From 81108a24bd067618b8df3c3e15f971c5ea0ac242 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Chris=20Suszy=C5=84ski?= <ksuszyns@redhat.com>
Date: Fri, 1 Mar 2024 16:55:58 +0100
Subject: [PATCH] Example WASM module that reverse the text from HTTP request

---
 README.md                                |  7 ++--
 examples/modules/reverse-text/Cargo.lock |  7 ++++
 examples/modules/reverse-text/Cargo.toml |  3 +-
 examples/modules/reverse-text/src/lib.rs | 45 ++++++++++++++++++------
 4 files changed, 47 insertions(+), 15 deletions(-)

diff --git a/README.md b/README.md
index c7f871f6..72540cf5 100644
--- a/README.md
+++ b/README.md
@@ -1,11 +1,10 @@
-# Knative Sample Controller
+# Knative WASM
 
 [![GoDoc](https://godoc.org/github.com/cardil/knative-serving-wasm?status.svg)](https://godoc.org/github.com/cardil/knative-serving-wasm)
 [![Go Report Card](https://goreportcard.com/badge/cardil/knative-serving-wasm)](https://goreportcard.com/report/cardil/knative-serving-wasm)
 
-Knative `knative-serving-wasm` defines a few simple resources that are validated by
-webhook and managed by a controller to demonstrate the canonical style in which
-Knative writes controllers.
+The `knative-serving-wasm` allows to run WASM modules that implement the
+[wasi-http](https://github.com/WebAssembly/wasi-http) interface on Kubernetes.
 
 To learn more about Knative, please visit our
 [Knative docs](https://github.com/knative/docs) repository.
diff --git a/examples/modules/reverse-text/Cargo.lock b/examples/modules/reverse-text/Cargo.lock
index 2b6123c1..36170502 100644
--- a/examples/modules/reverse-text/Cargo.lock
+++ b/examples/modules/reverse-text/Cargo.lock
@@ -99,6 +99,7 @@ name = "reverse-text"
 version = "0.1.0"
 dependencies = [
  "querystring",
+ "urlencoding",
  "wasi",
 ]
 
@@ -189,6 +190,12 @@ version = "0.2.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f962df74c8c05a667b5ee8bcf162993134c104e96440b663c8daa176dc772d8c"
 
+[[package]]
+name = "urlencoding"
+version = "2.1.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "daf8dba3b7eb870caf1ddeed7bc9d2a049f3cfdfae7cb521b087cc33ae4c49da"
+
 [[package]]
 name = "wasi"
 version = "0.12.1+wasi-0.2.0"
diff --git a/examples/modules/reverse-text/Cargo.toml b/examples/modules/reverse-text/Cargo.toml
index d7abd0e6..6553d214 100644
--- a/examples/modules/reverse-text/Cargo.toml
+++ b/examples/modules/reverse-text/Cargo.toml
@@ -6,7 +6,8 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-querystring = "1.1.0"
+querystring = "1.1"
+urlencoding = "2.1"
 
 [dependencies.wasi]
 git = "https://github.com/bytecodealliance/wasi"
diff --git a/examples/modules/reverse-text/src/lib.rs b/examples/modules/reverse-text/src/lib.rs
index 5b29381a..c9bef2d1 100644
--- a/examples/modules/reverse-text/src/lib.rs
+++ b/examples/modules/reverse-text/src/lib.rs
@@ -27,24 +27,49 @@ impl exports::wasi::http::incoming_handler::Guest for Reverse {
 }
 
 /**
-  Get query parameter named "text", or return "Hello, WASI!" if
-  it's not present
-*/
+Get query parameter named "text", or return "Hello, WASI!" if
+it's not present
+ */
 fn fetch_text_query_param(pq: String) -> String {
-    pq.split_once("?")
+    urlencoding::decode(&pq)
+        .unwrap()
+        .split_once("?")
         .and_then(|(_, s)| {
-            return Some(querystring::querify(s))
+            return Some(querystring::querify(s));
         })
         .map(|q| {
             HashMap::from_iter(q)
         })
-        .map(|q| {
-            q.get("text")
+        .and_then(|q: HashMap<&str, &str>| {
+            q.get("text").cloned()
         })
-        .unwrap_or(Some("Hello, WASI!".to_string()))
-        .unwrap()
+        .map(|s| {
+            s.to_string()
+        })
+        .unwrap_or("Hello, WASI!".to_string())
 }
 
 fn reverse_text(str: String) -> String {
     str.chars().rev().collect()
-}
\ No newline at end of file
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_fetch_text_query_param() {
+        assert_eq!(fetch_text_query_param("".to_string()), "Hello, WASI!");
+        assert_eq!(fetch_text_query_param("?".to_string()), "Hello, WASI!");
+        assert_eq!(fetch_text_query_param("?text=Hello".to_string()), "Hello");
+        assert_eq!(fetch_text_query_param("?text=Happy%20testing".to_string()), "Happy testing");
+    }
+
+    #[test]
+    fn test_reverse_text() {
+        assert_eq!(reverse_text("".to_string()), "");
+        assert_eq!(reverse_text("a".to_string()), "a");
+        assert_eq!(reverse_text("ab".to_string()), "ba");
+        assert_eq!(reverse_text("abc".to_string()), "cba");
+    }
+}