enact-core 0.0.2

//! Runner - executes callables and graphs with flow features

use crate::callable::Callable;
use crate::graph::{Checkpoint, CheckpointStore, CompiledGraph, NodeState};
use crate::kernel::{ExecutionError, ExecutionId, StepId, StepType};
use crate::streaming::{EventEmitter, StreamEvent};
use std::sync::Arc;
use std::time::Instant;
use tokio_util::sync::CancellationToken;

/// Runner - executes agents/graphs with abort, pause, and event streaming
pub struct Runner<S: CheckpointStore> {
    execution_id: ExecutionId,
    cancellation_token: CancellationToken,
    checkpoint_store: Arc<S>,
    emitter: EventEmitter,
    paused: std::sync::atomic::AtomicBool,
    start_time: Option<Instant>,
}

impl<S: CheckpointStore> Runner<S> {
    /// Create a new runner
    pub fn new(checkpoint_store: Arc<S>) -> Self {
        Self {
            execution_id: ExecutionId::new(),
            cancellation_token: CancellationToken::new(),
            checkpoint_store,
            emitter: EventEmitter::new(),
            paused: std::sync::atomic::AtomicBool::new(false),
            start_time: None,
        }
    }

    /// Get the execution ID
    pub fn execution_id(&self) -> &ExecutionId {
        &self.execution_id
    }

    /// Get the event emitter
    pub fn emitter(&self) -> &EventEmitter {
        &self.emitter
    }

    /// Cancel the run (abort signal)
    pub fn cancel(&self) {
        self.cancellation_token.cancel();
        self.emitter.emit(StreamEvent::execution_cancelled(
            &self.execution_id,
            "Run cancelled by user",
        ));
    }

    /// Check if cancelled
    pub fn is_cancelled(&self) -> bool {
        self.cancellation_token.is_cancelled()
    }

    /// Pause the run
    pub async fn pause(&self) -> anyhow::Result<()> {
        self.paused.store(true, std::sync::atomic::Ordering::SeqCst);
        self.emitter.emit(StreamEvent::execution_paused(
            &self.execution_id,
            "Paused by user",
        ));
        Ok(())
    }

    /// Resume the run
    pub fn resume(&self) {
        self.paused
            .store(false, std::sync::atomic::Ordering::SeqCst);
        self.emitter
            .emit(StreamEvent::execution_resumed(&self.execution_id));
    }

    /// Check if paused
    pub fn is_paused(&self) -> bool {
        self.paused.load(std::sync::atomic::Ordering::SeqCst)
    }

    /// Save checkpoint
    ///
    /// # Arguments
    /// * `state` - The current node state to save
    /// * `node` - Optional current node name
    /// * `agent_name` - Optional agent name for restoration on resume
    pub async fn save_checkpoint(
        &self,
        state: NodeState,
        node: Option<&str>,
        agent_name: Option<&str>,
    ) -> anyhow::Result<Checkpoint> {
        let mut checkpoint = Checkpoint::new(self.execution_id.clone()).with_state(state.data);

        if let Some(n) = node {
            checkpoint = checkpoint.with_node(n);
        }

        if let Some(name) = agent_name {
            checkpoint = checkpoint.with_agent_name(name);
        }

        self.checkpoint_store.save(checkpoint.clone()).await?;
        Ok(checkpoint)
    }

    /// Load latest checkpoint
    pub async fn load_checkpoint(&self) -> anyhow::Result<Option<Checkpoint>> {
        self.checkpoint_store
            .load_latest(self.execution_id.as_str())
            .await
    }

    /// Run a callable with event streaming
    pub async fn run_callable<A: Callable + ?Sized>(
        &mut self,
        callable: &A,
        input: &str,
    ) -> anyhow::Result<String> {
        self.start_time = Some(Instant::now());
        self.emitter
            .emit(StreamEvent::execution_start(&self.execution_id));

        // Check for cancellation before running
        if self.is_cancelled() {
            anyhow::bail!("Run cancelled");
        }

        let result = callable.run(input).await;
        let duration_ms = self
            .start_time
            .map(|t| t.elapsed().as_millis() as u64)
            .unwrap_or(0);

        match &result {
            Ok(output) => {
                self.emitter.emit(StreamEvent::execution_end(
                    &self.execution_id,
                    Some(output.clone()),
                    duration_ms,
                ));
            }
            Err(e) => {
                let error = ExecutionError::kernel_internal(e.to_string());
                self.emitter
                    .emit(StreamEvent::execution_failed(&self.execution_id, error));
            }
        }

        result
    }

    /// Run a compiled graph with event streaming
    pub async fn run_graph(
        &mut self,
        graph: &CompiledGraph,
        input: &str,
    ) -> anyhow::Result<NodeState> {
        self.start_time = Some(Instant::now());
        self.emitter
            .emit(StreamEvent::execution_start(&self.execution_id));

        let mut state = NodeState::from_string(input);
        let mut current_node = graph.entry_point().to_string();

        loop {
            // Check for cancellation
            if self.is_cancelled() {
                anyhow::bail!("Run cancelled");
            }

