//! Circuit Breaker Edge Case Tests
//! Target: Comprehensive edge case coverage for circuit breakers
//! Focus: Recovery scenarios, concurrent operations, extreme conditions

#![allow(
    unused_crate_dependencies,
    clippy::field_reassign_with_default,
    clippy::indexing_slicing,
    clippy::integer_division,
    clippy::str_to_string
)]

use chrono::{Duration, Utc};
use common::types::Price;
use risk::circuit_breaker::{CircuitBreakerConfig, CircuitBreakerState};

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

    #[test]
    fn test_recovery_after_multiple_trips() {
        let mut state = CircuitBreakerState::default();
        state.consecutive_violations = 3;

        // Simulate multiple trip-recovery cycles
        for _ in 0..5 {
            state.is_active = true;
            state.activation_reason = Some("Trip".to_string());
            state.activated_at = Some(Utc::now());

            // Recovery
            state.is_active = false;
            state.activation_reason = None;
            state.activated_at = None;
            state.consecutive_violations = 0;
        }

        assert!(!state.is_active);
        assert_eq!(state.consecutive_violations, 0);
    }

    #[test]
    fn test_recovery_with_partial_loss_recovery() {
        let mut state = CircuitBreakerState::default();
        state.portfolio_value = Price::new(1_000_000.0).unwrap();
        state.daily_loss_limit = Price::new(20_000.0).unwrap();
        state.current_daily_loss = Price::new(25_000.0).unwrap(); // Over limit
        state.is_active = true;

        // Partial recovery - loss reduced but still over limit
        state.current_daily_loss = Price::new(22_000.0).unwrap();
        assert!(state.current_daily_loss > state.daily_loss_limit);
        assert!(state.is_active);
    }

    #[test]
    fn test_recovery_cooldown_exactly_at_threshold() {
        let config = CircuitBreakerConfig::default();
        let activation_time = Utc::now();
        let cooldown_end = activation_time + Duration::seconds(config.cooldown_period_secs as i64);

        let elapsed = (cooldown_end - activation_time).num_seconds();
        assert_eq!(elapsed, config.cooldown_period_secs as i64);
    }

    #[test]
    fn test_recovery_with_portfolio_growth() {
        let mut state = CircuitBreakerState::default();
        state.portfolio_value = Price::new(1_000_000.0).unwrap();
        state.daily_loss_limit = Price::new(20_000.0).unwrap();
        state.current_daily_loss = Price::new(25_000.0).unwrap();

        // Portfolio grows, increasing absolute loss limit
        state.portfolio_value = Price::new(1_500_000.0).unwrap();
        let new_limit = state.portfolio_value.to_f64() * 0.02;
        state.daily_loss_limit = Price::new(new_limit).unwrap();

        // Now within limit due to portfolio growth
        assert!(state.current_daily_loss < state.daily_loss_limit);
    }
}

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

    #[test]
    fn test_concurrent_violation_increments() {
        let mut state = CircuitBreakerState::default();

        // Simulate concurrent violation attempts
        let initial = state.consecutive_violations;
        state.consecutive_violations += 1;
        state.consecutive_violations += 1;
        state.consecutive_violations += 1;

        assert_eq!(state.consecutive_violations, initial + 3);
    }

    #[test]
    fn test_trip_during_recovery_attempt() {
        let mut state = CircuitBreakerState::default();
        state.is_active = true;
        state.consecutive_violations = 3;

        // Start recovery
        state.is_active = false;

        // Immediate re-trip before cooldown
        state.is_active = true;
        state.consecutive_violations += 1;

        assert!(state.is_active);
        assert_eq!(state.consecutive_violations, 4);
    }

    #[test]
    fn test_simultaneous_limit_checks() {
        let state = CircuitBreakerState {
            portfolio_value: Price::new(1_000_000.0).unwrap(),
            daily_loss_limit: Price::new(20_000.0).unwrap(),
            current_daily_loss: Price::new(19_999.0).unwrap(),
            is_active: false,
            activation_reason: None,
            activated_at: None,
            last_updated: Utc::now(),
            account_id: "test".to_string(),
            consecutive_violations: 0,
        };

        // Multiple threads checking at boundary
        let check1 = state.current_daily_loss < state.daily_loss_limit;
        let check2 = state.current_daily_loss < state.daily_loss_limit;
        let check3 = state.current_daily_loss < state.daily_loss_limit;

        assert!(check1 && check2 && check3);
    }
}

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

    #[test]
    fn test_half_open_state_simulation() {
        let mut state = CircuitBreakerState::default();
        let config = CircuitBreakerConfig::default();

        // Use a fixed timestamp to avoid timing races
        let now = Utc::now();
        state.is_active = true;
        // Use 200 seconds (between half=150s and full=300s of default cooldown)
        state.activated_at = Some(now - Duration::seconds(200));

        // Calculate elapsed time with the same timestamp
        let elapsed = (now - state.activated_at.unwrap()).num_seconds();

