sta/backend/src/application/use_cases/toggle_relay.rs

//! Toggle relay use case.
//!
//! This use case handles toggling a single relay's state from on to off or vice versa.
//! It coordinates with the relay controller to read the current state, toggle it,
//! and write the new state back.

use std::sync::Arc;

use crate::domain::relay::{
    controller::{ControllerError, RelayController},
    entity::Relay,
    repository::{RelayLabelRepository, RepositoryError},
    types::RelayId,
};

/// Error type for toggle relay use case operations.
#[derive(Debug, thiserror::Error)]
pub enum ToggleRelayError {
    /// Error from the relay controller (connection, timeout, protocol issues).
    #[error("Controller error: {0}")]
    Controller(#[from] ControllerError),

    /// Error from the label repository.
    #[error("Repository error: {0}")]
    Repository(#[from] RepositoryError),
}

/// Use case for toggling a relay's state.
///
/// This use case:
/// 1. Reads the current state of the specified relay
/// 2. Toggles the state (On → Off, Off → On)
/// 3. Writes the new state to the relay
/// 4. Returns the updated relay entity with its label
///
/// # Example
///
/// ```rust,ignore
/// let use_case = ToggleRelayUseCase::new(controller, repository);
/// let relay = use_case.execute(RelayId::new(1).unwrap()).await?;
/// // relay.state() is now toggled from its previous value
/// ```
pub struct ToggleRelayUseCase {
    controller: Arc<dyn RelayController>,
    repository: Arc<dyn RelayLabelRepository>,
}

impl ToggleRelayUseCase {
    /// Creates a new toggle relay use case.
    ///
    /// # Arguments
    ///
    /// * `controller` - The relay controller for hardware communication
    /// * `repository` - The label repository for relay labels
    #[must_use]
    pub fn new(
        controller: Arc<dyn RelayController>,
        repository: Arc<dyn RelayLabelRepository>,
    ) -> Self {
        Self {
            controller,
            repository,
        }
    }

    /// Executes the toggle relay use case.
    ///
    /// Reads the current state, toggles it, writes the new state, and returns
    /// the updated relay entity including its label.
    ///
    /// # Arguments
    ///
    /// * `relay_id` - The ID of the relay to toggle (1-8)
    ///
    /// # Returns
    ///
    /// The updated `Relay` entity with the new state.
    ///
    /// # Errors
    ///
    /// Returns `ToggleRelayError` if:
    /// - Controller fails to read/write relay state
    /// - Repository fails to retrieve the label
    pub async fn execute(&self, relay_id: RelayId) -> Result<Relay, ToggleRelayError> {
        tracing::debug!(target: "use_case::toggle_relay", relay_id = relay_id.as_u8(), "Toggling relay state");
        let current_state = self.controller.read_relay_state(relay_id).await?;
        tracing::debug!(target: "use_case::toggle_relay", relay_id = relay_id.as_u8(), ?current_state, "Read current state");
        let new_state = current_state.toggle();
        tracing::debug!(target: "use_case::toggle_relay", relay_id = relay_id.as_u8(), ?new_state, "New state after toggle");
        self.controller
            .write_relay_state(relay_id, new_state)
            .await?;
        tracing::info!(target: "use_case::toggle_relay", relay_id = relay_id.as_u8(), ?new_state, "Successfully toggled relay");
        let label = self.repository.get_label(relay_id).await?;
        Ok(Relay::new(relay_id, new_state, label))
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::domain::relay::types::RelayState;
    use crate::infrastructure::modbus::mock_controller::MockRelayController;
    use crate::infrastructure::persistence::label_repository::MockRelayLabelRepository;

    /// Helper to create a test controller with initialized relays.
    async fn create_test_controller() -> MockRelayController {
        let controller = MockRelayController::new();
        for i in 1..=8 {
            controller
                .write_relay_state(RelayId::new(i).unwrap(), RelayState::Off)
                .await
                .unwrap();
        }
        controller
    }