            // Check for pause - wait until resumed
            while self.is_paused() {
                tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;
                if self.is_cancelled() {
                    anyhow::bail!("Run cancelled while paused");
                }
            }

            // Get the node
            let node = graph
                .get_node(&current_node)
                .ok_or_else(|| anyhow::anyhow!("Node '{}' not found", current_node))?;

            // Create step ID for this node execution
            let step_id = StepId::new();
            let step_start = Instant::now();

            // Emit step started
            self.emitter.emit(StreamEvent::step_start(
                &self.execution_id,
                &step_id,
                StepType::FunctionNode, // Graph nodes are function nodes by default
                current_node.clone(),
            ));

            // Execute node
            state = node.execute(state).await?;

            // Emit step completed
            let step_duration = step_start.elapsed().as_millis() as u64;
            self.emitter.emit(StreamEvent::step_end(
                &self.execution_id,
                &step_id,
                Some(state.as_str().unwrap_or_default().to_string()),
                step_duration,
            ));

            // Get next nodes
            let output = state.as_str().unwrap_or_default();
            let next = graph.get_next(&current_node, output);

            if next.is_empty() {
                break;
            }

            match &next[0] {
                crate::graph::EdgeTarget::End => break,
                crate::graph::EdgeTarget::Node(n) => {
                    current_node = n.clone();
                }
            }
        }

        let duration_ms = self
            .start_time
            .map(|t| t.elapsed().as_millis() as u64)
            .unwrap_or(0);
        self.emitter.emit(StreamEvent::execution_end(
            &self.execution_id,
            Some(state.as_str().unwrap_or_default().to_string()),
            duration_ms,
        ));

        Ok(state)
    }
}

/// Runner with in-memory checkpoint store (default)
pub type DefaultRunner = Runner<crate::graph::InMemoryCheckpointStore>;

impl DefaultRunner {
    /// Create a new runner with in-memory checkpoint store
    pub fn default_new() -> Self {
        Self::new(Arc::new(crate::graph::InMemoryCheckpointStore::new()))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::graph::InMemoryCheckpointStore;
    use async_trait::async_trait;

    /// Mock callable for testing
    struct MockCallable {
        name: String,
        response: Result<String, String>,
        delay_ms: Option<u64>,
    }

    impl MockCallable {
        fn success(name: &str, response: &str) -> Self {
            Self {
                name: name.to_string(),
                response: Ok(response.to_string()),
                delay_ms: None,
            }
        }

        fn failing(name: &str, error: &str) -> Self {
            Self {
                name: name.to_string(),
                response: Err(error.to_string()),
                delay_ms: None,
            }
        }
    }

    #[async_trait]
    impl Callable for MockCallable {
        fn name(&self) -> &str {
            &self.name
        }

        async fn run(&self, input: &str) -> anyhow::Result<String> {
            if let Some(delay) = self.delay_ms {
                tokio::time::sleep(tokio::time::Duration::from_millis(delay)).await;
            }
            match &self.response {
                Ok(r) => Ok(format!("{}:{}", r, input)),
                Err(e) => anyhow::bail!("{}", e),
            }
        }
    }

    // ============ Construction Tests ============

    #[test]
    fn test_runner_new() {
        let store = Arc::new(InMemoryCheckpointStore::new());
        let runner = Runner::new(store);

        // Should have a valid execution ID
        assert!(!runner.execution_id().as_str().is_empty());
        // Should not be cancelled initially
        assert!(!runner.is_cancelled());
        // Should not be paused initially
        assert!(!runner.is_paused());
    }

    #[test]
    fn test_default_runner_new() {
        let runner = DefaultRunner::default_new();
        assert!(!runner.execution_id().as_str().is_empty());
    }

    #[test]
    fn test_runner_execution_id_unique() {
        let store = Arc::new(InMemoryCheckpointStore::new());
        let runner1 = Runner::new(store.clone());
        let runner2 = Runner::new(store);

        // Each runner should have unique execution ID
        assert_ne!(
            runner1.execution_id().as_str(),
            runner2.execution_id().as_str()
        );
    }

    // ============ Cancellation Tests ============

    #[test]
    fn test_runner_cancel() {
        let runner = DefaultRunner::default_new();

        assert!(!runner.is_cancelled());
        runner.cancel();
        assert!(runner.is_cancelled());
    }

    #[tokio::test]
    async fn test_runner_callable_checks_cancellation_before_run() {
        let mut runner = DefaultRunner::default_new();
        let callable = MockCallable::success("test", "response");

        // Cancel before running
        runner.cancel();

        let result = runner.run_callable(&callable, "input").await;
        assert!(result.is_err());
        assert!(result.unwrap_err().to_string().contains("cancelled"));
    }

