refactor(lambda-events): align VPC Lattice with library conventions

- Add #[non_exhaustive] to all VPC Lattice structs
- Change status_code from u16 to i64 for consistency with ALB/API Gateway
- Move comma-separated header serde into custom_serde/headers.rs
- Fix test imports and function naming

Author: GradExMachina

lambda-events/src/custom_serde/headers.rs

@@ -34,6 +34,28 @@ where
     map.end()
 }
 
+/// Serialize a HeaderMap with multiple values per header combined as comma-separated strings.
+/// Used by VPC Lattice V1 which expects multi-value headers as "value1, value2".
+#[cfg(feature = "vpc_lattice")]
+pub(crate) fn serialize_comma_separated_headers<S>(headers: &HeaderMap, serializer: S) -> Result<S::Ok, S::Error>
+where
+    S: Serializer,
+{
+    let mut map = serializer.serialize_map(Some(headers.keys_len()))?;
+    for key in headers.keys() {
+        let values: Vec<&str> = headers
+            .get_all(key)
+            .iter()
+            .filter_map(|v| v.to_str().ok())
+            .collect();
+        if !values.is_empty() {
+            let combined_value = values.join(", ");
+            map.serialize_entry(key.as_str(), &combined_value)?;
+        }
+    }
+    map.end()
+}
+
 #[derive(serde::Deserialize)]
 #[serde(untagged)]
 enum OneOrMore<'a> {
@@ -44,6 +66,7 @@ enum OneOrMore<'a> {
 
 struct HeaderMapVisitor {
     is_human_readable: bool,
+    split_comma_separated: bool,
 }
 
 impl<'de> Visitor<'de> for HeaderMapVisitor {
@@ -97,17 +120,25 @@ impl<'de> Visitor<'de> for HeaderMapVisitor {
                     .map_err(|_| de::Error::invalid_value(Unexpected::Str(&key), &self))?;
                 match val {
                     OneOrMore::One(val) => {
-                        let val = val
-                            .parse()
-                            .map_err(|_| de::Error::invalid_value(Unexpected::Str(&val), &self))?;
-                        map.insert(key, val);
-                    }
-                    OneOrMore::Strings(arr) => {
-                        for val in arr {
+                        if self.split_comma_separated && val.contains(',') {
+                            split_and_append_header(&mut map, &key, &val, &self)?;
+                        } else {
                             let val = val
                                 .parse()
                                 .map_err(|_| de::Error::invalid_value(Unexpected::Str(&val), &self))?;
-                            map.append(&key, val);
+                            map.insert(key, val);
+                        }
+                    }
+                    OneOrMore::Strings(arr) => {
+                        for val in arr {
+                            if self.split_comma_separated && val.contains(',') {
+                                split_and_append_header(&mut map, &key, &val, &self)?;
+                            } else {
+                                let val = val
+                                    .parse()
+                                    .map_err(|_| de::Error::invalid_value(Unexpected::Str(&val), &self))?;
+                                map.append(&key, val);
+                            }
                         }
                     }
                     OneOrMore::Bytes(arr) => {
@@ -124,13 +155,51 @@ impl<'de> Visitor<'de> for HeaderMapVisitor {
     }
 }
 
