echo "$response"
	fi
}

function receive_file() {
	if [ "$HAS_JQ" = false ]; then
		echo "You need to have jq installed in order to be able to download files."
		exit 1
	fi

	result=$(curl "$CURL_OPTIONS $URL$TOKEN"/getUpdates?allowed_updates=message)
	log "$result"
	file_id=$(jq -r '.result[-1].message.document.file_id' <<<"$result")
	log "file_id: $file_id"
	if [ "$file_id" == "null" ]; then
		echo "Last message received apparently didn't contain a file. Aborting."
		exit 1
	fi
	file_name=$(jq -r '.result[-1].message.document.file_name' <<<"$result")
	log "file_name: $file_name"
	result=$(curl "$CURL_OPTIONS" "$URL$TOKEN"/getFile?file_id="$file_id")
	log "$result"
	# {"ok":true,"result":{"file_id":"BQAav-HkXugI","file_size":282,"file_path":"documents/file_271.ini"}}
	path=$(jq -r '.result.file_path' <<<"$result")
	log "path: $path"
	if [ "$path" == "null" ]; then
		echo "Could not parse telegram's response to getFile. Aborting."
		exit 1
	fi
	file_name="$(date +%s)_$file_name"
	log "file_name: $file_name"
	if [ -e "$file_name" ]; then
		echo "File $file_name already exists. This is unexpected, so I'm quitting now."
		exit 1
	fi
	curl "$FILE_URL$TOKEN/$path" --output "$file_name"
	echo "File downloaded as $file_name"
}

function log() {
	[ "$DEBUG" = true ] && echo "DEBUG: $1"
}

function check_file() {
	if [ ! -e "$1" ]; then
		echo "The file $1 does not exist."
		exit 1
	fi

	size=$(stat -c%s "$1")
	if ((size > 52428800)); then
		echo "File $1 is breaking the file size limit imposed on Telegram bots (currently 50MB)."
		exit 1
	fi
}

while getopts "t:c:i:f:MHhlvjnRDN" opt; do
	case $opt in
	t)
		TOKEN="$OPTARG"
		;;
	c)
		CHATS+=("$OPTARG")
		;;
	i)
		IMAGE_FILE="$OPTARG"
		;;
	f)
		DOCUMENT_FILE="$OPTARG"
		;;
	M)
		PARSE_MODE="Markdown"
		;;
	H)
		PARSE_MODE="HTML"
		;;
	l)
		ACTION="list_chats"
		;;
	v)
		DEBUG=true
		;;
	j)
		HAS_JQ=false
		;;
	n)
		DRY_RUN=true
		;;
	R)
		ACTION="receive_file"
		;;
	D)
		DISABLE_WEB_PAGE_PREVIEW=true
		;;
	N)
		DISABLE_NOTIFICATION=true
		;;
	h)
		help
		;;
	:)
		echo "Option -$OPTARG needs an argument."
		exit 1
		;;
	\?)
		echo "Invalid option -$OPTARG"
		exit 1
		;;
	esac
done

[ -z "$TOKEN" ] && TOKEN=$TELEGRAM_TOKEN
[ ${#CHATS[@]} -eq 0 ] && CHATS=("$TELEGRAM_CHAT")

log "TOKEN is now $TOKEN"
log "CHATS is now ${CHATS[*]}"

if [ -z "$TOKEN" ]; then
	echo "No bot token was given."
	exit 1
fi

if [ ${#CHATS[@]} -eq 0 ] && [ -z "$ACTION" ]; then
	echo "No chat(s) given."
	exit 1
fi

if [ "$ACTION" = "list_chats" ]; then
	list_chats
	exit 0
fi

if [ "$ACTION" = "receive_file" ]; then
	receive_file
	exit 0
fi

shift $((OPTIND - 1))
TEXT="$1"
if [ "$TEXT" = "-" ]; then
	TEXT=$(</dev/stdin)
fi

log "Text: $TEXT"

if [ -z "$TEXT" ] && [ -z "$DOCUMENT_FILE" ] && [ -z "$IMAGE_FILE" ]; then
	echo "Neither text nor image or other file given."
	exit 1
fi

if [ -n "$DOCUMENT_FILE" ] && [ -n "$IMAGE_FILE" ]; then
	echo "You can't send a file AND an image at the same time."
	exit 1
fi

if [ -n "$PARSE_MODE" ]; then
	CURL_OPTIONS="$CURL_OPTIONS --form-string parse_mode=$PARSE_MODE"
fi

if [ -n "$DOCUMENT_FILE" ]; then
	check_file "$DOCUMENT_FILE"

	CURL_OPTIONS="$CURL_OPTIONS --form document=@$DOCUMENT_FILE --form caption=<-"
	METHOD="sendDocument"
elif [ -n "$IMAGE_FILE" ]; then
	check_file "$IMAGE_FILE"
	CURL_OPTIONS="$CURL_OPTIONS --form photo=@$IMAGE_FILE --form caption=<-"
	METHOD="sendPhoto"
else
	CURL_OPTIONS="$CURL_OPTIONS --form text=<-"
	if [ "$DISABLE_WEB_PAGE_PREVIEW" = true ]; then
		CURL_OPTIONS="$CURL_OPTIONS --form-string disable_web_page_preview=true"
	fi
	METHOD="sendMessage"
fi

if [ "$DISABLE_NOTIFICATION" = true ]; then
	CURL_OPTIONS="$CURL_OPTIONS --form-string disable_notification=true"
fi

for id in "${CHATS[@]}"; do
	MY_CURL_OPTIONS="$CURL_OPTIONS --form-string chat_id=$id $URL$TOKEN/$METHOD"
	if [ "$DRY_RUN" = true ]; then
		echo "Executing: curl $MY_CURL_OPTIONS"
		echo "     Text: $TEXT"
		echo
		status=0
		response='{"ok": true}'
	else
		# shellcheck disable=SC2086
		response=$(curl $MY_CURL_OPTIONS <<<"$TEXT")
		status=$?
	fi
	log "Response was: $response"
	if [ $status -ne 0 ]; then
		echo "curl reported an error. Exit code was: $status."
		echo "Response was: $response"
		echo "Quitting."
		exit $status
	fi

	if [ "$HAS_JQ" = true ]; then
		if [ "$(jq -r '.ok' <<<"$response")" != "true" ]; then
			echo "Telegram reported following error:"
			jq -r '"\(.error_code): \(.description)"' <<<"$response"
			echo "Quitting."
			exit 1
		fi
	else
		if [[ $response != '{"ok":true'* ]]; then
			echo "Telegram reported an error:"
			echo "$response"
			echo "Quitting."
			exit 1
		fi
	fi
done