Kotlin: allow pluggable HTTP clients (#1381)

* Replace ktor with Google Java HTTP client

* Remove ktor and clean up methods

* Disable cookie management for Apache transport

Author: tjbanghart

kotlin/build.gradle

@@ -15,7 +15,6 @@ defaultTasks 'jar'
 
 repositories {
     mavenCentral()
-    maven { url "https://dl.bintray.com/kotlin/ktor" }
     maven { url "https://dl.bintray.com/kotlin/kotlinx" }
     maven { url "https://jitpack.io" }
 }
@@ -32,10 +31,10 @@ dependencies {
     implementation "io.github.cdimascio:dotenv-kotlin:6.2.2"
     implementation "org.ini4j:ini4j:0.5.4"
 
-    implementation "io.ktor:ktor-client:$ktorVersion"
-    implementation "io.ktor:ktor-client-okhttp:$ktorVersion"
-    implementation "io.ktor:ktor-client-json:$ktorVersion"
-    implementation "io.ktor:ktor-client-gson:$ktorVersion"
+    implementation "com.google.http-client:google-http-client:$googleHttpVersion"
+    implementation "com.google.http-client:google-http-client-apache-v2:$googleHttpVersion"
+    implementation "com.google.http-client:google-http-client-gson:$googleHttpVersion"
+
 
     implementation 'org.jetbrains.kotlinx:kotlinx-coroutines-core:1.3.0-RC'
     implementation 'com.google.code.gson:gson:2.8.5'

kotlin/gradle.properties

@@ -1,2 +1,2 @@
 kotlinVersion=1.7.10
-ktorVersion=1.6.7
+googleHttpVersion=1.43.3

kotlin/src/main/com/looker/rtl/APIMethods.kt

@@ -41,27 +41,27 @@ open class APIMethods(val authSession: AuthSession) {
         }
     }
 
-    inline fun <reified T> get(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
+    inline fun <reified T : Any> get(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
         return authSession.transport.request<T>(HttpMethod.GET, path, queryParams, body, authRequest)
     }
 
-    inline fun <reified T> head(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
+    inline fun <reified T : Any> head(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
         return authSession.transport.request<T>(HttpMethod.HEAD, path, queryParams, body, authRequest)
     }
 
-    inline fun <reified T> delete(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
+    inline fun <reified T : Any> delete(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
         return authSession.transport.request<T>(HttpMethod.DELETE, path, queryParams, body, authRequest)
     }
 
-    inline fun <reified T> post(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
+    inline fun <reified T : Any> post(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
         return authSession.transport.request<T>(HttpMethod.POST, path, queryParams, body, authRequest)
     }
 
-    inline fun <reified T> put(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
+    inline fun <reified T : Any> put(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
         return authSession.transport.request<T>(HttpMethod.PUT, path, queryParams, body, authRequest)
     }
 
-    inline fun <reified T> patch(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
+    inline fun <reified T : Any> patch(path: String, queryParams: Values = mapOf(), body: Any? = null): SDKResponse {
         return authSession.transport.request<T>(HttpMethod.PATCH, path, queryParams, body, authRequest)
     }
 

kotlin/src/main/com/looker/rtl/AuthSession.kt

@@ -24,8 +24,7 @@
 
 package com.looker.rtl
 
-import io.ktor.client.request.forms.*
-import io.ktor.http.*
+import com.google.api.client.http.UrlEncodedContent
 
 open class AuthSession(
     open val apiSettings: ConfigurationProvider,
@@ -144,12 +143,11 @@ open class AuthSession(
                 unQuote(System.getProperty("${apiSettings.environmentPrefix}_CLIENT_ID") ?: config[client_id])
             val clientSecret =
                 unQuote(System.getProperty("${apiSettings.environmentPrefix}_CLIENT_SECRET") ?: config[client_secret])
-            val body = FormDataContent(
-                Parameters.build {
-                    append(client_id, clientId)
-                    append(client_secret, clientSecret)
-                }
+            val params = mapOf(
+                client_id to clientId,
+                client_secret to clientSecret
             )
+            val body = UrlEncodedContent(params)
             val token = ok<AuthToken>(
                 transport.request<AuthToken>(
                     HttpMethod.POST,

