//! Basic SSTable header parsing security tests
//!
//! This module provides simplified tests that focus on the core security
//! aspects of header parsing without complex type dependencies.

use cqlite_core::parser::header::{parse_sstable_header, SSTABLE_MAGIC, SUPPORTED_VERSION};

/// Test suite for basic header corruption scenarios
#[cfg(test)]
mod basic_corruption_tests {
    use super::*;

    #[test]
    fn test_invalid_magic_number() {
        // Create header with invalid magic number
        let mut invalid_header = vec![0xFF, 0xFF, 0xFF, 0xFF]; // Invalid magic
        invalid_header.extend_from_slice(&[0x00, 0x01]); // Valid version
        invalid_header.extend_from_slice(&[0x00; 100]); // Padding

        let result = parse_sstable_header(&invalid_header);

        assert!(result.is_err(), "Should reject invalid magic number");

        // Test passes if parsing fails (which it should for invalid magic)
        match result {
            Err(_) => println!("✅ Correctly rejected invalid magic number"),
            Ok(_) => panic!("Should not accept invalid magic number"),
        }
    }

    #[test]
    fn test_corrupted_magic_partial() {
        // Test partial corruption of magic number
        let mut corrupted_header = SSTABLE_MAGIC.to_le_bytes().to_vec();
        corrupted_header[2] = 0xFF; // Corrupt one byte
        corrupted_header.extend_from_slice(&[0x00, 0x01]); // Valid version
        corrupted_header.extend_from_slice(&[0x00; 100]); // Padding

        let result = parse_sstable_header(&corrupted_header);

        assert!(result.is_err(), "Should reject corrupted magic number");
        println!("✅ Correctly rejected partially corrupted magic number");
    }

    #[test]
    fn test_truncated_header_scenarios() {
        // Test various truncation points
        let test_cases = vec![
            (0, "Empty data"),
            (2, "Partial magic"),
            (4, "Magic only"),
            (6, "Magic + partial version"),
        ];

        for (size, description) in test_cases {
            let truncated_data = vec![0x42; size];
            let result = parse_sstable_header(&truncated_data);

            assert!(result.is_err(), "Should fail for {}", description);
            println!("✅ Correctly rejected truncated header: {}", description);
        }
    }

    #[test]
    fn test_valid_magic_invalid_version() {
        // Create header with valid magic but invalid version
        let mut header = SSTABLE_MAGIC.to_le_bytes().to_vec();
        header.extend_from_slice(&[0xFF, 0xFF]); // Invalid version
        header.extend_from_slice(&[0x00; 100]); // Padding

        let result = parse_sstable_header(&header);

        assert!(result.is_err(), "Should reject invalid version");
        println!("✅ Correctly rejected invalid version with valid magic");
    }

    #[test]
    fn test_header_with_null_bytes() {
        // Create header filled with null bytes after magic and version
        let mut null_header = SSTABLE_MAGIC.to_le_bytes().to_vec();
        null_header.extend_from_slice(&SUPPORTED_VERSION.to_le_bytes());
        null_header.extend_from_slice(&[0x00; 1000]); // Large null section

        let result = parse_sstable_header(&null_header);

        // Should either parse successfully with defaults or fail gracefully
        match result {
            Ok((_, header)) => {
                println!("✅ Parsed null-padded header successfully");
                // Basic validation
                assert!(!header.keyspace.is_empty() || header.keyspace.is_empty());
                // Either is fine
            }
            Err(_) => {
                println!("✅ Correctly rejected null-padded header");
            }
        }
    }

    #[test]
    fn test_random_data_never_panics() {
        // Property: Parser should never panic on random input
        for seed in 0..100 {
            let data = generate_pseudo_random_data(seed, 1000);

            // Parser should never panic
            let result = std::panic::catch_unwind(|| {
                let _ = parse_sstable_header(&data);
            });

            assert!(result.is_ok(), "Parser panicked on seed {}", seed);
        }
        println!("✅ Parser never panicked on 100 random inputs");
    }

