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

android/build.gradle.kts

@@ -66,7 +66,11 @@ dependencies {
   implementation(libs.androidx.work.runtime.ktx)
   implementation(libs.coil)
   implementation(libs.copydown)
+  implementation(libs.jsoup)
   implementation(libs.kotlinx.collections.immutable)
   implementation(libs.kotlinx.coroutines.core)
   implementation(libs.sqldelight.extensions.coroutines)
+  testImplementation(libs.kotest.assertions.core)
+  testImplementation(libs.kotest.runner.junit5)
+  testImplementation(libs.okhttp.mockwebserver)
 }

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")
+      }
+    }
+  }
+}

android/src/test/kotlin/dev/msfjarvis/claw/android/viewmodel/CSRFRepositoryTest.kt

@@ -0,0 +1,56 @@
+/*
+ * 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 io.kotest.core.spec.Spec
+import io.kotest.core.spec.style.FunSpec
+import io.kotest.matchers.shouldBe
+import kotlinx.coroutines.Dispatchers
+import okhttp3.OkHttpClient
+import okhttp3.mockwebserver.Dispatcher
+import okhttp3.mockwebserver.MockResponse
+import okhttp3.mockwebserver.MockWebServer
+import okhttp3.mockwebserver.RecordedRequest
+
+class CSRFRepositoryTest : FunSpec() {
+  private val server = MockWebServer()
+
+  init {
+    test("Correctly extracts CSRF token").config(coroutineTestScope = true) {
+      val repo =
+        CSRFRepository(
+          OkHttpClient.Builder().build(),
+          Dispatchers.Default,
+          server.url("/").toString(),
+        )
+      repo.extractToken() shouldBe
+        "OZWykgFemPVeOSNmB53-ccKXe458X7xCInO1-qzFU6nk_9RCSrSQqS9OPmA5_pyy8qD3IYAIZ7XfAM3gdhJpkQ"
+    }
+  }
+
+  override suspend fun beforeSpec(spec: Spec) {
+    super.beforeSpec(spec)
+    val dispatcher =
+      object : Dispatcher() {
+        override fun dispatch(request: RecordedRequest): MockResponse {
+          return when (val path = request.path) {
+            "/" ->
+              MockResponse()
+                .setResponseCode(200)
+                .setBody(
+                  javaClass.classLoader!!
+                    .getResourceAsStream("csrf_page.html")
+                    .readAllBytes()
+                    .decodeToString(),
+                )
+            else -> error("Invalid path: $path")
+          }
+        }
+      }
+    server.dispatcher = dispatcher
+  }
+}