#!/usr/bin/env bash

# Originally borrowed from here: https://github.com/tomnomnom/with/blob/master/with
# As such credit should go to tomnomnom

# with tool
# usage: with <program>
# opens an interactive shell instance that automatically prefixes all subsequent commands with program name

pmpt="$*>"

prefix=$*

which $1 2>&1 > /dev/null
program_installed=$?
if [ ! $program_installed -eq 0 ]; then
	echo "error: Program" $1 "is not installed"
	exit 1
fi

stop=false
while [ true ]; do
	while IFS="" read -r -e -d $'\n' -p "$pmpt " options; do
		history -s "$options"

		curr_command="$(echo $options | { read first rest ; echo $first ; })" 

		if [ -z "$curr_command" ]; then
			# null case
			eval "${prefix}"
		else
			# remove with
			if [ $curr_command == - ]; then
				prefix=$( echo $prefix | awk '{$NF="";sub(/[ \t]+$/,"")}1' )
				pmpt="$prefix>"
				# nesting withs
			elif [[ $curr_command == +* ]]; then
				parsed=${options#"+"}
				prefix=$( echo "$prefix" "$parsed" )
				pmpt="$prefix>"
				# process shell commands
			elif [[ $curr_command == :* ]]; then
				parsed=${options#":"}
				if [ "$parsed" = "q" ]; then
					# terminate out of while loop instead of exiting so we can do some safe exiting
					stop=true
					break
				fi
				eval "$parsed"
			else
				eval "$prefix $options"
			fi
		fi
		# see if there are any commands left
		if [ -z "$prefix" ]; then
			echo "No program. Returning to shell."
			# null case
			stop=true
			break
		fi
	done

	if [ stop=true ]; then
		break
	fi

done