#!/bin/bash -e

#
#  Towel:  Randomly Useful Bash Functions
#          Never Leave Home Without Your Towel
#
#  Copyright (C) 2019 Scott Duensing <scott@kangaroopunch.com>
#
#  This software is provided 'as-is', without any express or implied
#  warranty.  In no event will the authors be held liable for any damages
#  arising from the use of this software.
#
#  Permission is granted to anyone to use this software for any purpose,
#  including commercial applications, and to alter it and redistribute it
#  freely, subject to the following restrictions:
#
#  1. The origin of this software must not be misrepresented; you must not
#     claim that you wrote the original software. If you use this software
#     in a product, an acknowledgment in the product documentation would be
#     appreciated but is not required.
#  2. Altered source versions must be plainly marked as such, and must not be
#     misrepresented as being the original software.
#  3. This notice may not be removed or altered from any source distribution.
#


#
#   Escapes a given string so it's safe to write into an XML document.
#
# Parameters:
#
#   RESULT - Variable in which to return the escaped string.
#   VAR    - String to escape.
#
function tEscapeXml() {
	local __RESULT=$1
	local __VAR=${*:2}

	__VAR=$(echo ${__VAR} | sed -e 's~&~\&amp;~g' -e 's~<~\&lt;~g' -e 's~>~\&gt;~g')

	eval $__RESULT=\${__VAR}
}


#
#   Displays a whiptail-based file browser for selecting a particular type of file.
#
# Parameters:
#
#   RESULT    - Variable in which to store selected filename, or empty if dialog is canceled.
#   TITLE     - Title to display in the file browser window.
#   EXTENSION - The extension to allow to be selected (in ".ext" format).
#   START     - Optional.  Path to begin browsing from.
#
function tFileBrowser() {
	local __RESULT=$1
	local __TITLE=$2
	local __EXTENSION=$3
	local __START=$4
	local __SELECTION=
	local __DIRLIST=()
	local __CURDIR=
	local __RET=
	local __LOOPING=1

	pushd . > /dev/null

	if [[ ! -z ${__START} ]]; then
		cd "${__START}"
	fi

	while [[ ${__LOOPING} -eq 1 ]]; do
		__DIRLIST=()
		if [[ "${__CURDIR}" != "/" ]]; then
			__DIRLIST[${#__DIRLIST[@]}+1]=".."
			__DIRLIST[${#__DIRLIST[@]}+1]="Up"
		fi
		for F in *; do
			if [[ -d "${F}" ]]; then
				__DIRLIST[${#__DIRLIST[@]}+1]=$(echo "${F}/   ")
			else
				__DIRLIST[${#__DIRLIST[@]}+1]=$(echo "${F}   ")
			fi
			__DIRLIST[${#__DIRLIST[@]}+1]=$(ls -lah "${F}" | awk '{ print $5 }')
		done

		__CURDIR=$(pwd)

		__SELECTION=$(whiptail --title "${__TITLE}" \
			--menu "PgUp/PgDn/Arrows ENTER Selects File/Folder\nor TAB Key\n\n${__CURDIR}" 0 0 0 \
			--cancel-button "Cancel" \
			--ok-button "Select" "${__DIRLIST[@]}" 3>&1 1>&2 2>&3)
		__RET=$?

		if [[ ${__RET} -eq 1 ]]; then
			# User Selected Cancel
			__SELECTION=
			__LOOPING=0
		elif [[ ${__RET} -eq 0 ]]; then
			tTrim __SELECTION "${__SELECTION}"
			if [[ -d "${__SELECTION}" ]]; then
				# Was a directory selected?
				cd "${__SELECTION}"
			elif [[ -f "${__SELECTION}" ]]; then 
				# Was a file selected?
				if [[ ${__SELECTION} == *${__EXTENSION} ]]; then   
					# Check if file has given extension
					if (whiptail --title "Confirm Selection" \
						--yesno "Directory:  ${__CURDIR}\n Filename:  ${__SELECTION}" 0 0 \
						--yes-button "Confirm" \
						--no-button "Reselect"); then
							__SELECTION="$(pwd)/${__SELECTION}"
							__LOOPING=0
					fi
				else
					# Not requested extension
					whiptail --title "Error" \
						--msgbox "Not a ${__EXTENSION} file" 0 0
				fi
			else
				# Not a file or folder
				whiptail --title "Error" \
					--msgbox "Unable to change to directory ${__SELECTION}" 0 0
			fi
		fi
	done

	eval $__RESULT=\${__SELECTION}

	popd > /dev/null
}


#
#   Returns the absolute path of a given file.
#
# Parameters:
#
#   RESULT - Variable in which to return the absolute path.
#   SOURCE - File which we wish to find the absolute path.
#
function tFindPath() {
	local __RESULT=$1
	local __SOURCE=$2
	local __DIR=
	
	while [[ -h "${__SOURCE}" ]]; do
		__DIR="$( cd -P "$( dirname "${__SOURCE}" )" && pwd )"
		__SOURCE="$(readlink "${__SOURCE}")"
		# If $__SOURCE was a relative symlink, we need to resolve it
		# relative to the path where the symlink file was located.
		[[ ${__SOURCE} != /* ]] && __SOURCE="${__DIR}/${__SOURCE}"
	done
	__DIR="$( cd -P "$( dirname "${__SOURCE}" )" && pwd )"

	eval $__RESULT=\${__DIR}
}


#
#   Returns the location and name of the parent script that included us.
#
# Parameters:
#
#   RESULT - Variable in which we want the absolute filename returned.
#
function tGetParentPath() {
	local __RESULT=$1
	local __PARENTPATH=

	tFindPath __PARENTPATH "${BASH_SOURCE[1]}"
	__TOWELPATH="${__PARENTPATH}/`basename \"${BASH_SOURCE[1]}\"`"

	eval $__RESULT=\${__PARENTPATH}
}


#
#   Returns the location and name of this Towel script.
#
# Parameters:
#
#   RESULT - Variable in which we want the absolute filename returned.
#
function tGetTowelPath() {
	local __RESULT=$1
	local __TOWELPATH=

	tFindPath __TOWELPATH "${BASH_SOURCE[0]}"
	__TOWELPATH="${__TOWELPATH}/`basename \"${BASH_SOURCE[0]}\"`"

	eval $__RESULT=\${__TOWELPATH}
}


#
#   Removes whitespace from the beginning and end of a string.
#
# Parameters:
#
#   RESULT - Variable in which to return the trimmed string.
#   VAR    - String to trim.
#
function tTrim() {
	local __RESULT=$1
	local __VAR="${*:2}"
	
	# remove leading whitespace characters
	__VAR="${__VAR#"${__VAR%%[![:space:]]*}"}"
	# remove trailing whitespace characters
	__VAR="${__VAR%"${__VAR##*[![:space:]]}"}"
	
	eval $__RESULT=\${__VAR}
}


#
# We're a library.  Don't run us.
#
if [ -z "${BASH_SOURCE[1]}" ]; then
	echo "This is a library.  Include it into other scripts.  Don't execute it."
	exit 0
fi