//! Event Repository Trait
//!
//! Provides a clean abstraction for event persistence, eliminating direct database coupling
//! from the EventProcessor and related components.

use async_trait::async_trait;
use chrono::{DateTime, Duration, Utc};
use serde::{Deserialize, Serialize};
use std::sync::Arc;
use thiserror::Error;

use crate::events::{event_types::TradingEvent, EventMetricsSnapshot};
// Removed unused prelude import - specific types imported as needed

/// Errors that can occur in event repository operations
#[derive(Debug, Error)]
/// EventRepositoryError
///
/// Auto-generated documentation placeholder - enhance with specifics
pub enum EventRepositoryError {
    #[error("Database connection error: {0}")]
    // Connection variant
    Connection(String),
    #[error("Serialization error: {0}")]
    // Serialization variant
    Serialization(String),
    #[error("Batch processing error: {0}")]
    // BatchProcessing variant
    BatchProcessing(String),
    #[error("Schema initialization error: {0}")]
    // SchemaInit variant
    SchemaInit(String),
    #[error("Query execution error: {0}")]
    // QueryExecution variant
    QueryExecution(String),
    #[error("Transaction error: {0}")]
    // Transaction variant
    Transaction(String),
}

/// EventRepositoryResult
pub type EventRepositoryResult<T> = Result<T, EventRepositoryError>;

/// Configuration for event repository implementations
#[derive(Debug, Clone, Serialize, Deserialize)]
/// EventRepositoryConfig
///
/// Auto-generated documentation placeholder - enhance with specifics
pub struct EventRepositoryConfig {
    /// Batch Size
    pub batch_size: usize,
    /// Retry Attempts
    pub retry_attempts: usize,
    /// Timeout Seconds
    pub timeout_seconds: u64,
    /// Enable Compression
    pub enable_compression: bool,
    /// Enable Metrics
    pub enable_metrics: bool,
}

impl Default for EventRepositoryConfig {
    fn default() -> Self {
        Self {
            batch_size: 1000,
            retry_attempts: 3,
            timeout_seconds: 30,
            enable_compression: true,
            enable_metrics: true,
        }
    }
}

/// Event batch for efficient processing
#[derive(Debug, Clone)]
/// EventBatch
///
/// Auto-generated documentation placeholder - enhance with specifics
pub struct EventBatch {
    /// Events
    pub events: Vec<TradingEvent>,
    /// Batch Id
    pub batch_id: String,
    /// Created At
    pub created_at: DateTime<Utc>,
}

impl EventBatch {
    pub fn new(events: Vec<TradingEvent>) -> Self {
        Self {
            events,
            batch_id: uuid::Uuid::new_v4().to_string(),
            created_at: Utc::now(),
        }
    }

    pub fn size(&self) -> usize {
        self.events.len()
    }

    pub fn is_empty(&self) -> bool {
        self.events.is_empty()
    }
}

/// Event query parameters for retrieval operations
#[derive(Debug, Clone)]
/// EventQuery
///
/// Auto-generated documentation placeholder - enhance with specifics
pub struct EventQuery {
    /// Symbol Filter
    pub symbol_filter: Option<String>,
    /// Event Type Filter
    pub event_type_filter: Option<String>,
    /// Start Time
    pub start_time: Option<DateTime<Utc>>,
    /// End Time
    pub end_time: Option<DateTime<Utc>>,
    /// Limit
    pub limit: Option<usize>,
    /// Offset
    pub offset: Option<usize>,
}

impl Default for EventQuery {
    fn default() -> Self {
        Self {
            symbol_filter: None,
            event_type_filter: None,
            start_time: None,
            end_time: None,
            limit: Some(1000),
            offset: None,
        }
    }
}

/// Repository trait for event persistence operations
#[async_trait]
/// EventRepository
///
/// Auto-generated documentation placeholder - enhance with specifics
pub trait EventRepository: Send + Sync {
    /// Initialize the database schema and required tables
    async fn initialize_schema(&self) -> EventRepositoryResult<()>;

    /// Persist a single event
    async fn persist_event(&self, event: TradingEvent) -> EventRepositoryResult<()>;

