use criterion::{black_box, criterion_group, criterion_main, BenchmarkId, Criterion, Throughput};
use rocksdb::{Options, DB};
use std::time::Duration;
use tempfile::TempDir;

const VALUE_SIZE: usize = 1024; // 1KB
const NUM_KEYS_THROUGHPUT: usize = 10_000; // 10K for throughput tests
const SCAN_RANGE_SIZE: usize = 1_000; // 1K keys per scan

fn create_test_db(temp_dir: &TempDir) -> DB {
    let mut opts = Options::default();
    opts.create_if_missing(true);
    opts.set_write_buffer_size(64 * 1024 * 1024); // 64MB
    opts.set_max_write_buffer_number(3);
    opts.set_target_file_size_base(64 * 1024 * 1024);
    opts.set_level_zero_file_num_compaction_trigger(8);
    opts.set_level_zero_slowdown_writes_trigger(17);
    opts.set_level_zero_stop_writes_trigger(24);
    opts.set_num_levels(4);
    opts.set_max_bytes_for_level_base(512 * 1024 * 1024);
    opts.set_max_bytes_for_level_multiplier(8.0);

    // Performance tuning
    opts.set_compression_type(rocksdb::DBCompressionType::Lz4);
    opts.set_allow_concurrent_memtable_write(true);
    opts.set_enable_write_thread_adaptive_yield(true);

    DB::open(&opts, temp_dir.path()).unwrap()
}

fn bench_write_throughput(c: &mut Criterion) {
    let temp_dir = TempDir::new().unwrap();
    let db = create_test_db(&temp_dir);

    let value = vec![b'x'; VALUE_SIZE];

    let mut group = c.benchmark_group("write_throughput");
    group.throughput(Throughput::Elements(NUM_KEYS_THROUGHPUT as u64));
    group.sample_size(10);
    group.measurement_time(Duration::from_secs(30));

    group.bench_function(BenchmarkId::from_parameter(NUM_KEYS_THROUGHPUT), |b| {
        b.iter(|| {
            for i in 0..NUM_KEYS_THROUGHPUT {
                let key = format!("bench_key_{:08}", i);
                db.put(black_box(key.as_bytes()), black_box(&value)).unwrap();
            }
        });
    });

    group.finish();
    drop(db);
}

fn bench_read_throughput(c: &mut Criterion) {
    let temp_dir = TempDir::new().unwrap();
    let db = create_test_db(&temp_dir);

    let value = vec![b'x'; VALUE_SIZE];

    // Pre-populate keys
    for i in 0..NUM_KEYS_THROUGHPUT {
        let key = format!("bench_key_{:08}", i);
        db.put(key.as_bytes(), &value).unwrap();
    }

    // Force flush to disk
    db.flush().unwrap();

    let mut group = c.benchmark_group("read_throughput");
    group.throughput(Throughput::Elements(NUM_KEYS_THROUGHPUT as u64));
    group.sample_size(10);
    group.measurement_time(Duration::from_secs(30));

    group.bench_function(BenchmarkId::from_parameter(NUM_KEYS_THROUGHPUT), |b| {
        b.iter(|| {
            for i in 0..NUM_KEYS_THROUGHPUT {
                let key = format!("bench_key_{:08}", i);
                let _ = db.get(black_box(key.as_bytes())).unwrap();
            }
        });
    });

    group.finish();
    drop(db);
}

fn bench_scan_throughput(c: &mut Criterion) {
    let temp_dir = TempDir::new().unwrap();
    let db = create_test_db(&temp_dir);

    let value = vec![b'x'; VALUE_SIZE];

    // Pre-populate keys for scanning
    for i in 0..NUM_KEYS_THROUGHPUT {
        let key = format!("scan_key_{:08}", i);
        db.put(key.as_bytes(), &value).unwrap();
    }

    // Force flush to disk
    db.flush().unwrap();

    let mut group = c.benchmark_group("scan_throughput");
    group.throughput(Throughput::Elements(SCAN_RANGE_SIZE as u64));
    group.sample_size(10);
    group.measurement_time(Duration::from_secs(30));

    group.bench_function(BenchmarkId::from_parameter(SCAN_RANGE_SIZE), |b| {
        b.iter(|| {
            let start_key = format!("scan_key_{:08}", 0);
            let end_key = format!("scan_key_{:08}", SCAN_RANGE_SIZE);

            let iter = db.iterator(rocksdb::IteratorMode::From(
                start_key.as_bytes(),
                rocksdb::Direction::Forward,
            ));

            let mut count = 0;
            for item in iter {
                if let Ok((key, _value)) = item {
                    if black_box(key.as_ref()) >= end_key.as_bytes() {
                        break;
                    }
                    count += 1;
                    if count >= SCAN_RANGE_SIZE {
                        break;
                    }
                }
            }
        });
    });

    group.finish();
    drop(db);
}

fn bench_write_latency(c: &mut Criterion) {
    let temp_dir = TempDir::new().unwrap();
    let db = create_test_db(&temp_dir);

    let value = vec![b'x'; VALUE_SIZE];

    let mut group = c.benchmark_group("write_latency");
    group.sample_size(1000); // Larger sample for better p99/p999 estimates
    group.measurement_time(Duration::from_secs(60));

    group.bench_function("single_write", |b| {
        let mut key_counter = 0;
        b.iter(|| {
            let key = format!("latency_key_{:08}", key_counter);
            key_counter += 1;
            db.put(black_box(key.as_bytes()), black_box(&value)).unwrap();
        });
    });

    group.finish();
    drop(db);
}

fn bench_read_latency(c: &mut Criterion) {
    let temp_dir = TempDir::new().unwrap();
    let db = create_test_db(&temp_dir);

    let value = vec![b'x'; VALUE_SIZE];

    // Pre-populate keys
    for i in 0..1000 {
        let key = format!("read_lat_key_{:08}", i);
        db.put(key.as_bytes(), &value).unwrap();
    }

    db.flush().unwrap();

    let mut group = c.benchmark_group("read_latency");
    group.sample_size(1000);
    group.measurement_time(Duration::from_secs(60));

    group.bench_function("single_read", |b| {
        let mut key_counter = 0;
        b.iter(|| {
            let key = format!("read_lat_key_{:08}", key_counter % 1000);
            key_counter += 1;
            let _ = db.get(black_box(key.as_bytes())).unwrap();
        });
    });

    group.finish();
    drop(db);
}

criterion_group!(
    benches,
    bench_write_throughput,
    bench_read_throughput,
    bench_scan_throughput,
    bench_write_latency,
    bench_read_latency
);
criterion_main!(benches);