Add fallback bodyHandler

We found that if http request is read first then forest handler is called,
it may complain "body already read". Workaround this by installing a
fallback bodyHandler.

Author: Bo Zhang

build.gradle.kts

@@ -15,7 +15,7 @@ val configureGroovy: Project.() -> Unit by rootProject.ext
 val configureKotlin: Project.() -> Unit by rootProject.ext
 
 rootProject.group = "io.forestframework"
-rootProject.version = "0.3.5-SNAPSHOT"
+rootProject.version = "0.3.6-SNAPSHOT"
 
 allprojects {
     repositories {

core/src/main/java/io/forestframework/core/http/DefaultHttpRequest.java

@@ -30,12 +30,20 @@ public class DefaultHttpRequest implements HttpRequest {
     private final HttpServerRequestInternal delegate;
     private final HttpResponse response;
     private final RoutingMatchResult routingMatchResult;
+    /**
+     * This allows a body to be read multiple times, in multiple handlers.
+     */
     private Future<Buffer> bodyCache;
 
     public DefaultHttpRequest(HttpServerRequestInternal delegate, RoutingMatchResult routingMatchResult) {
         this.delegate = delegate;
         this.routingMatchResult = routingMatchResult;
         this.response = new DefaultHttpResponse(delegate.response());
+        // TODO this is unsafe
+        // However, we need this to handle the situation in which HTTP request is read to the end
+        // before `body()` is called.
+        // Also, as said in `bodyHandler` documentation, it's unsafe to call it on a huge input
+        bodyHandler(buffer -> bodyCache = Future.succeededFuture(buffer));
     }
 
     @SuppressWarnings("unchecked")

core/src/test/kotlin/io/forestframework/core/http/JsonRequestBodyIntegrationTest.kt

@@ -0,0 +1,64 @@
+@file:Suppress("UNUSED_PARAMETER")
+
+package io.forestframework.core.http
+
+import io.forestframework.core.ForestApplication
+import io.forestframework.core.http.param.JsonRequestBody
+import io.forestframework.core.http.result.PlainText
+import io.forestframework.core.http.routing.Post
+import io.forestframework.core.http.routing.PreHandler
+import io.forestframework.testfixtures.AbstractForestIntegrationTest
+import io.forestframework.testfixtures.DisableAutoScan
+import io.forestframework.testsupport.ForestIntegrationTest
+import kotlinx.coroutines.delay
+import org.junit.jupiter.api.Test
+
+@ForestApplication
+class ReadBodyMultipleTimesIntegrationTestApp {
+    @PreHandler("/readMultipleTimes")
+    fun readCookie(
+        @JsonRequestBody body: String
+    ) {
+    }
+
+    @Post("/readMultipleTimes")
+    @PlainText
+    fun getText(@JsonRequestBody body: String) = body
+
+    @PreHandler("/delayInPreHandler")
+    suspend fun delayInPreHandler() {
+        delay(1000)
+    }
+
+    @Post("/delayInPreHandler")
+    @PlainText
+    fun delayInPreHandler(
+        @JsonRequestBody body: String
+    ) = body
+}
+
+@ForestIntegrationTest(appClass = ReadBodyMultipleTimesIntegrationTestApp::class)
+@DisableAutoScan
+class ReadBodyMultipleTimesIntegrationTest : AbstractForestIntegrationTest() {
+    @Test
+    fun canReadRequestMultipleTimes() {
+        post("/readMultipleTimes",
+            headers = mapOf("Content-Type" to "application/json"),
+            body = "{}")
+            .assertBody("{}")
+    }
+
+    /*
+    java.lang.IllegalStateException: Request has already been read
+	at io.vertx.core.http.impl.Http1xServerRequest.checkEnded(Http1xServerRequest.java:628) ~[vertx-core-4.0.3.jar:4.0.3]
+	at io.vertx.core.http.impl.Http1xServerRequest.body(Http1xServerRequest.java:506) ~[vertx-core-4.0.3.jar:4.0.3]
+	at io.forestframework.core.http.DefaultHttpRequest.body(DefaultHttpRequest.java:203)
+     */
+    @Test
+    fun canHaveDelayInPreHandler() {
+        post("/delayInPreHandler",
+            headers = mapOf("Content-Type" to "application/json"),
+            body = "{}")
+            .assertBody("{}")
+    }
+}