#!/usr/bin/env bash

# This script sends a message to Telegram.
# Every single line will be interpreted as a message update thus the message will be edited with the new content.

# exit if any command fails

usage() {
  echo "Usage: $(basename $0) <chat_id>"
}

if [ ! $# -eq 1 ]; then
  usage
  exit 1
fi

if [ -z $TELEGRAM_BOT_TOKEN ]; then
  echo "TELEGRAM_BOT_TOKEN must be set"
  exit 1
fi

TELEGRAM_CHAT_ID="$1"

mid=
retry_after=
while read -r line
do
    if [ -z $mid ]; then
        R=$(curl --silent "https://api.telegram.org/bot$TELEGRAM_BOT_TOKEN/sendMessage?disable_web_page_preview=true&chat_id=$TELEGRAM_CHAT_ID" --data-urlencode "text=$line")
        mid=$(echo "$R" | jq -e '.result.message_id')
    else
        R=$(curl --silent "https://api.telegram.org/bot$TELEGRAM_BOT_TOKEN/editMessageText?disable_web_page_preview=true&chat_id=$TELEGRAM_CHAT_ID&message_id=$mid" --data-urlencode "text=$line")
        # check for 429 Too Many Requests
        retry_after=$(echo "$R" | jq -e '.parameters.retry_after')
        if [ $? -eq 0 ]; then
            echo "Received 429 Too Many Requests. Waiting for $retry_after seconds ..."
            sleep $retry_after
        fi
    fi
    # https://core.telegram.org/bots/faq#my-bot-is-hitting-limits-how-do-i-avoid-this
    sleep 1
done < "${2:-/dev/stdin}"