use std::collections::HashMap;

use crate::metrics::MetricsCollector;
use crate::mmap_reader::{
    MmapReaderPhaseAware, MmapReaderPlain, MmapReaderPopulate, MmapReaderRandom,
    MmapReaderSequential,
};
use crate::pread_reader::{PreadReaderPlain, PreadReaderRandom, PreadReaderSequential};
use crate::runner::BenchConfig;
use crate::types::BenchmarkResult;
use crate::FileReaderBackend;

pub fn run(config: &BenchConfig) -> Vec<BenchmarkResult> {
    let mut results = Vec::new();

    results.extend(bench_idle_rss::<MmapReaderPlain>("mmap", "plain", config));
    results.extend(bench_idle_rss::<MmapReaderSequential>(
        "mmap",
        "sequential",
        config,
    ));
    results.extend(bench_idle_rss::<MmapReaderRandom>("mmap", "random", config));
    results.extend(bench_idle_rss::<MmapReaderPopulate>(
        "mmap", "populate", config,
    ));
    results.extend(bench_idle_rss::<MmapReaderPhaseAware>(
        "mmap",
        "phase_aware",
        config,
    ));
    results.extend(bench_idle_rss::<PreadReaderPlain>("pread", "plain", config));
    results.extend(bench_idle_rss::<PreadReaderRandom>(
        "pread", "random", config,
    ));
    results.extend(bench_idle_rss::<PreadReaderSequential>(
        "pread",
        "sequential",
        config,
    ));

    results.extend(bench_scroll_rss::<MmapReaderPlain>("mmap", "plain", config));
    results.extend(bench_scroll_rss::<PreadReaderPlain>(
        "pread", "plain", config,
    ));

    results.extend(bench_jump_end_rss::<MmapReaderPlain>(
        "mmap", "plain", config,
    ));
    results.extend(bench_jump_end_rss::<PreadReaderPlain>(
        "pread", "plain", config,
    ));

    results.extend(bench_rss_reclaim::<MmapReaderPlain>(
        "mmap", "plain", config,
    ));
    results.extend(bench_rss_reclaim::<PreadReaderPlain>(
        "pread", "plain", config,
    ));

    results
}

fn bench_idle_rss<B: FileReaderBackend>(
    backend: &str,
    variant: &str,
    config: &BenchConfig,
) -> Vec<BenchmarkResult> {
    let reader = B::open(&config.test_file).expect("Failed to open file");
    let rss = MetricsCollector::read_rss();
    let faults = MetricsCollector::read_page_faults();

    let mut extra = HashMap::new();
    extra.insert("total_lines".into(), reader.total_lines() as f64);
    extra.insert(
        "file_size_mb".into(),
        reader.file_size() as f64 / (1024.0 * 1024.0),
    );

    reader.close();

    vec![BenchmarkResult {
        category: "memory".into(),
        test_name: "idle_rss".into(),
        backend: backend.into(),
        variant: variant.into(),
        latency_us: vec![],
        rss_kb: rss.vm_rss_kb,
        rss_peak_kb: rss.vm_hwm_kb,
        page_faults: faults.minor_faults + faults.major_faults,
        extra,
    }]
}

fn bench_scroll_rss<B: FileReaderBackend>(
    backend: &str,
    variant: &str,
    config: &BenchConfig,
) -> Vec<BenchmarkResult> {
    let reader = B::open(&config.test_file).expect("Failed to open file");
    let total = reader.total_lines();
    let sample_interval = 100_000;
    let max_lines = if config.quick_mode { 100_000 } else { total };

    let upper = max_lines.min(total);
    let mut rss_samples = Vec::new();
    let mut hwm_samples = Vec::new();
    let mut lines_read = 0usize;

    for i in (0..upper).step_by(sample_interval) {
        if reader.get_line(i).is_some() {
            lines_read += 1;
        }
        let rss = MetricsCollector::read_rss();
        rss_samples.push(rss.vm_rss_kb);
        hwm_samples.push(rss.vm_hwm_kb);
    }

