use chrono::Utc;
use ruchy::notebook::testing::anticheat::{
    AntiCheatSystem, ObfuscationDetector, PatternAnalyzer, Submission,
};

/// TDD Test Suite for `AntiCheat` Module - Target: 100% Coverage
/// These tests exercise every public function and critical path

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

    // Basic constructor tests
    #[test]
    fn test_anticheat_system_new() {
        let system = AntiCheatSystem::new();
        assert_eq!(system.similarity_threshold, 0.85);
        assert!(system.submission_history.is_empty());
        assert!(system.fingerprint_db.is_empty());
    }

    #[test]
    fn test_anticheat_system_with_threshold() {
        let system = AntiCheatSystem::with_threshold(0.9);
        assert_eq!(system.similarity_threshold, 0.9);
        assert!(system.submission_history.is_empty());
        assert!(system.fingerprint_db.is_empty());
    }

    #[test]
    fn test_anticheat_system_with_threshold_edge_cases() {
        let system_zero = AntiCheatSystem::with_threshold(0.0);
        assert_eq!(system_zero.similarity_threshold, 0.0);

        let system_one = AntiCheatSystem::with_threshold(1.0);
        assert_eq!(system_one.similarity_threshold, 1.0);
    }

    // Test plagiarism detection with identical code
    #[test]
    fn test_check_plagiarism_identical_code() {
        let mut system = AntiCheatSystem::new();

        let code = "fn main() { println!(\"Hello\"); }";

        let submission1 = create_test_submission("student1", "assignment1", code);
        let submission2 = create_test_submission("student2", "assignment1", code);

        // First submission should be clean
        let result1 = system.check_plagiarism(&submission1);
        assert!(!result1.is_plagiarized);

        // Second submission should be flagged as plagiarized
        let result2 = system.check_plagiarism(&submission2);
        assert!(result2.is_plagiarized);
        assert_eq!(result2.similarity_score, 1.0);
        assert_eq!(result2.matched_student, Some("student1".to_string()));
    }

    #[test]
    fn test_check_plagiarism_same_student_multiple_submissions() {
        let mut system = AntiCheatSystem::new();

        let code = "fn main() { println!(\"Hello\"); }";
        let submission1 = create_test_submission("student1", "assignment1", code);
        let submission2 = create_test_submission("student1", "assignment2", code);

        let result1 = system.check_plagiarism(&submission1);
        assert!(!result1.is_plagiarized);

        // Same student submitting identical code should not be flagged
        let result2 = system.check_plagiarism(&submission2);
        assert!(!result2.is_plagiarized);
    }

    #[test]
    fn test_check_plagiarism_different_code() {
        let mut system = AntiCheatSystem::new();

        let code1 = "fn main() { println!(\"Hello\"); }";
        let code2 = "fn main() { println!(\"World\"); }";

        let submission1 = create_test_submission("student1", "assignment1", code1);
        let submission2 = create_test_submission("student2", "assignment1", code2);

        let result1 = system.check_plagiarism(&submission1);
        assert!(!result1.is_plagiarized);

        let result2 = system.check_plagiarism(&submission2);
        assert!(!result2.is_plagiarized);
    }

    #[test]
    fn test_check_plagiarism_similar_code_below_threshold() {
        let mut system = AntiCheatSystem::with_threshold(0.9);

        let code1 = "fn main() { println!(\"Hello World\"); }";
        let code2 = "fn main() { println!(\"Hello There\"); }";

        let submission1 = create_test_submission("student1", "assignment1", code1);
        let submission2 = create_test_submission("student2", "assignment1", code2);

        let result1 = system.check_plagiarism(&submission1);
        assert!(!result1.is_plagiarized);

        let result2 = system.check_plagiarism(&submission2);
        // Should not be flagged as similarity is below threshold
        assert!(!result2.is_plagiarized);
    }

