//! Mock implementation and tests for `RelayLabelRepository` trait.
//!
//! This module provides a simple in-memory mock implementation of the
//! `RelayLabelRepository` trait for testing purposes, along with comprehensive
//! tests that verify the trait's contract.

use std::collections::HashMap;
use std::sync::Arc;

use async_trait::async_trait;
use tokio::sync::{Mutex, MutexGuard};

use crate::domain::relay::{
    repository::{RelayLabelRepository, RepositoryError},
    types::{RelayId, RelayLabel},
};

/// In-memory mock implementation of `RelayLabelRepository` for testing.
///
/// This implementation uses a `HashMap` wrapped in `Arc<Mutex<_>>` to provide
/// thread-safe concurrent access to relay labels. It's useful for testing
/// application logic without requiring a database connection.
#[derive(Debug, Clone)]
pub struct MockRelayLabelRepository {
    /// Internal storage for relay labels, protected by a mutex for thread safety.
    labels: Arc<Mutex<HashMap<u8, RelayLabel>>>,
}

impl MockRelayLabelRepository {
    /// Creates a new empty mock repository.
    #[must_use]
    pub fn new() -> Self {
        Self {
            labels: Arc::new(Mutex::new(HashMap::new())),
        }
    }

    async fn labels(&self) -> MutexGuard<'_, HashMap<u8, RelayLabel>> {
        self.labels.lock().await
    }
}

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

#[async_trait]
impl RelayLabelRepository for MockRelayLabelRepository {
    async fn get_label(&self, id: RelayId) -> Result<Option<RelayLabel>, RepositoryError> {
        Ok(self.labels().await.get(&id.as_u8()).cloned())
    }

    async fn save_label(&self, id: RelayId, label: RelayLabel) -> Result<(), RepositoryError> {
        self.labels().await.insert(id.as_u8(), label);
        Ok(())
    }

    async fn get_all_labels(&self) -> Result<Vec<(RelayId, RelayLabel)>, RepositoryError> {
        let mut result: Vec<(RelayId, RelayLabel)> = self
            .labels()
            .await
            .iter()
            .filter_map(|(&id, label)| {
                RelayId::new(id).map_or(None, |relay_id| Some((relay_id, label.clone())))
            })
            .collect();

        // Sort by relay ID for consistent ordering
        result.sort_by_key(|(id, _)| id.as_u8());

        Ok(result)
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_get_label_returns_none_for_non_existent_relay() {
        // Test: get_label(RelayId(1)) → None when no label is set
        let repo = MockRelayLabelRepository::new();
        let relay_id = RelayId::new(1).unwrap();

        let result = repo.get_label(relay_id).await;

        assert!(result.is_ok());
        assert!(result.unwrap().is_none());
    }

    #[tokio::test]
    async fn test_save_label_and_get_label_returns_saved_label() {
        // Test: save_label(RelayId(1), "Pump") then get_label(RelayId(1)) → Some("Pump")
        let repo = MockRelayLabelRepository::new();
        let relay_id = RelayId::new(1).unwrap();
        let label = RelayLabel::new("Pump".to_string()).unwrap();

        // Save the label
        let save_result = repo.save_label(relay_id, label.clone()).await;
        assert!(save_result.is_ok());

        // Retrieve the label
        let get_result = repo.get_label(relay_id).await;
        assert!(get_result.is_ok());

        let retrieved_label = get_result.unwrap();
        assert!(retrieved_label.is_some());
        assert_eq!(retrieved_label.unwrap().as_str(), "Pump");
    }

    #[tokio::test]
    async fn test_save_label_overwrites_existing_label() {
        // Test: save_label twice with different values, get_label returns the latest
        let repo = MockRelayLabelRepository::new();
        let relay_id = RelayId::new(1).unwrap();
        let label1 = RelayLabel::new("First".to_string()).unwrap();
        let label2 = RelayLabel::new("Second".to_string()).unwrap();

        // Save first label
        repo.save_label(relay_id, label1).await.unwrap();

