:
##########################################################################
# Shellscript:	wordwrap - wrap lines on word boundaries
# Author     :	Heiner Steven <heiner.steven@odn.de>
# Date       :	2001-12-10
# Requires   :	
# Category   :	Text Utilities, Text Formatting
# SCCS-Id.   :	@(#) wordwrap	1.5 18/05/17
##########################################################################
# Description
#	A very simple text formatting program. The input is read
#	word by word.  All words are joined using a space (ASCII
#	32) character. If "-j" was specified, each line is
#	filled up to the maximum line length, or the next empty
#	line before it is printed. Each continued line can be
#	offset by a number of blanks.
#
# Note
#    o	Leading whitespace is ignored
#    o	An AWK program actually formats the input. It is written in
#	a way to be portable to a wide range of AWK dialects.
#    o  thanks for Samus-Aran for suggesting the "-l" option
#
# Caveats
#    o	Should have an option for keeping whitespace inbetween words
##########################################################################

PN=`basename "$0"`			# Program name
VER='1.5'

# Uncomment the following line to disable the search for the fastest AWK
#: ${AWK:=awk}

DEFWIDTH=72				# Default line length
DEFOFFSET=0				# Default continued line offset
DEFMARGIN=0				# Default left margin

Usage () {
    echo >&2 "$PN - wrap lines on word boundaries, $VER
usage: $PN [-j] [-w width] [-o offset] [-l margin] [file ...]
    -j  join multiple lines up to the maximum line length
    -l  left margin (default $DEFMARGIN)
    -o  offset of continued lines (default $DEFOFFSET)
    -w  max. line width (default is $DEFWIDTH characters)"
    exit 1
}

Msg () {
    for MsgLine
    do echo "$PN: $MsgLine" >&2
    done
}

Fatal () { Msg "$@"; exit 1; }

##########################################################################
# searchprog - search program using search PATH
# usage: searchprog program
##########################################################################

searchprog () {
    _search=$1; shift

    for _dir in `echo "$PATH" | sed "s/^:/.:/;s/:\$/:./;s/::/:.:/g;s/:/ /g"`
    do
        [ -x "$_dir/$_search" ] || continue
        echo "$_dir/$_search"
        return 0
    done

    return 1
}

# isint - is argument a valid integer number?
isint () {
    case "$1" in
    	*[!0-9]*)   return 1;;
	*)	    return 0;;
    esac
}

set -- `getopt :hjl:o:w: "$@"` || Usage
[ $# -lt 1 ] && Usage			# "getopt" detected an error

# Search for an AWK implementation, prefer the fastest one
: ${AWK:=`searchprog mawk || searchprog gawk || searchprog nawk || echo awk`}

LineWidth=
JoinLines=false
LeftMargin=
while [ $# -gt 0 ]
do
    case "$1" in
	-j)	JoinLines=true;;
	-l)	isint "$2" || Fatal "invalid margin: $2"
		LeftMargin=$2; shift;;
	-o)	isint "$2" || Fatal "invalid offset: $2"
		LineOffset=$2; shift;;
	-w)	isint "$2" || Fatal "invalid line width: $2"
		LineWidth=$2; shift;;
	--)	shift; break;;
	-h)	Usage;;
	-*)	Usage;;
	*)	break;;			# First file name
    esac
    shift
done

: ${LineWidth:=$DEFWIDTH}
: ${LineOffset:=$DEFOFFSET}
: ${LeftMargin:=$DEFMARGIN}

$AWK '
    BEGIN {
	WORDSEP = " "
	WORDSEPLEN = length (WORDSEP)
	maxwidth = '"$LineWidth"'
	if ( "'"$JoinLines"'" == "true" ) joinlines = 1; else joinlines = 0;
	line = ""
	offset = '"$LineOffset"'
	margin = '"$LeftMargin"'
	if ( offset >= 1 ) indent = sprintf ("%*s", offset, " ")
	if ( margin >= 1 ) leftmargin = sprintf ("%*s", margin, "")
    }
    {
    	# Special handling: preserve leading whitespace characters
	if ( line == "" ) {
	    for ( i=1; i<length($0); ++i ) {
		c = substr ($0, i, 1)
		if ( c != " " && c != "	" ) break
	    }
	    if ( i > 1 ) line = substr ($0, 1, i-1)
	}

	for ( i=1; i<=NF; ++i ) {
	    newlen = length (line) + length ($i)
	    if ( line != "" ) newlen += WORDSEPLEN
	    if ( newlen > maxwidth ) {
	        print leftmargin line
		line = indent $i
	    } else {
		if ( line != "" ) line = line WORDSEP
		line = line $i
	    }
	}

	# No joining of lines: print the current line immediately

	if ( !joinlines || NF == 0 ) {
	    print leftmargin line
	    if ( line != "" && NF == 0 ) print ""	# preserve empty line
	    line = ""
	}
    }
    END {
	if ( line != "" ) {
	    print leftmargin line
	}
    }
' "$@"