escher-execution-engine 0.1.2

//! Event system for Execution Engine
//!
//! Pluggable event handlers for real-time execution updates.
//! See docs/types.md for event type reference.

use crate::types::{ExecutionResult, ExecutionStatus};
use async_trait::async_trait;
use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use uuid::Uuid;

/// Events emitted during execution
#[derive(Debug, Clone, Serialize, Deserialize)]
#[serde(tag = "event_type", rename_all = "snake_case")]
pub enum ExecutionEvent {
    /// Execution started
    Started {
        execution_id: Uuid,
        command: String,
        timestamp: DateTime<Utc>,
    },

    /// Standard output line
    Stdout {
        execution_id: Uuid,
        line: String,
        timestamp: DateTime<Utc>,
    },

    /// Standard error line
    Stderr {
        execution_id: Uuid,
        line: String,
        timestamp: DateTime<Utc>,
    },

    /// Execution completed
    Completed {
        execution_id: Uuid,
        result: ExecutionResult,
        timestamp: DateTime<Utc>,
    },

    /// Execution failed
    Failed {
        execution_id: Uuid,
        error: String,
        timestamp: DateTime<Utc>,
    },

    /// Execution cancelled
    Cancelled {
        execution_id: Uuid,
        timestamp: DateTime<Utc>,
    },

    /// Execution timeout
    Timeout {
        execution_id: Uuid,
        timeout_ms: u64,
        timestamp: DateTime<Utc>,
    },

    /// Plan progress update
    Progress {
        plan_id: Uuid,
        completed: usize,
        total: usize,
        current_command: Option<String>,
        timestamp: DateTime<Utc>,
    },

    /// Status changed
    StatusChanged {
        execution_id: Uuid,
        old_status: ExecutionStatus,
        new_status: ExecutionStatus,
        timestamp: DateTime<Utc>,
    },
}

impl ExecutionEvent {
    /// Get the execution ID for this event (if applicable)
    #[must_use]
    pub fn execution_id(&self) -> Option<Uuid> {
        match self {
            ExecutionEvent::Started { execution_id, .. }
            | ExecutionEvent::Stdout { execution_id, .. }
            | ExecutionEvent::Stderr { execution_id, .. }
            | ExecutionEvent::Completed { execution_id, .. }
            | ExecutionEvent::Failed { execution_id, .. }
            | ExecutionEvent::Cancelled { execution_id, .. }
            | ExecutionEvent::Timeout { execution_id, .. }
            | ExecutionEvent::StatusChanged { execution_id, .. } => Some(*execution_id),
            ExecutionEvent::Progress { .. } => None,
        }
    }

    /// Get the plan ID for this event (if applicable)
    #[must_use]
    pub fn plan_id(&self) -> Option<Uuid> {
        match self {
            ExecutionEvent::Progress { plan_id, .. } => Some(*plan_id),
            _ => None,
        }
    }

    /// Get the timestamp for this event
    #[must_use]
    pub fn timestamp(&self) -> DateTime<Utc> {
        match self {
            ExecutionEvent::Started { timestamp, .. }
            | ExecutionEvent::Stdout { timestamp, .. }
            | ExecutionEvent::Stderr { timestamp, .. }
            | ExecutionEvent::Completed { timestamp, .. }
            | ExecutionEvent::Failed { timestamp, .. }
            | ExecutionEvent::Cancelled { timestamp, .. }
            | ExecutionEvent::Timeout { timestamp, .. }
            | ExecutionEvent::Progress { timestamp, .. }
            | ExecutionEvent::StatusChanged { timestamp, .. } => *timestamp,
        }
    }

    /// Check if this is a terminal event (execution finished)
    #[must_use]
    pub fn is_terminal(&self) -> bool {
        matches!(
            self,
            ExecutionEvent::Completed { .. }
                | ExecutionEvent::Failed { .. }
                | ExecutionEvent::Cancelled { .. }
                | ExecutionEvent::Timeout { .. }
        )
    }

