Automatic gas price

Use ethgasstation API for gas price if :auto-gas-price? is true in
config.

Fixes: #189

src/clj/commiteth/eth/core.clj

@@ -6,19 +6,40 @@
             [clojure.string :refer [join]]
             [clojure.tools.logging :as log]
             [clojure.string :as str]
-            [pandect.core :as pandect]))
+            [pandect.core :as pandect]
+            [commiteth.util.util :refer [json-api-request]]))
 
 (defn eth-rpc-url [] (env :eth-rpc-url "http://localhost:8545"))
 (defn eth-account [] (:eth-account env))
 (defn eth-password [] (:eth-password env))
 (defn gas-estimate-factor [] (env :gas-estimate-factor 1.0))
+(defn auto-gas-price? [] (env :auto-gas-price? false))
 
-(defn gas-price
+(defn eth-gasstation-gas-price
   []
+  (let [data (json-api-request "https://ethgasstation.info/json/ethgasAPI.json")
+        avg-price (-> (get data "average")
+                      bigint)
+        avg-price-gwei (/ avg-price (bigint 10))]
+    (->> (* (bigint (Math/pow 10 9)) avg-price-gwei) ;; for some reason the API returns 10x gwei price
+        .toBigInteger)))
+
+
+(defn gas-price-from-config []
   (-> (:gas-price env 20000000000) ;; 20 gwei default
       str
       BigInteger.))
 
+(defn gas-price
+  []
+  (if (auto-gas-price?)
+    (try
+      (eth-gasstation-gas-price)
+      (catch Throwable t
+        (log/error "Failed to get gas price with ethgasstation API" t)
+        (gas-price-from-config)))
+    (gas-price-from-config)))
+
 (defn eth-rpc
   [method params]
   (let [request-id (rand-int 4096)

src/clj/commiteth/util/crypto_fiat_value.clj

@@ -1,19 +1,13 @@
 (ns commiteth.util.crypto-fiat-value
-  (:require [clj-http.client :as http]
-            [mount.core :as mount]
+  (:require [mount.core :as mount]
             [clojure.tools.logging :as log]
             [commiteth.config :refer [env]]
-            [clojure.data.json :as json]))
+            [commiteth.util.util :refer [json-api-request]]))
 
 
 (defn fiat-api-provider []
   (env :fiat-api-provider :coinmarketcap))
 
-(defn json-api-request [url]
-  (->> (http/get url)
-       (:body)
-       (json/read-str)))
-
 
 (defn get-token-usd-price-cryptonator
   "Get current USD value for a token using cryptonator API"

src/clj/commiteth/util/util.clj

@@ -1,4 +1,7 @@
-(ns commiteth.util.util)
+(ns commiteth.util.util
+  (:require
+   [clj-http.client :as http]
+   [clojure.data.json :as json]))
 
 
 (defn eth-decimal->str [n]
@@ -6,3 +9,8 @@
 
 (defn usd-decimal->str [n]
   (format "%.2f" n))
+
+(defn json-api-request [url]
+  (->> (http/get url)
+       (:body)
+       (json/read-str)))