feat(android): add a repository for extracting CSRF token

android/src/main/kotlin/dev/msfjarvis/claw/android/viewmodel/CSRFRepository.kt

@@ -0,0 +1,36 @@
+/*
+ * Copyright © 2023 Harsh Shandilya.
+ * Use of this source code is governed by an MIT-style
+ * license that can be found in the LICENSE file or at
+ * https://opensource.org/licenses/MIT.
+ */
+package dev.msfjarvis.claw.android.viewmodel
+
+import dev.msfjarvis.claw.android.injection.IODispatcher
+import dev.msfjarvis.claw.api.injection.BaseUrl
+import javax.inject.Inject
+import kotlinx.coroutines.CoroutineDispatcher
+import kotlinx.coroutines.withContext
+import okhttp3.OkHttpClient
+import okhttp3.Request
+import org.jsoup.Jsoup
+
+/** Helper for extracting CSRF token for authenticated requests to https://lobste.rs. */
+class CSRFRepository
+@Inject
+constructor(
+  private val okHttpClient: OkHttpClient,
+  @IODispatcher private val dispatcher: CoroutineDispatcher,
+  @BaseUrl private val url: String,
+) {
+  suspend fun extractToken(): String? {
+    val request = Request.Builder().url(url).get().build()
+    return withContext(dispatcher) {
+      okHttpClient.newCall(request).execute().use { response ->
+        val doc = Jsoup.parse(response.body?.string() ?: return@use null)
+        val element = doc.select("meta[name=\"csrf-token\"]").first() ?: return@use null
+        return@use element.attr("content")
+      }
+    }
+  }
+}