#!/bin/sh
# preinst script for xCAT-server
#
# see: dh_installdeb(1)

set -e

xcat_systemd_os_release_status()
{
    [ -r /etc/os-release ] || return 2

    os_id=
    os_version=
    while IFS='=' read -r key value; do
        value=${value#\"}
        value=${value%\"}
        value=${value#\'}
        value=${value%\'}
        case "$key" in
            ID) os_id=$value ;;
            VERSION_ID) os_version=$value ;;
        esac
    done < /etc/os-release

    if [ "$os_id" = "debian" ] && [ -z "$os_version" ]; then
        return 0
    fi

    os_major=${os_version%%.*}
    case "$os_major" in
        ''|*[!0-9]*) return 2 ;;
    esac

    case "$os_id" in
        rhel|centos|rocky|almalinux|ol|scientific)
            [ "$os_major" -ge 7 ] && return 0
            return 1
            ;;
        fedora|ubuntu)
            [ "$os_major" -ge 15 ] && return 0
            return 1
            ;;
        debian)
            [ "$os_major" -ge 8 ] && return 0
            return 1
            ;;
        sles|sled|opensuse|opensuse-leap|opensuse-tumbleweed)
            [ "$os_major" -ge 12 ] && return 0
            return 1
            ;;
        *)
            return 2
            ;;
    esac

}

xcat_target_uses_systemd()
{
    if [ -d /run/systemd/system ]; then
        return 0
    fi

    if [ -L /sbin/init ]; then
        init_target=$(readlink /sbin/init 2>/dev/null || true)
        case "$init_target" in
            *systemd*) return 0 ;;
            *) return 1 ;;
        esac
    fi

    if [ -e /sbin/init ]; then
        return 1
    fi

    if xcat_systemd_os_release_status; then
        return 0
    else
        os_release_status=$?
        if [ "$os_release_status" -eq 1 ]; then
            return 1
        fi
    fi

    if [ -x /usr/lib/systemd/systemd ] || [ -x /lib/systemd/systemd ]; then
        return 0
    fi

    return 1
}

xcatd_init_state=/opt/xcat/share/xcat/scripts/xcatd-init-state
xcatd_init_compat=/opt/xcat/share/xcat/scripts/xcatd-init-compat
xcatd_legacy_init=/etc/init.d/xcatd
xcatd_state_dir=/var/lib/xcat/xcatd-init-state
xcatd_old_systemd_marker=/var/lib/xcat/xcatd-systemd-mode
xcatd_context_file=$xcatd_state_dir/context

write_xcatd_context()
(
    context_value=$1
    context_tmp="$xcatd_context_file.tmp.$$"
    umask 077
    if ! printf '%s\n' "$context_value" > "$context_tmp" ||
       ! mv -f "$context_tmp" "$xcatd_context_file"; then
        rm -f "$context_tmp"
        return 1
    fi
)

clear_xcatd_pending_state()
{
    rm -f "$xcatd_state_dir/pending-xcatd" \
        "$xcatd_state_dir/pending-deleted" \
        "$xcatd_state_dir/pending-enabled" \
        "$xcatd_state_dir/pending-xcatd.tmp."*
}

xcatd_legacy_enable_state()
{
    if [ -x "$xcatd_init_compat" ]; then
        if detected_legacy_state=$(
            "$xcatd_init_compat" debian-legacy-state 2>/dev/null
        ); then
            case "$detected_legacy_state" in
                enabled) printf '%s\n' yes ;;
                disabled) printf '%s\n' no ;;
                unregistered) printf '%s\n' unregistered ;;
                *)
                    echo "Invalid xcatd legacy state: $detected_legacy_state" >&2
                    return 1
                    ;;
            esac
            return
        else
            detector_status=$?
            if [ "$detector_status" -ne 2 ]; then
                echo "Unable to query xcatd Debian legacy state with $xcatd_init_compat" >&2
                return "$detector_status"
            fi
        fi
    fi

