refactor: implement HttpClient as a singleton

Author: sebastinto

app/src/main/java/com/coderGtm/yantra/commands/weather/Command.kt

@@ -1,19 +1,9 @@
 package com.coderGtm.yantra.commands.weather
 
-import android.util.Log
-import com.coderGtm.yantra.BuildConfig
 import com.coderGtm.yantra.R
 import com.coderGtm.yantra.blueprints.BaseCommand
 import com.coderGtm.yantra.models.CommandMetadata
 import com.coderGtm.yantra.terminal.Terminal
-import io.ktor.client.HttpClient
-import io.ktor.client.engine.android.Android
-import io.ktor.client.plugins.contentnegotiation.ContentNegotiation
-import io.ktor.client.plugins.logging.LogLevel
-import io.ktor.client.plugins.logging.Logging
-import io.ktor.serialization.kotlinx.json.json
-import io.ktor.util.logging.Logger
-import kotlinx.serialization.json.Json
 
 class Command(terminal: Terminal) : BaseCommand(terminal) {
     override val metadata = CommandMetadata(
@@ -22,28 +12,6 @@ class Command(terminal: Terminal) : BaseCommand(terminal) {
         description = terminal.activity.getString(R.string.cmd_weather_help)
     )
 
-    // todo: ideally this would be a singleton that is re-used across the app
-    private val httpClient = HttpClient(Android) {
-        expectSuccess = true
-
-        install(ContentNegotiation) {
-            json(Json {
-                ignoreUnknownKeys = true
-                coerceInputValues = true
-            })
-        }
-        if (BuildConfig.DEBUG) {
-            install(Logging) {
-                logger = object : io.ktor.client.plugins.logging.Logger {
-                    override fun log(message: String) {
-                        Log.d("HTTP call", message)
-                    }
-                }
-                level = LogLevel.ALL
-            }
-        }
-
-    }
 
     override fun execute(command: String) {
         when (val parseResult = parseWeatherCommand(command, this.terminal.activity)) {
@@ -55,7 +23,7 @@ class Command(terminal: Terminal) : BaseCommand(terminal) {
             )
 
             is ParseResult.ListCommand -> showAvailableFields(this)
-            is ParseResult.Success -> fetchWeatherData(parseResult.args, this, httpClient)
+            is ParseResult.Success -> fetchWeatherData(parseResult.args, this)
         }
     }
 }

app/src/main/java/com/coderGtm/yantra/commands/weather/Helper.kt

@@ -5,7 +5,7 @@ import android.graphics.Typeface
 import androidx.appcompat.app.AppCompatDelegate
 import com.coderGtm.yantra.R
 import com.coderGtm.yantra.blueprints.BaseCommand
-import io.ktor.client.HttpClient
+import com.coderGtm.yantra.network.HttpClientProvider
 import io.ktor.client.call.body
 import io.ktor.client.plugins.ClientRequestException
 import io.ktor.client.request.get
@@ -26,9 +26,8 @@ private var weatherJob: Job? = null
  *
  * @param args The [WeatherCommandArgs] containing the location for which to fetch weather data.
  * @param command The [BaseCommand] instance.
- * @param httpClient The [HttpClient] instance used to make the network request.
  */
-fun fetchWeatherData(args: WeatherCommandArgs, command: BaseCommand, httpClient: HttpClient) {
+fun fetchWeatherData(args: WeatherCommandArgs, command: BaseCommand) {
     val location = args.location
 
     val langCode = AppCompatDelegate.getApplicationLocales().toLanguageTags()
@@ -51,7 +50,7 @@ fun fetchWeatherData(args: WeatherCommandArgs, command: BaseCommand, httpClient:
         try {
             ensureActive()
             val weather = withContext(Dispatchers.IO) {
-                httpClient.get(url).body<WeatherResponse>()
+                HttpClientProvider.client.get(url).body<WeatherResponse>()
             }
             handleResponse(weather, args, command)
         } catch (e: Exception) {

app/src/main/java/com/coderGtm/yantra/network/HttpClientProvider.kt

@@ -0,0 +1,42 @@
+package com.coderGtm.yantra.network
+
+import android.util.Log
+import com.coderGtm.yantra.BuildConfig
+import io.ktor.client.HttpClient
+import io.ktor.client.engine.android.Android
+import io.ktor.client.plugins.contentnegotiation.ContentNegotiation
+import io.ktor.client.plugins.logging.LogLevel
+import io.ktor.client.plugins.logging.Logging
+import io.ktor.serialization.kotlinx.json.json
+import kotlinx.serialization.json.Json
+
+/**
+ * Provides a singleton HttpClient instance for the application.
+ * This ensures efficient resource usage and connection pool reuse across all network requests.
+ */
+object HttpClientProvider {
+
+    val client: HttpClient by lazy {
+        HttpClient(Android) {
+            expectSuccess = true
+
+            install(ContentNegotiation) {
+                json(Json {
+                    ignoreUnknownKeys = true
+                    coerceInputValues = true
+                })
+            }
+
+            if (BuildConfig.DEBUG) {
+                install(Logging) {
+                    logger = object : io.ktor.client.plugins.logging.Logger {
+                        override fun log(message: String) {
+                            Log.d("HTTP call", message)
+                        }
+                    }
+                    level = LogLevel.ALL
+                }
+            }
+        }
+    }
+}