    /// Get event type name
    #[must_use]
    pub fn event_type_name(&self) -> &str {
        match self {
            ExecutionEvent::Started { .. } => "started",
            ExecutionEvent::Stdout { .. } => "stdout",
            ExecutionEvent::Stderr { .. } => "stderr",
            ExecutionEvent::Completed { .. } => "completed",
            ExecutionEvent::Failed { .. } => "failed",
            ExecutionEvent::Cancelled { .. } => "cancelled",
            ExecutionEvent::Timeout { .. } => "timeout",
            ExecutionEvent::Progress { .. } => "progress",
            ExecutionEvent::StatusChanged { .. } => "status_changed",
        }
    }
}

/// Event handler trait
///
/// Implement this trait to receive execution events.
#[async_trait]
pub trait EventHandler: Send + Sync {
    /// Handle an execution event
    async fn handle_event(&self, event: ExecutionEvent);

    /// Handle error in event processing
    async fn handle_error(&self, error: String) {
        eprintln!("Event handler error: {error}");
    }
}

/// No-op event handler (does nothing)
pub struct NoopEventHandler;

#[async_trait]
impl EventHandler for NoopEventHandler {
    async fn handle_event(&self, _event: ExecutionEvent) {
        // Do nothing
    }
}

/// Logging event handler (logs to stderr)
pub struct LoggingEventHandler {
    pub verbose: bool,
}

impl LoggingEventHandler {
    #[must_use]
    pub fn new(verbose: bool) -> Self {
        Self { verbose }
    }
}

#[async_trait]
impl EventHandler for LoggingEventHandler {
    async fn handle_event(&self, event: ExecutionEvent) {
        if self.verbose {
            eprintln!(
                "[{}] Event: {} - {:?}",
                event.timestamp().format("%Y-%m-%d %H:%M:%S"),
                event.event_type_name(),
                event
            );
        } else {
            match event {
                ExecutionEvent::Started { command, .. } => {
                    eprintln!("Started: {command}");
                }
                ExecutionEvent::Completed { execution_id, .. } => {
                    eprintln!("Completed: {execution_id}");
                }
                ExecutionEvent::Failed { error, .. } => {
                    eprintln!("Failed: {error}");
                }
                _ => {}
            }
        }
    }
}

/// Multi-handler that broadcasts to multiple handlers
pub struct MultiEventHandler {
    handlers: Vec<Box<dyn EventHandler>>,
}

impl MultiEventHandler {
    #[must_use]
    pub fn new() -> Self {
        Self {
            handlers: Vec::new(),
        }
    }

    pub fn add_handler(&mut self, handler: Box<dyn EventHandler>) {
        self.handlers.push(handler);
    }
}

impl Default for MultiEventHandler {
    fn default() -> Self {
        Self::new()
    }
}

#[async_trait]
impl EventHandler for MultiEventHandler {
    async fn handle_event(&self, event: ExecutionEvent) {
        for handler in &self.handlers {
            handler.handle_event(event.clone()).await;
        }
    }

    async fn handle_error(&self, error: String) {
        for handler in &self.handlers {
            handler.handle_error(error.clone()).await;
        }
    }
}

// ============================================================================
// Tests
// ============================================================================

#[cfg(test)]
mod tests {
    use super::*;
    use crate::types::ExecutionResult;
    use std::time::Duration;

    #[test]
    fn test_execution_event_execution_id() {
        let id = Uuid::new_v4();
        let event = ExecutionEvent::Started {
            execution_id: id,
            command: "test".to_string(),
            timestamp: Utc::now(),
        };
        assert_eq!(event.execution_id(), Some(id));

        let plan_id = Uuid::new_v4();
        let event = ExecutionEvent::Progress {
            plan_id,
            completed: 1,
            total: 5,
            current_command: None,
            timestamp: Utc::now(),
        };
        assert_eq!(event.execution_id(), None);
        assert_eq!(event.plan_id(), Some(plan_id));
    }

