countdown_to shell command

countdown_to.sh

# DESCRIPTION
# -----------
# Countdown to the next occurrence of a specific time in 24-hour HH:MM format (e.g. 07:30, 14:00)

# USAGE
# -----
# Source this file or add this to your Shell profile (.bashprofile, .bashrc, .zshrc, ...), then run:
# 
#   countdown_to 14:00
#
# Useful when you're waiting for your usage limits to reset:
#
#   countdown_to 14:00 && claude --continue "continue what you were doing"
#

function countdown_to() {
    local input_time="$1"
    local now=$(date +%s)
    local end

    # Try to parse as 24-hour time (HH:MM)
    # We append ":00" to ensure the seconds are zeroed out.
    if ! end=$(date -j -f "%H:%M:%S" "${input_time}:00" +%s 2>/dev/null); then
      echo "Invalid format. Please use HH:MM (e.g., 14:00)."
      return 1
    fi

    # 3. If the parsed time is in the past, assume it is for tomorrow (+24 hours / 86400 seconds)
    if (( end <= now )); then
        end=$((end + 86400))
    fi

    # Optional: Let the user know exactly what time it's targeting
    echo "Counting down to: $(date -j -r "$end")"

    # 4. Run the countdown loop
    while (( now < end )); do
        printf "\t\t%s\r" "$(date -u -j -f %s $((end - now)) +%T)"
        sleep 0.1
        now=$(date +%s)
    done
    
    # Print a final zeroed-out timer and a newline so the shell prompt doesn't overwrite it
    echo "\t\t00:00:00"
}