//! Per-container HTTP UI. SPA shape: `GET /` returns a static shell;
//! `GET /static/*` serves CSS + JS; `GET /api/state` returns the page
//! state as JSON; the JS app renders. Live events stream on
//! `/events/stream`. Action POSTs (`/send`, `/login/*`) return either a
//! 303 Redirect (for browsers that submit the form normally) or just
//! 200 OK — the JS app re-fetches `/api/state` afterwards.
//!
//! Handlers are split by concern into the submodules below; this file owns the
//! shared [`AppState`], the listener + router wiring in [`serve`], and a couple
//! of small shared helpers ([`error_response`], [`SOCKET_FETCH_TIMEOUT`]).

mod actions;
mod auth;
mod proxy;
mod screen;
mod state;
mod stats;
mod stream;

use std::net::SocketAddr;
use std::path::{Path, PathBuf};
use std::sync::atomic::AtomicBool;
use std::sync::{Arc, Mutex};

use anyhow::{Context, Result};
use axum::{
    Router,
    http::StatusCode,
    response::{IntoResponse, Response},
    routing::{get, post},
};
use tower_http::services::ServeDir;

use crate::events::Bus;
use crate::login::LoginState;
use crate::login_session::LoginSession;

/// Deadline for broker-backed fetches on web-UI request paths. The
/// page's critical fields (status, turn state, usage) are all
/// in-memory; a busy or stalled hive-c0re must degrade the
/// socket-backed extras (inbox rows, loose ends, reminder stats)
/// instead of hanging the whole response — an unbounded await here is
/// what let `/api/state` stall long enough to bork the terminal.
const SOCKET_FETCH_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(3);

/// Live login state for the web UI. The harness updates this in place as it
/// transitions between `NeedsLogin` and `Online`; the UI reads on each
/// render.
pub type LoginStateCell = Arc<Mutex<LoginState>>;

#[derive(Clone)]
struct AppState {
    label: String,
    login: LoginStateCell,
    session: Arc<Mutex<Option<Arc<LoginSession>>>>,
    bus: Bus,
    socket: PathBuf,
    /// VNC port from the `HIVE_GUI_VNC_PORT` env var at startup.
    /// `None` when unset (gui not enabled for this agent).
    gui_vnc_port: Option<u16>,
    /// Set by `post_cancel_turn` on a successful SIGINT; read-and-cleared
    /// by the serve loop's next `handle_turn` to prepend
    /// `hive_sh4re::INTERRUPTED_HINT` to that turn's wake prompt. Shared
    /// with the serve loop via the same `Arc` (see `serve_main`) — an
    /// in-memory flag, not a marker file, since a `/cancel` from a prior
    /// process lifetime isn't meaningful once the harness restarts.
    interrupted: Arc<AtomicBool>,
}

