//! Plugin registry (plugin-ui-surface design): an in-memory, lease-based directory of running
//! `punktfunk-plugin-*` processes and the loopback UI each one serves.
//!
//! A plugin (an out-of-process script under the scripting runner, RFC §8) that wants a UI serves
//! it on a **loopback** port behind a per-boot secret, then **registers** here — `{title, ui:{port,
//! secret, icon}}` — over the admin/loopback lane it already holds via the SDK. The web console
//! reads [`list_plugins`] to grow a nav entry and reverse-proxies to the port (fetching the secret
//! from [`get_ui_credential`] server-side, never exposing it to the browser). The host itself never
//! dials the plugin, never health-checks it, and never persists any of this: it is a phone book with
//! expiry.
//!
//! Lease model (design §3, D8): a registration lives for [`LEASE_TTL`]; the plugin renews with the
//! same idempotent `PUT` every 30 s. Expiry is **lazy** — a crashed plugin's entry simply stops
//! listing once stale; there is no reaper task and nothing to persist across a host restart (the
//! supervised plugin re-registers on its next tick). Every consumer dials `127.0.0.1:<port>` only —
//! a registration stores a *port*, never an address, so it can never point the proxy elsewhere (D5).
//!
//! Auth: these routes carry no special handling — they are outside the [`super::auth::cert_may_access`]
//! read-only allowlist, so the middleware confines them to a **bearer + loopback** peer like every
//! other mutation. LAN clients have no business here.

use super::shared::*;
use crate::events::{emit, EventKind};
use std::collections::HashMap;
use std::sync::{OnceLock, RwLock};
use std::time::{Duration, Instant};

/// How long a registration stays live after its last renewal. The SDK helper renews every 30 s, so
/// this tolerates two missed ticks before a plugin drops out of the listing.
const LEASE_TTL: Duration = Duration::from_secs(90);

// ---------------------------------------------------------------- wire shapes

/// A plugin's UI surface as it registers it. Carries the secret — this shape is only ever a request
/// body, never a response ([`PluginUiPublic`] is the secret-free view).
#[derive(Deserialize, ToSchema)]
pub(crate) struct PluginUi {
    /// The **loopback** port the plugin serves its UI on. The host and console only ever dial
    /// `127.0.0.1:<port>`; a registration can never carry a hostname.
    pub port: u16,
    /// Per-boot shared secret the console proxy must present (as `Authorization: Bearer`) on every
    /// request to the plugin's UI server. Rotated whenever the plugin restarts.
    pub secret: String,
    /// Optional lucide icon name for the console nav entry (`^[a-z0-9-]{1,48}$`).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub icon: Option<String>,
}

/// Register/renew body for `PUT /plugins/{id}`.
#[derive(Deserialize, ToSchema)]
pub(crate) struct PluginRegistration {
    /// Human-readable title for the console nav entry (1–64 chars; control chars stripped).
    pub title: String,
    /// Optional plugin version, purely informational (≤32 chars).
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub version: Option<String>,
    /// Present iff the plugin serves a UI surface. A registration with no `ui` is a liveness/phone-book
    /// entry only (e.g. a future runner-management listing) and grows no nav entry.
    #[serde(default, skip_serializing_if = "Option::is_none")]
    pub ui: Option<PluginUi>,
}

/// The secret-free view of a plugin's UI surface — what [`list_plugins`] returns to the browser.
#[derive(Serialize, ToSchema)]
pub(crate) struct PluginUiPublic {
    pub port: u16,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub icon: Option<String>,
}

/// One entry in `GET /plugins`. **Never carries the secret** — the browser learns a plugin exists
/// and has a UI, nothing that lets it reach the plugin directly (it goes through the console proxy).
#[derive(Serialize, ToSchema)]
pub(crate) struct PluginSummary {
    pub id: String,
    pub title: String,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub version: Option<String>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub ui: Option<PluginUiPublic>,
}

/// `GET /plugins/{id}/ui-credential` — the console proxy's server-side lookup (bearer + loopback).
/// This is the only endpoint that returns a secret; the console BFF denylists it from the browser.
#[derive(Serialize, ToSchema)]
pub(crate) struct UiCredential {
    pub port: u16,
    pub secret: String,
}

// ---------------------------------------------------------------- registry core

/// The stored UI surface (internal — parsed + validated, no wire derives).
#[derive(Clone, PartialEq)]
struct StoredUi {
    port: u16,
    secret: String,
    icon: Option<String>,
}

/// One live registration. `expires_at` is a **monotonic** [`Instant`] (immune to wall-clock jumps).
struct Stored {
    title: String,
    version: Option<String>,
    ui: Option<StoredUi>,
    expires_at: Instant,
}

impl Stored {
    /// Do the operator-visible fields match (ignoring the lease clock)? A pure lease renewal leaves
    /// these unchanged and emits no event; a restart (new secret) or a re-scan (new title/icon) does.
    fn public_eq(&self, title: &str, version: &Option<String>, ui: &Option<StoredUi>) -> bool {
        self.title == title && self.version == *version && self.ui == *ui
    }
}

