//! Benchmark Tests for Hyperparameter Optimization
//!
//! These benchmarks measure the performance of key operations in the
//! hyperparameter optimization framework.

use criterion::{black_box, criterion_group, criterion_main, BenchmarkId, Criterion};
use ml::hyperopt::{BestHyperparameters, HyperparameterSpace, OptimizationResult, TrialResult};
use ndarray::Array1;

// Mock denormalize function for benchmarking (since we can't access private functions)
fn denormalize_params_mock(
    normalized: &Array1<f64>,
    space: &HyperparameterSpace,
) -> (f64, usize, f64, f64) {
    let lr_norm = normalized[0];
    let batch_norm = normalized[1];
    let dropout_norm = normalized[2];
    let wd_norm = normalized[3];

    // Learning rate (log scale)
    let lr_log = space.learning_rate_log_min
        + lr_norm * (space.learning_rate_log_max - space.learning_rate_log_min);
    let learning_rate = 10_f64.powf(lr_log);

    // Batch size (integer, linear scale)
    let batch_size = (space.batch_size_min as f64
        + batch_norm * (space.batch_size_max - space.batch_size_min) as f64)
        .round() as usize;

    // Dropout (linear scale)
    let dropout = space.dropout_min + dropout_norm * (space.dropout_max - space.dropout_min);

    // Weight decay (log scale)
    let wd_log = space.weight_decay_log_min
        + wd_norm * (space.weight_decay_log_max - space.weight_decay_log_min);
    let weight_decay = 10_f64.powf(wd_log);

    (learning_rate, batch_size, dropout, weight_decay)
}

fn benchmark_param_conversion(c: &mut Criterion) {
    let space = HyperparameterSpace::default();

    let mut group = c.benchmark_group("param_conversion");

    // Benchmark single conversion
    group.bench_function("single_conversion", |b| {
        let normalized = Array1::from_vec(vec![0.5, 0.5, 0.5, 0.5]);
        b.iter(|| {
            let result = denormalize_params_mock(black_box(&normalized), black_box(&space));
            black_box(result);
        });
    });

    // Benchmark batch conversions (simulating optimization)
    for batch_size in [10, 50, 100, 500].iter() {
        group.bench_with_input(
            BenchmarkId::from_parameter(format!("batch_{}", batch_size)),
            batch_size,
            |b, &size| {
                let normalized_batch: Vec<Array1<f64>> = (0..size)
                    .map(|i| {
                        let norm = i as f64 / size as f64;
                        Array1::from_vec(vec![norm, norm, norm, norm])
                    })
                    .collect();

                b.iter(|| {
                    for normalized in &normalized_batch {
                        let result =
                            denormalize_params_mock(black_box(normalized), black_box(&space));
                        black_box(result);
                    }
                });
            },
        );
    }

    group.finish();
}

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

    // Benchmark pow computation (expensive operation)
    group.bench_function("pow_computation", |b| {
        let log_value = -3.5;
        b.iter(|| {
            let result = 10_f64.powf(black_box(log_value));
            black_box(result);
        });
    });

    // Benchmark linear interpolation
    group.bench_function("linear_interpolation", |b| {
        let min = -5.0;
        let max = -2.0;
        let norm = 0.5;
        b.iter(|| {
            let result = black_box(min) + black_box(norm) * (black_box(max) - black_box(min));
            black_box(result);
        });
    });

    group.finish();
}

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

    // Benchmark integer rounding
    group.bench_function("round_to_integer", |b| {
        let value = 127.8;
        b.iter(|| {
            let result = black_box(value).round() as usize;
            black_box(result);
        });
    });

    // Benchmark floor
    group.bench_function("floor_to_integer", |b| {
        let value = 127.8;
        b.iter(|| {
            let result = black_box(value).floor() as usize;
            black_box(result);
        });
    });

    // Benchmark ceil
    group.bench_function("ceil_to_integer", |b| {
        let value = 127.8;
        b.iter(|| {
            let result = black_box(value).ceil() as usize;
            black_box(result);
        });
    });

    group.finish();
}

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

    let best_params = BestHyperparameters {
        learning_rate: 0.001,
        batch_size: 64,
        dropout: 0.2,
        weight_decay: 0.0001,
        best_validation_loss: 12.5,
        trials_used: 30,
    };

