//! End-to-end integration tests.
//!
//! Each test spins up the server in a background OS thread on an
//! ephemeral port, opens a regular `std::net::TcpStream` against it, and
//! exercises the wire. Single thread for the smarm runtime per test so
//! teardown happens cleanly when the test thread is dropped (the process
//! exits at the end of the test binary).

use std::io::{Read, Write};
use std::net::{SocketAddr, TcpListener, TcpStream};
use std::time::Duration;

use urus::{serve_with, Conn, Config, Next, Pipeline, Router};

// ---------------------------------------------------------------------------
// Helpers
// ---------------------------------------------------------------------------

/// Reserve a free localhost port by binding briefly and reading back the
/// assigned port number. The port is released the instant we drop the
/// listener; there's a tiny race window before the urus server claims it
/// but it's well below the threshold for flakiness in practice.
fn free_port() -> u16 {
    let l = TcpListener::bind("127.0.0.1:0").unwrap();
    l.local_addr().unwrap().port()
}

fn spawn_server(pipeline: Pipeline) -> u16 {
    let port = free_port();
    let addr: SocketAddr = format!("127.0.0.1:{port}").parse().unwrap();
    std::thread::spawn(move || {
        let cfg = Config {
            listener_pool:     2,
            scheduler_threads: Some(2),
            ..Config::new(addr)
        };
        serve_with(cfg, pipeline).unwrap();
    });
    // Wait for the server to actually be listening.
    for _ in 0..50 {
        if TcpStream::connect(addr).is_ok() {
            return port;
        }
        std::thread::sleep(Duration::from_millis(50));
    }
    panic!("server didn't come up on {addr}");
}

fn send_request(port: u16, req: &[u8]) -> Vec<u8> {
    let mut s = TcpStream::connect(("127.0.0.1", port)).unwrap();
    s.set_read_timeout(Some(Duration::from_secs(5))).unwrap();
    s.write_all(req).unwrap();
    s.shutdown(std::net::Shutdown::Write).ok();
    let mut buf = Vec::new();
    s.read_to_end(&mut buf).unwrap();
    buf
}

fn http_status(resp: &[u8]) -> u16 {
    let s = std::str::from_utf8(&resp[..resp.len().min(64)]).unwrap();
    let parts: Vec<&str> = s.splitn(3, ' ').collect();
    parts[1].parse().unwrap()
}

fn http_body(resp: &[u8]) -> &[u8] {
    // Split on the first \r\n\r\n.
    for i in 0..resp.len().saturating_sub(3) {
        if &resp[i..i + 4] == b"\r\n\r\n" {
            return &resp[i + 4..];
        }
    }
    &[]
}

// ---------------------------------------------------------------------------
// Tests
// ---------------------------------------------------------------------------

#[test]
fn hello_world() {
    let pipe = Pipeline::new().plug(
        Router::new().get("/", |c: Conn, _n: Next| {
            c.put_status(200).put_body("hello urus")
        })
    );
    let port = spawn_server(pipe);
    let resp = send_request(port, b"GET / HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n");
    assert_eq!(http_status(&resp), 200);
    assert_eq!(http_body(&resp), b"hello urus");
}

#[test]
fn echo_body() {
    let pipe = Pipeline::new().plug(
        Router::new().post("/echo", |c: Conn, _n: Next| {
            let body = c.body.as_bytes().to_vec();
            c.put_status(200).put_body(body)
        })
    );
    let port = spawn_server(pipe);
    let resp = send_request(
        port,
        b"POST /echo HTTP/1.1\r\nHost: x\r\nContent-Length: 5\r\nConnection: close\r\n\r\nhello",
    );
    assert_eq!(http_status(&resp), 200);
    assert_eq!(http_body(&resp), b"hello");
}

#[test]
fn path_params() {
    let pipe = Pipeline::new().plug(
        Router::new().get("/users/:id", |c: Conn, _n: Next| {
            let id = c.params.get("id").unwrap_or("?").to_string();
            c.put_status(200).put_body(format!("user={id}"))
        })
    );
    let port = spawn_server(pipe);
    let resp = send_request(port, b"GET /users/42 HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n");
    assert_eq!(http_status(&resp), 200);
    assert_eq!(http_body(&resp), b"user=42");
}

#[test]
fn method_not_allowed() {
    let pipe = Pipeline::new().plug(
        Router::new().get("/only-get", |c: Conn, _n: Next| c.put_status(200))
    );
    let port = spawn_server(pipe);
    let resp = send_request(port, b"POST /only-get HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n");
    assert_eq!(http_status(&resp), 405);
}

#[test]
fn unknown_route_falls_to_404() {
    // Router falls through; connection actor's default emits 404.
    let pipe = Pipeline::new().plug(
        Router::new().get("/known", |c: Conn, _n: Next| c.put_status(200))
    );
    let port = spawn_server(pipe);
    let resp = send_request(port, b"GET /missing HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n");
    assert_eq!(http_status(&resp), 404);
}

#[test]
fn keep_alive_two_requests_on_one_connection() {
    let pipe = Pipeline::new().plug(
        Router::new().get("/", |c: Conn, _n: Next| c.put_status(200).put_body("ok"))
    );
    let port = spawn_server(pipe);
    let mut s = TcpStream::connect(("127.0.0.1", port)).unwrap();
    s.set_read_timeout(Some(Duration::from_secs(5))).unwrap();

