Configured caching headers (#179)

Signed-off-by: Arnau Mora Gras <arnyminerz@proton.me>

build.gradle.kts

@@ -15,6 +15,7 @@ repositories {
 
 dependencies {
     // Ktor dependencies
+    implementation(libs.ktor.server.cachingHeaders)
     implementation(libs.ktor.server.conditionalHeaders)
     implementation(libs.ktor.server.contentNegotiation)
     implementation(libs.ktor.server.core)

gradle/libs.versions.toml

@@ -21,6 +21,7 @@ ktor-client-contentNegotiation = { module = "io.ktor:ktor-client-content-negotia
 ktor-client-core = { module = "io.ktor:ktor-client-core", version.ref = "ktor" }
 ktor-client-cio = { module = "io.ktor:ktor-client-cio", version.ref = "ktor" }
 ktor-serializationJson = { module = "io.ktor:ktor-serialization-kotlinx-json", version.ref = "ktor" }
+ktor-server-cachingHeaders = { module = "io.ktor:ktor-server-caching-headers", version.ref = "ktor" }
 ktor-server-conditionalHeaders = { module = "io.ktor:ktor-server-conditional-headers", version.ref = "ktor" }
 ktor-server-contentNegotiation = { module = "io.ktor:ktor-server-content-negotiation", version.ref = "ktor" }
 ktor-server-core = { module = "io.ktor:ktor-server-core", version.ref = "ktor" }

src/main/kotlin/server/plugins/CachingHeaders.kt

@@ -0,0 +1,57 @@
+package server.plugins
+
+import io.ktor.http.CacheControl
+import io.ktor.http.HttpHeaders
+import io.ktor.http.content.CachingOptions
+import io.ktor.server.http.content.CachingOptions
+import io.ktor.server.plugins.cachingheaders.CachingHeadersConfig
+import java.time.ZonedDateTime
+import server.response.FileSource
+import server.response.FileUUID
+import server.response.ResourceId
+import server.response.ResourceType
+
+/**
+ * Configures the maximum age in seconds that file requests should be cached for.
+ *
+ * Default: `24 hours`
+ */
+private const val FILE_MAX_AGE = 24 * 60 * 60
+
+/**
+ * Configures the maximum age in seconds that data requests should be cached for.
+ *
+ * Default: `10 minutes`
+ */
+private const val DATA_MAX_AGE = 10 * 60
+
+/**
+ * Generates [CachingOptions] for caching file requests.
+ *
+ * @param maxAge The maximum age in seconds that file requests should be cached for.
+ */
+private fun cachingOptions(maxAge: Int): CachingOptions {
+    return CachingOptions(
+        cacheControl = CacheControl.MaxAge(maxAge),
+        expires = ZonedDateTime.now().plusSeconds(maxAge.toLong())
+    )
+}
+
+fun CachingHeadersConfig.configure() {
+    options { call, outgoingContent ->
+        val headers = call.response.headers
+
+        val fileUUID = headers[HttpHeaders.FileUUID]
+        val fileSource = headers[HttpHeaders.FileSource]
+        val resourceType = headers[HttpHeaders.ResourceType]
+        val resourceId = headers[HttpHeaders.ResourceId]?.toIntOrNull()
+
+        if (fileUUID != null && fileSource != null) {
+            return@options cachingOptions(FILE_MAX_AGE)
+        } else if (resourceType != null && resourceId != null) {
+            return@options cachingOptions(DATA_MAX_AGE)
+        }
+
+        null
+    }
+}

src/main/kotlin/server/plugins/Plugins.kt

@@ -4,6 +4,7 @@ import database.serialization.Json
 import io.ktor.serialization.kotlinx.json.json
 import io.ktor.server.application.Application
 import io.ktor.server.application.install
+import io.ktor.server.plugins.cachingheaders.CachingHeaders
 import io.ktor.server.plugins.conditionalheaders.ConditionalHeaders
 import io.ktor.server.plugins.contentnegotiation.ContentNegotiation
 import io.ktor.server.plugins.statuspages.StatusPages
@@ -17,6 +18,7 @@ import io.ktor.server.plugins.statuspages.StatusPages
  * @receiver The application on which this method is called.
  */
 fun Application.installPlugins() {
+    install(CachingHeaders) { configure() }
     install(ConditionalHeaders) { configure() }
     install(ContentNegotiation) { json(Json) }
     install(StatusPages) { configureStatusPages() }