        // Half-open: cooldown partially elapsed (> 50% and < 100%)
        let is_half_open = elapsed > (config.cooldown_period_secs / 2) as i64
            && elapsed < config.cooldown_period_secs as i64;

        assert!(is_half_open);
    }

    #[test]
    fn test_graduated_recovery_by_loss_reduction() {
        let mut state = CircuitBreakerState::default();
        state.portfolio_value = Price::new(1_000_000.0).unwrap();
        state.daily_loss_limit = Price::new(20_000.0).unwrap();
        state.current_daily_loss = Price::new(30_000.0).unwrap();

        // Gradual loss reduction
        let reductions = vec![28_000.0, 25_000.0, 22_000.0, 19_000.0];
        for loss in reductions {
            state.current_daily_loss = Price::new(loss).unwrap();
            let ratio = state.current_daily_loss.to_f64() / state.daily_loss_limit.to_f64();

            if ratio < 1.0 {
                state.is_active = false;
                break;
            }
        }

        assert!(!state.is_active);
    }
}

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

    #[test]
    fn test_cooldown_timeout_boundary_plus_one() {
        let config = CircuitBreakerConfig::default();
        let activation_time = Utc::now();
        let check_time =
            activation_time + Duration::seconds(config.cooldown_period_secs as i64 + 1);

        let elapsed = (check_time - activation_time).num_seconds();
        assert!(elapsed > config.cooldown_period_secs as i64);
    }

    #[test]
    fn test_cooldown_timeout_boundary_minus_one() {
        let config = CircuitBreakerConfig::default();
        let activation_time = Utc::now();
        let check_time =
            activation_time + Duration::seconds(config.cooldown_period_secs as i64 - 1);

        let elapsed = (check_time - activation_time).num_seconds();
        assert!(elapsed < config.cooldown_period_secs as i64);
    }

    #[test]
    fn test_negative_time_delta_handling() {
        let state = CircuitBreakerState {
            activated_at: Some(Utc::now() + Duration::seconds(60)), // Future time (clock skew)
            ..Default::default()
        };

        let elapsed = (Utc::now() - state.activated_at.unwrap()).num_seconds();
        assert!(elapsed < 0);
    }

    #[test]
    fn test_very_long_cooldown_period() {
        let config = CircuitBreakerConfig {
            cooldown_period_secs: 86400, // 24 hours
            ..Default::default()
        };

        let activation_time = Utc::now();
        let check_time = activation_time + Duration::seconds(3600); // 1 hour

        let elapsed = (check_time - activation_time).num_seconds();
        assert!(elapsed < config.cooldown_period_secs as i64);
    }
}

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

    #[test]
    fn test_trip_with_zero_portfolio() {
        let mut state = CircuitBreakerState::default();
        state.portfolio_value = Price::ZERO;
        state.daily_loss_limit = Price::ZERO;
        state.current_daily_loss = Price::new(1000.0).unwrap();

        // Any loss with zero portfolio should trigger
        assert!(state.current_daily_loss > state.daily_loss_limit);
    }

    #[test]
    fn test_max_consecutive_violations_overflow() {
        let mut state = CircuitBreakerState::default();

        // Approach max u32
        state.consecutive_violations = u32::MAX - 5;
        state.consecutive_violations += 1;
        state.consecutive_violations += 1;

        assert!(state.consecutive_violations >= u32::MAX - 3);
    }

    #[test]
    fn test_max_portfolio_value() {
        let max_value = 1_000_000_000_000.0; // $1 trillion
        let state = CircuitBreakerState {
            portfolio_value: Price::new(max_value).unwrap(),
            daily_loss_limit: Price::new(max_value * 0.02).unwrap(),
            current_daily_loss: Price::new(max_value * 0.01).unwrap(),
            ..Default::default()
        };

        assert!(state.current_daily_loss < state.daily_loss_limit);
    }

    #[test]
    fn test_rapid_portfolio_value_changes() {
        let mut state = CircuitBreakerState::default();

        let values = vec![1_000_000.0, 500_000.0, 1_500_000.0, 200_000.0, 2_000_000.0];
        for value in values {
            state.portfolio_value = Price::new(value).unwrap();
            let new_limit = value * 0.02;
            state.daily_loss_limit = Price::new(new_limit).unwrap();

            assert!(state.daily_loss_limit.to_f64() > 0.0);
        }
    }
}

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

    #[test]
    fn test_loss_exceeds_portfolio_value() {
        let state = CircuitBreakerState {
            portfolio_value: Price::new(100_000.0).unwrap(),
            current_daily_loss: Price::new(150_000.0).unwrap(), // 150% loss
            daily_loss_limit: Price::new(2_000.0).unwrap(),
            ..Default::default()
        };

        assert!(state.current_daily_loss > state.portfolio_value);
        assert!(state.current_daily_loss > state.daily_loss_limit);
    }

