#!/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"
        if cmp -s "$current_file.tmp" "$current_file"; then
                rm -f "$current_file.tmp" || :
        else
                mv -Tf "$current_file.tmp" "$current_file"
        fi
}

main "$@"