feat: add post confirmation lambda hook

signup-lambda/src/handler.rs

@@ -0,0 +1,76 @@
+use lambda_runtime::LambdaEvent;
+use aws_sdk_cognitoidentityprovider::Client;
+use aws_config::BehaviorVersion;
+use serde::{Serialize, Deserialize};
+use std::collections::HashMap;
+use aws_sdk_cognitoidentityprovider::error::ProvideErrorMetadata;
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub(crate) struct PostConfirmationEvent {
+    version: String,
+    trigger_source: String,
+    region: String,
+    user_pool_id: String,
+    user_name: String,
+    caller_context: CallerContext,
+    request: Request,
+    response: Response
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub(crate) struct CallerContext {
+    client_id: String,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub(crate) struct Request {
+    user_attributes: HashMap<String, String>,
+}
+
+#[derive(Serialize, Deserialize, Debug)]
+#[serde(rename_all = "camelCase")]
+pub(crate) struct Response {}
+
+fn get_error_message(err: impl ProvideErrorMetadata) -> String {
+    err.message().unwrap_or("An unknown error occurred").to_string()
+}
+
+async fn add_user_to_group(provider: Client, user_id: String, group_name: impl Into<String>) -> Result<(), String> {
+    let group_name = group_name.into();
+    println!("Adding user {} to group {}", user_id, group_name);
+    match provider
+        .admin_add_user_to_group()
+        .user_pool_id("us-east-1_Lfjuy5zaM")
+        .username(user_id)
+        .group_name(group_name)
+        .send()
+        .await
+    {
+        Ok(_) => Ok(()),
+        Err(err) => Err(get_error_message(err)),
+    }
+}
+
+pub(crate) async fn handler(event: LambdaEvent<PostConfirmationEvent>) -> Result<PostConfirmationEvent, String> {
+    println!("Found event: {:?}", event.payload);
+
+    let user_id = event.payload.request.user_attributes.get("sub").unwrap().to_string();
+    let config = aws_config::load_defaults(BehaviorVersion::latest()).await;
+    let client = Client::new(&config);
+
+    // Check the client ID of the request to assign the user to the correct location.
+    let res = match event.payload.caller_context.client_id.as_str() {
+        "10jr2h3vtpu9n7gj46pvg5qo2q" => add_user_to_group(client, user_id, "ScholarshipStudents").await,
+        "56c2bqvl021rv8d5mq36blt7jv" => add_user_to_group(client, user_id, "ScholarshipProviders").await,
+        _ => Err("Invalid client ID, denying all user access.".to_string()),
+    };
+
+    if res.is_ok() {
+        Ok(event.payload)
+    } else {
+        Err(res.unwrap_err())
+    }
+}