feat(Http): support response caching

app/src/main/kotlin/com/aliucord/manager/di/Http.kt

@@ -1,18 +1,30 @@
 package com.aliucord.manager.di
 
+import android.app.Application
 import com.aliucord.manager.BuildConfig
 import io.ktor.client.HttpClient
+import io.ktor.client.call.HttpClientCall
 import io.ktor.client.engine.okhttp.OkHttp
+import io.ktor.client.plugins.cache.HttpCache
+import io.ktor.client.plugins.cache.storage.FileStorage
 import io.ktor.client.plugins.contentnegotiation.ContentNegotiation
 import io.ktor.client.plugins.defaultRequest
+import io.ktor.client.request.HttpRequestBuilder
 import io.ktor.client.request.header
-import io.ktor.http.HttpHeaders
+import io.ktor.client.statement.HttpReceivePipeline
+import io.ktor.client.statement.HttpResponse
+import io.ktor.http.*
 import io.ktor.serialization.kotlinx.json.json
+import io.ktor.util.AttributeKey
+import io.ktor.util.date.GMTDate
+import io.ktor.utils.io.ByteReadChannel
+import io.ktor.utils.io.InternalAPI
 import kotlinx.serialization.json.Json
 import okhttp3.Dns
 import org.koin.core.scope.Scope
 import java.net.Inet4Address
 import java.net.InetAddress
+import kotlin.coroutines.CoroutineContext
 
 @Suppress("UnusedReceiverParameter")
 fun Scope.provideJson() = Json {
@@ -21,10 +33,12 @@ fun Scope.provideJson() = Json {
 
 fun Scope.provideHttpClient() = HttpClient(OkHttp) {
     val json: Json = get()
+    val application: Application = get()
 
     defaultRequest {
         header(HttpHeaders.UserAgent, "Aliucord Manager/${BuildConfig.VERSION_NAME}")
     }
+
     engine {
         config {
             dns(object : Dns {
@@ -42,7 +56,43 @@ fun Scope.provideHttpClient() = HttpClient(OkHttp) {
             })
         }
     }
+
     install(ContentNegotiation) {
         json(json)
     }
+
+    install(HttpCache) {
+        val dir = application.cacheDir.resolve("ktor")
+        publicStorage(FileStorage(dir))
+    }
+
+    // Custom plugin to allow overriding response cache headers, and force caching
+    install("OverrideCacheControl") {
+        receivePipeline.intercept(HttpReceivePipeline.Before) { response ->
+            val customCacheControl = response.call.attributes.getOrNull(CustomCacheControl)
+                ?: return@intercept
+
+            proceedWith(object : HttpResponse() {
+                @InternalAPI
+                override val rawContent: ByteReadChannel = response.rawContent
+                override val call: HttpClientCall = response.call
+                override val coroutineContext: CoroutineContext = response.coroutineContext
+                override val requestTime: GMTDate = response.requestTime
+                override val responseTime: GMTDate = response.responseTime
+                override val status: HttpStatusCode = response.status
+                override val version: HttpProtocolVersion = response.version
+
+                override val headers: Headers = headers {
+                    appendAll(response.headers)
+                    set(HttpHeaders.CacheControl, customCacheControl.toString())
+                }
+            })
+        }
+    }
+}
+
+private val CustomCacheControl: AttributeKey<CacheControl> = AttributeKey("CustomCacheControl")
+
+fun HttpRequestBuilder.cacheControl(cacheControl: CacheControl) {
+    attributes.put(CustomCacheControl, cacheControl)
 }

app/src/main/kotlin/com/aliucord/manager/manager/download/KtorDownloadManager.kt

@@ -27,6 +27,8 @@ class KtorDownloadManager(private val http: HttpClient) : IDownloadManager {
 
         try {
             val httpStmt = http.prepareGet(url) {
+                header(HttpHeaders.CacheControl, "no-cache, no-store")
+
                 // Disable compression due to bug on emulators
                 // This header cannot be set with Android's DownloadManager
                 if (IS_PROBABLY_EMULATOR) {

app/src/main/kotlin/com/aliucord/manager/network/services/AliucordGithubService.kt

