foxhunt/ml/tests/backtesting_integration_test.rs

//! Comprehensive Backtesting Integration Test Suite
//!
//! This test suite validates the entire backtesting pipeline including:
//! - Position tracking logic and state transitions
//! - P&L calculation accuracy across different scenarios
//! - Metrics calculation formulas (Sharpe, Sortino, Drawdown, etc.)
//! - Edge cases and error handling
//! - End-to-end integration with realistic market data
//!
//! Test Coverage: 50 tests across 5 modules
//! - Module 1: Position Tracking (10 tests)
//! - Module 2: P&L Calculation (12 tests)
//! - Module 3: Metrics Calculation (15 tests)
//! - Module 4: Edge Cases (8 tests)
//! - Module 5: Integration (5 tests)

use chrono::{DateTime, Utc};

// =============================================================================
// Test Data Structures (Mirrors wave_d_backtest.rs implementation)
// =============================================================================

#[derive(Debug, Clone, Copy, PartialEq)]
enum PositionState {
    Flat,
    Long,
    Short,
}

#[derive(Debug, Clone, Copy, PartialEq)]
enum Action {
    Buy,
    Sell,
    Hold,
}

#[derive(Debug, Clone)]
struct Position {
    state: PositionState,
    entry_price: f64,
    entry_time: DateTime<Utc>,
    size: f64,
}

#[derive(Debug, Clone)]
struct Trade {
    entry_time: DateTime<Utc>,
    exit_time: DateTime<Utc>,
    entry_price: f64,
    exit_price: f64,
    side: PositionState, // Long or Short
    pnl: f64,
    size: f64,
}

#[derive(Debug, Clone)]
struct BacktestMetrics {
    total_trades: usize,
    winning_trades: usize,
    losing_trades: usize,
    win_rate: f64,
    total_pnl: f64,
    total_return: f64,
    sharpe_ratio: f64,
    sortino_ratio: f64,
    max_drawdown: f64,
    max_drawdown_duration: usize,
    calmar_ratio: f64,
    profit_factor: f64,
    avg_win: f64,
    avg_loss: f64,
    buy_and_hold_return: f64,
    alpha: f64,
    recovery_factor: f64,
}

// =============================================================================
// Backtesting Engine Implementation
// =============================================================================

struct BacktestEngine {
    initial_capital: f64,
    commission_per_side: f64,
}

impl BacktestEngine {
    fn new(initial_capital: f64, commission_per_side: f64) -> Self {
        Self {
            initial_capital,
            commission_per_side,
        }
    }

    /// Update position state based on action
    fn update_position(
        &self,
        current_position: Option<Position>,
        action: Action,
        price: f64,
        timestamp: DateTime<Utc>,
        size: f64,
    ) -> (Option<Position>, Option<Trade>) {
        match (current_position, action) {
            // From flat position
            (None, Action::Buy) => {
                let new_position = Position {
                    state: PositionState::Long,
                    entry_price: price,
                    entry_time: timestamp,
                    size,
                };
                (Some(new_position), None)
            },
            (None, Action::Sell) => {
                let new_position = Position {
                    state: PositionState::Short,
                    entry_price: price,
                    entry_time: timestamp,
                    size,
                };
                (Some(new_position), None)
            },
            (None, Action::Hold) => (None, None),

            // From long position
            (Some(pos), Action::Sell) if pos.state == PositionState::Long => {
                let pnl = self.calculate_pnl(PositionState::Long, pos.entry_price, price, pos.size);
                let trade = Trade {
                    entry_time: pos.entry_time,
                    exit_time: timestamp,
                    entry_price: pos.entry_price,
                    exit_price: price,
                    side: PositionState::Long,
                    pnl,
                    size: pos.size,
                };
                (None, Some(trade))
            },
            (Some(pos), Action::Hold) if pos.state == PositionState::Long => (Some(pos), None),
            (Some(pos), Action::Buy) if pos.state == PositionState::Long => (Some(pos), None), // Ignore duplicate buys

            // From short position
            (Some(pos), Action::Buy) if pos.state == PositionState::Short => {
                let pnl =
                    self.calculate_pnl(PositionState::Short, pos.entry_price, price, pos.size);
                let trade = Trade {
                    entry_time: pos.entry_time,
                    exit_time: timestamp,
                    entry_price: pos.entry_price,
                    exit_price: price,
                    side: PositionState::Short,
                    pnl,
                    size: pos.size,
                };
                (None, Some(trade))
            },
            (Some(pos), Action::Hold) if pos.state == PositionState::Short => (Some(pos), None),
            (Some(pos), Action::Sell) if pos.state == PositionState::Short => (Some(pos), None), // Ignore duplicate sells

            _ => unreachable!("Invalid position state transition"),
        }
    }

    /// Calculate P&L for a trade
    fn calculate_pnl(&self, side: PositionState, entry: f64, exit: f64, size: f64) -> f64 {
        let gross_pnl = match side {
            PositionState::Long => size * (exit - entry),
            PositionState::Short => size * (entry - exit),
            PositionState::Flat => 0.0,
        };
        // Deduct commissions (entry + exit)
        gross_pnl - (2.0 * self.commission_per_side)
    }