    #[test]
    fn test_length_boundary_conditions() {
        // Test headers at various size boundaries
        let boundary_sizes = vec![
            0,    // Empty
            1,    // Single byte
            4,    // Magic only
            6,    // Magic + version
            22,   // Magic + version + table ID
            1000, // Reasonable size
        ];

        for size in boundary_sizes {
            let mut data = vec![0x00; size];

            // If size allows, set valid magic and version
            if size >= 4 {
                data[0..4].copy_from_slice(&SSTABLE_MAGIC.to_le_bytes());
            }
            if size >= 6 {
                data[4..6].copy_from_slice(&SUPPORTED_VERSION.to_le_bytes());
            }

            let _result = parse_sstable_header(&data);

            // Should either parse or fail gracefully, never panic
            let panic_result = std::panic::catch_unwind(|| {
                let _ = parse_sstable_header(&data);
            });

            assert!(panic_result.is_ok(), "Parser panicked on size {}", size);
            println!("✅ Size {} handled without panic", size);
        }
    }

    #[test]
    fn test_error_consistency() {
        // Test that similar corruptions produce consistent error handling
        let similar_corruptions = [
            vec![0xFF; 8], // Invalid magic
            vec![0x00; 8], // Zero magic
            vec![0x42; 8], // Random magic
        ];

        for (i, corruption) in similar_corruptions.iter().enumerate() {
            let result = parse_sstable_header(corruption);

            // All should fail (which is what we want for security)
            assert!(result.is_err(), "Corruption {} should fail", i);

            // Should not panic
            let panic_test = std::panic::catch_unwind(|| {
                let _ = parse_sstable_header(corruption);
            });
            assert!(panic_test.is_ok(), "Corruption {} caused panic", i);
        }
        println!("✅ All similar corruptions handled consistently");
    }
}

/// Test suite for basic performance and DOS protection
#[cfg(test)]
mod performance_protection_tests {
    use super::*;

    #[test]
    fn test_large_input_handling() {
        // Test with very large inputs that could cause memory issues
        let large_sizes = vec![10_000, 100_000, 1_000_000];

        for size in large_sizes {
            let large_data = vec![0x42; size];

            let start_time = std::time::Instant::now();
            let _result = parse_sstable_header(&large_data);
            let elapsed = start_time.elapsed();

            // Should either succeed or fail quickly, not take forever
            assert!(
                elapsed.as_secs() < 5,
                "Parsing took too long for size {}: {:?}",
                size,
                elapsed
            );

            // Should not panic regardless of result
            let panic_test = std::panic::catch_unwind(|| {
                let _ = parse_sstable_header(&large_data);
            });
            assert!(panic_test.is_ok(), "Large input {} caused panic", size);

            println!("✅ Size {} processed in {:?}", size, elapsed);
        }
    }

    #[test]
    fn test_parser_deterministic() {
        // Property: Parser should be deterministic
        let test_data = generate_pseudo_random_data(12345, 1000);

        let result1 = parse_sstable_header(&test_data);
        let result2 = parse_sstable_header(&test_data);

        // Results should be identical
        match (result1, result2) {
            (Ok((rem1, _)), Ok((rem2, _))) => {
                assert_eq!(
                    rem1.len(),
                    rem2.len(),
                    "Different remaining data between runs"
                );
            }
            (Err(_), Err(_)) => {
                // Both failed consistently - this is fine
            }
            _ => {
                panic!("Parser non-deterministic - different results between runs");
            }
        }
        println!("✅ Parser is deterministic");
    }
}

/// Test suite for format validation
#[cfg(test)]
mod format_validation_tests {
    use super::*;

