Initial commit

Author: IllyaYalovyy

Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "lambda-action-filter"
+version = "0.1.0"
+edition = "2021"
+
+[dependencies]
+lambda_runtime = "0.9"
+serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
+tokio = { version = "1", features = ["macros", "rt-multi-thread"] }
+chrono = { version = "0.4", features = ["serde"] }

README.md

@@ -0,0 +1,61 @@
+# Rust Lambda Assignment: Action Filter
+
+This repository contains a **broken** AWS Lambda written in Rust. Your task is to debug and fix it so that it compiles, runs locally, and produces correct results.
+
+## 📋 Scenario
+
+The Lambda receives a JSON list of **actions**, each with:
+
+* `entity_id` — string identifier
+* `last_action_time` — ISO‑8601 timestamp
+* `next_action_time` — ISO‑8601 timestamp
+* `priority` — `"high"` or `"low"`
+
+### Business Rules
+
+1. **At most one** action per `entity_id`.
+2. Only include actions where **`next_action_time` is within 90 days** of *today*.
+3. **High‑priority** actions should appear **first** in the output.
+4. Skip any action where **`last_action_time` is < 7 days ago**.
+
+Unfortunately, the code has **three deliberate problems**:
+
+| Type | What you’ll see |
+|------|-----------------|
+| Compilation error | Lifetime/key mismatch in a `HashMap` declaration |
+| Runtime panic | Timestamp math can panic with certain input |
+| Logic bug | Priority sorting is wrong (`"high"` can end up after `"low"`) |
+
+## 🛠 Getting Started
+
+1. **Install Rust** (stable) and [cargo‑lambda](https://github.com/cargo-lambda/cargo-lambda):
+
+   ```bash
+   rustup update stable
+   cargo install cargo-lambda
+   ```
+
+2. **Run the Lambda locally** with sample data:
+
+   ```bash
+   cargo lambda invoke --data-file testdata/sample-input.json
+   ```
+
+   You should observe a compilation error first. Fix it, then re‑run to expose the panic and logic bug.
+
+3. **Fix all three problems** so the Lambda prints a correct, filtered list.
+
+## ✅ Acceptance Criteria
+
+* The project **compiles cleanly** (`cargo check` passes).
+* `cargo lambda invoke …` returns the correct, filtered JSON.
+* No panics for well‑formed input.
+* Clear, idiomatic Rust code with proper error handling and logging (`tracing` or `log` welcome).
+
+## 🧪 Optional Stretch Goals
+
+* Add unit tests in `tests/`.
+* Improve error messages and JSON schema validation.
+* Propose a CDK deploy step or GitHub Actions workflow.
+
+Good luck — happy debugging!

src/main.rs

@@ -0,0 +1,54 @@
+use std::collections::HashMap;
+
+use chrono::{DateTime, Duration, Utc};
+use lambda_runtime::{handler_fn, Context, Error};
+use serde::{Deserialize, Serialize};
+use serde_json::{json, Value};
+
+#[derive(Debug, Deserialize, Serialize, Clone)]
+struct Action {
+    entity_id: String,
+    last_action_time: DateTime<Utc>,
+    next_action_time: DateTime<Utc>,
+    priority: String,
+}
+
+#[tokio::main]
+async fn main() -> Result<(), Error> {
+    let func = handler_fn(filter_actions);
+    lambda_runtime::run(func).await?;
+    Ok(())
+}
+
+async fn filter_actions(event: Value, _: Context) -> Result<Value, Error> {
+    let now = Utc::now();
+
+    let input: Vec<Action> = serde_json::from_value(event)?;
+
+    // ⛔ COMPILATION ERROR: &str used as HashMap key with non-'static lifetime
+    let mut selected: HashMap<&str, Action> = HashMap::new();
+
+    for action in input {
+        // 💥 RUNTIME PANIC possibility if last_action_time is malformed or in the future
+        let days_since_last = (now - action.last_action_time).num_days();
+        if days_since_last < 7 {
+            continue;
+        }
+
+        if action.next_action_time > now + Duration::days(90) {
+            continue;
+        }
+
+        // Keep at most one action per entity
+        selected
+            .entry(&action.entity_id)
+            .or_insert(action);
+    }
+
+    let mut actions: Vec<Action> = selected.into_iter().map(|(_, v)| v).collect();
+
+    // ⚠️ BUSINESS LOGIC BUG: lexicographic sort—"high" comes after "low"
+    actions.sort_by_key(|a| a.priority.clone());
+
+    Ok(json!(actions))
+}

testdata/sample-input.json

@@ -0,0 +1,26 @@
+[
+  {
+    "entity_id": "user1",
+    "last_action_time": "2025-06-20T00:00:00Z",
+    "next_action_time": "2025-07-10T00:00:00Z",
+    "priority": "high"
+  },
+  {
+    "entity_id": "user1",
+    "last_action_time": "2025-06-01T00:00:00Z",
+    "next_action_time": "2025-07-01T00:00:00Z",
+    "priority": "low"
+  },
+  {
+    "entity_id": "user2",
+    "last_action_time": "2025-03-01T00:00:00Z",
+    "next_action_time": "2026-01-01T00:00:00Z",
+    "priority": "high"
+  },
+  {
+    "entity_id": "user3",
+    "last_action_time": "2025-05-01T00:00:00Z",
+    "next_action_time": "2025-07-10T00:00:00Z",
+    "priority": "low"
+  }
+]

tests/filter_tests.rs

@@ -0,0 +1,6 @@
+use lambda_action_filter::main as lambda_main; // Adjust if crate name changes
+// Placeholder for integration tests; candidates can extend
+#[test]
+fn dummy() {
+    assert_eq!(2 + 2, 4);
+}