#!/bin/sh -e

version=Fossil

die() {
    printf '%s: %s\n' "${0##*/}" "$*" >&2
    exit 1
}

out() { printf '%s\n' "$@" ;}

_check() {
    for arg; do
        printf 'checking for %s... ' "$arg"
        command -v "$arg" || { out no; die "'$arg' not found" ;}
    done
}

_check_multi() {
    c=$1; shift
    printf 'checking for %s... ' "$c"
    for arg; do command -v "$arg" && return 0; done
    out no; die "no $c was found"
}

usage() {
    out "usage: $0 [options]" \
        "Options:" \
        "  --prefix=dir        Set prefix directory" \
        "  --bindir=dir        User executables [PREFIX/bin]" \
        "  --datarootdir=dir   Data root directory [PREFIX/share]" \
        "  --mandir=dir        Manual pages [DATAROOTDIR/man]" \
        "  --infodir=dir       info documentation [DATAROOTDIR/info]" \
        "  --docdir=dir        Documentation directory [DATAROOTDIR/doc/cpt]" \
        "  --with-docs=opt     Whether to build the texinfo documentation [auto]" "" \
        "  MAKEINFO            Name of the 'makeinfo' executable" \
        "  EMACS               Name of the 'emacs' executable" "" \
        "Use these variables to override the behaviour of '$0'."
    exit 1
}

prefix=/usr/local
# We don't want expansion
# shellcheck disable=2016
{
bindir='$(PREFIX)/bin'
datarootdir='$(PREFIX)/share'
mandir='$(DATAROOTDIR)/man'
infodir='$(DATAROOTDIR)/info'
docdir='$(DATAROOTDIR)/doc/cpt'
}
docs=auto

for arg; do
    case $arg in
        -h|--help) usage ;;
        --prefix=*) prefix=${arg#*=}   ;;
        --bindir=*) bindir=${arg#*=}   ;;
        --mandir=*) mandir=${arg#*=}   ;;
        --infodir=*) infodir=${arg#*=} ;;
        --docdir=*) docdir=${arg#*=}   ;;
        --without-docs) docs=no        ;;
        --with-docs)    docs=yes       ;;
        --with-docs=*)  docs=${arg#*=} ;;
        *-*) die "Unknown option: '$arg'" ;;
        *=*) export "${arg:?}" ;;
        *) die "Unknown argument: '$arg'"
    esac
done

trap 'rm -f config.mk' EXIT
trap 'rm -f config.mk; exit 1' INT

: "${EMACS:=emacs}" "${MAKEINFO:=makeinfo}"

out "starting configuration..."

cat <<EOF > config.mk
PREFIX = $prefix
BINDIR = $bindir
DATAROOTDIR = $datarootdir
MANDIR  = $mandir
INFODIR = $infodir
DOCDIR  = $docdir
MAN1    = \$(MANDIR)/man1

VERSION = $version
EMACS   = $EMACS
EOF

case $docs in
    auto|yes)
        printf 'checking for makeinfo... '
        if makeinfo=$(command -v "$MAKEINFO"); then
            out "$makeinfo"
            docs=yes
            out "MAKEINFO = $makeinfo" >>config.mk
        else
            out no
            [ "$docs" = yes ] && die "'$MAKEINFO' not found"
            docs=no
        fi
esac
[ "$docs" = no ] && out "not building documentation"
out "DOCS = $docs" >>config.mk

out "checking runtime dependencies"
_check pax rsync sed awk grep b3sum
_check_multi "sha256 provider" sha256sum sha256 openssl
_check_multi "download utility" curl wget wget2 aria2c axel

trap - EXIT INT
out "written config.mk" "Run 'make' to build cpt"