#!/bin/awk -f
BEGIN {
# We assume an awk implementation that is just plain dumb.
# We will convert an character to its ASCII value with the
# table ord[], and produce two-digit hexadecimal output
# without the printf("%02X") feature.

EOL = "%0A"	# "end of line" string (encoded)
split ("1 2 3 4 5 6 7 8 9 A B C D E F", hextab, " ")
hextab [0] = 0
for ( i=1; i<=255; ++i ) ord [ sprintf ("%c", i) "" ] = i + 0
}
{
encoded = ""
for ( i=1; i<=length ($0); ++i ) {
	c = substr ($0, i, 1)
	if ( c ~ /[a-zA-Z0-9.-]/ ) {
	encoded = encoded c	# safe character
	} else if ( c == " " ) {
	encoded = encoded "+"	# special handling
	} else {
	# unsafe character, encode it as a two-digit hex-number
	lo = ord [c] % 16
	hi = int (ord [c] / 16);
	encoded = encoded "%" hextab [hi] hextab [lo]
	}
}
if ( EncodeEOL ) {
	printf ("%s", encoded EOL)
} else {
	print encoded
}
}
END {
	#if ( EncodeEOL ) print ""
}