/// The process-wide plugin registry.
pub(crate) struct PluginRegistry {
    inner: RwLock<HashMap<String, Stored>>,
}

/// A validated registration ready to store (title trimmed, ui fields checked).
struct Valid {
    title: String,
    version: Option<String>,
    ui: Option<StoredUi>,
}

impl PluginRegistry {
    fn new() -> Self {
        Self {
            inner: RwLock::new(HashMap::new()),
        }
    }

    /// Insert or renew `id`. Returns `true` when an operator-visible field changed (new plugin,
    /// restart, or re-scan) — the signal the caller emits `plugins.changed` on. A pure renewal
    /// returns `false`.
    fn upsert(&self, id: &str, v: Valid) -> bool {
        let expires_at = Instant::now() + LEASE_TTL;
        let mut map = self.inner.write().unwrap_or_else(|e| e.into_inner());
        let changed = match map.get(id) {
            // An *expired* prior entry counts as a change (it had stopped listing).
            Some(prev) => !prev.is_live() || !prev.public_eq(&v.title, &v.version, &v.ui),
            None => true,
        };
        map.insert(
            id.to_string(),
            Stored {
                title: v.title,
                version: v.version,
                ui: v.ui,
                expires_at,
            },
        );
        changed
    }

    /// The current listing (sorted by title, then id), plus the ids of entries that had expired and
    /// were pruned by this call — the caller emits `plugins.changed` for those. Prunes under the
    /// write lock so a stale entry is reaped exactly once.
    fn snapshot(&self) -> (Vec<PluginSummary>, Vec<String>) {
        let now = Instant::now();
        let mut map = self.inner.write().unwrap_or_else(|e| e.into_inner());
        let mut expired: Vec<String> = map
            .iter()
            .filter(|(_, s)| now >= s.expires_at)
            .map(|(id, _)| id.clone())
            .collect();
        for id in &expired {
            map.remove(id);
        }
        expired.sort();
        let mut live: Vec<PluginSummary> = map
            .iter()
            .map(|(id, s)| PluginSummary {
                id: id.clone(),
                title: s.title.clone(),
                version: s.version.clone(),
                ui: s.ui.as_ref().map(|u| PluginUiPublic {
                    port: u.port,
                    icon: u.icon.clone(),
                }),
            })
            .collect();
        live.sort_by(|a, b| a.title.cmp(&b.title).then_with(|| a.id.cmp(&b.id)));
        (live, expired)
    }

    /// The `{port, secret}` for a live plugin's UI, or `None` if unknown/expired/UI-less. Does not
    /// prune (a read path) — a stale entry is reaped by the next [`snapshot`](Self::snapshot).
    fn credential(&self, id: &str) -> Option<UiCredential> {
        let map = self.inner.read().unwrap_or_else(|e| e.into_inner());
        let s = map.get(id)?;
        if !s.is_live() {
            return None;
        }
        let ui = s.ui.as_ref()?;
        Some(UiCredential {
            port: ui.port,
            secret: ui.secret.clone(),
        })
    }

    /// Remove `id`. Returns `true` if a **live** entry existed (a clean deregister); removing an
    /// already-expired or unknown id returns `false` (nothing to announce).
    fn remove(&self, id: &str) -> bool {
        let mut map = self.inner.write().unwrap_or_else(|e| e.into_inner());
        map.remove(id).is_some_and(|s| s.is_live())
    }
}

impl Stored {
    fn is_live(&self) -> bool {
        Instant::now() < self.expires_at
    }
}

/// The process-wide registry singleton (the [`crate::events::bus`] shape).
pub(crate) fn registry() -> &'static PluginRegistry {
    static REG: OnceLock<PluginRegistry> = OnceLock::new();
    REG.get_or_init(PluginRegistry::new)
}

// ---------------------------------------------------------------- validation

/// A plugin id: `definePlugin`'s kebab-case name (`^[a-z][a-z0-9-]*$`, ≤64) — the same regex the SDK
/// enforces, so a plugin's registration id always matches its package name.
fn valid_plugin_id(id: &str) -> bool {
    !id.is_empty()
        && id.len() <= 64
        && id.as_bytes()[0].is_ascii_lowercase()
        && id
            .bytes()
            .all(|b| b.is_ascii_lowercase() || b.is_ascii_digit() || b == b'-')
}

/// Strip control characters (defense against a title/version smuggling terminal escapes or newlines
/// into a log line or the console nav), then trim.
fn sanitize(s: &str) -> String {
    s.chars()
        .filter(|c| !c.is_control())
        .collect::<String>()
        .trim()
        .to_string()
}