    # Direct upgrades from a package without the Debian-specific command
    # still need to capture registration before dpkg removes the conffile.
    for rc_link in /etc/rc?.d/S??xcatd; do
        if [ -e "$rc_link" ] || [ -L "$rc_link" ]; then
            printf '%s\n' yes
            return
        fi
    done
    for rc_link in /etc/rc?.d/K??xcatd; do
        if [ -e "$rc_link" ] || [ -L "$rc_link" ]; then
            printf '%s\n' no
            return
        fi
    done
    printf '%s\n' unregistered
}

if xcat_target_uses_systemd; then
    xcatd_uses_systemd=yes
else
    xcatd_uses_systemd=no
fi

xcatd_transition_context=
case "$1" in
    upgrade) xcatd_transition_context=upgrade ;;
    install) xcatd_transition_context=fresh ;;
esac

if [ -n "$xcatd_transition_context" ] || [ "$1" = abort-upgrade ]; then
    if [ -L "$xcatd_state_dir" ] || \
       { [ -e "$xcatd_state_dir" ] && [ ! -d "$xcatd_state_dir" ]; }; then
        echo "Invalid xcatd init state directory: $xcatd_state_dir" >&2
        exit 1
    fi
    mkdir -p "$xcatd_state_dir"
    chmod 700 "$xcatd_state_dir"
fi

if [ -n "$xcatd_transition_context" ] && \
   [ "$xcatd_uses_systemd" = yes ] && [ -x "$xcatd_init_state" ]; then
    "$xcatd_init_state" prepare-systemd "$xcatd_transition_context"
elif [ -n "$xcatd_transition_context" ] && [ ! -x "$xcatd_init_state" ]; then
    # Before the first package carrying the state helper is unpacked, save
    # only the evidence that dpkg-maintscript-helper could remove.
    recovery_candidate=
    for candidate in \
        "$xcatd_legacy_init" \
        "$xcatd_legacy_init.dpkg-bak" \
        "$xcatd_legacy_init.dpkg-backup" \
        "$xcatd_legacy_init.dpkg-remove"; do
        if [ -e "$candidate" ] || [ -L "$candidate" ]; then
            recovery_candidate=$candidate
            break
        fi
    done

    known_legacy=no
    if [ -e "$xcatd_state_dir/state" ] || \
       [ -L "$xcatd_state_dir/state" ]; then
        # Durable state from an earlier package is stronger than the
        # legacy dpkg metadata left behind after removal.
        clear_xcatd_pending_state
    elif [ -n "$recovery_candidate" ]; then
        clear_xcatd_pending_state
        pending_tmp="$xcatd_state_dir/pending-xcatd.tmp.$$"
        if ! cp -a "$recovery_candidate" "$pending_tmp" ||
           ! mv -f "$pending_tmp" "$xcatd_state_dir/pending-xcatd"; then
            rm -f "$pending_tmp"
            exit 1
        fi
        rm -f "$xcatd_old_systemd_marker"
        known_legacy=yes
    else
        conffile_record=
        if command -v dpkg-query >/dev/null 2>&1; then
            conffile_record=$(
                dpkg-query -W -f='${Conffiles}\n' xcat-server 2>/dev/null |
                    sed -n '\|^ /etc/init.d/xcatd |p'
            )
        fi
        if [ -n "$conffile_record" ]; then
            case "$conffile_record" in
                *" obsolete"*)
                    # The installed package already removed the conffile.
                    # Record package omission rather than an admin deletion.
                    clear_xcatd_pending_state
                    touch "$xcatd_old_systemd_marker"
                    ;;
                *)
                    # A still-owned conffile that is absent was deleted by
                    # the administrator and must stay absent.
                    clear_xcatd_pending_state
                    rm -f "$xcatd_old_systemd_marker"
                    touch "$xcatd_state_dir/pending-deleted"
                    known_legacy=yes
                    ;;
            esac
        else
            # A retry without an installed conffile record must not reuse
            # evidence captured by an earlier, interrupted installation.
            clear_xcatd_pending_state
        fi
    fi

    if [ "$known_legacy" = yes ]; then
        xcatd_legacy_enable_state > "$xcatd_state_dir/pending-enabled"
    fi
fi

if [ "$xcatd_uses_systemd" = yes ] && \
   command -v dpkg-maintscript-helper >/dev/null 2>&1 && \
   dpkg-maintscript-helper supports rm_conffile; then
    dpkg-maintscript-helper rm_conffile /etc/init.d/xcatd -- "$@"
fi

# summary of how this script can be called:
#        * <new-preinst> `install'
#        * <new-preinst> `install' <old-version>
#        * <new-preinst> `upgrade' <old-version>
#        * <old-preinst> `abort-upgrade' <new-version>
# for details, see http://www.debian.org/doc/debian-policy/ or
# the debian-policy package


case "$1" in
    upgrade)
	write_xcatd_context upgrade
    ;;
    install)
        write_xcatd_context fresh
    ;;

    abort-upgrade)
        rm -f "$xcatd_context_file" "$xcatd_context_file.tmp."*
    ;;

    *)
        echo "preinst called with unknown argument \`$1'" >&2
        exit 1
    ;;
esac

# dh_installdeb will replace this with shell code automatically
# generated by other debhelper scripts.

#DEBHELPER#

exit 0