kotlin/src/main/com/looker/rtl/Constants.kt

@@ -42,6 +42,7 @@ val BinaryMatch = Regex(MATCH_MODE_BINARY, RegexOption.IGNORE_CASE)
 
 const val DEFAULT_TIMEOUT = 120
 const val DEFAULT_API_VERSION = "4.0" // Kotlin requires at least API 4.0
+const val DEFAULT_HTTP_TRANSPORT = "apache"
 
 typealias Values = Map<String, Any?>
 

kotlin/src/main/com/looker/rtl/ErrorDoc.kt

@@ -30,7 +30,7 @@ class ErrorDocItem(var url: String)
 /** Structure of the error code document index */
 typealias ErrorCodeIndex = HashMap<String, ErrorDocItem>
 
- interface IErrorDocLink {
+interface IErrorDocLink {
     /** base redirector url */
     var redirector: String
     /** api version of the error link */
@@ -39,9 +39,9 @@ typealias ErrorCodeIndex = HashMap<String, ErrorDocItem>
     var statusCode: String
     /** REST API Path */
     var apiPath: String
- }
+}
 
- interface IErrorDoc {
+interface IErrorDoc {
     /** Index of all known error codes. Call load() to populate it */
     var index: ErrorCodeIndex?
 
@@ -103,10 +103,10 @@ typealias ErrorCodeIndex = HashMap<String, ErrorDocItem>
      * @param errorMdUrl url for the error document
      */
     fun methodName(errorMdUrl: String): String
- }
+}
 
 /** Class to process Looker API error payloads and retrieve error documentation */
-class ErrorDoc(val sdk: APIMethods, val cdnUrl: String = ErrorCodesUrl): IErrorDoc {
+class ErrorDoc(val sdk: APIMethods, val cdnUrl: String = ErrorCodesUrl) : IErrorDoc {
     companion object {
         /** Location of the public CDN for Looker API Error codes */
         const val ErrorCodesUrl = "https://static-a.cdn.looker.app/errorcodes/"

kotlin/src/main/com/looker/rtl/GsonObjectParser.kt.kt

@@ -0,0 +1,47 @@
+package com.looker.rtl
+
+import com.google.api.client.util.ObjectParser
+import com.google.gson.Gson
+import com.google.gson.stream.JsonReader
+import java.io.InputStream
+import java.io.InputStreamReader
+import java.io.Reader
+import java.lang.reflect.Type
+import java.nio.charset.Charset
+
+/** Custom GSON based parser for deserialization. */
+class GsonObjectParser : ObjectParser {
+    override fun <T : Any?> parseAndClose(
+        inputStream: InputStream?,
+        charset: Charset?,
+        clazz: Class<T>?,
+    ): T {
+        return doParseAndClose(InputStreamReader(inputStream, charset), clazz)
+    }
+
+    override fun parseAndClose(inputStream: InputStream?, charset: Charset?, type: Type?): Any {
+        return doParseAndClose(InputStreamReader(inputStream, charset), type)
+    }
+
+    override fun <T : Any?> parseAndClose(reader: Reader?, clazz: Class<T>?): T {
+        return doParseAndClose(reader, clazz)
+    }
+
+    override fun parseAndClose(reader: Reader?, type: Type?): Any {
+        return doParseAndClose(reader, type)
+    }
+
+    private fun <T : Any?> doParseAndClose(reader: Reader?, type: Type?): T {
+        val jsonReader = JsonReader(reader)
+        jsonReader.use {
+            return GSON.fromJson(reader, type)
+        }
+    }
+
+    companion object {
+        /** [Gson] instance used for serializing Kotlin data classes and deserializing responses */
+        val GSON: Gson = Gson().newBuilder()
+            .registerTypeAdapter(AuthToken::class.java, AuthTokenAdapter())
+            .create()
+    }
+}