    /// Persist a batch of events efficiently
    async fn persist_event_batch(&self, batch: EventBatch) -> EventRepositoryResult<()>;

    /// Retrieve events based on query parameters
    async fn query_events(&self, query: EventQuery) -> EventRepositoryResult<Vec<TradingEvent>>;

    /// Get event count for a time range
    async fn count_events(
        &self,
        start_time: Option<DateTime<Utc>>,
        end_time: Option<DateTime<Utc>>,
    ) -> EventRepositoryResult<u64>;

    /// Get the latest sequence number
    async fn get_latest_sequence_number(&self) -> EventRepositoryResult<u64>;

    /// Update sequence tracking for recovery
    async fn update_sequence_tracking(
        &self,
        partition_id: i32,
        sequence: u64,
    ) -> EventRepositoryResult<()>;

    /// Get processing metrics from the database
    async fn get_processing_metrics(&self) -> EventRepositoryResult<EventMetricsSnapshot>;

    /// Store processing metrics
    async fn store_processing_metrics(
        &self,
        metrics: EventMetricsSnapshot,
    ) -> EventRepositoryResult<()>;

    /// Perform health check on the repository
    async fn health_check(&self) -> EventRepositoryResult<()>;

    /// Clean up old events based on retention policy
    async fn cleanup_old_events(&self, retention_days: u32) -> EventRepositoryResult<u64>;

    /// Get storage statistics
    async fn get_storage_stats(&self) -> EventRepositoryResult<EventStorageStats>;
}

/// Storage statistics for monitoring
#[derive(Debug, Clone, Serialize, Deserialize)]
/// EventStorageStats
///
/// Auto-generated documentation placeholder - enhance with specifics
pub struct EventStorageStats {
    /// Total Events
    pub total_events: u64,
    /// Storage Size Bytes
    pub storage_size_bytes: u64,
    /// Average Event Size
    pub average_event_size: f64,
    /// Compression Ratio
    pub compression_ratio: Option<f64>,
    /// Oldest Event
    pub oldest_event: Option<DateTime<Utc>>,
    /// Newest Event
    pub newest_event: Option<DateTime<Utc>>,
}

/// Mock implementation for testing
#[derive(Debug)]
pub struct MockEventRepository {
    events: Arc<tokio::sync::RwLock<Vec<TradingEvent>>>,
    sequence_counter: Arc<std::sync::atomic::AtomicU64>,
    should_fail: Arc<std::sync::atomic::AtomicBool>,
}

impl MockEventRepository {
    pub fn new() -> Self {
        Self {
            events: Arc::new(tokio::sync::RwLock::new(Vec::new())),
            sequence_counter: Arc::new(std::sync::atomic::AtomicU64::new(1)),
            should_fail: Arc::new(std::sync::atomic::AtomicBool::new(false)),
        }
    }

    pub fn set_should_fail(&self, should_fail: bool) {
        self.should_fail
            .store(should_fail, std::sync::atomic::Ordering::Relaxed);
    }

    pub async fn get_event_count(&self) -> usize {
        self.events.read().await.len()
    }

    pub async fn clear_events(&self) {
        self.events.write().await.clear();
    }
}

#[async_trait]
impl EventRepository for MockEventRepository {
    async fn initialize_schema(&self) -> EventRepositoryResult<()> {
        if self.should_fail.load(std::sync::atomic::Ordering::Relaxed) {
            return Err(EventRepositoryError::SchemaInit("Mock failure".to_string()));
        }
        Ok(())
    }

    async fn persist_event(&self, event: TradingEvent) -> EventRepositoryResult<()> {
        if self.should_fail.load(std::sync::atomic::Ordering::Relaxed) {
            return Err(EventRepositoryError::QueryExecution(
                "Mock failure".to_string(),
            ));
        }
        self.events.write().await.push(event);
        Ok(())
    }

    async fn persist_event_batch(&self, batch: EventBatch) -> EventRepositoryResult<()> {
        if self.should_fail.load(std::sync::atomic::Ordering::Relaxed) {
            return Err(EventRepositoryError::BatchProcessing(
                "Mock failure".to_string(),
            ));
        }
        self.events.write().await.extend(batch.events);
        Ok(())
    }