    // ============ Pause/Resume Tests ============

    #[tokio::test]
    async fn test_runner_pause_resume() {
        let runner = DefaultRunner::default_new();

        assert!(!runner.is_paused());

        runner.pause().await.unwrap();
        assert!(runner.is_paused());

        runner.resume();
        assert!(!runner.is_paused());
    }

    // ============ Run Callable Tests ============

    #[tokio::test]
    async fn test_run_callable_success() {
        let mut runner = DefaultRunner::default_new();
        let callable = MockCallable::success("test", "hello");

        let result = runner.run_callable(&callable, "world").await;
        assert!(result.is_ok());
        assert_eq!(result.unwrap(), "hello:world");
    }

    #[tokio::test]
    async fn test_run_callable_failure() {
        let mut runner = DefaultRunner::default_new();
        let callable = MockCallable::failing("test", "Something went wrong");

        let result = runner.run_callable(&callable, "input").await;
        assert!(result.is_err());
        assert!(result
            .unwrap_err()
            .to_string()
            .contains("Something went wrong"));
    }

    #[tokio::test]
    async fn test_run_callable_emits_events() {
        let mut runner = DefaultRunner::default_new();
        let callable = MockCallable::success("test", "response");

        runner.run_callable(&callable, "input").await.unwrap();

        // Drain and check collected events
        let events = runner.emitter().drain();

        // Should have execution start and end events
        assert!(events.len() >= 2);

        // First event should be execution start
        let first = &events[0];
        assert!(matches!(first, StreamEvent::ExecutionStart { .. }));

        // Last event should be execution end
        let last = &events[events.len() - 1];
        assert!(matches!(last, StreamEvent::ExecutionEnd { .. }));
    }

    #[tokio::test]
    async fn test_run_callable_failure_emits_failed_event() {
        let mut runner = DefaultRunner::default_new();
        let callable = MockCallable::failing("test", "error message");

        let _ = runner.run_callable(&callable, "input").await;

        // Drain and check collected events
        let events = runner.emitter().drain();

        // Should have execution start and failed events
        assert!(events.len() >= 2);

        // Last event should be execution failed
        let last = &events[events.len() - 1];
        assert!(matches!(last, StreamEvent::ExecutionFailed { .. }));
    }

    // ============ Checkpoint Tests ============

    #[tokio::test]
    async fn test_runner_save_and_load_checkpoint() {
        let runner = DefaultRunner::default_new();

        // Save a checkpoint
        let state = NodeState::from_string("test state data");
        let checkpoint = runner
            .save_checkpoint(state, Some("node1"), Some("test_agent"))
            .await
            .unwrap();

        assert_eq!(checkpoint.current_node.as_ref().unwrap(), "node1");

        // Load the checkpoint
        let loaded = runner.load_checkpoint().await.unwrap();
        assert!(loaded.is_some());

        let loaded = loaded.unwrap();
        assert_eq!(
            loaded.state,
            serde_json::Value::String("test state data".to_string())
        );
    }

    #[tokio::test]
    async fn test_runner_checkpoint_without_node() {
        let runner = DefaultRunner::default_new();

        let state = NodeState::from_string("some data");
        let checkpoint = runner.save_checkpoint(state, None, None).await.unwrap();

        assert!(checkpoint.current_node.is_none());
        assert!(checkpoint.agent_name().is_none());
    }

    #[tokio::test]
    async fn test_runner_checkpoint_with_agent_name() {
        let runner = DefaultRunner::default_new();

        let state = NodeState::from_string("agent state");
        let checkpoint = runner
            .save_checkpoint(state, Some("planning_node"), Some("planner"))
            .await
            .unwrap();

        assert_eq!(checkpoint.current_node.as_ref().unwrap(), "planning_node");
        assert_eq!(checkpoint.agent_name(), Some("planner"));

        // Load and verify agent_name persists
        let loaded = runner.load_checkpoint().await.unwrap().unwrap();
        assert_eq!(loaded.agent_name(), Some("planner"));
    }

    #[tokio::test]
    async fn test_runner_load_checkpoint_no_data() {
        let runner = DefaultRunner::default_new();

        // Without saving, load should return None
        let loaded = runner.load_checkpoint().await.unwrap();
        assert!(loaded.is_none());
    }

    // ============ Emitter Tests ============

    #[test]
    fn test_runner_emitter_access() {
        let runner = DefaultRunner::default_new();
        let emitter = runner.emitter();

        // Should be able to emit and drain events
        emitter.emit(StreamEvent::execution_start(runner.execution_id()));
        let events = emitter.drain();
        assert_eq!(events.len(), 1);
    }

    #[test]
    fn test_emitter_mode() {
        use crate::streaming::StreamMode;

        let runner = DefaultRunner::default_new();
        let emitter = runner.emitter();

        // Default mode should be Full
        assert_eq!(emitter.mode(), StreamMode::Full);
    }
}