    /// Calculate comprehensive backtest metrics
    fn calculate_metrics(
        &self,
        trades: &[Trade],
        equity_curve: &[f64],
        first_price: f64,
        last_price: f64,
    ) -> BacktestMetrics {
        let total_trades = trades.len();
        let winning_trades = trades.iter().filter(|t| t.pnl > 0.0).count();
        let losing_trades = trades.iter().filter(|t| t.pnl < 0.0).count();

        let win_rate = if total_trades > 0 {
            winning_trades as f64 / total_trades as f64
        } else {
            0.0
        };

        let total_pnl: f64 = trades.iter().map(|t| t.pnl).sum();
        let total_return = if self.initial_capital > 0.0 {
            total_pnl / self.initial_capital
        } else {
            0.0
        };

        // Calculate returns for Sharpe/Sortino
        let returns: Vec<f64> = trades
            .iter()
            .map(|t| t.pnl / self.initial_capital)
            .collect();

        let sharpe_ratio = self.calculate_sharpe(&returns);
        let sortino_ratio = self.calculate_sortino(&returns);

        let (max_drawdown, max_drawdown_duration) = self.calculate_max_drawdown(equity_curve);

        let calmar_ratio = if max_drawdown > 0.0 {
            (total_return * 100.0) / (max_drawdown * 100.0)
        } else {
            0.0
        };

        let gross_profit: f64 = trades.iter().filter(|t| t.pnl > 0.0).map(|t| t.pnl).sum();
        let gross_loss: f64 = trades
            .iter()
            .filter(|t| t.pnl < 0.0)
            .map(|t| t.pnl.abs())
            .sum();

        let profit_factor = if gross_loss > 0.0 {
            gross_profit / gross_loss
        } else if gross_profit > 0.0 {
            f64::INFINITY
        } else {
            0.0
        };

        let avg_win = if winning_trades > 0 {
            gross_profit / winning_trades as f64
        } else {
            0.0
        };

        let avg_loss = if losing_trades > 0 {
            gross_loss / losing_trades as f64
        } else {
            0.0
        };

        let buy_and_hold_return = if first_price > 0.0 {
            (last_price - first_price) / first_price
        } else {
            0.0
        };

        let alpha = total_return - buy_and_hold_return;

        let recovery_factor = if max_drawdown > 0.0 {
            total_return / max_drawdown
        } else {
            0.0
        };

        BacktestMetrics {
            total_trades,
            winning_trades,
            losing_trades,
            win_rate,
            total_pnl,
            total_return,
            sharpe_ratio,
            sortino_ratio,
            max_drawdown,
            max_drawdown_duration,
            calmar_ratio,
            profit_factor,
            avg_win,
            avg_loss,
            buy_and_hold_return,
            alpha,
            recovery_factor,
        }
    }

    fn calculate_sharpe(&self, returns: &[f64]) -> f64 {
        if returns.is_empty() {
            return 0.0;
        }

        let mean_return = returns.iter().sum::<f64>() / returns.len() as f64;
        let variance = returns
            .iter()
            .map(|r| (r - mean_return).powi(2))
            .sum::<f64>()
            / returns.len() as f64;
        let std_dev = variance.sqrt();

        if std_dev > 0.0 {
            (mean_return / std_dev) * (252.0_f64).sqrt() // Annualized
        } else {
            0.0
        }
    }

    fn calculate_sortino(&self, returns: &[f64]) -> f64 {
        if returns.is_empty() {
            return 0.0;
        }

        let mean_return = returns.iter().sum::<f64>() / returns.len() as f64;

        // Only consider downside deviation (negative returns)
        let downside_returns: Vec<f64> = returns.iter().filter(|&&r| r < 0.0).copied().collect();

        if downside_returns.is_empty() {
            return if mean_return > 0.0 {
                f64::INFINITY
            } else {
                0.0
            };
        }

        let downside_variance =
            downside_returns.iter().map(|r| r.powi(2)).sum::<f64>() / downside_returns.len() as f64;
        let downside_std_dev = downside_variance.sqrt();

        if downside_std_dev > 0.0 {
            (mean_return / downside_std_dev) * (252.0_f64).sqrt() // Annualized
        } else {
            0.0
        }
    }

    fn calculate_max_drawdown(&self, equity_curve: &[f64]) -> (f64, usize) {
        if equity_curve.is_empty() {
            return (0.0, 0);
        }

        let mut max_drawdown = 0.0;
        let mut max_duration = 0;
        let mut peak = equity_curve[0];
        let mut current_duration = 0;

        for &equity in equity_curve {
            if equity > peak {
                peak = equity;
                current_duration = 0;
            } else {
                current_duration += 1;
                let drawdown = (peak - equity) / peak;
                if drawdown > max_drawdown {
                    max_drawdown = drawdown;
                    max_duration = current_duration;
                }
            }
        }

