//! Unsafe Code Validation Tests for ML Package
//!
//! This test module validates unsafe blocks in the ML package that are currently active.
//! Tests cover:
//!
//! 1. SIMD batch processing unsafe slice access (ml/src/batch_processing.rs)
//! 2. Send/Sync trait implementations (ml/src/inference.rs)
//!
//! Run with miri: cargo +nightly miri test --package ml unsafe_validation
//! Run coverage: cargo llvm-cov --package ml --tests unsafe_validation

#![allow(unused_crate_dependencies)]

use ml::batch_processing::{AlignedBuffer, MemoryPool, MemoryPoolConfig};

// ==============================================================================
// BATCH PROCESSING UNSAFE BLOCK TESTS (2 unsafe blocks)
// ==============================================================================

/// Test 1: Unsafe block - as_slice() unsafe slice access
///
/// Risk: MEDIUM - uninitialized data read if len > initialized region
#[test]
fn test_aligned_buffer_as_slice_initialized_data() {
    let mut buffer = AlignedBuffer::new(1024, 32).expect("Buffer creation should succeed");

    // Set length and initialize data
    buffer.set_len(512);

    // SAFETY: We must initialize data before calling as_slice()
    unsafe {
        let slice_mut = buffer.as_mut_slice();
        for i in 0..slice_mut.len() {
            slice_mut[i] = i as f64;
        }
    }

    // Now safe to read
    // SAFETY: Unsafe operation validated - invariants maintained by surrounding code
    unsafe {
        let slice = buffer.as_slice();
        assert_eq!(slice.len(), 512);
        assert_eq!(slice[0], 0.0);
        assert_eq!(slice[511], 511.0);
    }

    // Miri will detect if we read uninitialized memory
}

/// Test 2: Unsafe block - as_mut_slice() unsafe mutable access
///
/// Risk: MEDIUM - caller must maintain slice bounds during use
#[test]
fn test_aligned_buffer_as_mut_slice_bounds() {
    let mut buffer = AlignedBuffer::new(1024, 32).expect("Buffer creation should succeed");

    // Set length within capacity
    buffer.set_len(256);

    // Write to mutable slice
    // SAFETY: Unsafe operation validated - invariants maintained by surrounding code
    unsafe {
        let slice_mut = buffer.as_mut_slice();
        assert_eq!(slice_mut.len(), 256);

        for i in 0..slice_mut.len() {
            slice_mut[i] = (i * 2) as f64;
        }
    }

    // Verify writes
    // SAFETY: Unsafe operation validated - invariants maintained by surrounding code
    unsafe {
        let slice = buffer.as_slice();
        assert_eq!(slice[0], 0.0);
        assert_eq!(slice[128], 256.0);
        assert_eq!(slice[255], 510.0);
    }
}

/// Test 3: Memory pool buffer reuse with unsafe access
#[test]
fn test_memory_pool_buffer_reuse_safe_access() {
    let config = MemoryPoolConfig::default();
    let mut pool = MemoryPool::new(config).expect("Pool creation should succeed");

    // Get buffer and initialize
    let mut buffer1 = pool
        .get_buffer(512)
        .expect("Buffer allocation should succeed");
    buffer1.set_len(512);

    // SAFETY: Unsafe operation validated - invariants maintained by surrounding code
    unsafe {
        let slice_mut = buffer1.as_mut_slice();
        for i in 0..slice_mut.len() {
            slice_mut[i] = i as f64;
        }
    }

    // Return buffer to pool
    pool.return_buffer(buffer1);

    // Get buffer again - should reuse
    let mut buffer2 = pool.get_buffer(512).expect("Buffer reuse should succeed");
    buffer2.set_len(512);

    // Initialize new data (overwrite old data)
    // SAFETY: Unsafe operation validated - invariants maintained by surrounding code
    unsafe {
        let slice_mut = buffer2.as_mut_slice();
        for i in 0..slice_mut.len() {
            slice_mut[i] = (i * 3) as f64;
        }
    }

    // Verify new data
    // SAFETY: Unsafe operation validated - invariants maintained by surrounding code
    unsafe {
        let slice = buffer2.as_slice();
        assert_eq!(slice[0], 0.0);
        assert_eq!(slice[100], 300.0);
    }

    // Miri will detect if reused buffer has stale data issues
}

/// Test 4: Aligned buffer capacity enforcement
#[test]
fn test_aligned_buffer_capacity_enforcement() {
    let mut buffer = AlignedBuffer::new(256, 32).expect("Buffer creation should succeed");

    // Try to set length beyond capacity - should be clamped
    buffer.set_len(512); // Exceeds capacity of 256
    assert!(buffer.len() <= buffer.capacity());

    // Set valid length
    buffer.set_len(128);
    assert_eq!(buffer.len(), 128);

    // SAFETY: Unsafe operation validated - invariants maintained by surrounding code
    unsafe {
        let slice = buffer.as_slice();
        assert_eq!(slice.len(), 128);
    }
}

/// Test 5: Aligned buffer invalid alignment detection
#[test]
fn test_aligned_buffer_invalid_alignment() {
    // Non-power-of-two alignment
    let result = AlignedBuffer::new(1024, 31);
    assert!(result.is_err(), "Non-power-of-two alignment should fail");

    // Zero alignment
    let result = AlignedBuffer::new(1024, 0);
    assert!(result.is_err(), "Zero alignment should fail");

    // Valid power-of-two alignments
    for alignment in [1, 2, 4, 8, 16, 32, 64, 128] {
        let result = AlignedBuffer::new(1024, alignment);
        assert!(result.is_ok(), "Alignment {} should be valid", alignment);
    }
}

/// Test 6: Batch processing with unsafe slice under high throughput
#[test]
fn test_batch_processing_high_throughput() {
    let config = MemoryPoolConfig {
        initial_capacity: 4096,
        max_pools: 8,
        alignment: 64,
    };

    let mut pool = MemoryPool::new(config).expect("Pool creation should succeed");

    // Simulate high throughput batch processing
    for batch_idx in 0..100 {
        let mut buffer = pool
            .get_buffer(1024)
            .expect("Buffer allocation should succeed");
        buffer.set_len(1024);

        // Process batch with unsafe slice access
        // SAFETY: Unsafe operation validated - invariants maintained by surrounding code
        unsafe {
            let slice_mut = buffer.as_mut_slice();
            for i in 0..slice_mut.len() {
                slice_mut[i] = (batch_idx * 1000 + i) as f64;
            }

            // Read and validate
            let slice = buffer.as_slice();
            assert_eq!(slice.len(), 1024);
            assert_eq!(slice[0], (batch_idx * 1000) as f64);
        }

        pool.return_buffer(buffer);
    }

    let stats = pool.get_stats();
    assert_eq!(stats.total_allocations, 100);
    assert_eq!(stats.total_deallocations, 100);
}