    #[tokio::test]
    async fn test_execute_toggles_relay_state_off_to_on() {
        let controller = Arc::new(create_test_controller().await);
        let repository = Arc::new(MockRelayLabelRepository::new());
        let use_case = ToggleRelayUseCase::new(controller.clone(), repository);
        let relay_id = RelayId::new(1).unwrap();
        let initial_state = controller.read_relay_state(relay_id).await.unwrap();
        assert_eq!(initial_state, RelayState::Off);
        let result = use_case.execute(relay_id).await.unwrap();
        assert_eq!(result.state(), RelayState::On);
        assert_eq!(result.id(), relay_id);
    }

    #[tokio::test]
    async fn test_execute_toggles_relay_state_on_to_off() {
        let controller = Arc::new(create_test_controller().await);
        let repository = Arc::new(MockRelayLabelRepository::new());
        let relay_id = RelayId::new(1).unwrap();
        controller
            .write_relay_state(relay_id, RelayState::On)
            .await
            .unwrap();
        let use_case = ToggleRelayUseCase::new(controller.clone(), repository);
        let result = use_case.execute(relay_id).await.unwrap();
        assert_eq!(result.state(), RelayState::Off);
    }

    #[tokio::test]
    async fn test_execute_returns_error_if_controller_fails() {
        let controller = Arc::new(MockRelayController::new().with_timeout_simulation());
        let repository = Arc::new(MockRelayLabelRepository::new());
        let use_case = ToggleRelayUseCase::new(controller, repository);
        let relay_id = RelayId::new(1).unwrap();
        let result = use_case.execute(relay_id).await;
        assert!(result.is_err());
        assert!(matches!(
            result.unwrap_err(),
            ToggleRelayError::Controller(_)
        ));
    }

    #[tokio::test]
    async fn test_execute_updates_state_in_controller() {
        let controller = Arc::new(create_test_controller().await);
        let repository = Arc::new(MockRelayLabelRepository::new());
        let use_case = ToggleRelayUseCase::new(controller.clone(), repository);
        let relay_id = RelayId::new(1).unwrap();
        use_case.execute(relay_id).await.unwrap();
        let state_in_controller = controller.read_relay_state(relay_id).await.unwrap();
        assert_eq!(state_in_controller, RelayState::On);
    }

    #[tokio::test]
    async fn test_execute_returns_relay_with_label() {
        let controller = Arc::new(create_test_controller().await);
        let repository = Arc::new(MockRelayLabelRepository::new());
        let relay_id = RelayId::new(1).unwrap();
        let label = crate::domain::relay::types::RelayLabel::new("Test Label".to_string()).unwrap();
        repository
            .save_label(relay_id, label.clone())
            .await
            .unwrap();
        let use_case = ToggleRelayUseCase::new(controller, repository);
        let result = use_case.execute(relay_id).await.unwrap();
        assert_eq!(result.label(), Some(label));
    }

    #[tokio::test]
    async fn test_execute_returns_relay_without_label_when_none_set() {
        let controller = Arc::new(create_test_controller().await);
        let repository = Arc::new(MockRelayLabelRepository::new());
        let use_case = ToggleRelayUseCase::new(controller, repository);
        let relay_id = RelayId::new(1).unwrap();
        let result = use_case.execute(relay_id).await.unwrap();
        assert_eq!(result.label(), None);
    }

    #[tokio::test]
    async fn test_execute_double_toggle_returns_to_original_state() {
        let controller = Arc::new(create_test_controller().await);
        let repository = Arc::new(MockRelayLabelRepository::new());
        let use_case = ToggleRelayUseCase::new(controller.clone(), repository);
        let relay_id = RelayId::new(1).unwrap();
        let initial_state = controller.read_relay_state(relay_id).await.unwrap();
        assert_eq!(initial_state, RelayState::Off);
        use_case.execute(relay_id).await.unwrap();
        let result = use_case.execute(relay_id).await.unwrap();
        assert_eq!(result.state(), RelayState::Off);
    }
}