        (max_drawdown, max_duration)
    }

    /// Force close position at end of data
    fn force_close_position(
        &self,
        position: Option<Position>,
        price: f64,
        timestamp: DateTime<Utc>,
    ) -> Option<Trade> {
        position.map(|pos| {
            let pnl = self.calculate_pnl(pos.state, pos.entry_price, price, pos.size);
            Trade {
                entry_time: pos.entry_time,
                exit_time: timestamp,
                entry_price: pos.entry_price,
                exit_price: price,
                side: pos.state,
                pnl,
                size: pos.size,
            }
        })
    }
}

// =============================================================================
// MODULE 1: Position Tracking Tests (10 tests)
// =============================================================================

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

    fn create_timestamp(offset_secs: i64) -> DateTime<Utc> {
        DateTime::from_timestamp(1_700_000_000 + offset_secs, 0).unwrap()
    }

    #[test]
    fn test_01_open_long_position_from_flat() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let (position, trade) =
            engine.update_position(None, Action::Buy, 100.0, create_timestamp(0), 10.0);

        assert!(position.is_some());
        assert!(trade.is_none());
        let pos = position.unwrap();
        assert_eq!(pos.state, PositionState::Long);
        assert_eq!(pos.entry_price, 100.0);
        assert_eq!(pos.size, 10.0);
    }

    #[test]
    fn test_02_close_long_position_on_sell() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let initial_position = Position {
            state: PositionState::Long,
            entry_price: 100.0,
            entry_time: create_timestamp(0),
            size: 10.0,
        };

        let (position, trade) = engine.update_position(
            Some(initial_position),
            Action::Sell,
            110.0,
            create_timestamp(100),
            10.0,
        );

        assert!(position.is_none());
        assert!(trade.is_some());
        let t = trade.unwrap();
        assert_eq!(t.side, PositionState::Long);
        assert_eq!(t.entry_price, 100.0);
        assert_eq!(t.exit_price, 110.0);
        assert_eq!(t.pnl, 10.0 * (110.0 - 100.0) - 5.0); // $95 profit
    }

    #[test]
    fn test_03_reverse_from_long_to_flat_on_sell() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let long_position = Position {
            state: PositionState::Long,
            entry_price: 100.0,
            entry_time: create_timestamp(0),
            size: 10.0,
        };

        let (position, trade) = engine.update_position(
            Some(long_position),
            Action::Sell,
            95.0,
            create_timestamp(50),
            10.0,
        );

        assert!(position.is_none()); // Closes to flat
        assert!(trade.is_some());
        let t = trade.unwrap();
        assert_eq!(t.pnl, 10.0 * (95.0 - 100.0) - 5.0); // -$55 loss
    }

    #[test]
    fn test_04_reverse_from_short_to_flat_on_buy() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let short_position = Position {
            state: PositionState::Short,
            entry_price: 110.0,
            entry_time: create_timestamp(0),
            size: 10.0,
        };

        let (position, trade) = engine.update_position(
            Some(short_position),
            Action::Buy,
            100.0,
            create_timestamp(50),
            10.0,
        );

        assert!(position.is_none()); // Closes to flat
        assert!(trade.is_some());
        let t = trade.unwrap();
        assert_eq!(t.side, PositionState::Short);
        assert_eq!(t.pnl, 10.0 * (110.0 - 100.0) - 5.0); // $95 profit
    }

    #[test]
    fn test_05_hold_maintains_position() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let long_position = Position {
            state: PositionState::Long,
            entry_price: 100.0,
            entry_time: create_timestamp(0),
            size: 10.0,
        };

        let (position, trade) = engine.update_position(
            Some(long_position.clone()),
            Action::Hold,
            105.0,
            create_timestamp(10),
            10.0,
        );

        assert!(position.is_some());
        assert!(trade.is_none());
        assert_eq!(position.unwrap().state, PositionState::Long);
    }

    #[test]
    fn test_06_multiple_buys_dont_stack() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let long_position = Position {
            state: PositionState::Long,
            entry_price: 100.0,
            entry_time: create_timestamp(0),
            size: 10.0,
        };

        let (position, trade) = engine.update_position(
            Some(long_position.clone()),
            Action::Buy,
            105.0,
            create_timestamp(10),
            10.0,
        );

        assert!(position.is_some());
        assert!(trade.is_none());
        // Position should remain unchanged
        assert_eq!(position.unwrap().entry_price, 100.0);
    }

    #[test]
    fn test_07_multiple_sells_dont_stack() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let short_position = Position {
            state: PositionState::Short,
            entry_price: 110.0,
            entry_time: create_timestamp(0),
            size: 10.0,
        };

        let (position, trade) = engine.update_position(
            Some(short_position.clone()),
            Action::Sell,
            105.0,
            create_timestamp(10),
            10.0,
        );

        assert!(position.is_some());
        assert!(trade.is_none());
        assert_eq!(position.unwrap().entry_price, 110.0);
    }