/// Bind the per-container web listener and serve the SPA.
///
/// `HIVE_WEB_SOCKET` opt-in selects unix-socket vs TCP binding; the
/// dual-mode transition + gateway-side consumer live in
/// [`docs/web-ui/shape.md::Listener bind`](../../../docs/web-ui/shape.md) and
/// [`docs/gateway.md::Per-agent unix-socket upstream`](../../../docs/gateway.md).
///
/// # Errors
///
/// Returns an error if neither the TCP listener (default) nor the
/// unix-socket bind (`HIVE_WEB_SOCKET`, if set) can be acquired, or
/// if `HIVE_STATIC_DIR` is missing.
pub async fn serve(
    label: String,
    port: u16,
    login: LoginStateCell,
    bus: Bus,
    socket: PathBuf,
    interrupted: Arc<AtomicBool>,
) -> Result<()> {
    let gui_vnc_port = read_gui_vnc_port();
    let static_dir: PathBuf = std::env::var_os("HIVE_STATIC_DIR")
        .map(PathBuf::from)
        .context(
            "HIVE_STATIC_DIR env var not set — point it at the merged \
             per-agent dist (see hyperhive.frontend.mergedDist in nix)",
        )?;
    if !static_dir.is_dir() {
        anyhow::bail!(
            "HIVE_STATIC_DIR ({}) is not a directory",
            static_dir.display()
        );
    }
    tracing::info!(static_dir = %static_dir.display(), "web UI static dir resolved");
    let state = AppState {
        label,
        login,
        session: Arc::new(Mutex::new(None)),
        bus,
        socket,
        gui_vnc_port,
        interrupted,
    };
    let app: Router<AppState> = Router::new()
        .route("/api/state", get(state::api_state))
        .route("/api/dashboard-state", get(state::api_dashboard_state))
        .route("/events/stream", get(stream::events_stream))
        .route("/events/history", get(stream::events_history))
        .route("/send", post(actions::post_send))
        .route("/login/start", post(auth::post_login_start))
        .route("/login/code", post(auth::post_login_code))
        .route("/login/cancel", post(auth::post_login_cancel))
        .route("/api/cancel", post(actions::post_cancel_turn))
        .route("/api/compact", post(actions::post_compact))
        .route("/api/model", post(actions::post_set_model))
        .route("/api/effort", post(actions::post_set_effort))
        .route("/api/new-session", post(actions::post_new_session))
        .route("/api/logout", post(auth::post_logout))
        .route("/api/todos", get(stats::api_todos))
        .route("/api/todos/mark-done", post(actions::post_mark_todos_done))
        .route("/api/stats", get(stats::api_stats))
        .route("/screen/ws", get(screen::screen_ws))
        .route("/icon", get(screen::serve_icon));
    // Mount any `hyperhive.extraWebProxies` under `/extra/<name>/` before the
    // static fallback so declared proxies win over `ServeDir`.
    let app = proxy::mount_extra_proxies(app)
        // Anything else (`/`, `/stats`, `/screen`, `/static/*`)
        // falls through to the merged dist. ServeDir auto-appends
        // `.html` when the URL is a bare path that matches a file
        // (so `/stats` → `dist/stats.html`, `/screen` → `dist/
        // screen.html`). Per-agent `extraFiles` additions are
        // already layered into this same directory (see
        // hyperhive.frontend.mergedDist in nix).
        .fallback_service(ServeDir::new(&static_dir))
        .with_state(state);
    // `HIVE_WEB_SOCKET` opt-in: when set + non-empty, bind a
    // `UnixListener` at the given path. Empty string treated as
    // unset so a stray `HIVE_WEB_SOCKET=` doesn't trap us into an
    // un-bindable empty path. Falls through to the TCP path below
    // otherwise. See docs/gateway.md::Per-agent unix-socket upstream
    // for the gateway-side consumer.
    if let Some(socket_path) = std::env::var_os("HIVE_WEB_SOCKET")
        && !socket_path.is_empty()
    {
        let path = PathBuf::from(socket_path);
        let listener = bind_unix(&path)?;
        tracing::info!(socket = %path.display(), "web UI listening on unix socket");
        axum::serve(listener, app).await?;
        return Ok(());
    }
    let addr = SocketAddr::from(([0, 0, 0, 0], port));
    let listener = bind_with_retry(addr, "web UI").await?;
    tracing::info!(%port, "web UI listening on tcp");
    axum::serve(listener, app).await?;
    Ok(())
}

/// Bind a `UnixListener` at `path` and drop a `.bound` marker next
/// to it so c0re's gateway-map writer knows the socket is live.
/// Best-effort unlinks any stale socket left from a crashed previous
/// harness (clean exit removes it, but `bind(2)` refuses to overwrite
/// an existing file) and `mkdir -p`s the parent for first-boot. Mode
/// `0o666` — world-accessible so the gateway container's nginx process
/// can `connect(2)` without sharing a group with the agent user.
/// The per-agent subdir (`/run/hive-agent/<name>/`) is only accessible
/// to containers that have it bind-mounted, so world-accessible sockets
/// are not a material risk.
///
/// Marker-gating + the gateway-side consumer: see
/// [`docs/gateway.md::Per-agent unix-socket upstream`](../../../docs/gateway.md).
fn bind_unix(path: &Path) -> Result<tokio::net::UnixListener> {
    use std::os::unix::fs::PermissionsExt;
    if let Some(parent) = path.parent() {
        std::fs::create_dir_all(parent)
            .with_context(|| format!("create socket parent dir {}", parent.display()))?;
    }
    // Best-effort: ENOENT is fine (no stale file); any other error
    // surfaces via the bind below with a clearer "AddrInUse" / perms
    // message than a partial cleanup would.
    let _ = std::fs::remove_file(path);
    let listener = tokio::net::UnixListener::bind(path)
        .with_context(|| format!("bind unix socket at {}", path.display()))?;
    std::fs::set_permissions(path, std::fs::Permissions::from_mode(0o666))
        .with_context(|| format!("set perms on {}", path.display()))?;
    // Best-effort ready marker: failed write isn't fatal (the harness
    // still binds + serves), it just means the gateway side keeps the
    // TCP upstream for one more sync tick.
    if let Some(parent) = path.parent() {
        let marker = parent.join("hyperhive-socket-bound");
        if let Err(e) = std::fs::write(&marker, b"") {
            tracing::warn!(
                marker = %marker.display(), error = %e,
                "failed to write hyperhive-socket-bound marker — gateway may keep TCP upstream"
            );
        }
    }
    Ok(listener)
}

