#!/bin/bash
#  $HeadURL$ $LastChangedRevision$
set -e
PROGNAME=$(basename $0)

#  Load support functions
. $(pcms-config PCMS_SHARE_PREFIX)/scripts/support.sh

main()
{
    local REAL_FUNCTION PRESENT BEFORE AFTER TEXT FILE REPLACE STATE

    #  Defaults for options
    VERBOSELEVEL=2
    LOGIC=true
    PRESENT=unset
    BEFORE=unset
    AFTER=unset
    REPLACE=unset
    TEXT=unset
    FILE=unset
  
    #  Process options
    while [ $# -ge 1 ]; do
        case $1 in
            --present=*)     PRESENT="${1#*=}" ;;
            --before=*)      BEFORE="${1#*=}" ;;
            --after=*)       AFTER="${1#*=}" ;;
            --replace=*)     REPLACE="${1#*=}" ;;
            --text=*)        TEXT="${1#*=}" ;;
            --file=*)        FILE=${1#*=} ;;
            -d)              VERBOSELEVEL=$2; shift ;;
            --debug=*)       VERBOSELEVEL=${1#*=} ;;
            -v|--verbose)    VERBOSELEVEL=3 ;;
            --)              shift; break ;;
            -*)              error "main: $1: bad option" ;;
            *)               break ;;
        esac
        shift
    done

    ##  Sanity checks and derivations
    check_not_unset TEXT FILE
    check_all_but_one_unset AFTER BEFORE REPLACE
    if [[ $PRESENT = unset ]]; then
        PRESENT=$TEXT
        PRESENT="${PRESENT//./\\.}"
        PRESENT="${PRESENT//\*/\\*}"
        PRESENT="${PRESENT//\+/\\+}"
        PRESENT="${PRESENT//\(/\\\(}"
        PRESENT="${PRESENT//\)/\\\)}"
        PRESENT="^$PRESENT\$"
        debug 4 "main: PRESENT not defined; converted [$TEXT] safe regexp [$PRESENT]"
    fi
    if [ "X$BEFORE" = XSOF ]; then
        warning "please use 'BOF' instead of 'SOF'"
        BEFORE=BOF
    fi

    #  Get state
    if  [ ! -f $FILE -o ! -r $FILE ]; then
        STATE=unconfigured
    elif perlgrep "$PRESENT" $FILE; then
        STATE=configured
    else 
        STATE=unconfigured
    fi
    debug 4 "main: STATE=$STATE"

    #  If already in desired state, do nothing
    if $LOGIC && [ $STATE = configured ]; then
        return 0

    elif ! $LOGIC && [ $STATE = unconfigured ]; then
        return 0

    #  Make changes
    elif ! $LOGIC && [ $STATE = configured ]; then
        internal "not implemented"
    
    elif $LOGIC && [ $STATE = unconfigured ]; then
	mkdir -p $(dirname $FILE)
        touch $FILE
        if [[ $AFTER =~ ^EOF$ ]]; then
            echo "$TEXT" >> $FILE
        elif [[ $BEFORE =~ ^BOF$ ]]; then
            TMP_FILE=$(mktemp)
            { echo "$TEXT"; cat $FILE; } > $TMP_FILE
            cat $TMP_FILE > $FILE
            rm -f $TMP_FILE
        elif [[ $AFTER != unset ]] && perlgrep "$AFTER" $FILE; then
            perl -pi -e 'BEGIN { sub r { ($s)=@_; $s =~ s/\\\\/\\/g; $s =~ s/\\n/\n/g; $s =~ s/\\t/\t/g; return $s; } $desired_after = &r(shift); $desired_text = &r(shift); } s/($desired_after)/$1\n$desired_text/;' "$AFTER" "$TEXT" $FILE
        elif [[ $AFTER != unset ]]; then
            error "$FILE: $AFTER: not found in file (1)"
        elif [[ $BEFORE != unset ]] && perlgrep "$BEFORE" $FILE; then
            perl -pi -e 'BEGIN { sub r { ($s)=@_; $s =~ s/\\\\/\\/g; $s =~ s/\\n/\n/g; $s =~ s/\\t/\t/g; return $s; } $desired_before = &r(shift); $desired_text = &r(shift); } s/($desired_before)/$desired_text\n$1/;' "$BEFORE" "$TEXT" $FILE
        elif [[ $BEFORE != unset ]]; then
            error "$FILE: $BEFORE: not found in file (2)"
        elif [[ $BEFORE != unset ]] && perlgrep "$BEFORE" $FILE; then
            perl -pi -e 'BEGIN { sub r { ($s)=@_; $s =~ s/\\\\/\\/g; $s =~ s/\\n/\n/g; $s =~ s/\\t/\t/g; return $s; } $desired_before = &r(shift); $desired_text = &r(shift); } s/($desired_before)/$desired_text\n$1/;' "$BEFORE" "$TEXT" $FILE
        elif [[ $BEFORE != unset ]]; then
            error "$FILE: $BEFORE: not found in file (3)"
        elif [[ $REPLACE != unset ]] && perlgrep "$REPLACE" $FILE; then
            perl -pi -e 'BEGIN { sub r { ($s)=@_; $s =~ s/\\\\/\\/g; $s =~ s/\\n/\n/g; $s =~ s/\\t/\t/g; return $s; } $desired_replace = &r(shift); $desired_text = &r(shift); } s/$desired_replace/$desired_text/;' "$REPLACE" "$TEXT" $FILE
        elif [[ $REPLACE != unset ]]; then
            error "$FILE: $REPLACE: not found in file (4)"
        else
            internal "this should not happen"
        fi
    fi
}

perlgrep()
{
    local PATTERN FILE RC

    PATTERN="$1"
    FILE="$2"

    RC=0
    perl -ne 'BEGIN { sub r { ($s)=@_; $s =~ s/\\\\/\\/g; $s =~ s/\\n/\n/g; $s =~ s/\\t/\t/g; return $s; } $rc = 1; $pattern = &r(shift); } END { exit $rc; } if (/$pattern/) { $rc=0; last; }' "$PATTERN" "$FILE" || RC=$?

    return $RC
}

main "$@"