@@ -2,17 +2,23 @@ package com.aliucord.manager.network.services
 
 import com.aliucord.manager.network.models.BuildInfo
 import com.aliucord.manager.network.utils.ApiResponse
+import io.ktor.client.request.header
 import io.ktor.client.request.url
-import kotlinx.coroutines.Dispatchers
+import io.ktor.http.HttpHeaders
-import kotlinx.coroutines.withContext
 
 class AliucordGithubService(
     val github: GithubService,
     val http: HttpService,
 ) {
-    suspend fun getDataJson(): ApiResponse<BuildInfo> {
+    /**
-        return withContext(Dispatchers.IO) {
+     * Fetches the build data of Aliucord (excluding Aliuhook).
-            http.request { url(DATA_JSON_URL) }
+     * @param force Whether to force Ktor to refetch/revalidate cache.
+     */
+    suspend fun getBuildData(force: Boolean = false): ApiResponse<BuildInfo> = http.request {
+        url(DATA_JSON_URL)
+
+        if (force) {
+            header(HttpHeaders.CacheControl, "no-cache")
         }
     }
 

app/src/main/kotlin/com/aliucord/manager/network/services/AliucordMavenService.kt

@@ -1,12 +1,22 @@
 package com.aliucord.manager.network.services
 
+import com.aliucord.manager.di.cacheControl
 import com.aliucord.manager.network.utils.*
+import io.ktor.client.request.header
 import io.ktor.client.request.url
-import io.ktor.http.HttpStatusCode
+import io.ktor.http.*
 
 class AliucordMavenService(private val http: HttpService) {
-    suspend fun getAliuhookVersion(): ApiResponse<SemVer> {
+    suspend fun getAliuhookVersion(force: Boolean = false): ApiResponse<SemVer> {
-        val metadataResponse = http.request<String> { url(ALIUHOOK_METADATA_URL) }
+        val metadataResponse = http.request<String> {
+            url(ALIUHOOK_METADATA_URL)
+
+            if (!force) {
+                cacheControl(CacheControl.MaxAge(maxAgeSeconds = 60 * 30)) // 30 min
+            } else {
+                header(HttpHeaders.CacheControl, "no-cache")
+            }
+        }
 
         return metadataResponse.transform {
             val versionString = "<release>(.+?)</release>".toRegex()

app/src/main/kotlin/com/aliucord/manager/patcher/steps/download/DownloadAliuhookStep.kt

@@ -35,7 +35,7 @@ class DownloadAliuhookStep : DownloadStep(), IDexProvider, KoinComponent {
 
     override suspend fun execute(container: StepRunner) {
         container.log("Obtaining latest aliuhook version")
-        targetVersion = maven.getAliuhookVersion().getOrThrow()
+        targetVersion = maven.getAliuhookVersion(force = true).getOrThrow()
         container.log("Fetched aliuhook version: $targetVersion")
 
         super.execute(container)

app/src/main/kotlin/com/aliucord/manager/patcher/steps/prepare/FetchInfoStep.kt

@@ -26,7 +26,7 @@ class FetchInfoStep : Step(), KoinComponent {
 
     override suspend fun execute(container: StepRunner) {
         container.log("Fetching ${AliucordGithubService.DATA_JSON_URL}")
-        data = github.getDataJson().getOrThrow()
+        data = github.getBuildData(force = true).getOrThrow()
         container.log("Fetched build data: $data")
     }
 }

app/src/main/kotlin/com/aliucord/manager/ui/screens/home/HomeModel.kt

@@ -154,7 +154,7 @@ class HomeModel(
     }
 
     suspend fun fetchRemoteData() {
-        github.getDataJson().fold(
+        github.getBuildData().fold(
             success = {
                 val versionCode = it.discordVersionCode.toIntOrNull()
                 if (versionCode == null) {