#![allow(missing_docs)]
#![allow(clippy::float_cmp)]
#![allow(clippy::cast_possible_truncation)]

#![allow(clippy::cast_precision_loss)]
//! Translation performance benchmarks
//!
//! Benchmarks for measuring translation latency and throughput.
//! Target: 135ns average translation time (matching C++ baseline)

use criterion::{black_box, criterion_group, criterion_main, BenchmarkId, Criterion};
use smmu::SMMU;
use std::time::Duration;

// ============================================================================
// Benchmark Configuration
// ============================================================================

fn configure_criterion() -> Criterion {
    Criterion::default()
        .warm_up_time(Duration::from_secs(3))
        .measurement_time(Duration::from_secs(10))
        .sample_size(1000)
        .significance_level(0.05)
        .noise_threshold(0.02)
}

// ============================================================================
// Simple Translation Benchmarks
// ============================================================================

fn bench_translation_simple(c: &mut Criterion) {
    let _smmu = SMMU::new();

    c.bench_function("translation_simple", |b| {
        b.iter(|| {
            // TODO: Implement when translation API is ready
            // Measure single translation with no PASID, single stream
            // Target: < 135ns
            black_box(());
        });
    });
}

fn bench_translation_with_pasid(c: &mut Criterion) {
    let _smmu = SMMU::new();

    c.bench_function("translation_with_pasid", |b| {
        b.iter(|| {
            // TODO: Implement when PASID translation is ready
            // Measure translation with PASID lookup
            black_box(());
        });
    });
}

// ============================================================================
// Cached vs Uncached Translation
// ============================================================================

fn bench_translation_cached(c: &mut Criterion) {
    let _smmu = SMMU::new();

    c.bench_function("translation_cached", |b| {
        b.iter(|| {
            // TODO: Implement when caching is ready
            // Measure cached translation (TLB hit)
            // Expected: Much faster than uncached
            black_box(());
        });
    });
}

fn bench_translation_uncached(c: &mut Criterion) {
    let _smmu = SMMU::new();

    c.bench_function("translation_uncached", |b| {
        b.iter(|| {
            // TODO: Implement when caching is ready
            // Measure uncached translation (TLB miss)
            // This is the worst-case scenario
            black_box(());
        });
    });
}

// ============================================================================
// Multi-PASID Benchmarks
// ============================================================================

fn bench_translation_multi_pasid(c: &mut Criterion) {
    let mut group = c.benchmark_group("translation_multi_pasid");

    for num_pasids in &[1, 2, 4, 8, 16, 32] {
        group.bench_with_input(BenchmarkId::from_parameter(num_pasids), num_pasids, |b, &num_pasids| {
            let _smmu = SMMU::new();

            b.iter(|| {
                // TODO: Implement when PASID support is ready
                // Measure translation with varying number of PASIDs
                // Verify O(1) or O(log n) lookup performance
                black_box(num_pasids);
            });
        });
    }

    group.finish();
}

// ============================================================================
// Page Size Benchmarks
// ============================================================================

fn bench_translation_page_sizes(c: &mut Criterion) {
    let mut group = c.benchmark_group("translation_page_sizes");

    // Test with different page sizes: 4K, 2M, 1G
    for page_size in &[4096, 2 * 1024 * 1024, 1024 * 1024 * 1024] {
        group.bench_with_input(BenchmarkId::from_parameter(page_size), page_size, |b, &page_size| {
            let _smmu = SMMU::new();

            b.iter(|| {
                // TODO: Implement when page size configuration is ready
                // Measure translation with different page sizes
                black_box(page_size);
            });
        });
    }

    group.finish();
}

// ============================================================================
// Throughput Benchmarks
// ============================================================================

fn bench_translation_throughput(c: &mut Criterion) {
    let mut group = c.benchmark_group("translation_throughput");

    // Measure throughput with batches of translations
    for batch_size in &[10, 100, 1000, 10_000] {
        group.bench_with_input(BenchmarkId::from_parameter(batch_size), batch_size, |b, &batch_size| {
            let _smmu = SMMU::new();

            b.iter(|| {
                // TODO: Implement when translation API is ready
                // Measure throughput (ops/sec) for batch translations
                for _ in 0..batch_size {
                    black_box(());
                }
            });
        });
    }

    group.finish();
}

// ============================================================================
// Worst-Case Scenario Benchmarks
// ============================================================================

fn bench_translation_worst_case(c: &mut Criterion) {
    let _smmu = SMMU::new();

    c.bench_function("translation_worst_case", |b| {
        b.iter(|| {
            // TODO: Implement when translation is ready
            // Measure worst-case: TLB miss, deep page table walk
            black_box(());
        });
    });
}

// ============================================================================
// Comparison Benchmarks
// ============================================================================

fn bench_translation_comparison(c: &mut Criterion) {
    let mut group = c.benchmark_group("translation_comparison");

    // Compare different translation scenarios
    group.bench_function("no_pasid", |b| {
        let _smmu = SMMU::new();
        b.iter(|| {
            // TODO: Translation without PASID
            black_box(());
        });
    });

    group.bench_function("with_pasid", |b| {
        let _smmu = SMMU::new();
        b.iter(|| {
            // TODO: Translation with PASID
            black_box(());
        });
    });

    group.bench_function("cached", |b| {
        let _smmu = SMMU::new();
        b.iter(|| {
            // TODO: Cached translation
            black_box(());
        });
    });

    group.bench_function("uncached", |b| {
        let _smmu = SMMU::new();
        b.iter(|| {
            // TODO: Uncached translation
            black_box(());
        });
    });

    group.finish();
}

// ============================================================================
// Latency Distribution Analysis
// ============================================================================

fn bench_translation_latency_distribution(c: &mut Criterion) {
    let _smmu = SMMU::new();

    c.bench_function("translation_latency_p50", |b| {
        b.iter(|| {
            // TODO: Measure median latency
            black_box(());
        });
    });

    c.bench_function("translation_latency_p99", |b| {
        b.iter(|| {
            // TODO: Measure 99th percentile latency
            black_box(());
        });
    });
}

// ============================================================================
// Benchmark Groups
// ============================================================================

criterion_group! {
    name = benches;
    config = configure_criterion();
    targets =
        bench_translation_simple,
        bench_translation_with_pasid,
        bench_translation_cached,
        bench_translation_uncached,
        bench_translation_multi_pasid,
        bench_translation_page_sizes,
        bench_translation_throughput,
        bench_translation_worst_case,
        bench_translation_comparison,
        bench_translation_latency_distribution
}

criterion_main!(benches);