    #[test]
    fn test_execution_event_is_terminal() {
        let id = Uuid::new_v4();

        let event = ExecutionEvent::Started {
            execution_id: id,
            command: "test".to_string(),
            timestamp: Utc::now(),
        };
        assert!(!event.is_terminal());

        let event = ExecutionEvent::Stdout {
            execution_id: id,
            line: "output".to_string(),
            timestamp: Utc::now(),
        };
        assert!(!event.is_terminal());

        let result = ExecutionResult {
            id,
            status: ExecutionStatus::Completed,
            success: true,
            exit_code: 0,
            stdout: "".to_string(),
            stderr: "".to_string(),
            duration: Duration::from_secs(1),
            started_at: Utc::now(),
            completed_at: Some(Utc::now()),
            error: None,
            stdout_overflow_file: None,
            stderr_overflow_file: None,
        };

        let event = ExecutionEvent::Completed {
            execution_id: id,
            result,
            timestamp: Utc::now(),
        };
        assert!(event.is_terminal());

        let event = ExecutionEvent::Failed {
            execution_id: id,
            error: "error".to_string(),
            timestamp: Utc::now(),
        };
        assert!(event.is_terminal());

        let event = ExecutionEvent::Cancelled {
            execution_id: id,
            timestamp: Utc::now(),
        };
        assert!(event.is_terminal());

        let event = ExecutionEvent::Timeout {
            execution_id: id,
            timeout_ms: 5000,
            timestamp: Utc::now(),
        };
        assert!(event.is_terminal());
    }

    #[test]
    fn test_event_type_name() {
        let id = Uuid::new_v4();

        let event = ExecutionEvent::Started {
            execution_id: id,
            command: "test".to_string(),
            timestamp: Utc::now(),
        };
        assert_eq!(event.event_type_name(), "started");

        let event = ExecutionEvent::Stdout {
            execution_id: id,
            line: "output".to_string(),
            timestamp: Utc::now(),
        };
        assert_eq!(event.event_type_name(), "stdout");

        let event = ExecutionEvent::StatusChanged {
            execution_id: id,
            old_status: ExecutionStatus::Pending,
            new_status: ExecutionStatus::Running,
            timestamp: Utc::now(),
        };
        assert_eq!(event.event_type_name(), "status_changed");
    }

    #[tokio::test]
    async fn test_noop_event_handler() {
        let handler = NoopEventHandler;
        let event = ExecutionEvent::Started {
            execution_id: Uuid::new_v4(),
            command: "test".to_string(),
            timestamp: Utc::now(),
        };
        handler.handle_event(event).await;
        // Should not panic
    }

    #[tokio::test]
    async fn test_logging_event_handler() {
        let handler = LoggingEventHandler::new(false);
        let event = ExecutionEvent::Started {
            execution_id: Uuid::new_v4(),
            command: "test".to_string(),
            timestamp: Utc::now(),
        };
        handler.handle_event(event).await;
        // Should log to stderr
    }

    #[tokio::test]
    async fn test_multi_event_handler() {
        let mut multi = MultiEventHandler::new();
        multi.add_handler(Box::new(NoopEventHandler));
        multi.add_handler(Box::new(LoggingEventHandler::new(false)));

        let event = ExecutionEvent::Started {
            execution_id: Uuid::new_v4(),
            command: "test".to_string(),
            timestamp: Utc::now(),
        };
        multi.handle_event(event).await;
        // Should broadcast to all handlers
    }

    #[test]
    fn test_event_serialization() {
        let event = ExecutionEvent::Started {
            execution_id: Uuid::new_v4(),
            command: "echo hello".to_string(),
            timestamp: Utc::now(),
        };

        let json = serde_json::to_string(&event).unwrap();
        assert!(json.contains("started"));
        assert!(json.contains("echo hello"));

        let deserialized: ExecutionEvent = serde_json::from_str(&json).unwrap();
        match deserialized {
            ExecutionEvent::Started { command, .. } => {
                assert_eq!(command, "echo hello");
            }
            _ => panic!("Wrong event type"),
        }
    }
}