demo-magic.sh

#!/usr/bin/env bash

###############################################################################
#
# demo-magic.sh
#
# Copyright (c) 2015 Paxton Hare
#
# This script lets you script demos in bash. It runs through your demo script when you press
# ENTER. It simulates typing and runs commands.
#
###############################################################################

# the speed to "type" the text
TYPE_SPEED=20

# no wait after "p" or "pe"
NO_WAIT=false

# if > 0, will pause for this amount of seconds before automatically proceeding with any p or pe
PROMPT_TIMEOUT=0

# don't show command number unless user specifies it
SHOW_CMD_NUMS=false

# handy color vars for pretty prompts
BLACK="\033[0;30m"
BLUE="\033[0;34m"
GREEN="\033[0;32m"
GREY="\033[0;90m"
CYAN="\033[0;36m"
RED="\033[0;31m"
PURPLE="\033[0;35m"
BROWN="\033[0;33m"
WHITE="\033[1;37m"
COLOR_RESET="\033[0m"

C_NUM=0

# prompt and command color which can be overriden
DEMO_PROMPT="$ "
DEMO_CMD_COLOR=$WHITE
DEMO_COMMENT_COLOR=$GREY

##
# prints the script usage
##
function usage() {
    echo -e ""
    echo -e "Usage: $0 [options]"
    echo -e ""
    echo -e "\tWhere options is one or more of:"
    echo -e "\t-h\tPrints Help text"
    echo -e "\t-d\tDebug mode. Disables simulated typing"
    echo -e "\t-n\tNo wait"
    echo -e "\t-w\tWaits max the given amount of seconds before proceeding with demo (e.g. '-w5')"
    echo -e ""
}

##
# wait for user to press ENTER
# if $PROMPT_TIMEOUT > 0 this will be used as the max time for proceeding automatically
##
function wait() {
    if [[ "$PROMPT_TIMEOUT" == "0" ]]; then
        read -rs
    else
        read -rst "$PROMPT_TIMEOUT"
    fi
}

##
# print command only. Useful for when you want to pretend to run a command
#
# takes 1 param - the string command to print
#
# usage: p "ls -l"
#
##
function p() {
    if [[ ${1:0:1} == "#" ]]; then
        cmd=$DEMO_COMMENT_COLOR$1$COLOR_RESET
    else
        cmd=$DEMO_CMD_COLOR$1$COLOR_RESET
    fi

    # render the prompt
    x=$(PS1="$DEMO_PROMPT" "$BASH" --norc -i < /dev/null 2>&1 | sed -n '${s/^\(.*\)exit$/\1/p;}')

    # show command number is selected
    if $SHOW_CMD_NUMS; then
        printf "[$((++C_NUM))] $x"
    else
        printf "$x"
    fi

    # wait for the user to press a key before typing the command
    if [ $NO_WAIT = false ]; then
        wait
    fi

    if [[ -z $TYPE_SPEED ]]; then
        echo -en "$cmd"
    else
        echo -en "$cmd" | pv -qL $(($TYPE_SPEED + (-2 + RANDOM % 5)))
    fi

    # wait for the user to press a key before moving on
    if [ $NO_WAIT = false ]; then
        wait
    fi
    echo ""
}

##
# Prints and executes a command
#
# takes 1 parameter - the string command to run
#
# usage: pe "ls -l"
#
##
function pe() {
    # print the command
    p "$@"
    run_cmd "$@"
}

##
# print and executes a command immediately
#
# takes 1 parameter - the string command to run
#
# usage: pei "ls -l"
#
##
function pei {
    NO_WAIT=true pe "$@"
}

##
# Enters script into interactive mode
#
# and allows newly typed commands to be executed within the script
#
# usage : cmd
#
##
function cmd() {
    # render the prompt
    x=$(PS1="$DEMO_PROMPT" "$BASH" --norc -i < /dev/null 2>&1 | sed -n '${s/^\(.*\)exit$/\1/p;}')
    printf "$x\033[0m"
    read command
    run_cmd "${command}"
}

function run_cmd() {
    function handle_cancel() {
        printf ""
    }

    trap handle_cancel SIGINT
    stty -echoctl
    eval "$@"
    stty echoctl
    trap - SIGINT
}

function check_pv() {
    command -v pv > /dev/null 2>&1 || {

        echo ""
        echo -e "${RED}##############################################################"
        echo "# HOLD IT!! I require pv but it's not installed.  Aborting." >&2
        echo -e "${RED}##############################################################"
        echo ""
        echo -e "${COLOR_RESET}Installing pv:"
        echo ""
        echo -e "${BLUE}Mac:${COLOR_RESET} $ brew install pv"
        echo ""
        echo -e "${BLUE}Other:${COLOR_RESET} http://www.ivarch.com/programs/pv.shtml"
        echo -e "${COLOR_RESET}"
        exit 1
    }
}

check_pv
#
# handle some default params
# -h for help
# -d for disabling simulated typing
#
while getopts ":dhncw:" opt; do
    case $opt in
    h)
        usage
        exit 1
        ;;
    d)
        unset TYPE_SPEED
        ;;
    n)
        NO_WAIT=true
        ;;
    c)
        SHOW_CMD_NUMS=true
        ;;
    w)
        PROMPT_TIMEOUT=$OPTARG
        ;;
    esac
done