    // Benchmark JSON serialization
    group.bench_function("json_serialize", |b| {
        b.iter(|| {
            let json = serde_json::to_string(black_box(&best_params)).unwrap();
            black_box(json);
        });
    });

    // Benchmark JSON deserialization
    let json = serde_json::to_string(&best_params).unwrap();
    group.bench_function("json_deserialize", |b| {
        b.iter(|| {
            let result: BestHyperparameters = serde_json::from_str(black_box(&json)).unwrap();
            black_box(result);
        });
    });

    // Benchmark YAML serialization
    group.bench_function("yaml_serialize", |b| {
        b.iter(|| {
            let yaml = serde_yaml::to_string(black_box(&best_params)).unwrap();
            black_box(yaml);
        });
    });

    // Benchmark YAML deserialization
    let yaml = serde_yaml::to_string(&best_params).unwrap();
    group.bench_function("yaml_deserialize", |b| {
        b.iter(|| {
            let result: BestHyperparameters = serde_yaml::from_str(black_box(&yaml)).unwrap();
            black_box(result);
        });
    });

    group.finish();
}

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

    // Benchmark creating OptimizationResult
    for trial_count in [10, 30, 50, 100].iter() {
        group.bench_with_input(
            BenchmarkId::from_parameter(format!("trials_{}", trial_count)),
            trial_count,
            |b, &count| {
                b.iter(|| {
                    let best_params = BestHyperparameters {
                        learning_rate: 0.001,
                        batch_size: 64,
                        dropout: 0.2,
                        weight_decay: 0.0001,
                        best_validation_loss: 12.5,
                        trials_used: count,
                    };

                    let trial_history: Vec<TrialResult> = (0..count)
                        .map(|i| TrialResult {
                            trial_number: i + 1,
                            learning_rate: 0.001,
                            batch_size: 64,
                            dropout: 0.2,
                            weight_decay: 0.0001,
                            validation_loss: 15.0 - i as f64 * 0.05,
                            training_time_seconds: 18.0,
                        })
                        .collect();

                    let result = OptimizationResult {
                        best_params,
                        trial_history,
                    };

                    black_box(result);
                });
            },
        );
    }

    group.finish();
}

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

    // Benchmark Array1 creation
    group.bench_function("array1_from_vec", |b| {
        let values = vec![0.1, 0.2, 0.3, 0.4];
        b.iter(|| {
            let arr = Array1::from_vec(black_box(values.clone()));
            black_box(arr);
        });
    });

    // Benchmark Array1 indexing
    group.bench_function("array1_indexing", |b| {
        let arr = Array1::from_vec(vec![0.1, 0.2, 0.3, 0.4]);
        b.iter(|| {
            let val = black_box(&arr)[0];
            black_box(val);
        });
    });

    // Benchmark Array1 to owned
    group.bench_function("array1_to_owned", |b| {
        let arr = Array1::from_vec(vec![0.1, 0.2, 0.3, 0.4]);
        let view = arr.view();
        b.iter(|| {
            let owned = black_box(&view).to_owned();
            black_box(owned);
        });
    });

    group.finish();
}

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

    // Benchmark default space creation
    group.bench_function("default_space", |b| {
        b.iter(|| {
            let space = HyperparameterSpace::default();
            black_box(space);
        });
    });

    // Benchmark custom space creation
    group.bench_function("custom_space", |b| {
        b.iter(|| {
            let space = HyperparameterSpace {
                learning_rate_log_min: -4.0,
                learning_rate_log_max: -1.0,
                batch_size_min: 32,
                batch_size_max: 128,
                dropout_min: 0.1,
                dropout_max: 0.3,
                weight_decay_log_min: -5.0,
                weight_decay_log_max: -3.0,
            };
            black_box(space);
        });
    });

    // Benchmark space cloning
    group.bench_function("clone_space", |b| {
        let space = HyperparameterSpace::default();
        b.iter(|| {
            let cloned = black_box(&space).clone();
            black_box(cloned);
        });
    });

    group.finish();
}

criterion_group!(
    benches,
    benchmark_param_conversion,
    benchmark_log_scale_computation,
    benchmark_batch_size_rounding,
    benchmark_serialization,
    benchmark_optimization_result_creation,
    benchmark_array_creation,
    benchmark_hyperparameter_space_creation
);
criterion_main!(benches);