        // Overwrite with second label
        repo.save_label(relay_id, label2).await.unwrap();

        // Retrieve should return the second label
        let retrieved_label = repo.get_label(relay_id).await.unwrap();
        assert!(retrieved_label.is_some());
        assert_eq!(retrieved_label.unwrap().as_str(), "Second");
    }

    #[tokio::test]
    async fn test_get_all_labels_returns_empty_vec_when_no_labels() {
        // Test: get_all_labels() → [] when repository is empty
        let repo = MockRelayLabelRepository::new();

        let result = repo.get_all_labels().await;

        assert!(result.is_ok());
        assert!(result.unwrap().is_empty());
    }

    #[tokio::test]
    async fn test_get_all_labels_returns_all_saved_labels() {
        // Test: save multiple labels, get_all_labels() returns all of them
        let repo = MockRelayLabelRepository::new();

        let relay1 = RelayId::new(1).unwrap();
        let relay3 = RelayId::new(3).unwrap();
        let relay5 = RelayId::new(5).unwrap();

        let label1 = RelayLabel::new("Pump".to_string()).unwrap();
        let label3 = RelayLabel::new("Heater".to_string()).unwrap();
        let label5 = RelayLabel::new("Fan".to_string()).unwrap();

        // Save labels
        repo.save_label(relay1, label1.clone()).await.unwrap();
        repo.save_label(relay3, label3.clone()).await.unwrap();
        repo.save_label(relay5, label5.clone()).await.unwrap();

        // Retrieve all labels
        let result = repo.get_all_labels().await.unwrap();

        assert_eq!(result.len(), 3);

        // Verify labels are sorted by relay ID
        assert_eq!(result[0].0.as_u8(), 1);
        assert_eq!(result[0].1.as_str(), "Pump");

        assert_eq!(result[1].0.as_u8(), 3);
        assert_eq!(result[1].1.as_str(), "Heater");

        assert_eq!(result[2].0.as_u8(), 5);
        assert_eq!(result[2].1.as_str(), "Fan");
    }

    #[tokio::test]
    async fn test_get_all_labels_excludes_relays_without_labels() {
        // Test: Only relays with labels are returned, not all possible relay IDs
        let repo = MockRelayLabelRepository::new();

        let relay2 = RelayId::new(2).unwrap();
        let label2 = RelayLabel::new("Only This One".to_string()).unwrap();

        repo.save_label(relay2, label2).await.unwrap();

        let result = repo.get_all_labels().await.unwrap();

        assert_eq!(result.len(), 1);
        assert_eq!(result[0].0.as_u8(), 2);
    }

    #[tokio::test]
    async fn test_save_label_for_all_valid_relay_ids() {
        // Test: All relay IDs (1-8) can have labels saved
        let repo = MockRelayLabelRepository::new();

        for id in 1..=8 {
            let relay_id = RelayId::new(id).unwrap();
            let label = RelayLabel::new(format!("Relay {id}")).unwrap();

            let result = repo.save_label(relay_id, label).await;
            assert!(result.is_ok(), "Failed to save label for relay {id}");
        }

        // Verify all labels were saved
        let all_labels = repo.get_all_labels().await.unwrap();
        assert_eq!(all_labels.len(), 8);
    }

    #[tokio::test]
    async fn test_concurrent_access_is_thread_safe() {
        // Test: Multiple concurrent operations don't cause data races
        let repo = MockRelayLabelRepository::new();

        let handles: Vec<_> = (1..=8)
            .map(|id| {
                let repo = repo.clone();
                tokio::spawn(async move {
                    let relay_id = RelayId::new(id).unwrap();
                    let label = RelayLabel::new(format!("Relay {id}")).unwrap();
                    repo.save_label(relay_id, label).await.unwrap();
                })
            })
            .collect();

        // Wait for all tasks to complete
        for handle in handles {
            handle.await.unwrap();
        }

        // Verify all labels were saved correctly
        let all_labels = repo.get_all_labels().await.unwrap();
        assert_eq!(all_labels.len(), 8);
    }
}