ao-mud/spells/cantrips/ask_yn

#!/bin/sh

question=$1
default_answer=$(echo $2 | tr a-z A-Z)

# Capitalize the default answer and construct the prompt
if [ "$default_answer" = "Y" ]; then
    prompt="${question} (Y/n)? "
else
    prompt="${question} (y/N)? "
fi

# Save stty configuration
old_stty_cfg=$(stty -g)

# Use stty to make read command work for single character input
stty raw -echo 
printf "%s" "$prompt" >&2
while true
do
    answer=$(head -c 1)
    if [ "$answer" = $'\n' ] || [ "$answer" = $'\r' ]; then
        answer=""
        break
    elif printf "%s" "$answer" | grep -iq "^y\|^n"; then
        break
    elif [ "$answer" = $'\003' ]; then
        stty "$old_stty_cfg"
        printf '\n'
        exit 2
    fi
done
stty "$old_stty_cfg" >&2 # Restore original stty configuration

# If no answer is given, use the default answer
if [ -z "$answer" ]; then
    answer=$default_answer
fi

# Print the answer and return appropriate exit code
printf "%s\n" "$(echo $answer | tr a-z A-Z)" >&2
if [ "$answer" = "Y" -o "$answer" = "y" ]; then
    exit 0
else
    exit 1
fi