//! One `gatewayd` per home (M5b spec, section 9a): a second `gatewayd serve` against the same home
//! is refused with the lock's line, and the first keeps serving `gateway.sock`; once the first is
//! killed, a new one removes the stale socket and serves. Each runs against the fake Mattermost.
//! Every wait has a deadline, and every process is killed and every path removed by a guard (tip
//! T44). Do not edit.

#[path = "support/brokerd_client.rs"]
mod brokerd_client;
#[path = "support/fake_mm.rs"]
mod fake_mm;
#[path = "support/tmp.rs"]
mod tmp;

use std::os::unix::fs::PermissionsExt;
use std::path::{Path, PathBuf};
use std::process::{Child, Command, Stdio};
use std::time::{Duration, Instant};

use brokerd_client::{ask, pending};
use fake_mm::{FakeMm, KYLE};
use tmp::TempDir;

const POINTER: &str = "see docs/runbook.md#already-running";
const TOKEN: &str = "tok-instance-test";
const WAIT: Duration = Duration::from_secs(10);

struct Home {
    dir: TempDir,
    config: PathBuf,
}

impl Home {
    fn new(tag: &str, mm: &FakeMm) -> Home {
        let dir = TempDir::new(tag);
        let text = format!(
            "[mattermost]\nurl = \"{}\"\n[secrets.mattermost_token]\nenv = \"GW_TEST_TOKEN\"\n\
             [allow]\nusers = [\"{KYLE}\"]\n[paths]\nhome = \"{}\"\n",
            mm.url(),
            dir.path().display()
        );
        let config = dir.write("gatewayd.toml", &text);
        Home { dir, config }
    }

    fn path(&self, relative: &str) -> PathBuf {
        self.dir.path().join(relative)
    }

    fn socket(&self) -> PathBuf {
        self.path("run/gateway/gateway.sock")
    }

    fn command(&self) -> Command {
        let mut command = Command::new(env!("CARGO_BIN_EXE_gatewayd"));
        command
            .args(["serve", "--config"])
            .arg(&self.config)
            .env_remove("CREDENTIALS_DIRECTORY")
            .env("GW_TEST_TOKEN", TOKEN)
            .stdin(Stdio::null())
            .stdout(Stdio::null());
        command
    }

    /// `gatewayd serve` with its stderr in `<home>/<name>.err`, for the messages of a failing test.
    fn start(&self, name: &str) -> Daemon {
        let err = std::fs::File::create(self.path(&format!("{name}.err"))).unwrap();
        Daemon(self.command().stderr(Stdio::from(err)).spawn().unwrap())
    }

    fn stderr_of(&self, name: &str) -> String {
        std::fs::read_to_string(self.path(&format!("{name}.err"))).unwrap_or_default()
    }

    /// Runs `gatewayd serve` to its end, at most 10 s (then it is killed), and gives its exit code
    /// (`None` if it had to be killed) and its stderr.
    fn run_to_end(&self) -> (Option<i32>, String) {
        let mut child = Daemon(self.command().stderr(Stdio::piped()).spawn().unwrap());
        let deadline = Instant::now() + WAIT;
        let mut code = None;
        while Instant::now() < deadline {
            if let Ok(Some(status)) = child.0.try_wait() {
                code = status.code();
                break;
            }
            std::thread::sleep(Duration::from_millis(20));
        }
        let _ = child.0.kill();
        let _ = child.0.wait();
        let mut stderr = String::new();
        if let Some(mut pipe) = child.0.stderr.take() {
            let _ = std::io::Read::read_to_string(&mut pipe, &mut stderr);
        }
        (code, stderr)
    }
}

/// A running `gatewayd serve`, killed and waited for when dropped. Declared after the `Home` and
/// the `FakeMm`, so it drops first.
struct Daemon(Child);

impl Drop for Daemon {
    fn drop(&mut self) {
        let _ = self.0.kill();
        let _ = self.0.wait();
    }
}

impl Daemon {
    fn running(&mut self) -> bool {
        matches!(self.0.try_wait(), Ok(None))
    }
}

/// True when `gatewayd` answers on `gateway.sock` as it does for `brokerd`: approval `approval`,
/// of a `bxctl chat` session, is posted to the first approver and the posts come back. The
/// connection is then closed, which ends the approval.
fn answers(socket: &Path, approval: u64) -> bool {
    match ask(socket, pending(approval, "chat-1789700000-1", "{}")) {
        Ok(asking) => {
            let answered = !asking.posts.is_empty();
            asking.close();
            answered
        }
        Err(_) => false,
    }
}

/// Waits up to 10 s for `gatewayd` to answer on `socket`.
fn wait_until_it_answers(socket: &Path, approval: u64) -> bool {
    let deadline = Instant::now() + WAIT;
    while Instant::now() < deadline {
        if answers(socket, approval) {
            return true;
        }
        std::thread::sleep(Duration::from_millis(50));
    }
    false
}

fn inode(path: &Path) -> u64 {
    use std::os::unix::fs::MetadataExt;
    std::fs::symlink_metadata(path)
        .map(|m| m.ino())
        .unwrap_or(0)
}

#[test]
fn a_second_gatewayd_on_the_same_home_is_refused_and_the_first_keeps_serving() {
    let mm = FakeMm::start();
    let home = Home::new("inst-twice", &mm);
    let mut first = home.start("first");
    let _ws = mm.next_ws(WAIT);
    assert!(
        wait_until_it_answers(&home.socket(), 1),
        "the first gatewayd never answered; stderr: {}",
        home.stderr_of("first")
    );
    let before = inode(&home.socket());

    let (code, stderr) = home.run_to_end();
    let line = format!(
        "gatewayd: another gatewayd is running (it holds {}); {POINTER}",
        home.path("run/gatewayd.lock").display()
    );
    assert_eq!(code, Some(1), "the second gatewayd: {stderr}");
    assert_eq!(
        stderr,
        format!("{line}\n"),
        "the lock's line, and nothing else"
    );

    assert!(first.running(), "the first gatewayd is still running");
    assert_eq!(
        inode(&home.socket()),
        before,
        "the first's socket is still there"
    );
    assert!(
        answers(&home.socket(), 2),
        "the first gatewayd still answers; its stderr: {}",
        home.stderr_of("first")
    );
}

#[test]
fn after_the_first_is_killed_a_new_gatewayd_removes_the_stale_socket_and_serves() {
    let mm = FakeMm::start();
    let home = Home::new("inst-restart", &mm);
    let mut first = home.start("first");
    let _ws = mm.next_ws(WAIT);
    assert!(
        wait_until_it_answers(&home.socket(), 1),
        "the first gatewayd never answered; stderr: {}",
        home.stderr_of("first")
    );
    let _ = first.0.kill();
    let _ = first.0.wait();
    assert!(
        home.socket().exists(),
        "a killed gatewayd leaves its socket"
    );
    assert!(
        !answers(&home.socket(), 2),
        "nobody serves the stale socket"
    );

    let _next = home.start("next");
    let _ws = mm.next_ws(WAIT);
    assert!(
        wait_until_it_answers(&home.socket(), 3),
        "the new gatewayd never answered; stderr: {}",
        home.stderr_of("next")
    );
    let lock = home.path("run/gatewayd.lock");
    let mode = std::fs::metadata(&lock).map(|m| m.permissions().mode() & 0o777);
    assert_eq!(mode.ok(), Some(0o600), "the lock file, mode 0600");
}