#!/bin/sh

[ -z "$AGENT" ] && AGENT='curl -sA "Mozilla/5.0"'

if [ "$1" = "-l" ]; then
	$AGENT 'https://www.google.com/finance/converter' \
		| awk -F'<|>|"' '/select name=from value/, /\/select/ {if ($5 != "") {sub(/\(.*\)/, "", $5); print $3, $5}}'
	exit
fi

usage() {
	cat <<EOF
Usage: ${0##*/} IN-CURRENCY OUT-CURRENCY [VALUES...]
       ${0##*/} -l

Convert VALUES from IN-CURRENCY to OUT-CURRENCY.
VALUES are read from stdin if not provided.

CURRENCY is a 3-letters code like EUR, SEK, USD, etc.
See the list of codes with the '-l' option.

The download agent is specified from environment variable AGENT='$AGENT'.
EOF
}

if [ $# -lt 2 ]; then
	usage
	exit
fi

change="$($AGENT "http://www.google.com/finance?q=$1$2" | \
	awk -F '<|>' '/^1 / {print substr($3, 1, index($3, " "))}')"

if [ -z "$change" ]; then
	usage
	exit
fi	

shift 2

mul() {
	[ -n "$1" ] && [ -n "$2" ] && awk "BEGIN {print $1*$2}"
}

if [ -z "$1" ]; then
	while read v; do
		mul $v $change
	done
else
	for v; do
		mul $v $change
	done
fi