    #[test]
    fn test_08_position_closes_at_end_of_data() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let long_position = Position {
            state: PositionState::Long,
            entry_price: 100.0,
            entry_time: create_timestamp(0),
            size: 10.0,
        };

        let trade = engine.force_close_position(Some(long_position), 108.0, create_timestamp(1000));

        assert!(trade.is_some());
        let t = trade.unwrap();
        assert_eq!(t.side, PositionState::Long);
        assert_eq!(t.exit_price, 108.0);
        assert_eq!(t.pnl, 10.0 * (108.0 - 100.0) - 5.0); // $75 profit
    }

    #[test]
    fn test_09_empty_position_list_when_only_hold() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let mut trades = Vec::new();

        // Simulate 10 bars with only HOLD actions
        for i in 0..10 {
            let (_, trade) = engine.update_position(
                None,
                Action::Hold,
                100.0 + i as f64,
                create_timestamp(i * 60),
                10.0,
            );
            if let Some(t) = trade {
                trades.push(t);
            }
        }

        assert_eq!(trades.len(), 0);
    }

    #[test]
    fn test_10_position_state_transitions_correct() {
        let engine = BacktestEngine::new(100_000.0, 2.50);

        // Flat -> Long
        let (pos, _) = engine.update_position(None, Action::Buy, 100.0, create_timestamp(0), 10.0);
        assert_eq!(pos.as_ref().unwrap().state, PositionState::Long);

        // Long -> Flat
        let (pos, _) = engine.update_position(pos, Action::Sell, 105.0, create_timestamp(10), 10.0);
        assert!(pos.is_none());

        // Flat -> Short
        let (pos, _) =
            engine.update_position(None, Action::Sell, 105.0, create_timestamp(20), 10.0);
        assert_eq!(pos.as_ref().unwrap().state, PositionState::Short);

        // Short -> Flat
        let (pos, _) = engine.update_position(pos, Action::Buy, 102.0, create_timestamp(30), 10.0);
        assert!(pos.is_none());
    }
}

// =============================================================================
// MODULE 2: P&L Calculation Tests (12 tests)
// =============================================================================

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

    #[test]
    fn test_11_long_profit() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let pnl = engine.calculate_pnl(PositionState::Long, 100.0, 110.0, 1.0);
        assert_eq!(pnl, 10.0 - 5.0); // $10 profit - $5 commission
    }

    #[test]
    fn test_12_long_loss() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let pnl = engine.calculate_pnl(PositionState::Long, 110.0, 100.0, 1.0);
        assert_eq!(pnl, -10.0 - 5.0); // -$10 loss - $5 commission
    }

    #[test]
    fn test_13_short_profit() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let pnl = engine.calculate_pnl(PositionState::Short, 110.0, 100.0, 1.0);
        assert_eq!(pnl, 10.0 - 5.0); // $10 profit - $5 commission
    }

    #[test]
    fn test_14_short_loss() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let pnl = engine.calculate_pnl(PositionState::Short, 100.0, 110.0, 1.0);
        assert_eq!(pnl, -10.0 - 5.0); // -$10 loss - $5 commission
    }

    #[test]
    fn test_15_commissions_deducted() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        // Zero price movement, only commissions
        let pnl = engine.calculate_pnl(PositionState::Long, 100.0, 100.0, 1.0);
        assert_eq!(pnl, -5.0); // $2.50 entry + $2.50 exit
    }

    #[test]
    fn test_16_multiple_trades_accumulate_correctly() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let mut total_pnl = 0.0;

        // Trade 1: Long profit
        total_pnl += engine.calculate_pnl(PositionState::Long, 100.0, 110.0, 1.0);

        // Trade 2: Short profit
        total_pnl += engine.calculate_pnl(PositionState::Short, 110.0, 105.0, 1.0);

        // Trade 3: Long loss
        total_pnl += engine.calculate_pnl(PositionState::Long, 105.0, 100.0, 1.0);

        assert_eq!(total_pnl, 5.0 + 0.0 - 10.0); // $5 - $15 commissions
    }

    #[test]
    fn test_17_percentage_returns_calculated_correctly() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let pnl = engine.calculate_pnl(PositionState::Long, 100.0, 110.0, 10.0);
        let return_pct = pnl / engine.initial_capital;

        // Expected: (10 * 10 - 5) / 100000 = 95 / 100000 = 0.00095
        assert!((return_pct - 0.00095).abs() < 1e-6);
    }

    #[test]
    fn test_18_zero_profit_trades_handled() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let pnl = engine.calculate_pnl(PositionState::Long, 100.0, 100.0, 10.0);
        assert_eq!(pnl, -5.0); // Only commissions
    }

    #[test]
    fn test_19_very_small_price_moves() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let pnl = engine.calculate_pnl(PositionState::Long, 100.0, 100.005, 100.0);
        // Profit: 100 * 0.005 = 0.50, minus commissions = -4.50
        assert!((pnl - (-4.5)).abs() < 1e-6); // Use floating-point tolerance
    }

    #[test]
    fn test_20_large_price_moves() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let pnl = engine.calculate_pnl(PositionState::Long, 1000.0, 2500.0, 10.0);
        // Profit: 10 * 1500 = 15000, minus commissions
        assert_eq!(pnl, 15000.0 - 5.0);
    }

