//check if the ertmp node is fully filled in; if so - update er object
public bool CheckAndPush(ERTMP node)
{
if (node.am == 0 || node.cd == null || node.rt == 0.0F)
{
return(false);
}
if (node.am > 1)
{
node.rt = node.rt / node.am;
node.am = 1;
}
er = new ExchangeRate(new Currency(node.cd), new Currency("CZK"), (decimal)node.rt);
return(true);
}
public IEnumerable <ExchangeRate> GetExchangeRates(IEnumerable <Currency> currencies)
{
// getting html code from the webpage
var client = new WebClient();
var text = client.DownloadString(
"https://www.cnb.cz/en/financial_markets/foreign_exchange_market/exchange_rate_fixing/daily.jsp");
// processing the html code string, using regular expressions
StringReader sr = new StringReader(text);
string s = null;
Regex rgx = new Regex(@"kurzy_tisk");
// I studied the initial html code and after the lines with "kurzy tisk" there are a few lines with
// the codes and rates that we need, so I just made a simple loop which breaks as soon as I find those
// works as follows: finds "kurzy tisk", then for 20 lines (enough to read all rates) processes another
// regular expression to extract the required info and parses to another method
while (true)
{
s = sr.ReadLine();
if (rgx.IsMatch(s))
{
for (int i = 0; i < 20; i++)
{
String k = sr.ReadLine();
MatchCollection mc = Regex.Matches(k, @"(<td>|<td align=.right.>)(.+?)</td>");
int c = 0; // iterator for matches of the regex (because the expression extracts some extra info which we need to dispose of)
int y = 0; // iterator for the insides of ertmp class
ERTMP tmp = new ERTMP();
foreach (Match m in mc)
{
if (c % 5 < 2) // we don't need names of the countries and names of their currencies
{
y = 0;
c++;
continue;
}
else
{
String x = m.Groups[2].Value; //once we reach what we need, we push it to the corresponding values of a node
//pushing info to different fields of the ertmp class
switch (y)
{
case 0:
tmp.am = int.Parse(x);
break;
case 1:
tmp.cd = x;
break;
case 2:
tmp.rt = float.Parse(x);
break;
}
// if our temp class is fully filled with info, we process it, push to the list and renew
if (CheckAndPush(tmp))
{
tmp = new ERTMP();
foreach (Currency cu in currencies)
{
if (cu.Code.Equals(er.SourceCurrency.Code))
{
data.Add(er);
er = new ExchangeRate(new Currency(""), new Currency(""), 0);
break;
}
}
}
c++;
y++;
}
}
}
break;
}
}
return(data);
}