+fn split_and_append_header<E>(
+    map: &mut HeaderMap,
+    key: &HeaderName,
+    value: &str,
+    visitor: &HeaderMapVisitor,
+) -> Result<(), E>
+where
+    E: DeError,
+{
+    for split_val in value.split(',') {
+        let trimmed_val = split_val.trim();
+        if !trimmed_val.is_empty() {
+            let header_val = trimmed_val
+                .parse()
+                .map_err(|_| de::Error::invalid_value(Unexpected::Str(trimmed_val), visitor))?;
+            map.append(key, header_val);
+        }
+    }
+    Ok(())
+}
+
 /// Implementation detail.
 pub(crate) fn deserialize_headers<'de, D>(de: D) -> Result<HeaderMap, D::Error>
 where
     D: Deserializer<'de>,
 {
     let is_human_readable = de.is_human_readable();
-    de.deserialize_option(HeaderMapVisitor { is_human_readable })
+    de.deserialize_option(HeaderMapVisitor {
+        is_human_readable,
+        split_comma_separated: false,
+    })
+}
+
+/// Deserialize headers, splitting comma-separated values into multiple header values.
+/// Used by VPC Lattice V1 which sends multi-value headers as "value1, value2".
+#[cfg(feature = "vpc_lattice")]
+pub(crate) fn deserialize_comma_separated_headers<'de, D>(de: D) -> Result<HeaderMap, D::Error>
+where
+    D: Deserializer<'de>,
+{
+    let is_human_readable = de.is_human_readable();
+    de.deserialize_option(HeaderMapVisitor {
+        is_human_readable,
+        split_comma_separated: true,
+    })
 }
 
 #[cfg(test)]

lambda-events/src/custom_serde/mod.rs

@@ -16,22 +16,24 @@ pub type CodeBuildNumber = f32;
     feature = "apigw",
     feature = "s3",
     feature = "iot",
-    feature = "lambda_function_urls"
+    feature = "lambda_function_urls",
+    feature = "vpc_lattice"
 ))]
 mod headers;
 #[cfg(any(
     feature = "alb",
     feature = "apigw",
     feature = "s3",
     feature = "iot",
-    feature = "lambda_function_urls"
+    feature = "lambda_function_urls",
+    feature = "vpc_lattice"
 ))]
 pub(crate) use self::headers::*;
 
 #[cfg(feature = "dynamodb")]
 pub(crate) mod float_unix_epoch;
 
-#[cfg(any(feature = "alb", feature = "apigw"))]
+#[cfg(any(feature = "alb", feature = "apigw", feature = "vpc_lattice"))]
 pub(crate) mod http_method;
 
 #[cfg(feature = "alb")]
@@ -89,6 +91,7 @@ where
     feature = "code_commit",
     feature = "cognito",
     feature = "sns",
+    feature = "vpc_lattice",
     test
 ))]
 pub(crate) fn deserialize_nullish_boolean<'de, D>(deserializer: D) -> Result<bool, D::Error>

lambda-events/src/event/vpc_lattice/common.rs

@@ -7,6 +7,7 @@ use serde_json::Value;
 
 /// `VpcLatticeResponse` configures the response to be returned
 /// by VPC Lattice (both V1 and V2) for the request
+#[non_exhaustive]
 #[derive(Clone, Debug, Default, Deserialize, PartialEq, Serialize)]
 #[serde(rename_all = "camelCase")]
 pub struct VpcLatticeResponse {
@@ -16,7 +17,8 @@ pub struct VpcLatticeResponse {
     pub is_base64_encoded: bool,
 
     /// The HTTP status code for the request
-    pub status_code: u16,
+    // i64 for consistency with other event types (e.g. AlbTargetGroupResponse, ApiGatewayProxyResponse)
+    pub status_code: i64,
 
     /// The HTTP status description (optional)
     #[serde(default)]
@@ -48,7 +50,7 @@ mod test {
 
     #[test]
     #[cfg(feature = "vpc_lattice")]
-    fn example_alb_lambda_target_response() {
+    fn example_vpc_lattice_response() {
         let data = include_bytes!("../../fixtures/example-vpc-lattice-response.json");
         let parsed: VpcLatticeResponse = serde_json::from_slice(data).unwrap();
         let output: String = serde_json::to_string(&parsed).unwrap();

lambda-events/src/event/vpc_lattice/mod.rs

@@ -1,10 +1,6 @@
 mod common;
-mod serialization_comma_separated_headers;
 mod v1;
 mod v2;
 
 // re-export types
 pub use self::{common::*, v1::*, v2::*};
-
-// helper code
-pub(crate) use self::serialization_comma_separated_headers::*;