    #[test]
    fn test_21_negative_prices_handled_gracefully() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        // Theoretical negative prices (e.g., oil futures)
        let pnl = engine.calculate_pnl(PositionState::Short, -10.0, -20.0, 1.0);
        assert_eq!(pnl, 10.0 - 5.0); // Short profits when price goes down
    }

    #[test]
    fn test_22_price_gaps_handled() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        // Large gap down
        let pnl = engine.calculate_pnl(PositionState::Long, 100.0, 50.0, 10.0);
        assert_eq!(pnl, -500.0 - 5.0); // -$505 total
    }
}

// =============================================================================
// MODULE 3: Metrics Calculation Tests (15 tests)
// =============================================================================

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

    fn create_timestamp(offset_secs: i64) -> DateTime<Utc> {
        DateTime::from_timestamp(1_700_000_000 + offset_secs, 0).unwrap()
    }

    #[test]
    fn test_23_sharpe_ratio_formula_correct() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let returns = vec![0.01, 0.02, -0.01, 0.015, 0.005];

        // Manual calculation
        let mean = returns.iter().sum::<f64>() / returns.len() as f64;
        let variance =
            returns.iter().map(|r| (r - mean).powi(2)).sum::<f64>() / returns.len() as f64;
        let std_dev = variance.sqrt();
        let expected_sharpe = (mean / std_dev) * (252.0_f64).sqrt();

        let sharpe = engine.calculate_sharpe(&returns);
        assert!((sharpe - expected_sharpe).abs() < 1e-6);
    }

    #[test]
    fn test_24_sharpe_with_zero_std_dev() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let returns = vec![0.01, 0.01, 0.01]; // No variance

        let sharpe = engine.calculate_sharpe(&returns);
        assert_eq!(sharpe, 0.0); // Should return 0 when std_dev is 0
    }

    #[test]
    fn test_25_sortino_ratio_formula_correct() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let returns = vec![0.02, -0.01, 0.015, -0.005, 0.01];

        let sortino = engine.calculate_sortino(&returns);
        assert!(sortino.is_finite());
        assert!(sortino > 0.0); // Positive mean return
    }

    #[test]
    fn test_26_max_drawdown_calculation_correct() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let equity_curve = vec![100_000.0, 110_000.0, 105_000.0, 95_000.0, 100_000.0];

        let (max_dd, _) = engine.calculate_max_drawdown(&equity_curve);
        // Peak at 110000, trough at 95000 = (110000 - 95000) / 110000 = 0.1364
        assert!((max_dd - 0.1364).abs() < 0.001);
    }

    #[test]
    fn test_27_max_drawdown_zero_for_all_wins() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let equity_curve = vec![100_000.0, 105_000.0, 110_000.0, 115_000.0];

        let (max_dd, _) = engine.calculate_max_drawdown(&equity_curve);
        assert_eq!(max_dd, 0.0);
    }

    #[test]
    fn test_28_drawdown_duration_tracked() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let equity_curve = vec![
            100_000.0, 110_000.0, 105_000.0, 100_000.0, 95_000.0, 100_000.0,
        ];

        let (_, duration) = engine.calculate_max_drawdown(&equity_curve);
        assert!(duration > 0);
    }

    #[test]
    fn test_29_win_rate_equals_wins_divided_by_total() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![
            Trade {
                entry_time: create_timestamp(0),
                exit_time: create_timestamp(100),
                entry_price: 100.0,
                exit_price: 110.0,
                side: PositionState::Long,
                pnl: 95.0, // Win
                size: 10.0,
            },
            Trade {
                entry_time: create_timestamp(200),
                exit_time: create_timestamp(300),
                entry_price: 110.0,
                exit_price: 105.0,
                side: PositionState::Long,
                pnl: -55.0, // Loss
                size: 10.0,
            },
        ];

        let equity = vec![100_000.0, 100_095.0, 100_040.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 105.0);

        assert_eq!(metrics.win_rate, 0.5); // 1 win / 2 total
    }

    #[test]
    fn test_30_profit_factor_calculation() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![
            Trade {
                entry_time: create_timestamp(0),
                exit_time: create_timestamp(100),
                entry_price: 100.0,
                exit_price: 120.0,
                side: PositionState::Long,
                pnl: 195.0, // $200 - $5
                size: 10.0,
            },
            Trade {
                entry_time: create_timestamp(200),
                exit_time: create_timestamp(300),
                entry_price: 110.0,
                exit_price: 100.0,
                side: PositionState::Long,
                pnl: -105.0, // -$100 - $5
                size: 10.0,
            },
        ];

        let equity = vec![100_000.0, 100_195.0, 100_090.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 100.0);

        // Profit factor = 195 / 105 = 1.857
        assert!((metrics.profit_factor - 1.857).abs() < 0.01);
    }

    #[test]
    fn test_31_profit_factor_infinity_when_no_losses() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![Trade {
            entry_time: create_timestamp(0),
            exit_time: create_timestamp(100),
            entry_price: 100.0,
            exit_price: 110.0,
            side: PositionState::Long,
            pnl: 95.0,
            size: 10.0,
        }];

        let equity = vec![100_000.0, 100_095.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 110.0);

        assert_eq!(metrics.profit_factor, f64::INFINITY);
    }

    #[test]
    fn test_32_buy_and_hold_calculation_correct() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![];
        let equity = vec![100_000.0];

