use anyhow::Result;
use reqwest::{Client, header};
use std::fs::{File, OpenOptions};
use std::io::{BufRead, BufReader, Write};
use std::sync::Arc;
use std::sync::atomic::{AtomicU64, AtomicUsize, Ordering};
use std::time::Duration;
use tokio::sync::Semaphore;
use futures::stream::{self, StreamExt};

const CONCURRENT: usize = 1000;  // MAXED
const TARGET_BYTES: u64 = 300_000_000_000;
const OUTPUT: &str = "/workspace/crawled";
const SEEDS: &str = "/workspace/seeds_2m.txt";

static TOTAL_BYTES: AtomicU64 = AtomicU64::new(0);
static PAGES: AtomicUsize = AtomicUsize::new(0);
static ERRORS: AtomicUsize = AtomicUsize::new(0);

#[tokio::main]
async fn main() -> Result<()> {
    std::fs::create_dir_all(OUTPUT)?;
    
    let mut headers = header::HeaderMap::new();
    headers.insert(header::ACCEPT, "text/html,*/*".parse()?);
    headers.insert(header::ACCEPT_LANGUAGE, "en-US,en;q=0.9".parse()?);
    headers.insert(header::ACCEPT_ENCODING, "gzip, deflate".parse()?);
    headers.insert(header::CACHE_CONTROL, "no-cache".parse()?);
    
    let client = Client::builder()
        .timeout(Duration::from_secs(10))
        .connect_timeout(Duration::from_secs(5))
        .user_agent("Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/121.0.0.0 Safari/537.36")
        .default_headers(headers)
        .pool_max_idle_per_host(200)
        .pool_idle_timeout(Duration::from_secs(30))
        .redirect(reqwest::redirect::Policy::limited(3))
        .danger_accept_invalid_certs(true)
        .build()?;
    
    println!("🔥 AGGRESSIVE CRAWLER - 1000 concurrent, NO DELAYS");
    println!("Target: 300GB | Seeds: 2M");
    
    let file = File::open(SEEDS)?;
    let seeds: Vec<String> = BufReader::new(file).lines().filter_map(|l| l.ok()).collect();
    println!("Loaded {} seeds - FIRING", seeds.len());
    
    let sem = Arc::new(Semaphore::new(CONCURRENT));
    let client = Arc::new(client);
    
    // Status thread
    let start = std::time::Instant::now();
    tokio::spawn(async move {
        loop {
            tokio::time::sleep(Duration::from_secs(15)).await;
            let bytes = TOTAL_BYTES.load(Ordering::Relaxed);
            let pages = PAGES.load(Ordering::Relaxed);
            let errs = ERRORS.load(Ordering::Relaxed);
            let elapsed = start.elapsed().as_secs_f64();
            let rate = bytes as f64 / elapsed / 1_000_000.0;
            let pct = 100.0 * bytes as f64 / TARGET_BYTES as f64;
            let eta_h = if rate > 0.0 { (TARGET_BYTES - bytes) as f64 / rate / 1_000_000.0 / 3600.0 } else { 999.0 };
            
            println!("[{:.0}s] {:.2}% | {:.2} GB | {} pg | {} err | {:.1} MB/s | ETA {:.1}h", 
                elapsed, pct, bytes as f64/1e9, pages, errs, rate, eta_h);
        }
    });
    
    // BLAST through all seeds
    stream::iter(seeds)
        .for_each_concurrent(CONCURRENT, |url| {
            let client = client.clone();
            let sem = sem.clone();
            
            async move {
                if TOTAL_BYTES.load(Ordering::Relaxed) >= TARGET_BYTES { return; }
                
                let _permit = sem.acquire().await.unwrap();
                
                match client.get(&url).send().await {
                    Ok(resp) if resp.status().is_success() => {
                        if let Ok(html) = resp.text().await {
                            let text = strip_html(&html);
                            if text.len() > 300 {
                                let n = PAGES.fetch_add(1, Ordering::Relaxed);
                                let path = format!("{}/p_{:08}.txt", OUTPUT, n);
                                if let Ok(mut f) = OpenOptions::new().create(true).write(true).open(&path) {
                                    let content = format!("URL: {}\n\n{}", url, text);
                                    let _ = f.write_all(content.as_bytes());
                                    TOTAL_BYTES.fetch_add(content.len() as u64, Ordering::Relaxed);
                                }
                            }
                        }
                    }
                    _ => { ERRORS.fetch_add(1, Ordering::Relaxed); }
                }
            }
        })
        .await;
    
    println!("✅ DONE: {} GB", TOTAL_BYTES.load(Ordering::Relaxed) / 1_000_000_000);
    Ok(())
}

fn strip_html(html: &str) -> String {
    let mut out = String::with_capacity(html.len() / 4);
    let mut in_tag = false;
    let mut skip = 0u8;
    let bytes = html.as_bytes();
    let len = bytes.len();
    let mut i = 0;
    
    while i < len {
        let c = bytes[i];
        match c {
            b'<' => {
                in_tag = true;
                // Check for script/style
                if i + 7 < len {
                    let slice = &bytes[i..i+8];
                    if slice.eq_ignore_ascii_case(b"<script>") || slice.eq_ignore_ascii_case(b"<script ") { skip = 1; }
                    if slice.eq_ignore_ascii_case(b"<style>s") || slice.eq_ignore_ascii_case(b"<style s") { skip = 2; }
                }
                if i + 8 < len && skip == 1 && bytes[i..i+9].eq_ignore_ascii_case(b"</script>") { skip = 0; }
                if i + 7 < len && skip == 2 && bytes[i..i+8].eq_ignore_ascii_case(b"</style>") { skip = 0; }
            }
            b'>' => { in_tag = false; }
            _ if !in_tag && skip == 0 => {
                if c.is_ascii_whitespace() {
                    if !out.ends_with(' ') && !out.is_empty() { out.push(' '); }
                } else {
                    out.push(c as char);
                }
            }
            _ => {}
        }
        i += 1;
    }
    out
}