/// Maximum bind attempts before `bind_with_retry` gives up on `AddrInUse`.
const MAX_BIND_ATTEMPTS: u32 = 12;

/// Bind a TCP listener with `SO_REUSEADDR` set, retrying on `AddrInUse` with
/// exponential backoff capped at 2s, up to [`MAX_BIND_ATTEMPTS`] attempts. If
/// the port is still held after the final attempt, returns the `AddrInUse`
/// error rather than looping forever (a genuine collision needs the operator,
/// not an unbounded wait).
///
/// Retry rationale + dashboard-banner-on-real-collision:
/// see [`docs/web-ui/shape.md::Listener bind`](../../../docs/web-ui/shape.md).
async fn bind_with_retry(addr: SocketAddr, label: &str) -> Result<tokio::net::TcpListener> {
    let mut delay_ms = 250u64;
    let mut attempts = 0u32;
    loop {
        match try_bind(addr) {
            Ok(l) => {
                if attempts > 0 {
                    tracing::info!(
                        %addr, attempts,
                        "{label}: bind succeeded after retry"
                    );
                }
                return Ok(l);
            }
            Err(e) if e.kind() == std::io::ErrorKind::AddrInUse => {
                let attempt = attempts + 1;
                if attempt >= MAX_BIND_ATTEMPTS {
                    return Err(e).with_context(|| {
                        format!("bind {label} on {addr}: still AddrInUse after {attempt} attempts")
                    });
                }
                tracing::warn!(
                    %addr, attempt,
                    "{label}: AddrInUse, retrying in {delay_ms}ms"
                );
                tokio::time::sleep(std::time::Duration::from_millis(delay_ms)).await;
                attempts += 1;
                delay_ms = (delay_ms * 2).min(2000);
            }
            Err(e) => {
                return Err(e).with_context(|| format!("bind {label} on {addr}"));
            }
        }
    }
}

fn try_bind(addr: SocketAddr) -> std::io::Result<tokio::net::TcpListener> {
    let sock = match addr {
        SocketAddr::V4(_) => tokio::net::TcpSocket::new_v4()?,
        SocketAddr::V6(_) => tokio::net::TcpSocket::new_v6()?,
    };
    sock.set_reuseaddr(true)?;
    sock.bind(addr)?;
    sock.listen(1024)
}

/// The fixed VNC port weston bound, from the `HIVE_GUI_VNC_PORT` env var
/// the harness service sets when gui is enabled (see weston-vnc.nix).
/// `None` when unset (gui not enabled for this agent) or unparseable.
/// The port is a fixed, container-local value — no per-agent hashing, no
/// marker file — because network isolation is unconditional (each agent
/// has its own netns, so the port can't collide across containers).
fn read_gui_vnc_port() -> Option<u16> {
    std::env::var("HIVE_GUI_VNC_PORT").ok()?.parse().ok()
}

/// Outcome of [`sigint_claude`] — shared by `/api/cancel` and `/api/logout`
/// so both can render the same three cases.
enum SigintOutcome {
    /// The tracked pid was signalled.
    Signalled,
    /// No claude child is currently tracked (turn not in flight, or it
    /// finished/exited between the check and the signal — same "nothing to
    /// interrupt" outcome either way).
    NoProcess,
    /// The `kill` syscall itself failed for a reason other than "no such
    /// process" (permission issue, etc).
    Failed(std::io::Error),
}

/// Find a `claude` process that is a direct OS child of this harness
/// process, if any. `hive-claude`'s driver spawns the turn's claude
/// directly (`Command::new(program).spawn()`, no shell in between), so the
/// harness is always the immediate parent of any claude turn it started —
/// scanning `/proc/*/status` for `PPid: <our own pid>` plus `/proc/*/cmdline`
/// for an argv[0] of `claude` finds *that* specific process without needing
/// the driver to surface its pid through any extra plumbing. Distinguishes
/// the harness's own tracked turn from an unrelated `claude` someone is
/// running interactively in the same container (a manually shelled-in
/// "choom" session) — that one's parent is a login shell, not us.
///
/// **Matches on `cmdline`, not `status`'s `Name:` field.** The nixpkgs
/// `claude-code` package wraps its real binary (`wrapProgram`-style: the
/// executable on `PATH` is a thin `exec -a claude .../.claude-wrapped ...`
/// shim) — `exec -a` only overrides argv[0] as the process itself/`cmdline`
/// see it, not the kernel's own `comm` (what `status`'s `Name:` line
/// reports, set from the executed binary's own basename at `execve` time).
/// So `Name:` shows `.claude-wrapped`, not `claude`, on a wrapped package —
/// `cmdline`'s first argument still carries the bare name
/// `Command::new("claude")` resolved on `PATH`, which is what actually
/// matters here. Best-effort: a process that exits mid-scan (its
/// `/proc/<pid>/{status,cmdline}` read fails, ESRCH) is just skipped.
fn find_claude_child() -> Option<u32> {
    let own_pid = std::process::id();
    for entry in std::fs::read_dir("/proc").ok()?.flatten() {
        let Ok(pid) = entry.file_name().to_string_lossy().parse::<u32>() else {
            continue; // not a pid dir (self, cwd, net, ...)
        };
        let Ok(status) = std::fs::read_to_string(entry.path().join("status")) else {
            continue;
        };
        let parent_pid = status
            .lines()
            .find_map(|line| line.strip_prefix("PPid:"))
            .and_then(|v| v.trim().parse::<u32>().ok());
        if parent_pid != Some(own_pid) {
            continue;
        }
        let Ok(cmdline) = std::fs::read(entry.path().join("cmdline")) else {
            continue;
        };
        let argv0 = cmdline.split(|&b| b == 0).next().unwrap_or_default();
        if argv0 == b"claude" {
            return Some(pid);
        }
    }
    None
}

