private async Task <IEnumerable <KeyValuePair <string, ExchangeOrderBook> > > GetOrderBooks(
string[] marketSymbols,
IExchangeAPI api
)
{
IEnumerable <KeyValuePair <string, ExchangeOrderBook> > orderBooks;
if (marketSymbols.Length == 0)
{
orderBooks = await api.GetOrderBooksAsync(Max);
}
else
{
var orderBooksList = await Task.WhenAll(
marketSymbols.Select(async ms =>
{
var orderBook = await api.GetOrderBookAsync(ms, Max);
orderBook.MarketSymbol ??= ms;
return(orderBook);
})
);
orderBooks = orderBooksList.ToDictionary(k => k.MarketSymbol, v => v);
}
return(orderBooks);
}