        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 120.0);

        // Buy and hold: (120 - 100) / 100 = 0.20 (20%)
        assert_eq!(metrics.buy_and_hold_return, 0.20);
    }

    #[test]
    fn test_33_alpha_equals_returns_minus_buy_and_hold() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![Trade {
            entry_time: create_timestamp(0),
            exit_time: create_timestamp(100),
            entry_price: 100.0,
            exit_price: 130.0,
            side: PositionState::Long,
            pnl: 295.0, // $300 - $5
            size: 10.0,
        }];

        let equity = vec![100_000.0, 100_295.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 120.0);

        // Strategy return: 295 / 100000 = 0.00295
        // Buy and hold: 0.20
        // Alpha: 0.00295 - 0.20 = -0.19705
        assert!((metrics.alpha - (-0.19705)).abs() < 0.0001);
    }

    #[test]
    fn test_34_calmar_ratio_calculation() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![Trade {
            entry_time: create_timestamp(0),
            exit_time: create_timestamp(100),
            entry_price: 100.0,
            exit_price: 110.0,
            side: PositionState::Long,
            pnl: 95.0,
            size: 10.0,
        }];

        let equity = vec![100_000.0, 105_000.0, 102_000.0, 100_095.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 110.0);

        // Calmar = total_return% / max_drawdown%
        // If return is 0.095% and max DD is ~2.857%, Calmar ≈ 0.033
        assert!(metrics.calmar_ratio > 0.0);
    }

    #[test]
    fn test_35_recovery_factor_calculated() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![Trade {
            entry_time: create_timestamp(0),
            exit_time: create_timestamp(100),
            entry_price: 100.0,
            exit_price: 115.0,
            side: PositionState::Long,
            pnl: 145.0,
            size: 10.0,
        }];

        let equity = vec![100_000.0, 108_000.0, 105_000.0, 100_145.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 115.0);

        // Recovery factor = total_return / max_drawdown
        assert!(metrics.recovery_factor.is_finite());
    }

    #[test]
    fn test_36_avg_win_loss_correct() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![
            Trade {
                entry_time: create_timestamp(0),
                exit_time: create_timestamp(100),
                entry_price: 100.0,
                exit_price: 120.0,
                side: PositionState::Long,
                pnl: 195.0, // Win
                size: 10.0,
            },
            Trade {
                entry_time: create_timestamp(200),
                exit_time: create_timestamp(300),
                entry_price: 110.0,
                exit_price: 130.0,
                side: PositionState::Long,
                pnl: 195.0, // Win
                size: 10.0,
            },
            Trade {
                entry_time: create_timestamp(400),
                exit_time: create_timestamp(500),
                entry_price: 120.0,
                exit_price: 100.0,
                side: PositionState::Long,
                pnl: -205.0, // Loss
                size: 10.0,
            },
        ];

        let equity = vec![100_000.0, 100_195.0, 100_390.0, 100_185.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 100.0);

        assert_eq!(metrics.avg_win, 195.0);
        assert_eq!(metrics.avg_loss, 205.0);
    }

    #[test]
    fn test_37_all_metrics_serialize_to_json() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![];
        let equity = vec![100_000.0];

        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 100.0);

        // Verify all metrics are accessible
        assert!(metrics.sharpe_ratio.is_finite() || metrics.sharpe_ratio == 0.0);
        assert!(
            metrics.sortino_ratio.is_finite()
                || metrics.sortino_ratio == 0.0
                || metrics.sortino_ratio.is_infinite()
        );
        assert!(metrics.max_drawdown >= 0.0);
        assert!(metrics.profit_factor >= 0.0 || metrics.profit_factor.is_infinite());
        assert!(metrics.win_rate >= 0.0 && metrics.win_rate <= 1.0);
    }
}

// =============================================================================
// MODULE 4: Edge Cases Tests (8 tests)
// =============================================================================

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

    fn create_timestamp(offset_secs: i64) -> DateTime<Utc> {
        DateTime::from_timestamp(1_700_000_000 + offset_secs, 0).unwrap()
    }

    #[test]
    fn test_38_single_trade() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![Trade {
            entry_time: create_timestamp(0),
            exit_time: create_timestamp(100),
            entry_price: 100.0,
            exit_price: 105.0,
            side: PositionState::Long,
            pnl: 45.0,
            size: 10.0,
        }];

        let equity = vec![100_000.0, 100_045.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 105.0);

        assert_eq!(metrics.total_trades, 1);
        assert_eq!(metrics.win_rate, 1.0);
    }

    #[test]
    fn test_39_no_trades_all_hold() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![];
        let equity = vec![100_000.0];

        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 100.0);

        assert_eq!(metrics.total_trades, 0);
        assert_eq!(metrics.win_rate, 0.0);
        assert_eq!(metrics.total_pnl, 0.0);
    }