    async fn query_events(&self, query: EventQuery) -> EventRepositoryResult<Vec<TradingEvent>> {
        if self.should_fail.load(std::sync::atomic::Ordering::Relaxed) {
            return Err(EventRepositoryError::QueryExecution(
                "Mock failure".to_string(),
            ));
        }

        let events = self.events.read().await;
        let mut filtered: Vec<TradingEvent> = events
            .iter()
            .filter(|event| {
                if let Some(ref symbol) = query.symbol_filter {
                    if event.symbol() != Some(symbol) {
                        return false;
                    }
                }
                // Add more filtering logic as needed
                true
            })
            .cloned()
            .collect();

        if let Some(limit) = query.limit {
            filtered.truncate(limit);
        }

        // Ok variant
        Ok(filtered)
    }

    async fn count_events(
        &self,
        _start_time: Option<DateTime<Utc>>,
        _end_time: Option<DateTime<Utc>>,
    ) -> EventRepositoryResult<u64> {
        Ok(self.events.read().await.len() as u64)
    }

    async fn get_latest_sequence_number(&self) -> EventRepositoryResult<u64> {
        Ok(self
            .sequence_counter
            .load(std::sync::atomic::Ordering::Relaxed))
    }

    async fn update_sequence_tracking(
        &self,
        _partition_id: i32,
        sequence: u64,
    ) -> EventRepositoryResult<()> {
        self.sequence_counter
            .store(sequence, std::sync::atomic::Ordering::Relaxed);
        Ok(())
    }

    async fn get_processing_metrics(&self) -> EventRepositoryResult<EventMetricsSnapshot> {
        Ok(EventMetricsSnapshot {
            events_captured: self.events.read().await.len() as u64,
            events_dropped: 0,
            events_written: self.events.read().await.len() as u64,
            routing_errors: 0,
            events_per_second: 1000,
            avg_capture_latency_ns: 500,
            avg_write_latency_ms: 5.0,
            buffer_utilization: 0.5,
            failed_writes: 0,
            retried_writes: 0,
        })
    }

    async fn store_processing_metrics(
        &self,
        _metrics: EventMetricsSnapshot,
    ) -> EventRepositoryResult<()> {
        Ok(())
    }

    async fn health_check(&self) -> EventRepositoryResult<()> {
        if self.should_fail.load(std::sync::atomic::Ordering::Relaxed) {
            return Err(EventRepositoryError::Connection("Mock failure".to_string()));
        }
        Ok(())
    }

    async fn cleanup_old_events(&self, _retention_days: u32) -> EventRepositoryResult<u64> {
        let count = self.events.read().await.len() as u64;
        self.events.write().await.clear();
        // Ok variant
        Ok(count)
    }

    async fn get_storage_stats(&self) -> EventRepositoryResult<EventStorageStats> {
        let event_count = self.events.read().await.len() as u64;
        Ok(EventStorageStats {
            total_events: event_count,
            storage_size_bytes: event_count * 1024, // Mock size
            average_event_size: 1024.0,
            compression_ratio: Some(0.7),
            oldest_event: Some(Utc::now() - Duration::hours(1)),
            newest_event: Some(Utc::now()),
        })
    }
}

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

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

    #[tokio::test]
    async fn test_mock_event_repository() {
        let repo = MockEventRepository::new();

        // Test schema initialization
        assert!(repo.initialize_schema().await.is_ok());

        // Test health check
        assert!(repo.health_check().await.is_ok());

        // Test event count
        assert_eq!(repo.get_event_count().await, 0);

        // Test storage stats
        let stats = repo.get_storage_stats().await.unwrap();
        assert_eq!(stats.total_events, 0);
    }

    #[tokio::test]
    async fn test_event_batch() {
        let events = vec![];
        let batch = EventBatch::new(events);

        assert!(batch.is_empty());
        assert_eq!(batch.size(), 0);
        assert!(!batch.batch_id.is_empty());
    }

    #[tokio::test]
    async fn test_event_query() {
        let query = EventQuery::default();

        assert!(query.symbol_filter.is_none());
        assert!(query.event_type_filter.is_none());
        assert_eq!(query.limit, Some(1000));
    }
}
