//! PPO Stress Testing Framework Tests
//!
//! TDD Red Phase: Tests written BEFORE implementation.
//! These tests will initially fail and guide the implementation.

use ml::ppo::stress_testing::{
    PPOStressTester, StressScenario,
    flash_crash_scenario, liquidity_crisis_scenario,
};
use ml::hyperopt::adapters::PPOTrainer;
use anyhow::Result;

/// Helper to create a minimal PPO trainer for testing
fn create_test_trainer() -> Result<PPOTrainer> {
    // PPOTrainer requires a DBN data directory and episodes count
    // For stress testing, we use the test data directory
    // Tests run from the workspace root, so we need to go up one level from ml/
    let data_dir = "../test_data";
    let episodes = 100;

    PPOTrainer::new(data_dir, episodes)
}

#[test]
fn test_flash_crash_scenario() -> Result<()> {
    // TDD Red Phase: This test will fail until implementation exists

    // Setup
    let trainer = create_test_trainer()?;
    let mut stress_tester = PPOStressTester::new(trainer);
    let scenario = flash_crash_scenario();

    // Execute stress test
    let result = stress_tester.run_scenario(&scenario)?;

    // Validate flash crash scenario parameters
    assert_eq!(result.scenario_name, "Flash Crash");
    assert_eq!(scenario.price_shock_pct, -10.0, "Flash crash should be -10% shock");
    assert_eq!(scenario.volatility_multiplier, 3.0, "Flash crash should be 3x volatility");
    assert_eq!(scenario.spread_multiplier, 10.0, "Flash crash should be 10x spreads");
    assert_eq!(scenario.duration_steps, 300, "Flash crash should last 300 steps (5 min)");

    // Validate robustness criteria
    assert!(
        result.max_drawdown <= scenario.max_drawdown_threshold,
        "Max drawdown {:.2}% exceeded threshold {:.2}%",
        result.max_drawdown,
        scenario.max_drawdown_threshold
    );

    assert!(
        !result.bankruptcy,
        "Agent went bankrupt during flash crash (portfolio <= 0)"
    );

    assert!(
        result.action_diversity >= scenario.min_action_diversity,
        "Action diversity {:.2}% below threshold {:.2}%",
        result.action_diversity,
        scenario.min_action_diversity
    );

    println!("✅ Flash Crash Test: Drawdown={:.2}%, Diversity={:.2}%",
             result.max_drawdown, result.action_diversity);

    Ok(())
}

#[test]
fn test_liquidity_crisis_scenario() -> Result<()> {
    // TDD Red Phase: This test will fail until implementation exists

    // Setup
    let trainer = create_test_trainer()?;
    let mut stress_tester = PPOStressTester::new(trainer);
    let scenario = liquidity_crisis_scenario();

    // Execute stress test
    let result = stress_tester.run_scenario(&scenario)?;

    // Validate liquidity crisis scenario parameters
    assert_eq!(result.scenario_name, "Liquidity Crisis");
    assert_eq!(scenario.price_shock_pct, -2.0, "Liquidity crisis should be -2% shock");
    assert_eq!(scenario.volatility_multiplier, 2.0, "Liquidity crisis should be 2x volatility");
    assert_eq!(scenario.spread_multiplier, 50.0, "Liquidity crisis should be 50x spreads");
    assert_eq!(scenario.duration_steps, 600, "Liquidity crisis should last 600 steps (10 min)");

    // Validate agent survived extreme spread widening
    assert!(
        !result.bankruptcy,
        "Agent went bankrupt during liquidity crisis"
    );

    assert!(
        result.max_drawdown <= scenario.max_drawdown_threshold,
        "Max drawdown {:.2}% exceeded threshold {:.2}%",
        result.max_drawdown,
        scenario.max_drawdown_threshold
    );

    println!("✅ Liquidity Crisis Test: Drawdown={:.2}%, Final Portfolio={:.2}%",
             result.max_drawdown, result.final_portfolio_pct);

    Ok(())
}

#[test]
fn test_bankruptcy_detection() -> Result<()> {
    // TDD Red Phase: Test bankruptcy detection logic

    // Setup
    let trainer = create_test_trainer()?;
    let mut stress_tester = PPOStressTester::new(trainer);