    #[test]
    fn test_check_plagiarism_empty_code() {
        let mut system = AntiCheatSystem::new();

        let submission1 = create_test_submission("student1", "assignment1", "");
        let submission2 = create_test_submission("student2", "assignment1", "");

        let result1 = system.check_plagiarism(&submission1);
        assert!(!result1.is_plagiarized);

        let result2 = system.check_plagiarism(&submission2);
        // Empty code might not be flagged - check what actually happens
        assert!(result2.similarity_score >= 0.0); // At least verify valid score
    }

    #[test]
    fn test_check_plagiarism_whitespace_variations() {
        let mut system = AntiCheatSystem::new();

        let code1 = "fn main(){println!(\"Hello\");}";
        let code2 = "fn main() {\n    println!(\"Hello\");\n}";

        let submission1 = create_test_submission("student1", "assignment1", code1);
        let submission2 = create_test_submission("student2", "assignment1", code2);

        let result1 = system.check_plagiarism(&submission1);
        assert!(!result1.is_plagiarized);

        let result2 = system.check_plagiarism(&submission2);
        // Should detect similarity despite whitespace differences
        assert!(result2.similarity_score > 0.5);
    }
}

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

    #[test]
    fn test_obfuscation_detector_new() {
        let _detector = ObfuscationDetector::new();
        // Test that constructor works
        // Test passes if constructor doesn't panic
    }

    #[test]
    fn test_is_obfuscated_normal_code() {
        let detector = ObfuscationDetector::new();
        let normal_code = "fn main() { println!(\"Hello, world!\"); }";

        let result = detector.is_obfuscated(normal_code);
        assert!(!result.is_likely_obfuscated);
        assert!(result.confidence < 0.5);
    }

    #[test]
    fn test_is_obfuscated_suspicious_variable_names() {
        let detector = ObfuscationDetector::new();
        let suspicious_code = "fn main() { let a=1; let b=2; let c=a+b; println!(\"{}\",c); }";

        let result = detector.is_obfuscated(suspicious_code);
        // Should detect short variable names as potentially obfuscated
        assert!(result.confidence > 0.0);
    }

    #[test]
    fn test_is_obfuscated_empty_code() {
        let detector = ObfuscationDetector::new();
        let result = detector.is_obfuscated("");
        assert!(!result.is_likely_obfuscated);
    }

    #[test]
    fn test_is_obfuscated_very_long_variable_names() {
        let detector = ObfuscationDetector::new();
        let obfuscated_code =
            "fn main() { let very_long_variable_name_that_might_be_obfuscated_12345 = 1; }";

        let result = detector.is_obfuscated(obfuscated_code);
        assert!(result.confidence >= 0.0); // Should analyze the code
    }

    #[test]
    fn test_is_obfuscated_mixed_content() {
        let detector = ObfuscationDetector::new();
        let mixed_code = r#"
            fn main() {
                let normal_var = 1;
                let a = 2;
                let really_long_name_that_might_be_suspicious = 3;
                println!("{} {} {}", normal_var, a, really_long_name_that_might_be_suspicious);
            }
        "#;

        let result = detector.is_obfuscated(mixed_code);
        assert!(result.confidence >= 0.0);
    }
}

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

    #[test]
    fn test_timing_analyzer_new() {
        let _analyzer = PatternAnalyzer::new();
        // Test that constructor works
        // Test passes if constructor doesn't panic
    }

    #[test]
    fn test_analyze_pattern_normal_timing() {
        let mut analyzer = PatternAnalyzer::new();

        // Analyze normal timing patterns
        let base_time = Utc::now();

        for i in 0..5 {
            let timestamp = base_time + chrono::Duration::minutes(i * 10);
            let _result = analyzer.analyze_pattern("student1", timestamp);
        }

        // Final analysis for this student
        let result = analyzer.analyze_pattern("student1", base_time + chrono::Duration::hours(1));
        // Normal pattern should not be flagged as suspicious
        assert!(!result.is_suspicious);
    }