    #[test]
    fn test_zero_loss_percentage() {
        let config = CircuitBreakerConfig {
            daily_loss_percentage: Price::ZERO,
            ..Default::default()
        };

        let portfolio = 1_000_000.0;
        let limit = portfolio * config.daily_loss_percentage.to_f64() / 100.0;

        assert_eq!(limit, 0.0);
    }

    #[test]
    fn test_hundred_percent_loss_limit() {
        let config = CircuitBreakerConfig {
            daily_loss_percentage: Price::new(100.0).unwrap(),
            ..Default::default()
        };

        let portfolio = 1_000_000.0;
        let limit = portfolio * config.daily_loss_percentage.to_f64() / 100.0;

        assert_eq!(limit, portfolio);
    }

    #[test]
    fn test_negative_loss_as_profit() {
        let mut state = CircuitBreakerState::default();
        state.portfolio_value = Price::new(1_000_000.0).unwrap();
        state.daily_loss_limit = Price::new(20_000.0).unwrap();

        // Negative loss = profit (should not trigger)
        // Note: In practice, losses are positive, profits negative
        // But testing the edge case
        state.current_daily_loss = Price::ZERO;

        assert!(state.current_daily_loss <= state.daily_loss_limit);
    }

    #[test]
    fn test_flash_crash_scenario() {
        let mut state = CircuitBreakerState::default();
        state.portfolio_value = Price::new(1_000_000.0).unwrap();
        state.daily_loss_limit = Price::new(20_000.0).unwrap();

        // Sudden 50% loss
        let flash_loss = state.portfolio_value.to_f64() * 0.50;
        state.current_daily_loss = Price::new(flash_loss).unwrap();

        assert!(state.current_daily_loss > state.daily_loss_limit);
        let loss_ratio = state.current_daily_loss.to_f64() / state.daily_loss_limit.to_f64();
        assert!(loss_ratio > 10.0); // More than 10x the limit
    }
}

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

    #[test]
    fn test_violation_counter_at_exactly_max() {
        let config = CircuitBreakerConfig::default();
        let mut state = CircuitBreakerState::default();

        state.consecutive_violations = config.max_consecutive_violations;

        assert_eq!(
            state.consecutive_violations,
            config.max_consecutive_violations
        );
    }

    #[test]
    fn test_violation_counter_exceeds_max() {
        let config = CircuitBreakerConfig::default();
        let mut state = CircuitBreakerState::default();

        state.consecutive_violations = config.max_consecutive_violations + 10;

        assert!(state.consecutive_violations > config.max_consecutive_violations);
    }

    #[test]
    fn test_violation_reset_after_recovery() {
        let mut state = CircuitBreakerState::default();
        state.consecutive_violations = 5;
        state.is_active = true;

        // Successful recovery
        state.is_active = false;
        state.consecutive_violations = 0;

        assert_eq!(state.consecutive_violations, 0);
    }

    #[test]
    fn test_violation_counter_wrapping() {
        let mut state = CircuitBreakerState::default();
        state.consecutive_violations = u32::MAX;

        // This would overflow in unsafe arithmetic
        // Rust u32 will panic in debug, wrap in release
        // We test the current state is at max
        assert_eq!(state.consecutive_violations, u32::MAX);
    }
}

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

    #[test]
    fn test_limit_recalc_after_portfolio_increase() {
        let mut state = CircuitBreakerState::default();
        state.portfolio_value = Price::new(1_000_000.0).unwrap();

        let old_limit = state.portfolio_value.to_f64() * 0.02;

        state.portfolio_value = Price::new(2_000_000.0).unwrap();
        let new_limit = state.portfolio_value.to_f64() * 0.02;

        assert!(new_limit > old_limit);
        assert_eq!(new_limit, 40_000.0);
    }

    #[test]
    fn test_limit_recalc_after_portfolio_decrease() {
        let mut state = CircuitBreakerState::default();
        state.portfolio_value = Price::new(1_000_000.0).unwrap();

        let old_limit = state.portfolio_value.to_f64() * 0.02;

        state.portfolio_value = Price::new(500_000.0).unwrap();
        let new_limit = state.portfolio_value.to_f64() * 0.02;

        assert!(new_limit < old_limit);
        assert_eq!(new_limit, 10_000.0);
    }

    #[test]
    fn test_limit_recalc_with_different_percentages() {
        let portfolio = Price::new(1_000_000.0).unwrap();

        let percentages = vec![1.0, 2.0, 5.0, 10.0];
        let mut limits = Vec::new();

        for pct in percentages {
            let limit = portfolio.to_f64() * (pct / 100.0);
            limits.push(limit);
        }

        // Ensure monotonic increase
        for i in 1..limits.len() {
            assert!(limits[i] > limits[i - 1]);
        }
    }

    #[test]
    fn test_limit_recalc_at_portfolio_zero() {
        let state = CircuitBreakerState {
            portfolio_value: Price::ZERO,
            ..Default::default()
        };

        let limit = state.portfolio_value.to_f64() * 0.02;
        assert_eq!(limit, 0.0);
    }
}