    #[test]
    fn test_magic_number_validation() {
        // Test that only valid magic numbers are accepted
        let test_cases = vec![
            (SSTABLE_MAGIC, true, "Valid magic"),
            (0x00000000, false, "Zero magic"),
            (0xFFFFFFFF, false, "Max magic"),
            (0x12345678, false, "Random magic"),
            (SSTABLE_MAGIC + 1, false, "Off-by-one magic"),
        ];

        for (magic, should_succeed, description) in test_cases {
            let mut header = magic.to_le_bytes().to_vec();
            header.extend_from_slice(&SUPPORTED_VERSION.to_le_bytes());
            header.extend_from_slice(&[0x00; 100]);

            let result = parse_sstable_header(&header);

            if should_succeed {
                // For valid magic, we might still fail due to other reasons, but shouldn't panic
                let panic_test = std::panic::catch_unwind(|| {
                    let _ = parse_sstable_header(&header);
                });
                assert!(
                    panic_test.is_ok(),
                    "Valid magic caused panic: {}",
                    description
                );
            } else {
                // Invalid magic should be rejected
                assert!(
                    result.is_err(),
                    "Invalid magic was accepted: {}",
                    description
                );
            }

            println!("✅ {}: handled correctly", description);
        }
    }

    #[test]
    fn test_version_validation() {
        // Test version field validation
        let test_versions = vec![
            (SUPPORTED_VERSION, "Supported version"),
            (0x0000, "Zero version"),
            (0xFFFF, "Max version"),
            (SUPPORTED_VERSION + 1, "Future version"),
        ];

        for (version, description) in test_versions {
            let mut header = SSTABLE_MAGIC.to_le_bytes().to_vec();
            header.extend_from_slice(&version.to_le_bytes());
            header.extend_from_slice(&[0x00; 100]);

            let result = parse_sstable_header(&header);

            // Should not panic regardless of version
            let panic_test = std::panic::catch_unwind(|| {
                let _ = parse_sstable_header(&header);
            });
            assert!(
                panic_test.is_ok(),
                "Version test caused panic: {}",
                description
            );

            // Use result to avoid compiler warning
            match result {
                Ok(_) => println!("✅ {}: parsed successfully", description),
                Err(_) => println!("✅ {}: failed parsing (may be expected)", description),
            }
        }
    }
}

// Helper functions

/// Generate pseudo-random data for testing
fn generate_pseudo_random_data(seed: u64, size: usize) -> Vec<u8> {
    let mut data = Vec::with_capacity(size);
    let mut state = seed;

    for _ in 0..size {
        state = state.wrapping_mul(1103515245).wrapping_add(12345);
        data.push((state >> 16) as u8);
    }

    data
}

/// Test coverage verification
#[cfg(test)]
mod coverage_verification {
    use super::*;

    #[test]
    fn test_security_properties_verified() {
        // Verify key security properties are testable

        // 1. Magic number validation
        let invalid_magic = vec![0xFF; 10];
        assert!(parse_sstable_header(&invalid_magic).is_err());

        // 2. No panic guarantee
        let result = std::panic::catch_unwind(|| {
            let _ = parse_sstable_header(&[0xFF; 1000]);
        });
        assert!(result.is_ok());

        // 3. Truncation handling
        let truncated = vec![0x42; 2];
        assert!(parse_sstable_header(&truncated).is_err());

        // 4. Performance bounds (simple check)
        let start = std::time::Instant::now();
        let _ = parse_sstable_header(&vec![0x00; 10000]);
        let elapsed = start.elapsed();
        assert!(elapsed.as_millis() < 1000); // Should be fast

        println!("✅ All security properties verified");
    }

    #[test]
    fn test_constants_accessible() {
        // Verify required constants are accessible
        let _magic = SSTABLE_MAGIC;
        let _version = SUPPORTED_VERSION;

        // Test they have expected properties
        assert_ne!(_magic, 0, "Magic should not be zero");
        assert_ne!(_version, 0, "Version should not be zero");

        println!("✅ Required constants accessible and valid");
    }
}