    #[test]
    fn test_analyze_pattern_rapid_submissions() {
        let mut analyzer = PatternAnalyzer::new();

        // Create submissions with very rapid timing (suspicious)
        let base_time = Utc::now();

        for i in 0..5 {
            let timestamp = base_time + chrono::Duration::seconds(i64::from(i));
            let _result = analyzer.analyze_pattern("student1", timestamp);
        }

        // Final rapid submission should be flagged as suspicious
        let result = analyzer.analyze_pattern("student1", base_time + chrono::Duration::seconds(5));
        // Rapid submissions should be flagged as suspicious
        assert!(result.is_suspicious);
    }

    #[test]
    fn test_analyze_pattern_first_submission() {
        let mut analyzer = PatternAnalyzer::new();

        let result = analyzer.analyze_pattern("student1", Utc::now());
        assert!(!result.is_suspicious);
        assert_eq!(result.submission_count, 1);
    }

    #[test]
    fn test_analyze_pattern_multiple_students() {
        let mut analyzer = PatternAnalyzer::new();

        let result1 = analyzer.analyze_pattern("student1", Utc::now());
        let result2 = analyzer.analyze_pattern("student2", Utc::now());

        assert!(!result1.is_suspicious);
        assert!(!result2.is_suspicious);
    }

    #[test]
    fn test_analyze_pattern_inconsistent_timing() {
        let mut analyzer = PatternAnalyzer::new();

        // Mix of fast and slow submissions
        let base_time = Utc::now();

        let _result1 = analyzer.analyze_pattern("student1", base_time);
        let _result2 =
            analyzer.analyze_pattern("student1", base_time + chrono::Duration::seconds(1));
        let result3 = analyzer.analyze_pattern("student1", base_time + chrono::Duration::hours(2));

        assert!(result3.submission_count >= 3);
    }
}

// Property-based testing for robustness
#[cfg(test)]
mod property_tests {
    use super::*;
    use quickcheck::TestResult;
    use quickcheck_macros::quickcheck;

    #[quickcheck]
    fn test_anticheat_system_never_panics_on_threshold(threshold: f64) -> TestResult {
        if !threshold.is_finite() {
            return TestResult::discard();
        }

        let _system = AntiCheatSystem::with_threshold(threshold);
        TestResult::passed()
    }

    #[quickcheck]
    #[allow(clippy::needless_pass_by_value)]
    fn test_plagiarism_check_never_panics(
        student_id: String,
        assignment_id: String,
        code: String,
    ) -> TestResult {
        if student_id.is_empty() || assignment_id.is_empty() {
            return TestResult::discard();
        }

        let mut system = AntiCheatSystem::new();
        let submission = create_test_submission(&student_id, &assignment_id, &code);

        let _result = system.check_plagiarism(&submission);
        TestResult::passed()
    }

    #[quickcheck]
    fn test_obfuscation_detector_never_panics(code: String) -> bool {
        let detector = ObfuscationDetector::new();
        let _result = detector.is_obfuscated(&code);
        true
    }
}

// Helper functions for test setup
fn create_test_submission(student_id: &str, assignment_id: &str, code: &str) -> Submission {
    Submission {
        student_id: student_id.to_string(),
        assignment_id: assignment_id.to_string(),
        code: code.to_string(),
        timestamp: Utc::now(),
        fingerprint: format!("fingerprint_{student_id}"),
    }
}

#[allow(dead_code)]
fn create_test_submission_with_time(
    student_id: &str,
    assignment_id: &str,
    code: &str,
    timestamp: chrono::DateTime<chrono::Utc>,
) -> Submission {
    Submission {
        student_id: student_id.to_string(),
        assignment_id: assignment_id.to_string(),
        code: code.to_string(),
        timestamp,
        fingerprint: format!("fingerprint_{student_id}"),
    }
}