    // Create extreme scenario designed to cause bankruptcy
    let extreme_scenario = StressScenario {
        name: "Extreme Bankruptcy Test".to_string(),
        price_shock_pct: -95.0,  // 95% crash (unrealistic but tests edge case)
        volatility_multiplier: 10.0,
        spread_multiplier: 100.0,
        duration_steps: 100,
        max_drawdown_threshold: 100.0,  // Accept any drawdown for this test
        min_action_diversity: 0.0,       // No diversity requirement
    };

    // Execute stress test
    let result = stress_tester.run_scenario(&extreme_scenario)?;

    // Validate bankruptcy was detected
    assert!(
        result.bankruptcy,
        "Bankruptcy should be detected when portfolio <= 0"
    );

    assert!(
        !result.passed,
        "Test should FAIL when bankruptcy occurs"
    );

    assert!(
        result.failure_reasons.iter().any(|r| r.contains("Bankruptcy")),
        "Failure reasons should mention bankruptcy: {:?}",
        result.failure_reasons
    );

    println!("✅ Bankruptcy Detection Test: Correctly detected portfolio collapse");

    Ok(())
}

#[test]
fn test_metrics_collection() -> Result<()> {
    // TDD Red Phase: Test metrics collection logic

    // Setup
    let trainer = create_test_trainer()?;
    let mut stress_tester = PPOStressTester::new(trainer);
    let scenario = flash_crash_scenario();

    // Execute stress test
    let result = stress_tester.run_scenario(&scenario)?;

    // Validate all metrics are collected
    assert!(
        result.max_drawdown >= 0.0,
        "Max drawdown should be non-negative: {:.2}%",
        result.max_drawdown
    );

    assert!(
        result.action_diversity >= 0.0 && result.action_diversity <= 100.0,
        "Action diversity should be 0-100%: {:.2}%",
        result.action_diversity
    );

    assert!(
        result.total_trades > 0,
        "Should have executed trades during stress test"
    );

    assert!(
        result.q_value_std >= 0.0,
        "Q-value standard deviation should be non-negative: {:.4}",
        result.q_value_std
    );

    assert!(
        result.execution_time_ms > 0,
        "Execution time should be positive: {} ms",
        result.execution_time_ms
    );

    // Validate result has scenario name
    assert_eq!(
        result.scenario_name,
        scenario.name,
        "Result should contain scenario name"
    );

    println!("✅ Metrics Collection Test: All metrics tracked correctly");
    println!("   - Max Drawdown: {:.2}%", result.max_drawdown);
    println!("   - Portfolio Change: {:.2}%", result.final_portfolio_pct);
    println!("   - Action Diversity: {:.2}%", result.action_diversity);
    println!("   - Total Trades: {}", result.total_trades);
    println!("   - Q-Value Std: {:.4}", result.q_value_std);
    println!("   - Execution Time: {} ms", result.execution_time_ms);

    Ok(())
}

#[test]
fn test_scenario_definitions() {
    // Validate all 8 predefined scenarios exist and have reasonable parameters
    let scenarios = vec![
        flash_crash_scenario(),
        liquidity_crisis_scenario(),
        ml::ppo::stress_testing::vix_spike_scenario(),
        ml::ppo::stress_testing::trending_market_scenario(),
        ml::ppo::stress_testing::whipsaw_scenario(),
        ml::ppo::stress_testing::gap_risk_scenario(),
        ml::ppo::stress_testing::correlation_breakdown_scenario(),
        ml::ppo::stress_testing::multi_asset_stress_scenario(),
    ];

    assert_eq!(scenarios.len(), 8, "Should have 8 predefined scenarios");

    // Verify all scenarios have reasonable thresholds
    for scenario in scenarios {
        assert!(
            scenario.max_drawdown_threshold > 0.0,
            "Max drawdown threshold must be positive: {}",
            scenario.name
        );
        assert!(
            scenario.min_action_diversity >= 0.0 && scenario.min_action_diversity <= 100.0,
            "Action diversity must be 0-100%: {}",
            scenario.name
        );
        assert!(
            scenario.duration_steps > 0,
            "Duration must be positive: {}",
            scenario.name
        );
    }
}