#!/bin/bash

# convertcurrency--Given an amount and base currency, convertw it to the
#   specified target currency using ISO currency identifiers.

# Uses Google's finance converter for the heavy lifting:
#   http://www.google.com/finance/converter?a=1&from=USD&to=GBP

if [ $# -eq 0 ]; then
   echo "Usage: $(basename $0) amount currency to currency"
   echo "Most common currencies are CAD, CNY, EUR, USD, INR, JPY, and MXN"
   echo "Use \"$(basename $0) list\" for the full list of supported currencies"
fi

if [ $(uname) = "Darwin" ]; then
  LANG=C # For an issue on Macs with invalid byte sequences and lynx
fi
     url="https://www.google.com/finance/converter"
tempfile="/tmp/converter.$$"
    lynx=$(which lynx)

# Since this has multiple uses, let's grab this data before anything else.

currencies=$($lynx -source "$url" | grep "option  value=" | \
    cut -d\" -f2- | sed 's/">/ /' | cut -d\( -f1 | sort | uniq)

########### Deal with all non-conversion requests.

if [ $# -ne 4 ] ; then
  if [ "$1" = "list" ] ; then
    # Produce a listing of all currency symbols known by the converter.
    echo "List of supported currencies:"
    echo "$currencies"
  fi
  exit 0
fi

########### Now let's do a conversion.

if [ $3 != "to" ] ; then
  echo "Usage: $(basename $0) value currency TO currency"
  echo "(use \"$(basename $0) list\" to get a list of all currency values)"
  exit 0
fi

amount=$1
basecurrency="$(echo $2 | tr '[:lower:]' '[:upper:]')"
targetcurrency="$(echo $4 | tr '[:lower:]' '[:upper:]')"

# And let's do it--finally!

$lynx -source "$url?a=$amount&from=$basecurrency&to=$targetcurrency" | \
  grep 'id=currency_converter_result' | sed 's/<[^>]*>//g'

exit 0