#!/bin/sh

# Avoid using full paths instead only use the program names.
argv0="${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] [--reload-compositor] [--on-success <cmd>] [--on-failure <cmd>] <command> [success-msg] [failure-msg]
# @DESCRIPTION:
# Safely execute a simple shell command, print optional success/failure messages,
# and optionally reload status bars or restart the compositor.
#
# Success messages are printed to stdout; failure messages are printed to stderr.
# To specify a failure message, a success message must also be provided.
# Command output is not suppressed.
#
# Options:
#   --reload-status        Reload the status bar (via `slreload`).
#   --reload-compositor    Restart the compositor (kills and restarts `picom`).
#   --on-success <cmd>     Run another command if the main command succeeds.
#   --on-failure <cmd>     Run another command if the main command fails.
#
# Restrictions:
#   - Does NOT use `eval`; only simple commands and arguments are supported.
#   - Shell operators like `&&`, `||`, `|`, `>`, `>>`, etc. will NOT work.
#   - This design prevents unintended execution and makes the function safe in scripts.
#
# Return value:
#   0 if the command succeeds, 1 otherwise.
#
# @EXAMPLES:
#   # Run xwallpaper and print the image path on success
#   run "xwallpaper --zoom ${image}" "${image}"
#
#   # Restart compositor and show a success message
#   run --reload-compositor "xwallpaper --zoom ${image}" "Wallpaper updated" "Wallpaper failed"
#
#   # With success and failure hooks
#   run --on-success "notify-send 'OK'" \
#       --on-failure "notify-send 'Failed'" \
#       "cp config config.bak" "Backup complete" "Backup failed"

run() {
	relstat=0
	compstat=0

	while [ $# -gt 0 ]; do
		case "$1" in
			--reload-status) relstat=1 ;;
			--reload-compositor) compstat=1 ;;
			--on-success) success_command="${2}"; shift ;;
			--on-failure) failure_command="${2}"; shift ;;
			*) break;
		esac
		shift
	done

	if [ "${compstat}" -eq 1 ]; then
		pgrep -x picom > /dev/null && killall picom
	fi

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

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

	if [ "${compstat}" -eq 1 ]; then
    		picom -b || echo "Warning: Failed to start picom" >&2
	fi

	exit 0
}