Add optional logging to SubsonicAPI.

Signed-off-by: Yahor Berdnikau <egorr.berd@gmail.com>

dependencies.gradle

@@ -30,11 +30,12 @@ ext.androidSupport = [
 ]
 
 ext.other = [
-        kotlinStdlib  : "org.jetbrains.kotlin:kotlin-stdlib-common:$versions.kotlin",
+        kotlinStdlib       : "org.jetbrains.kotlin:kotlin-stdlib-common:$versions.kotlin",
         retrofit           : "com.squareup.retrofit2:retrofit:$versions.retrofit",
         gsonConverter      : "com.squareup.retrofit2:converter-gson:$versions.retrofit",
         jacksonConverter   : "com.squareup.retrofit2:converter-jackson:$versions.retrofit",
         jacksonKotlin      : "com.fasterxml.jackson.module:jackson-module-kotlin:$versions.jackson",
+        okhttpLogging      : "com.squareup.okhttp3:logging-interceptor:$versions.okhttp",
 ]
 
 ext.testing = [

subsonic-api/build.gradle

@@ -12,6 +12,7 @@ dependencies {
     compile other.retrofit
     compile other.jacksonConverter
     compile other.jacksonKotlin
+    compile other.okhttpLogging
 
     testCompile testing.junit
     testCompile testing.kotlinJunit

subsonic-api/src/main/kotlin/org/moire/ultrasonic/api/subsonic/SubsonicAPI.kt

@@ -4,6 +4,7 @@ import com.fasterxml.jackson.databind.DeserializationFeature
 import com.fasterxml.jackson.databind.ObjectMapper
 import com.fasterxml.jackson.module.kotlin.KotlinModule
 import okhttp3.OkHttpClient
+import okhttp3.logging.HttpLoggingInterceptor
 import retrofit2.Retrofit
 import retrofit2.converter.jackson.JacksonConverterFactory
 import java.math.BigInteger
@@ -17,7 +18,8 @@ class SubsonicAPI(baseUrl: String,
                   username: String,
                   private val password: String,
                   clientProtocolVersion: SubsonicAPIVersions,
-                  clientID: String) {
+                  clientID: String,
+                  debug: Boolean = false) {
     private val okHttpClient = OkHttpClient.Builder()
             .addInterceptor { chain ->
                 // Adds default request params
@@ -30,6 +32,13 @@ class SubsonicAPI(baseUrl: String,
                         .addQueryParameter("f", "json")
                         .build()
                 chain.proceed(originalRequest.newBuilder().url(newUrl).build())
+            }
+            .apply {
+                if (debug) {
+                    val loggingInterceptor = HttpLoggingInterceptor()
+                    loggingInterceptor.level = HttpLoggingInterceptor.Level.BASIC
+                    this.addInterceptor(loggingInterceptor)
+                }
             }.build()
 
     private val jacksonMapper = ObjectMapper()
@@ -49,7 +58,7 @@ class SubsonicAPI(baseUrl: String,
      *
      * @return initialized API instance
      */
-    fun getApi() = subsonicAPI
+    fun getApi(): SubsonicAPIDefinition = subsonicAPI
 
     private fun passwordHex() = "enc:${password.toHexBytes()}"