    let final_rss = MetricsCollector::read_rss();
    let faults = MetricsCollector::read_page_faults();

    let mut extra = HashMap::new();
    extra.insert("rss_samples_count".into(), rss_samples.len() as f64);
    extra.insert(
        "max_rss_kb".into(),
        rss_samples.iter().copied().fold(0u64, u64::max) as f64,
    );
    extra.insert(
        "max_hwm_kb".into(),
        hwm_samples.iter().copied().fold(0u64, u64::max) as f64,
    );
    extra.insert("lines_read".into(), lines_read as f64);

    reader.close();

    vec![BenchmarkResult {
        category: "memory".into(),
        test_name: "scroll_rss".into(),
        backend: backend.into(),
        variant: variant.into(),
        latency_us: vec![],
        rss_kb: final_rss.vm_rss_kb,
        rss_peak_kb: final_rss.vm_hwm_kb,
        page_faults: faults.minor_faults + faults.major_faults,
        extra,
    }]
}

fn bench_jump_end_rss<B: FileReaderBackend>(
    backend: &str,
    variant: &str,
    config: &BenchConfig,
) -> Vec<BenchmarkResult> {
    let reader = B::open(&config.test_file).expect("Failed to open file");
    let total = reader.total_lines();
    let last_line = total.saturating_sub(1);

    let _ = reader.get_line(last_line);

    let rss = MetricsCollector::read_rss();
    let faults = MetricsCollector::read_page_faults();

    let mut extra = HashMap::new();
    extra.insert("last_line_idx".into(), last_line as f64);
    extra.insert("total_lines".into(), total as f64);

    reader.close();

    vec![BenchmarkResult {
        category: "memory".into(),
        test_name: "jump_end_rss".into(),
        backend: backend.into(),
        variant: variant.into(),
        latency_us: vec![],
        rss_kb: rss.vm_rss_kb,
        rss_peak_kb: rss.vm_hwm_kb,
        page_faults: faults.minor_faults + faults.major_faults,
        extra,
    }]
}

fn bench_rss_reclaim<B: FileReaderBackend>(
    backend: &str,
    variant: &str,
    config: &BenchConfig,
) -> Vec<BenchmarkResult> {
    let reader = B::open(&config.test_file).expect("Failed to open file");
    let total = reader.total_lines();
    let last_line = total.saturating_sub(1);

    let _ = reader.get_line(last_line);

    let wait_secs: u64 = if config.quick_mode { 5 } else { 30 };
    let sample_interval: u64 = 5;
    let num_samples = (wait_secs / sample_interval) as usize;

    let mut rss_samples = Vec::with_capacity(num_samples);
    let mut hwm_samples = Vec::with_capacity(num_samples);

    for _ in 0..num_samples {
        std::thread::sleep(std::time::Duration::from_secs(sample_interval));
        let rss = MetricsCollector::read_rss();
        rss_samples.push(rss.vm_rss_kb);
        hwm_samples.push(rss.vm_hwm_kb);
    }

    let final_rss = MetricsCollector::read_rss();
    let faults = MetricsCollector::read_page_faults();
    reader.close();

    let mut extra = HashMap::new();
    extra.insert("wait_total_secs".into(), wait_secs as f64);
    extra.insert("rss_samples".into(), rss_samples.len() as f64);
    if let (Some(&first), Some(&last)) = (rss_samples.first(), rss_samples.last()) {
        extra.insert("rss_first_kb".into(), first as f64);
        extra.insert("rss_last_kb".into(), last as f64);
        extra.insert(
            "rss_change_pct".into(),
            if first > 0 {
                ((last as f64 - first as f64) / first as f64) * 100.0
            } else {
                0.0
            },
        );
    }

    vec![BenchmarkResult {
        category: "memory".into(),
        test_name: "rss_reclaim".into(),
        backend: backend.into(),
        variant: variant.into(),
        latency_us: vec![],
        rss_kb: final_rss.vm_rss_kb,
        rss_peak_kb: final_rss.vm_hwm_kb,
        page_faults: faults.minor_faults + faults.major_faults,
        extra,
    }]
}