    #[test]
    fn test_40_all_wins_100_percent_win_rate() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![
            Trade {
                entry_time: create_timestamp(0),
                exit_time: create_timestamp(100),
                entry_price: 100.0,
                exit_price: 105.0,
                side: PositionState::Long,
                pnl: 45.0,
                size: 10.0,
            },
            Trade {
                entry_time: create_timestamp(200),
                exit_time: create_timestamp(300),
                entry_price: 105.0,
                exit_price: 110.0,
                side: PositionState::Long,
                pnl: 45.0,
                size: 10.0,
            },
        ];

        let equity = vec![100_000.0, 100_045.0, 100_090.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 110.0);

        assert_eq!(metrics.win_rate, 1.0);
        assert_eq!(metrics.profit_factor, f64::INFINITY);
    }

    #[test]
    fn test_41_all_losses_0_percent_win_rate() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![
            Trade {
                entry_time: create_timestamp(0),
                exit_time: create_timestamp(100),
                entry_price: 100.0,
                exit_price: 95.0,
                side: PositionState::Long,
                pnl: -55.0,
                size: 10.0,
            },
            Trade {
                entry_time: create_timestamp(200),
                exit_time: create_timestamp(300),
                entry_price: 95.0,
                exit_price: 90.0,
                side: PositionState::Long,
                pnl: -55.0,
                size: 10.0,
            },
        ];

        let equity = vec![100_000.0, 99_945.0, 99_890.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 90.0);

        assert_eq!(metrics.win_rate, 0.0);
        assert_eq!(metrics.profit_factor, 0.0);
    }

    #[test]
    fn test_42_alternating_wins_losses() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let mut trades = Vec::new();

        for i in 0..10 {
            let pnl = if i % 2 == 0 { 45.0 } else { -55.0 };
            trades.push(Trade {
                entry_time: create_timestamp(i * 100),
                exit_time: create_timestamp(i * 100 + 50),
                entry_price: 100.0,
                exit_price: if pnl > 0.0 { 105.0 } else { 95.0 },
                side: PositionState::Long,
                pnl,
                size: 10.0,
            });
        }

        let equity: Vec<f64> = (0..=10).map(|_| 100_000.0).collect(); // Simplified
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 100.0);

        assert_eq!(metrics.win_rate, 0.5);
    }

    #[test]
    fn test_43_very_long_hold_periods() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let long_position = Position {
            state: PositionState::Long,
            entry_price: 100.0,
            entry_time: create_timestamp(0),
            size: 10.0,
        };

        // Hold for 1000 bars (simulated)
        let trade = engine.force_close_position(
            Some(long_position),
            120.0,
            create_timestamp(1000 * 60), // 1000 minutes
        );

        assert!(trade.is_some());
        let t = trade.unwrap();
        assert_eq!(t.pnl, 10.0 * (120.0 - 100.0) - 5.0);
    }

    #[test]
    fn test_44_rapid_trading_every_bar() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let mut trades = Vec::new();

        // Simulate 100 rapid trades
        for i in 0..100 {
            let pnl = if i % 3 == 0 { 5.0 } else { -5.0 };
            trades.push(Trade {
                entry_time: create_timestamp(i * 10),
                exit_time: create_timestamp(i * 10 + 5),
                entry_price: 100.0,
                exit_price: 100.0 + pnl / 10.0,
                side: PositionState::Long,
                pnl,
                size: 10.0,
            });
        }

        let equity: Vec<f64> = (0..=100).map(|_| 100_000.0).collect();
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 100.0);

        assert_eq!(metrics.total_trades, 100);
    }

    #[test]
    fn test_45_empty_data_array_handled() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![];
        let equity = vec![];

        // Should not panic with empty data
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 100.0);

        assert_eq!(metrics.total_trades, 0);
        assert_eq!(metrics.max_drawdown, 0.0);
    }
}

// =============================================================================
// MODULE 5: Integration Tests (5 tests)
// =============================================================================

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

    fn create_timestamp(offset_secs: i64) -> DateTime<Utc> {
        DateTime::from_timestamp(1_700_000_000 + offset_secs, 0).unwrap()
    }

    fn create_synthetic_prices(count: usize, trend: f64) -> Vec<f64> {
        (0..count)
            .map(|i| 100.0 + (i as f64) * trend + ((i as f64 / 10.0).sin() * 2.0))
            .collect()
    }

    #[test]
    fn test_46_full_pipeline_on_synthetic_data() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let prices = create_synthetic_prices(100, 0.1);

        let mut trades = Vec::new();
        let mut equity_curve = vec![100_000.0];
        let mut current_capital = 100_000.0;
        let mut position: Option<Position> = None;

        // Simple strategy: Buy when price below 105, Sell when above 110
        for (i, &price) in prices.iter().enumerate() {
            let action = if position.is_none() && price < 105.0 {
                Action::Buy
            } else if position.is_some() && price > 110.0 {
                Action::Sell
            } else {
                Action::Hold
            };

            let (new_pos, trade) = engine.update_position(
                position,
                action,
                price,
                create_timestamp(i as i64 * 60),
                10.0,
            );

            position = new_pos;
            if let Some(t) = trade {
                current_capital += t.pnl;
                equity_curve.push(current_capital);
                trades.push(t);
            }
        }

