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

#![allow(clippy::cast_precision_loss)]
//! Address space performance benchmarks
//!
//! Benchmarks for page table operations and memory efficiency

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

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

fn configure_criterion() -> Criterion {
    Criterion::default()
        .warm_up_time(Duration::from_secs(2))
        .measurement_time(Duration::from_secs(5))
        .sample_size(500)
}

// ============================================================================
// Page Table Walk Benchmarks
// ============================================================================

fn bench_page_table_walk(c: &mut Criterion) {
    c.bench_function("page_table_walk", |b| {
        b.iter(|| {
            // TODO: Implement when AddressSpace is ready
            // Measure page table walk latency
            // Expected: O(log n) or better with sparse structure
            black_box(());
        });
    });
}

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

    // Test with different table depths (levels)
    for depth in &[1, 2, 3, 4] {
        group.bench_with_input(BenchmarkId::from_parameter(depth), depth, |b, &depth| {
            b.iter(|| {
                // TODO: Measure walk performance at different depths
                black_box(depth);
            });
        });
    }

    group.finish();
}

// ============================================================================
// Page Mapping Benchmarks
// ============================================================================

fn bench_page_mapping(c: &mut Criterion) {
    c.bench_function("page_mapping", |b| {
        b.iter(|| {
            // TODO: Implement when mapping API is ready
            // Measure time to add a new page mapping
            black_box(());
        });
    });
}

fn bench_page_unmapping(c: &mut Criterion) {
    c.bench_function("page_unmapping", |b| {
        b.iter(|| {
            // TODO: Implement when unmapping API is ready
            // Measure time to remove a page mapping
            black_box(());
        });
    });
}

fn bench_page_remapping(c: &mut Criterion) {
    c.bench_function("page_remapping", |b| {
        b.iter(|| {
            // TODO: Implement when mapping API is ready
            // Measure time to change existing mapping
            black_box(());
        });
    });
}

// ============================================================================
// Sparse Data Structure Benchmarks
// ============================================================================

fn bench_sparse_lookup(c: &mut Criterion) {
    c.bench_function("sparse_lookup", |b| {
        b.iter(|| {
            // TODO: Benchmark sparse data structure performance
            // HashMap/BTreeMap lookup should be O(1) or O(log n)
            black_box(());
        });
    });
}

fn bench_sparse_insert(c: &mut Criterion) {
    c.bench_function("sparse_insert", |b| {
        b.iter(|| {
            // TODO: Benchmark insertion into sparse structure
            black_box(());
        });
    });
}

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

    // Test iteration over different numbers of mappings
    for num_pages in &[100, 1000, 10_000] {
        group.bench_with_input(BenchmarkId::from_parameter(num_pages), num_pages, |b, &num_pages| {
            b.iter(|| {
                // TODO: Measure iteration performance
                black_box(num_pages);
            });
        });
    }

    group.finish();
}

// ============================================================================
// Memory Efficiency Benchmarks
// ============================================================================

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

    // Measure memory overhead with sparse mappings
    for num_pages in &[1000, 10_000, 100_000] {
        group.bench_with_input(BenchmarkId::from_parameter(num_pages), num_pages, |b, &num_pages| {
            b.iter(|| {
                // TODO: Create address space with sparse mappings
                // Measure actual memory usage
                black_box(num_pages);
            });
        });
    }

    group.finish();
}

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

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

    // Test with different page sizes
    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| {
            b.iter(|| {
                // TODO: Measure operations with different page sizes
                black_box(page_size);
            });
        });
    }

    group.finish();
}

// ============================================================================
// Bulk Operations Benchmarks
// ============================================================================

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

    // Measure bulk mapping performance
    for num_pages in &[10, 100, 1000] {
        group.bench_with_input(BenchmarkId::from_parameter(num_pages), num_pages, |b, &num_pages| {
            b.iter(|| {
                // TODO: Map multiple pages at once
                // Measure if there's benefit to bulk operations
                black_box(num_pages);
            });
        });
    }

    group.finish();
}

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

    for num_pages in &[10, 100, 1000] {
        group.bench_with_input(BenchmarkId::from_parameter(num_pages), num_pages, |b, &num_pages| {
            b.iter(|| {
                // TODO: Unmap multiple pages at once
                black_box(num_pages);
            });
        });
    }

    group.finish();
}

// ============================================================================
// Contiguous vs Non-Contiguous Benchmarks
// ============================================================================

fn bench_contiguous_mapping(c: &mut Criterion) {
    c.bench_function("contiguous_mapping", |b| {
        b.iter(|| {
            // TODO: Measure performance with contiguous mappings
            // May benefit from optimizations
            black_box(());
        });
    });
}

fn bench_noncontiguous_mapping(c: &mut Criterion) {
    c.bench_function("noncontiguous_mapping", |b| {
        b.iter(|| {
            // TODO: Measure performance with scattered mappings
            // Tests sparse structure effectiveness
            black_box(());
        });
    });
}

// ============================================================================
// Lookup Pattern Benchmarks
// ============================================================================

fn bench_sequential_lookup(c: &mut Criterion) {
    c.bench_function("sequential_lookup", |b| {
        b.iter(|| {
            // TODO: Sequential address lookups
            // May benefit from cache locality
            black_box(());
        });
    });
}

fn bench_random_lookup(c: &mut Criterion) {
    c.bench_function("random_lookup", |b| {
        b.iter(|| {
            // TODO: Random address lookups
            // Worst case for cache
            black_box(());
        });
    });
}

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

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

    group.bench_function("small_sparse", |b| {
        b.iter(|| {
            // TODO: Small sparse address space (< 1000 pages)
            black_box(());
        });
    });

    group.bench_function("large_sparse", |b| {
        b.iter(|| {
            // TODO: Large sparse address space (> 10_000 pages)
            black_box(());
        });
    });

    group.bench_function("dense", |b| {
        b.iter(|| {
            // TODO: Dense address space (most pages mapped)
            black_box(());
        });
    });

    group.finish();
}

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

criterion_group! {
    name = benches;
    config = configure_criterion();
    targets =
        bench_page_table_walk,
        bench_page_table_walk_depths,
        bench_page_mapping,
        bench_page_unmapping,
        bench_page_remapping,
        bench_sparse_lookup,
        bench_sparse_insert,
        bench_sparse_iteration,
        bench_memory_usage_sparse,
        bench_large_page_operations,
        bench_bulk_mapping,
        bench_bulk_unmapping,
        bench_contiguous_mapping,
        bench_noncontiguous_mapping,
        bench_sequential_lookup,
        bench_random_lookup,
        bench_address_space_comparison
}

criterion_main!(benches);
