#!/usr/bin/env bash

panic() {
	>&2 echo panic
	exit 2
}

out() {
	printf '%q ' "$@"
}

# system
# linux
# public
# protected
# private
classify() {
	local path=$1
	if [[ "$path" = linux/* ]]; then
		out linux "$path"
	elif [[ -f "${current_file%/*}/${path}" ]]; then
		out private "$path"
	elif [[ "$path" != systemd/* ]] &&
	     [[ "$path" != libudev.h ]] &&
	     cpp -include "$path" <<<'' &>/dev/null; then
		out system "$path"
	else
		case "$path" in
			*-to-name.h|*-from-name.h)
				base="${path##*/}"
				base="${base%-to-name.h}"
				base="${base%-from-name.h}"
				case "$base" in
					dns_type)	     d=src/grp-resolve/systemd-resolved;;
					keyboard-keys)	     d=src/grp-udev/libudev-core;;
					af|arphrd|cap|errno) d=src/libbasic/include/basic;;
					audit_type)	     d=src/libsystemd/src/sd-journal;;
					*)
						>&2 printf 'Unknown gperf base: %q\n' "$base"
						>&2 printf 'Cannot figure out: %q\n' "$path"
						exit 2
						;;
				esac
				file="$d/${path##*/}"
				if [[ "$current_file" = "$d"/* ]]; then
					out private "${file##*/}"
				elif [[ "$file" = */include/* ]]; then
					out protected "${file##*/include/}"
				else
					out protected "${file##*/}"
				fi
				;;
			asm/sgidefs.h|dbus/dbus.h|efi.h|efilib.h|gio/gio.h|glib.h|libmount.h)
				out system "$path"
				;;
			util.h|*/util.h)
				if [[ "$current_file" = */systemd-boot/* ]]; then
					out private util.h
				else
					out protected basic/util.h
				fi
				;;
			*)
				file=$(find src -type f -name "${path##*/}")
				if [[ -f "$file" ]]; then
					case "$file" in
						*/src/*)
							if [[ "${current_file%/*}" = "${file%/*}" ]]; then
								out private "${file##*/}"
							else
								out protected "${file##*/src/}"
							fi
							;;
						*/libsystemd/include/*|*/libudev/include/*)
							out public "${file##*/include/}"
							;;
						*/include/*)
							out protected "${file##*/include/}"
							;;
						*)
							if [[ "${current_file%/*}" = "${file%/*}" ]]; then
								out private "${file##*/}"
							else
								out protected "${file##*/}"
							fi
							;;
					esac
				else
					>&2 printf 'Cannot figure out: %q\n' "$path"
					exit 2
				fi
				;;
		esac
	fi
}

phase=phase0
hook=:

phase0() {
	phase=phase0
	hook=:
	local line="$1"
	case "$line" in
		'#include'*|'typedef '*';')
			phase1 "$line"
			;;
		*)
			printf '%s\n' "$line"
			;;
	esac
}

phase1_init() {
	phase1_tail=
	system=()
	linux=()
	public=()
	protected=()
	typedef=(); typedef_last=true
	private=()
}
phase1_init
phase1_flush() {
	local b=:
	if [[ ${#system[@]} -gt 0 ]]; then
		printf '%s\n' "${system[@]}" | sort -u
		b=echo
	fi
	if [[ ${#linux[@]} -gt 0 ]]; then
		$b
		printf '%s\n' "${linux[@]}"
		b=echo
	fi
	if [[ ${#public[@]} -gt 0 ]]; then
		$b
		printf '%s\n' "${public[@]}" | sort -u
		b=echo
	fi
	if [[ ${#protected[@]} -gt 0 ]]; then
		$b
		printf '%s\n' "${protected[@]}" | sort -u
		b=echo
	fi
	if [[ ${#typedef[@]} -gt 0 ]] && ! $typedef_last; then
		$b
		printf '%s\n' "${typedef[@]}" | sort -u
		b=echo
	fi
	if [[ ${#private[@]} -gt 0 ]]; then
		$b
		printf '%s\n' "${private[@]}" | sort -u
		b=echo
	fi
	if [[ ${#typedef[@]} -gt 0 ]] && $typedef_last; then
		$b
		printf '%s\n' "${typedef[@]}"
	fi
	printf '%s' "$phase1_tail"
	phase1_init
}
phase1() {
	phase=phase1
	hook=phase1_flush
	local line="$1"
	case "$line" in
		'')
			phase1_tail+=$'\n'
			;;
		'#include'*)
			phase1_tail=''
			local re='^#include [<"]([^">]*)[">](.*)'
			if [[ "$line" =~ $re ]]; then
				IFS=' '
				local buf
				buf="$(classify "${BASH_REMATCH[1]}")" || panic
				read -r class path <<<"$buf"
				case "$class" in
					system)
						printf -v line '#include <%s>%s' "$path" "${BASH_REMATCH[2]}"
						system+=("$line")
						;;
					linux)
						printf -v line '#include <%s>%s' "$path" "${BASH_REMATCH[2]}"
						linux+=("$line")
						;;
					public)
						printf -v line '#include <%s>%s' "$path" "${BASH_REMATCH[2]}"
						public+=("$line")
						;;
					protected)
						printf -v line '#include "%s"%s' "$path" "${BASH_REMATCH[2]}"
						protected+=("$line")
						;;
					private)
						if [[ ${#typedef[@]} -gt 0 ]]; then
							typedef_last=false
						fi
						printf -v line '#include "%s"%s' "$path" "${BASH_REMATCH[2]}"
						private+=("$line")
						;;
				esac
			else
				panic
			fi
			;;
		'typedef '*';')
			phase1_tail=''
			typedef+=("$line")
			;;
		*)
			phase1_flush
			phase0 "$line"
			;;
	esac
}

main() {
	current_file="$1"
	printf ' => %q %q\n' "$0" "$current_file"
	set -o pipefail
	trap 'rm -f -- "$current_file.tmp"' EXIT
	{
		IFS=''
		while read -r line; do
			"$phase" "$line"
			IFS=''
		done
		"$hook"
	} < "$current_file" > "$current_file.tmp"
	# I specificially don't use write-ifchanged because I don't want the
	# temporary file to have the .c suffix.
	if cmp -s "$current_file.tmp" "$current_file"; then
		rm -f "$current_file.tmp" || :
	else
		mv -Tf "$current_file.tmp" "$current_file"
	fi
}

main "$@"