        // Force close remaining position
        if let Some(final_trade) = engine.force_close_position(
            position,
            *prices.last().unwrap(),
            create_timestamp(prices.len() as i64 * 60),
        ) {
            current_capital += final_trade.pnl;
            equity_curve.push(current_capital);
            trades.push(final_trade);
        }

        let metrics =
            engine.calculate_metrics(&trades, &equity_curve, prices[0], *prices.last().unwrap());

        // Validate metrics make sense
        assert!(metrics.total_trades > 0);
        assert!(metrics.win_rate >= 0.0 && metrics.win_rate <= 1.0);
        assert!(metrics.sharpe_ratio.is_finite());
        assert!(metrics.max_drawdown >= 0.0);
    }

    #[test]
    fn test_47_results_match_manual_calculation() {
        let engine = BacktestEngine::new(100_000.0, 2.50);

        // Manually create 3 trades
        let trades = vec![
            Trade {
                entry_time: create_timestamp(0),
                exit_time: create_timestamp(100),
                entry_price: 100.0,
                exit_price: 110.0,
                side: PositionState::Long,
                pnl: 95.0, // 10 * 10 - 5
                size: 10.0,
            },
            Trade {
                entry_time: create_timestamp(200),
                exit_time: create_timestamp(300),
                entry_price: 110.0,
                exit_price: 105.0,
                side: PositionState::Long,
                pnl: -55.0, // 10 * -5 - 5
                size: 10.0,
            },
            Trade {
                entry_time: create_timestamp(400),
                exit_time: create_timestamp(500),
                entry_price: 105.0,
                exit_price: 115.0,
                side: PositionState::Long,
                pnl: 95.0, // 10 * 10 - 5
                size: 10.0,
            },
        ];

        let equity = vec![100_000.0, 100_095.0, 100_040.0, 100_135.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 115.0);

        // Manual verification
        assert_eq!(metrics.total_trades, 3);
        assert_eq!(metrics.winning_trades, 2);
        assert_eq!(metrics.losing_trades, 1);
        assert_eq!(metrics.win_rate, 2.0 / 3.0);
        assert_eq!(metrics.total_pnl, 95.0 - 55.0 + 95.0);
    }

    #[test]
    fn test_48_json_output_parseable() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![Trade {
            entry_time: create_timestamp(0),
            exit_time: create_timestamp(100),
            entry_price: 100.0,
            exit_price: 105.0,
            side: PositionState::Long,
            pnl: 45.0,
            size: 10.0,
        }];

        let equity = vec![100_000.0, 100_045.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 105.0);

        // Serialize to JSON-like format (verify all fields are serializable)
        let json_str = format!(
            r#"{{"total_trades": {}, "win_rate": {}, "sharpe_ratio": {}, "max_drawdown": {}}}"#,
            metrics.total_trades, metrics.win_rate, metrics.sharpe_ratio, metrics.max_drawdown
        );

        assert!(json_str.contains("total_trades"));
        assert!(json_str.contains("win_rate"));
    }

    #[test]
    fn test_49_markdown_report_generated() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![Trade {
            entry_time: create_timestamp(0),
            exit_time: create_timestamp(100),
            entry_price: 100.0,
            exit_price: 110.0,
            side: PositionState::Long,
            pnl: 95.0,
            size: 10.0,
        }];

        let equity = vec![100_000.0, 100_095.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 110.0);

        // Generate markdown report
        let report = format!(
            "# Backtest Results\n\n\
             - Total Trades: {}\n\
             - Win Rate: {:.2}%\n\
             - Sharpe Ratio: {:.2}\n\
             - Max Drawdown: {:.2}%\n",
            metrics.total_trades,
            metrics.win_rate * 100.0,
            metrics.sharpe_ratio,
            metrics.max_drawdown * 100.0
        );

        assert!(report.contains("# Backtest Results"));
        assert!(report.contains("Total Trades"));
    }

    #[test]
    fn test_50_baseline_comparison_correct() {
        let engine = BacktestEngine::new(100_000.0, 2.50);
        let trades = vec![Trade {
            entry_time: create_timestamp(0),
            exit_time: create_timestamp(100),
            entry_price: 100.0,
            exit_price: 120.0,
            side: PositionState::Long,
            pnl: 195.0, // 10 * 20 - 5
            size: 10.0,
        }];

        let equity = vec![100_000.0, 100_195.0];
        let metrics = engine.calculate_metrics(&trades, &equity, 100.0, 120.0);

        // Buy-and-hold: (120 - 100) / 100 = 0.20 (20%)
        // Strategy: 195 / 100000 = 0.00195 (0.195%)
        // Alpha: 0.00195 - 0.20 = -0.19805

        assert_eq!(metrics.buy_and_hold_return, 0.20);
        assert!((metrics.alpha - (-0.19805)).abs() < 0.0001);

        // Strategy underperformed buy-and-hold
        assert!(metrics.total_return < metrics.buy_and_hold_return);
    }
}