#!/usr/bin/env bash
# This is an attempt to replace xdg-open with something sane.

usage() {
	cat <<- EOF
		sx-open [-dhv] <uri/file>
		Flags:
		  -d   Dry run
		  -v   Verbose mode
		  -n   Disable desktop notifications
		  -h   Help
	EOF
}

act() {
	(( verbose )) && printf 'CMD: %s\n' "$*" >&2
	(( dry_run )) || { "$@"; return $?; }

	return 0
}

notify() {
	[[ $DISPLAY ]] || return 3
	[[ $notifier ]] || return 5

	"${notifier[@]}" 'sx-open' "$@"
}

error() {
	printf '%s\n' "$*" >&2
	notify "$*"
}

# handle_target <res> <uri>
# 1: cmd failed
# 3: no handler
handle_target() {
	declare -n result=$1
	declare h cmd regex target_is_file target target_left cmd_is_template
		target_is_file=0
		target=$2
		target_left=$target

	if [[ -e "$target" ]]; then
		target_is_file=1

		[[ "$target" =~ ^/.* ]] || { target="${PWD}/${target}"; } # Turn relative paths to absolute ones.

		IFS=';' read target_mimetype charset <<< $( file -ib "$target" )
		target_left=$target_mimetype

		set -- "${mime_handlers[@]}"
	elif is_uri "$target"; then
		set -- "${uri_handlers[@]}"
	else
		return 2
	fi

	while (( $# )); do
		cmd=( $1 ); regex=$2

		for c in "${!cmd[@]}"; do
			if [[ "${cmd[c]}" == '%target%' ]]; then
				cmd_is_template=1
				cmd[c]="$target"
			fi
		done

		(( cmd_is_template )) || cmd+=( "$target" )

		if [[ "$target_left" =~ $regex ]]; then
			act "${cmd[@]}"; result=$?
			(( result )) && return 1

			return 0
		fi

		shift 2
	done

	return 3
}

# DSL
uri() {
	declare r handler=$1; shift

	for r in "$@"; do
		uri_handlers+=( "$handler" "$r" )
	done
}

mime() {
	declare r handler=$1; shift

	for r in "$@"; do
		mime_handlers+=( "$handler" "$r" )
	done
}

scheme() {
	declare r handler=$1; shift

	for s in "$@"; do
		uri_handlers+=( "$handler" "^$s:" )
	done
}

is_uri() [[ $1 =~ ^[a-zA-Z][a-zA-Z0-9\+\.\-]+:.+ ]]

main() {
	declare cmd_result target

	# Source the config file.
	cfg_file="$HOME/.config/sx-open.cfg"
	[[ -f "$cfg_file" ]] && { source "$cfg_file"; }

	while (( $# )); do
		case $1 in
			(-d) dry_run=1; verbose=1;;
			(-v) verbose=1;;
			(-h) usage; return 0;;

			(-n) notify() { true; };; # disable desktop notifications

			(--) shift; break;;
			(*) break;;
		esac

		shift
	done

	target=$1; [[ "$target" ]] || { usage; exit; }

	(( dry_run )) && printf 'Dry run: not actually running the handler\n' >&2

	# Treat file:// as local paths.
	[[ "$target" =~ ^file:(//)?(/.+) ]] && target=${BASH_REMATCH[2]}

	# Figure out if we're in X and set $notifier if we are.
	if [[ $DISPLAY ]]; then
		# Do we have notify-send?
		notifier=$(type -P 'notify-send')
	fi

	handle_target cmd_result "$target"

	case $? in
		(1)
			error "Action on “$target” failed with exit code: “$cmd_result”"
			return 4
		;;

		(2)
			error "No such file or directory: “$target”"
			return 2
		;;

		(3)
			error "No handlers found for “$target”"
			return 3
		;;
	esac

	return 0
}

main "$@"