From 6ea7f16fb97313aab207439f0da90f2bc070baa9 Mon Sep 17 00:00:00 2001
From: Ben Fradet <benjamin.fradet@gmail.com>
Date: Mon, 22 Apr 2019 11:15:20 +0200
Subject: [PATCH] Remove infinite recursion when converting currencies (closes
 #166)

---
 .../com.snowplowanalytics/forex/Forex.scala   | 23 ++++++++-----------
 .../forex/OerClient.scala                     |  2 +-
 .../ForexNowSpec.scala                        |  8 +++++++
 3 files changed, 19 insertions(+), 14 deletions(-)

diff --git a/src/main/scala/com.snowplowanalytics/forex/Forex.scala b/src/main/scala/com.snowplowanalytics/forex/Forex.scala
index e294964..b0b9e22 100644
--- a/src/main/scala/com.snowplowanalytics/forex/Forex.scala
+++ b/src/main/scala/com.snowplowanalytics/forex/Forex.scala
@@ -92,7 +92,7 @@ object Forex {
  */
 final case class Forex[F[_]: Monad: ZonedClock](config: ForexConfig, client: OerClient[F]) {
 
-  def rate: ForexLookupTo[F] = ForexLookupTo(1, config.baseCurrency, config, client)
+  def rate: ForexLookupTo[F] = convert(1d, config.baseCurrency)
 
   /**
    * Starts building a fluent interface, performs currency look up from *source* currency.
@@ -100,26 +100,23 @@ final case class Forex[F[_]: Monad: ZonedClock](config: ForexConfig, client: Oer
    * @param currency Source currency
    * @return ForexLookupTo object which is the part of the fluent interface
    */
-  def rate(currency: CurrencyUnit): ForexLookupTo[F] =
-    ForexLookupTo(1, currency, config, client)
+  def rate(currency: CurrencyUnit): ForexLookupTo[F] = convert(1d, currency)
 
   /**
-   * Starts building a currency conversion from the supplied currency, for the supplied amount.
+   * Starts building a currency conversion for the supplied amount, using the currency specified in config
    * @param amount The amount of currency to be converted
-   * @param currency CurrencyUnit to convert from
-   * @return a ForexLookupTo, part of the currency conversion fluent interface.
+   * @return a ForexLookupTo, part of the currency conversion fluent interface
    */
-  def convert(amount: Double, currency: CurrencyUnit): ForexLookupTo[F] =
-    convert(amount, currency)
+  def convert(amount: Double): ForexLookupTo[F] = convert(amount, config.baseCurrency)
 
   /**
-   * Starts building a currency conversion for the supplied amount, using the currency specified in config
+   * Starts building a currency conversion from the supplied currency, for the supplied amount.
    * @param amount The amount of currency to be converted
-   * @return a ForexLookupTo, part of the currency conversion fluent interface
+   * @param currency CurrencyUnit to convert from
+   * @return a ForexLookupTo, part of the currency conversion fluent interface.
    */
-  def convert(amount: Double): ForexLookupTo[F] =
-    ForexLookupTo(amount, config.baseCurrency, config, client)
-
+  def convert(amount: Double, currency: CurrencyUnit): ForexLookupTo[F] =
+    ForexLookupTo(amount, currency, config, client)
 }
 
 /**
diff --git a/src/main/scala/com.snowplowanalytics/forex/OerClient.scala b/src/main/scala/com.snowplowanalytics/forex/OerClient.scala
index cd5bd70..90c9dd0 100644
--- a/src/main/scala/com.snowplowanalytics/forex/OerClient.scala
+++ b/src/main/scala/com.snowplowanalytics/forex/OerClient.scala
@@ -31,7 +31,7 @@ import responses._
  * @param nowishCache - user defined nowishCache
  * @param eodCache - user defined eodCache
  */
-case class OerClient[F[_]: Monad](
+final case class OerClient[F[_]: Monad](
   config: ForexConfig,
   nowishCache: Option[NowishCache[F]] = None,
   eodCache: Option[EodCache[F]]       = None
diff --git a/src/test/scala/com.snowplowanalytics.forex/ForexNowSpec.scala b/src/test/scala/com.snowplowanalytics.forex/ForexNowSpec.scala
index 53b1f1b..d4c4123 100644
--- a/src/test/scala/com.snowplowanalytics.forex/ForexNowSpec.scala
+++ b/src/test/scala/com.snowplowanalytics.forex/ForexNowSpec.scala
@@ -39,9 +39,17 @@ class ForexNowSpec extends Specification {
       val ioTradeInYenNow = ioFx.flatMap(_.convert(10000).to(CurrencyUnit.JPY).now)
       ioTradeInYenNow.unsafeRunSync() must beRight(
         (m: Money) => m.isGreaterThan(Money.of(CurrencyUnit.JPY, 10000, RoundingMode.HALF_EVEN)))
+      val ioTradeInYenNow2 = ioFx
+        .flatMap(_.convert(10000, CurrencyUnit.USD).to(CurrencyUnit.JPY).now)
+      ioTradeInYenNow2.unsafeRunSync() must beRight(
+        (m: Money) => m.isGreaterThan(Money.of(CurrencyUnit.JPY, 10000, RoundingMode.HALF_EVEN)))
       val evalTradeInYenNow = evalFx.flatMap(_.convert(10000).to(CurrencyUnit.JPY).now)
       evalTradeInYenNow.value must beRight(
         (m: Money) => m.isGreaterThan(Money.of(CurrencyUnit.JPY, 10000, RoundingMode.HALF_EVEN)))
+      val evalTradeInYenNow2 = evalFx
+        .flatMap(_.convert(10000, CurrencyUnit.USD).to(CurrencyUnit.JPY).now)
+      evalTradeInYenNow2.value must beRight(
+        (m: Money) => m.isGreaterThan(Money.of(CurrencyUnit.JPY, 10000, RoundingMode.HALF_EVEN)))
     }
   }