Calculating each exchange's fees (#188)

* Adds some constants for fee types
Adds some fee calculation in an attempt to be generic
Adds fee stuff to Bittrex
Adds fee stuff to bitstamp

* Fixes bitstamp fee calculation

* Tests
Tests all scenarios for GetFeeByType

* Adds method to wrapper
Adds err to response
Checks for err

* Adds support for Bittrex fees

* Adds maker/taker dynamic to fees
Updates tests
Adds bitmex fee support
Removes unused switch case scenarios to not waste space

* Adds bithumb support for fee calculation

* Adds Bitfinex fee support
Adds list of currencies as const strings
Sets up bitflyer

* Fixes arguments

* Greatly expands symbols
Adds Binance fee calculation support
Cleans up previous exchanges

* Fixes errors for fee calculations

* Adds ANX fee support

* Adds btcc fee support
Adds alphapoint fee wrapper support
Renames method to match "enum"
Uses symbols in tests, not inline strings

* Adds support for BTCMarkets fee calculation
Adds new method to retrieve fee amount from BTCMarkets
Adds new fee type struct: FeeBuilder
Updates ANX and BTCMarkets to use new FeeBuilder type struct
Standardises the tests to run when it comes to fee calculation

* Migrates all existing exchange fee to use new feebuilder type struct
Uses standard testing model

* Fixes unit tests

* Updates maker taker fees in test config

* Removes parallel from fee testing

* Removes more parallel from tests

* Adds coinbasepro fee support

* Adds Coinut fee support

* Adds Exmo fee support
Adds maker fee support to coinut
Introduces a type for fees and bank transfers to prevent random strings being used

* Adds partial bitflyer support
Moves bitflyer to feeBuilder struct

* Adds gateio fee support

* Adds Gemini fee support

* Adds hitbtc fee support

* Adds huobi fee support

* Adds HuobiHadax fee support

* Adds itbit fee support

* Adds partial kraken fee support with trading fees

* Finishes basic Kraken fee support

* Adds basic LakeBTC fee support

* Adds basic liqui fee support

* Adds localbitcoins fee support.......

* Adds basic okcoin fee support

* Adds simple OKEX fee support
Adds many new currency symbols
Fixes liqui's fees

* Adds poloniex fee support

* Adds fee support for Yobit

* Adds WEX fee support

* Adds ZB fee support

* Removes bad reference

* Improves accuracy of variable name

* trading fee method names are now consistent

(cherry picked from commit 21c82e8b90cae590cfd73d365d7be39e1a00e973)

* Fixes rebasing issues

* Fixes issues from rebase
Removes "IsTaker" as IsMaker bool can imply taker
Updates tests to actually work.

* Adds a zero to the test

* Fixes bitfinex api endpoints and fixes fee calculations

* Updates btcmarkets trading fee calculation

* Verifies tests with apis for all exchanges except coinbasepro, itbit and bitflyer
Removes taker fee test as taker is default

* Removes redundant all exchange wrapper error checks due to the error checks being redundant

* Addresses review comments:
- Renames variables
- Changes how functions return data
- Fixes typo

exchanges/bithumb/bithumb.go

@@ -11,6 +11,7 @@ import (
 
 	"github.com/thrasher-/gocryptotrader/common"
 	"github.com/thrasher-/gocryptotrader/config"
+	"github.com/thrasher-/gocryptotrader/currency/symbol"
 	exchange "github.com/thrasher-/gocryptotrader/exchanges"
 	"github.com/thrasher-/gocryptotrader/exchanges/request"
 	"github.com/thrasher-/gocryptotrader/exchanges/ticker"
@@ -564,3 +565,67 @@ func (b *Bithumb) SendAuthenticatedHTTPRequest(path string, params url.Values, r
 
 	return b.SendPayload("POST", b.APIUrl+path, headers, bytes.NewBufferString(payload), result, true, b.Verbose)
 }
+
+// GetFee returns an estimate of fee based on type of transaction
+func (b *Bithumb) GetFee(feeBuilder exchange.FeeBuilder) (float64, error) {
+	var fee float64
+
+	switch feeBuilder.FeeType {
+	case exchange.CryptocurrencyTradeFee:
+		fee = calculateTradingFee(feeBuilder.PurchasePrice, feeBuilder.Amount)
+	case exchange.CyptocurrencyDepositFee:
+		fee = getDepositFee(feeBuilder.FirstCurrency, feeBuilder.Amount)
+	case exchange.CryptocurrencyWithdrawalFee:
+		fee = getWithdrawalFee(feeBuilder.FirstCurrency)
+	}
+	if fee < 0 {
+		fee = 0
+	}
+	return fee, nil
+}
+
+// getDepositFee returns fee when performing a trade
+func calculateTradingFee(purchasePrice float64, amount float64) float64 {
+	fee := 0.0015
+
+	return fee * amount * purchasePrice
+}
+
+// getDepositFee returns fee on a currency when depositing small amounts to bithumb
+func getDepositFee(currency string, amount float64) float64 {
+	var fee float64
+
+	switch currency {
+	case symbol.BTC:
+		if amount <= 0.005 {
+			fee = 0.001
+		}
+	case symbol.LTC:
+		if amount <= 0.3 {
+			fee = 0.01
+		}
+	case symbol.DASH:
+		if amount <= 0.04 {
+			fee = 0.01
+		}
+	case symbol.BCH:
+		if amount <= 0.03 {
+			fee = 0.001
+		}
+	case symbol.ZEC:
+		if amount <= 0.02 {
+			fee = 0.001
+		}
+	case symbol.BTG:
+		if amount <= 0.15 {
+			fee = 0.001
+		}
+	}
+
+	return fee
+}
+
+// getWithdrawalFee returns fee on a currency when withdrawing out of bithumb
+func getWithdrawalFee(currency string) float64 {
+	return WithdrawalFees[currency]
+}