use std::collections::HashMap;
use std::path::Path;

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

    if !config.quick_mode {
        if MetricsCollector::clear_file_cache(&config.test_file).is_ok() {
            results.extend(bench_cold_open::<MmapReaderPlain>("mmap", "plain", config));
            results.extend(bench_cold_open::<MmapReaderSequential>(
                "mmap",
                "sequential",
                config,
            ));
            results.extend(bench_cold_open::<MmapReaderRandom>(
                "mmap", "random", config,
            ));
            results.extend(bench_cold_open::<MmapReaderPopulate>(
                "mmap", "populate", config,
            ));
            results.extend(bench_cold_open::<MmapReaderPhaseAware>(
                "mmap",
                "phase_aware",
                config,
            ));
            results.extend(bench_cold_open::<PreadReaderPlain>(
                "pread", "plain", config,
            ));
            results.extend(bench_cold_open::<PreadReaderRandom>(
                "pread", "random", config,
            ));
            results.extend(bench_cold_open::<PreadReaderSequential>(
                "pread",
                "sequential",
                config,
            ));
        }
    }

    results
}

fn bench_hot_open<B: FileReaderBackend>(
    backend: &str,
    variant: &str,
    config: &BenchConfig,
) -> Vec<BenchmarkResult> {
    open_and_measure::<B>(backend, variant, &config.test_file, "hot_open")
}

fn bench_cold_open<B: FileReaderBackend>(
    backend: &str,
    variant: &str,
    config: &BenchConfig,
) -> Vec<BenchmarkResult> {
    let _ = MetricsCollector::clear_file_cache(&config.test_file);
    open_and_measure::<B>(backend, variant, &config.test_file, "cold_open")
}

fn open_and_measure<B: FileReaderBackend>(
    backend: &str,
    variant: &str,
    path: &Path,
    test_name: &str,
) -> Vec<BenchmarkResult> {
    let start = std::time::Instant::now();
    let reader = B::open(path).expect("Failed to open file");
    let elapsed = start.elapsed();

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

    let result = BenchmarkResult {
        category: "startup".into(),
        test_name: test_name.into(),
        backend: backend.into(),
        variant: variant.into(),
        latency_us: vec![elapsed.as_micros() as u64],
        rss_kb: rss.vm_rss_kb,
        rss_peak_kb: rss.vm_hwm_kb,
        page_faults: faults.minor_faults + faults.major_faults,
        extra: {
            let mut m = HashMap::new();
            m.insert("total_lines".into(), reader.total_lines() as f64);
            m.insert(
                "file_size_mb".into(),
                reader.file_size() as f64 / (1024.0 * 1024.0),
            );
            m
        },
    };
    reader.close();
    vec![result]
}