#!/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 test $Argc -eq 0 {
   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"
}

if test $[uname] = "Darwin" {
  setglobal LANG = 'C' # For an issue on Macs with invalid byte sequences and lynx
}
     setglobal url = '"https://www.google.com/finance/converter'"
setglobal tempfile = ""/tmp/converter.$Pid""
    setglobal lynx = $[which lynx]

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

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

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

if test $Argc -ne 4  {
  if test $1 = "list"  {
    # Produce a listing of all currency symbols known by the converter.
    echo "List of supported currencies:"
    echo $currencies
  }
  exit 0
}

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

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

setglobal amount = $1
setglobal basecurrency = $[echo $2 | tr '[:lower:]' '[:upper:]]
setglobal 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