Migrate PackagerStatusCheck to Kotlin (facebook#48838)

Summary:
Pull Request resolved: facebook#48838

Migrate PackagerStatusCheck to Kotlin

changelog: [internal] internal

Reviewed By: tdn120, cortinico

Differential Revision: D68467780

packages/react-native/ReactAndroid/src/main/java/com/facebook/react/devsupport/PackagerStatusCheck.kt

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+@file:Suppress("DEPRECATION_ERROR") // Conflicting okhttp versions
+
+package com.facebook.react.devsupport
+
+import com.facebook.common.logging.FLog
+import com.facebook.react.common.ReactConstants
+import com.facebook.react.devsupport.interfaces.PackagerStatusCallback
+import java.io.IOException
+import java.util.Locale
+import java.util.concurrent.TimeUnit
+import okhttp3.Call
+import okhttp3.Callback
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import okhttp3.Response
+
+/** Use this class to check if the JavaScript packager is running on the provided host. */
+public open class PackagerStatusCheck {
+
+  private val client: OkHttpClient
+
+  public constructor() {
+    client =
+        OkHttpClient.Builder()
+            .connectTimeout(HTTP_CONNECT_TIMEOUT_MS.toLong(), TimeUnit.MILLISECONDS)
+            .readTimeout(0, TimeUnit.MILLISECONDS)
+            .writeTimeout(0, TimeUnit.MILLISECONDS)
+            .build()
+  }
+
+  public constructor(client: OkHttpClient) {
+    this.client = client
+  }
+
+  public open fun run(host: String, callback: PackagerStatusCallback): Unit {
+    val statusURL = createPackagerStatusURL(host)
+    val request = Request.Builder().url(statusURL).build()
+
+    client
+        .newCall(request)
+        .enqueue(
+            object : Callback {
+              override fun onFailure(call: Call, e: IOException) {
+                FLog.w(
+                    ReactConstants.TAG,
+                    "The packager does not seem to be running as we got an IOException requesting its status: ${e.message}")
+                callback.onPackagerStatusFetched(false)
+              }
+
+              override fun onResponse(call: Call, response: Response) {
+                if (!response.isSuccessful) {
+                  FLog.e(
+                      ReactConstants.TAG,
+                      "Got non-success http code from packager when requesting status: ${response.code()}")
+                  callback.onPackagerStatusFetched(false)
+                  return
+                }
+                val body = response.body()
+                if (body == null) {
+                  FLog.e(
+                      ReactConstants.TAG,
+                      "Got null body response from packager when requesting status")
+                  callback.onPackagerStatusFetched(false)
+                  return
+                }
+                val bodyString =
+                    body.string() // cannot call body.string() twice, stored it into variable.
+                // https://github.com/square/okhttp/issues/1240#issuecomment-68142603
+                if (PACKAGER_OK_STATUS != bodyString) {
+                  FLog.e(
+                      ReactConstants.TAG,
+                      "Got unexpected response from packager when requesting status: ${bodyString}")
+                  callback.onPackagerStatusFetched(false)
+                  return
+                }
+                callback.onPackagerStatusFetched(true)
+              }
+            })
+  }
+
+  private companion object {
+    private const val PACKAGER_OK_STATUS = "packager-status:running"
+    private const val HTTP_CONNECT_TIMEOUT_MS = 5_000
+    private const val PACKAGER_STATUS_URL_TEMPLATE = "http://%s/status"
+
+    private fun createPackagerStatusURL(host: String): String =
+        String.format(Locale.US, PACKAGER_STATUS_URL_TEMPLATE, host)
+  }
+}