#!/bin/bash
#  $HeadURL$ $LastChangedRevision$

#  Modules
. $(miniade) || { echo "${0##*/}: ERROR: miniade failed (hint: run 'miniade' to see error)" >&2; exit 1; }
. <(pcms-config --format=shell)

#  Configurable stuff

#  Other globals

main()
{
    local MY_ARGS
    #  Defaults for options
    OPT_OWNER=root
    OPT_GROUP=root
    OPT_PERMS=644
    OPT_BACKUP_FLAG=true
    OPT_COMMENT_FLAG=true

    #  Process options
    special_opts_handler()
    {
        case $1 in
            --owner=*)    OPT_OWNER=${1#*=} ;;
            --group=*)    OPT_GROUP=${1#*=} ;;
            --perms=*)    OPT_PERMS=${1#*=} ;;
            --backup)     OPT_BACKUP_FLAG=true ;;
            --no-backup)  OPT_BACKUP_FLAG=false ;;
            --comment)    OPT_COMMENT_FLAG=true ;;
            --no-comment) OPT_COMMENT_FLAG=false ;;
            *)            return 1 ;;
        esac
    }
    miniade_process_options --help-handler=help --special-opts-handler=special_opts_handler MY_ARGS "$@" && set -- "${MY_ARGS[@]}"

    #  Process arguments
    [ $# = 1 ] || miniade_bad_usage
    eval "GENERATOR_ABSFILE=\"\$(realpath \"\$$#\")\""

    #  Sanity checks and derivations
    TARGET="$PCMS_STATE_PREFIX/generated-files/${GENERATOR_ABSFILE#*/generators/}"
    miniade_debug 5 "main: TARGET=$TARGET"
    TMP_TARGET=/tmp/$PROGNAME.$$
    COMMENT="#  This file was generated by $PROGNAME on $(date) for host $HOSTNAME. Manual edits will be lost!"
    COMMENT_REGEXP="^${COMMENT/on * for/on .* for}\$"
    miniade_debug 5 "main: COMMENT_REGEXP=[$COMMENT_REGEXP]"

    #  Guts
    miniade_debug 5 "main: $TARGET: generating ..."
    mkdir -p "${TARGET%/*}"
    { ! $OPT_BACKUP_FLAG; } || [ ! -f "$TARGET" ] || cp "$TARGET" "$TARGET.bak"
    {
        { ! $OPT_COMMENT_FLAG; } || echo "$COMMENT"
        RC=0
        bash "$1" || RC=$?
    } > "$TMP_TARGET"
    if [ $RC != 0 ]; then
        rm -f "$TMP_TARGET"
        miniade_error "failed to generate (hint: see messages above)"
    fi
    chown "$OPT_OWNER" "$TMP_TARGET"
    chgrp "$OPT_GROUP" "$TMP_TARGET"
    chmod "$OPT_PERMS" "$TMP_TARGET"

    if [ ! -f "$TARGET" ]; then
        miniade_debug 5 "main: $TARGET: does not exist"
        MOVE_FLAG=true
    elif ! diff -I "$COMMENT_REGEXP" "$TMP_TARGET" "$TARGET" > /dev/null; then
        miniade_debug 5 "main: $TARGET: exists but differs"
        MOVE_FLAG=true
    elif [ $(stat -c %U "$TARGET") != $OPT_OWNER -o $(stat -c %G "$TARGET") != $OPT_GROUP -o $(stat -c %a "$TARGET") != $OPT_PERMS ]; then
        miniade_debug 5 "main: $TARGET: exists, doesn't differ but has wrong owner/group/perms"
        MOVE_FLAG=true
    else
        miniade_debug 5 "main: $TARGET: identical"
        MOVE_FLAG=false
    fi

    if $MOVE_FLAG; then
        mv "$TMP_TARGET" "$TARGET"
    else
        rm -f "$TMP_TARGET"
    fi
}

help()
{
    local PROGNAME

    miniade_get_progname PROGNAME
    echo "Usage: $PROGNAME [ <standard-options> ] [ --owner=<owner> ] [ --group=<group> ] [ --perms=<perms> ] <script>"
    exit 0
}

main "$@"