/// SIGINT this container's harness-spawned claude child, if any
/// (best-effort). See [`find_claude_child`] for how it's identified —
/// **not** a name-based `pkill claude`, which would also hit an unrelated
/// `claude` process someone is running interactively in the container.
async fn sigint_claude() -> SigintOutcome {
    let Some(pid) = find_claude_child() else {
        return SigintOutcome::NoProcess;
    };
    match tokio::process::Command::new("kill")
        .args(["-INT", &pid.to_string()])
        .status()
        .await
    {
        Ok(status) if status.success() => SigintOutcome::Signalled,
        // Non-zero from `kill` means "no such process" (ESRCH) — it already
        // exited between the check above and the signal. Same as never
        // having found it.
        Ok(_) => SigintOutcome::NoProcess,
        Err(e) => SigintOutcome::Failed(e),
    }
}

fn error_response(status: StatusCode, message: &str) -> Response {
    // Plain text — JS app surfaces in `alert()`, HTML wrapping would just
    // be noise. Status is per-caller: 400 for bad input, 409 for a
    // retryable state conflict (turn in flight / hive-c0re busy), 500 only
    // for a genuine server/transport failure — the frontend shows the code
    // in its alert, so a benign "busy, retry" must not read as a 500.
    (status, message.to_owned()).into_response()
}

/// Why a deadline-bounded broker request via the per-agent socket didn't
/// yield a response. Kept distinct so action handlers pick the right status
/// code (see [`broker_error_response`]) while decorative fetches `.ok()` both.
enum BrokerError {
    /// Outran [`SOCKET_FETCH_TIMEOUT`] — hive-c0re is busy or stalled. A
    /// retryable state conflict (→ 409), not a server fault.
    Timeout,
    /// The socket transport itself failed (connect / encode / decode).
    Transport(anyhow::Error),
}

/// Issue a broker request over the per-agent socket, bounded by
/// [`SOCKET_FETCH_TIMEOUT`] so a busy or stalled hive-c0re degrades the
/// response instead of hanging it. Callers match the returned [`Response`]
/// variant themselves; the error side distinguishes a retryable timeout from
/// a transport failure. This is the one shared broker-call scaffold — every
/// web-UI handler that talks to the broker goes through it.
async fn broker_request(
    socket: &Path,
    req: &hive_core_agent_sock::Request,
) -> std::result::Result<hive_core_agent_sock::Response, BrokerError> {
    match tokio::time::timeout(
        SOCKET_FETCH_TIMEOUT,
        hive_sock_client::request::<_, hive_core_agent_sock::Response>(
            socket,
            req,
            crate::CONTROL_SOCKET_RETRY,
        ),
    )
    .await
    {
        Ok(Ok(resp)) => Ok(resp),
        Ok(Err(e)) => Err(BrokerError::Transport(e)),
        Err(_) => Err(BrokerError::Timeout),
    }
}

/// Map a [`BrokerError`] to an operator-facing error response: a timeout is a
/// retryable "busy" conflict (409), a transport failure is a 500. `action`
/// prefixes the message (e.g. `"send"`, `"get_loose_ends"`).
fn broker_error_response(err: &BrokerError, action: &str) -> Response {
    match err {
        BrokerError::Timeout => error_response(
            StatusCode::CONFLICT,
            &format!("{action}: timed out — hive-c0re busy, retry"),
        ),
        BrokerError::Transport(e) => error_response(
            StatusCode::INTERNAL_SERVER_ERROR,
            &format!("{action}: transport: {e:#}"),
        ),
    }
}