#!/bin/sh

# Avoid using full paths instead only use the program names.
argv0=$(basename "${0}")

# @FUNCTION: err
# @USAGE: [-x] <message> ...
# @DESCRIPTION:
# Print given messages to stderr line by line and exit with status 1.
#
# If "-x" is specified, suppress the program prefix (`program: `)
# from the output. Otherwise, the first line is prefixed with "program: ".
#
# This function is intended for fatal errors; it always exits the script.
# @EXAMPLE:
# err "Invalid usage" "Try '${argv0} -h' for help."


err() {
	if [ "${1}" != "-x" ]; then
		printf "%s: " "${argv0}"
	else
		shift
	fi

	for line in "${@}"; do
		echo "${line}" >&2
	done
	exit 1
}

# @FUNCTION: invalid_use
# USAGE: [-h]
# @DESCRIPTION:
# Output a usage error message. If `-h` is not specified output: 
# 	"<program>: Invalid usage "
# 	"Try 'program -h' for help."
# else output only:
# 	"Try 'program -h' for help."

invalid_use() {
	[ "${1}" = "-h" ] && err -x "Try '${argv0} -h' for help."
	err "Invalid usage" "Try '${argv0} -h' for help."
}

# @FUNCTION: check_program
# USAGE: <command> [error-msg]
# @DESCRIPTION:
# Check if command exists on the system.
# If not, print an error message to stderr and exit with status 1.
# The default error message is "`command` must be installed"
# but can optionally be overwritten.
#
# @EXAMPLE:
# Check if pulseaudio is installed.
#
# check_program "pactl" "pulseaudio must be installed"

check_program() {
	command -v "${1}" > /dev/null 2>&1 && return 0
	[ -n "${2}" ] && err "${2}"
	err "${1} must be installed"
}

# @FUNCTION: run
# USAGE: [--reload-status] <command> [success-msg] [failure-msg]
# @DESCRIPTION:
# Run the specified command and output success/failure message if provided.
# Optionally reload the status bar.
#
# Success messages are printed to stdout, failure messages are printed to stderr.
# To add a failure message a success message must also be present.
# The output of the command is not suppressed.
#
# @EXAMPLE:
# Run xwallpaper command if success print out ${image}:
#
# run "xwallpaper --zoom ${image}" "${image}"

run() {
	relstat=0
	if [ "${1}" = "--reload-status" ];then
		relstat=1
		shift
	fi

	if ${1}; then
		[ -n "${2}" ] && echo "${2}"
	else
		[ -n "${3}" ] && err "${3}"
		exit 1
	fi

	if [ "${relstat}" -eq 1 ]; then
		slreload || echo "Warning: Failed to reload slstatus" >&2
	fi

	exit 0
}