#!/bin/sh
# SHIN --- include files in shell scripts
# Copyright (C) Case Duckworth <acdw@acdw.net>

_shin_check_SHINPATH() {
	printf "%s\n" "${SHINPATH:-.}" |
		tr : '\n' |
		while read -r path
		do
			if test -f "$path/$1"
			then
				printf '%s\n' "$path/$1"
				return 0
			fi
		done
	return 1
}

_shin_resolve_file() {
	f=
	case "$1" in
		~/*) f="$HOME/${1#~/}" ;;
		/*) f="/${1#/}" ;;
		*) f="$(_shin_check_SHINPATH "$1")" ;;
	esac

	if test -f "$f"
	then
		printf '%s\n' "$f"
	elif test -f "$f.sh"
	then
		printf '%s\n' "$f.sh"
	else
		return 1
	fi
	return 0
}

_shin_include() { # _shin_include FILE ...
	for lib
	do
		lib="$(_shin_resolve_file "$lib")"
		test -f "$lib" && . "$lib"
	done
}

_shin_cleanup() {
	if "$_shin_rmtemp" && test -f "$_shin_temp"
	then
		rm -f "$_shin_temp"
	fi
}

_shin_build() ( # _shin_build FILE ...
	for file
	do
		file="$(_shin_resolve_file "$file")"

		# Determine output file
		if test -z "$_shin_output"
		then
			case "$file" in
				# file.shin -> file.sh
				*.shin) _shin_output="${file%in}" ;;
				# file.sh -> file
				*.sh) _shin_output="${file%.sh}" ;;
				# file.ext -> file.ext.sh
				*) _shin_output="$file.sh" ;;
			esac
		fi

		while read -r line
		do
			case "$line" in
				# skip lines where the user sources the library
				.*shin) ;;
				.*shin.sh) ;;
				# where the user invokes shin, replace with file
				shin*) # cursed
					eval \
						for file in ${line#shin}\; \
						do \
						test -f \"\$file\" \&\& \
						sed \"/^#!/d\" \"\$file\"\; \
						done
					;;
				# else, print the line
				*) printf '%s\n' "$line" ;;
			esac
		done < "$file" > "$_shin_temp"

		ec=$?

		if test "x$_shin_output" = x-
		then # already output to standard out
			cat "$_shin_temp"
			continue
		elif test $ec -ne 0
		then # uh oh we messed up
			echo >&2 "shin: errors building."
			echo >&2 "shin: part-built file: $_shin_temp"
			_shin_rmtemp=false
		elif test -f "$_shin_output" && ! "$_shin_force"
		then # can't overwrite sumthin without -f
			echo >&2 "shin: file already exists: $_shin_output"
			echo >&2 "shin: part-built file: $_shin_temp"
			_shin_rmtemp=false
		else # move the temp file to the output
			if mv "$_shin_temp" "$_shin_output"
			then
				printf >&2 '%s\n' "$_shin_output"
			else
				echo >&2 "shin: errors moving $_shin_output"
				echo >&2 "shin: part-built file: $_shin_temp"
				_shin_rmtemp=false
			fi
		fi
	done
)

shin() {
	_shin_func="${_shin_func:-_shin_include}"
	_shin_temp=/tmp/shinf
	_shin_rmtemp=true
	_shin_force=false
	_shin_debug=false

	trap _shin_cleanup INT EXIT QUIT

	while getopts dfcio: OPT
	do
		case "$OPT" in
			c) _shin_func=_shin_build ;;
			i) _shin_func=_shin_include ;;
			o) # output file implies build.
				_shin_func=_shin_build
				_shin_output="$OPTARG"
				echo "$_shin_output"
				;;
			f) _shin_force=true ;;
			d) _shin_debug=true ;;
			*) exit 1 ;;
		esac
	done
	shift $((OPTIND - 1))
	OPTIND=0

	if "$_shin_debug"
	then
		cat >&2 <<EOF
SHIN DEBUGGING: ON
VARIABLES:
	_shin_func	$_shin_func
	_shin_output	$_shin_output
	_shin_temp	$_shin_temp

	_shin_rmtemp	$_shin_rmtemp
	_shin_force	$_shin_force
EOF
		set -x
	fi

	"$_shin_func" "$@"
}