    // First request, no Connection header (HTTP/1.1 default = keep-alive).
    s.write_all(b"GET / HTTP/1.1\r\nHost: x\r\n\r\n").unwrap();

    // Read the first response (Content-Length: 2 -> body "ok").
    let mut buf = vec![0u8; 1024];
    let mut total = 0;
    let mut first_end = None;
    while first_end.is_none() {
        let n = s.read(&mut buf[total..]).unwrap();
        assert!(n > 0, "server hung up early");
        total += n;
        // First response ends at header-terminator + 2 bytes of body.
        for i in 0..total.saturating_sub(3) {
            if &buf[i..i + 4] == b"\r\n\r\n" {
                let body_start = i + 4;
                if total >= body_start + 2 {
                    first_end = Some(body_start + 2);
                }
                break;
            }
        }
    }
    let first = &buf[..first_end.unwrap()];
    assert_eq!(http_status(first), 200);
    assert_eq!(http_body(first), b"ok");

    // Second request on the same socket — proves keep-alive works.
    s.write_all(b"GET / HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n").unwrap();
    let mut rest = Vec::new();
    s.read_to_end(&mut rest).unwrap();
    assert_eq!(http_status(&rest), 200);
    assert_eq!(http_body(&rest), b"ok");
}

#[test]
fn panicking_handler_yields_500() {
    let pipe = Pipeline::new().plug(
        Router::new().get("/boom", |_c: Conn, _n: Next| -> Conn {
            panic!("handler explosion")
        })
    );
    let port = spawn_server(pipe);
    let resp = send_request(port, b"GET /boom HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n");
    assert_eq!(http_status(&resp), 500);
}

#[test]
fn middleware_can_short_circuit() {
    // Middleware that requires `X-Auth: secret`; otherwise returns 401
    // without calling `next.run(conn)`.
    let auth = |c: Conn, n: Next| {
        if c.headers.get("x-auth").map(|s| s == "secret").unwrap_or(false) {
            n.run(c)
        } else {
            c.put_status(401).halt()
        }
    };
    let pipe = Pipeline::new()
        .plug(auth)
        .plug(Router::new().get("/secret", |c: Conn, _n: Next| c.put_status(200).put_body("ok")));

    let port = spawn_server(pipe);

    // Without auth → 401.
    let resp = send_request(port, b"GET /secret HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n");
    assert_eq!(http_status(&resp), 401);

    // With auth → 200 + body.
    let resp = send_request(
        port,
        b"GET /secret HTTP/1.1\r\nHost: x\r\nX-Auth: secret\r\nConnection: close\r\n\r\n",
    );
    assert_eq!(http_status(&resp), 200);
    assert_eq!(http_body(&resp), b"ok");
}

// ---------------------------------------------------------------------------
// Supervision (v0.2 chunk 1)
// ---------------------------------------------------------------------------

/// A panicking listener must be restarted by the pool supervisor, and the
/// connection that was pending when it died must still be served.
///
/// Pool size is 1 on purpose: with a sibling listener the test would pass
/// even if restarts were broken (the sibling would pick up the accept).
/// With one listener, the request after the injected panic can only
/// succeed if a fresh listener came up on the same fd.
#[test]
fn panicking_listener_restarts() {
    let pipe = Pipeline::new().plug(
        Router::new().get("/ping", |c: Conn, _n: Next| c.put_status(200).put_body("pong"))
    );

    let port = free_port();
    let addr: SocketAddr = format!("127.0.0.1:{port}").parse().unwrap();
    std::thread::spawn(move || {
        let cfg = Config {
            listener_pool:     1,
            scheduler_threads: Some(2),
            ..Config::new(addr)
        };
        serve_with(cfg, pipe).unwrap();
    });
    for _ in 0..50 {
        if TcpStream::connect(addr).is_ok() {
            break;
        }
        std::thread::sleep(Duration::from_millis(50));
    }

    // Sanity: server answers before the fault.
    let resp = send_request(port, b"GET /ping HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n");
    assert_eq!(http_status(&resp), 200);

    // Arm the fault: the listener's next accept-loop iteration panics
    // *before* accepting, so our connection waits in the kernel backlog
    // until the restarted listener picks it up.
    urus::serve::INJECT_LISTENER_PANICS.store(1, std::sync::atomic::Ordering::Relaxed);

    let resp = send_request(port, b"GET /ping HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n");
    assert_eq!(http_status(&resp), 200, "request pending across the panic was not served");
    assert_eq!(http_body(&resp), b"pong");
    assert_eq!(
        urus::serve::INJECT_LISTENER_PANICS.load(std::sync::atomic::Ordering::Relaxed),
        0,
        "fault was never consumed — listener didn't wake for the connection"
    );

    // The restarted listener keeps serving.
    for _ in 0..5 {
        let resp = send_request(port, b"GET /ping HTTP/1.1\r\nHost: x\r\nConnection: close\r\n\r\n");
        assert_eq!(http_status(&resp), 200);
    }
}