#!/usr/bin/env bash
#
# A handy collection of tools to create interactive demos:
#     type():      simulates typing its arguments
#     execute():   simuates typing then executing its arguments in a shell
#     wait():      waits for user input with optional timeout
#     cmd():       gives control to user until she enters 'end' (or for a single command if you pass an argument)
#     color():     allows you to color (second argument, defaults to $clr) some text (first argument)
#
# Helpers (internal stuff):
#     simtyping(): let's data piped to it through at rates similar to typing
#     prompt():    prints the bash PS1 prompt on your system with a nasty hack

TYPE_SPEED="${TYPE_SPEED:-15}"
PROMPT_TIMEOUT="${PROMPT_TIMEOUT:--1}"

# some colors
def="\033[0;00m"
wht="\033[1;37m"
red="\033[0;31m"
grn="\033[0;32m"
blu="\033[0;34m"

clr="$wht"
function color()
{
    printf "${2:-$clr}"
    printf "${1}"
    printf "${def}"
}

function simtyping()
{ pv -qL $(($TYPE_SPEED+$((-2 + RANDOM%5)))); }

function type()
{ printf "$*" | simtyping; }

function wait()
{
    [ "$PROMPT_TIMEOUT" == "-1" ] && 
        read -rs ||
        read -rst "$PROMPT_TIMEOUT"
}

function prompt()
{
    invalidcmd="somethingthatshouldbetotallynotacommandinanygivenenvironment"
    expPS1=$(echo $invalidcmd    |
             bash --norc -i 2>&1 |
             grep $invalidcmd    |
             head -n 1           |
             sed "s/$invalidcmd//g")
    printf "$expPS1"
}

function execute()
{
    prompt
    type "$@" && wait
    printf "\n"
    eval "$@"
}

function cmd()
{
    while : ; do
        prompt
        read -e command
        [ "$command" != "end" ] && eval "${command}" || break
        [ "$1" ] && break
    done
}