/// Validate a registration body into the internal [`Valid`] form, or a human-readable reason.
fn validate(reg: PluginRegistration) -> Result<Valid, String> {
    let title = sanitize(&reg.title);
    if title.is_empty() {
        return Err("title must not be empty".into());
    }
    if title.chars().count() > 64 {
        return Err("title must be at most 64 characters".into());
    }
    let version = match reg.version {
        Some(v) => {
            let v = sanitize(&v);
            if v.chars().count() > 32 {
                return Err("version must be at most 32 characters".into());
            }
            (!v.is_empty()).then_some(v)
        }
        None => None,
    };
    let ui = match reg.ui {
        Some(u) => Some(validate_ui(u)?),
        None => None,
    };
    Ok(Valid { title, version, ui })
}

fn validate_ui(u: PluginUi) -> Result<StoredUi, String> {
    if u.port < 1024 {
        return Err("ui.port must be a non-privileged port (>= 1024)".into());
    }
    let n = u.secret.len();
    if !(16..=128).contains(&n) {
        return Err("ui.secret must be 16–128 characters".into());
    }
    if !u
        .secret
        .bytes()
        .all(|b| b.is_ascii_alphanumeric() || b == b'_' || b == b'-')
    {
        return Err("ui.secret must be [A-Za-z0-9_-]".into());
    }
    let icon = match u.icon {
        Some(icon) => {
            let ok = (1..=48).contains(&icon.len())
                && icon
                    .bytes()
                    .all(|b| b.is_ascii_lowercase() || b.is_ascii_digit() || b == b'-');
            if !ok {
                return Err("ui.icon must be a lucide name ([a-z0-9-], 1–48 chars)".into());
            }
            Some(icon)
        }
        None => None,
    };
    Ok(StoredUi {
        port: u.port,
        secret: u.secret,
        icon,
    })
}

// ---------------------------------------------------------------- handlers

/// Register or renew a plugin
///
/// Upserts the plugin's directory entry and renews its lease (TTL 90 s). Idempotent: a plugin PUTs
/// this every ~30 s while it runs. The optional `ui` block declares a loopback UI surface the console
/// will proxy and add to its nav. Emits `plugins.changed` when an operator-visible field changed
/// (first registration, restart, or re-scan) — a pure renewal is silent.
#[utoipa::path(
    put,
    path = "/plugins/{id}",
    tag = "plugins",
    operation_id = "registerPlugin",
    params(("id" = String, Path, description = "The plugin id (its `definePlugin` name: `[a-z][a-z0-9-]*`)")),
    request_body = PluginRegistration,
    responses(
        (status = NO_CONTENT, description = "Registered / renewed"),
        (status = BAD_REQUEST, description = "Invalid id or registration", body = ApiError),
        (status = UNAUTHORIZED, description = "Missing or invalid bearer token", body = ApiError),
    )
)]
pub(crate) async fn register_plugin(
    Path(id): Path<String>,
    ApiJson(reg): ApiJson<PluginRegistration>,
) -> Response {
    if !valid_plugin_id(&id) {
        return api_error(
            StatusCode::BAD_REQUEST,
            "invalid plugin id (expected kebab-case `[a-z][a-z0-9-]*`, ≤64)",
        );
    }
    let valid = match validate(reg) {
        Ok(v) => v,
        Err(e) => return api_error(StatusCode::BAD_REQUEST, &e),
    };
    if registry().upsert(&id, valid) {
        tracing::info!(plugin = %id, "plugin registered");
        emit(EventKind::PluginsChanged { id });
    }
    StatusCode::NO_CONTENT.into_response()
}

/// List registered plugins
///
/// The live plugin directory (lease not expired), sorted by title. **Secret-free**: each entry
/// reports its id, title, optional version, and — for plugins that serve one — a UI descriptor
/// (loopback port + icon). The console renders these as nav entries and proxies to the port; it
/// fetches the secret separately, server-side.
#[utoipa::path(
    get,
    path = "/plugins",
    tag = "plugins",
    operation_id = "listPlugins",
    responses(
        (status = OK, description = "Live plugin registrations", body = [PluginSummary]),
        (status = UNAUTHORIZED, description = "Missing or invalid bearer token", body = ApiError),
    )
)]
pub(crate) async fn list_plugins() -> Json<Vec<PluginSummary>> {
    let (plugins, expired) = registry().snapshot();
    // Lazy expiry: an entry that aged out is reaped here (exactly once) and announced, so a consumer
    // watching the event stream sees the departure even though nothing actively deregistered it.
    for id in expired {
        tracing::info!(plugin = %id, "plugin lease expired");
        emit(EventKind::PluginsChanged { id });
    }
    Json(plugins)
}

/// Fetch a plugin UI's proxy credential
///
/// Returns `{port, secret}` for a live plugin's loopback UI — the console proxy's server-side lookup.
/// Bearer + loopback only (like every mutation), and additionally excluded from the console's browser
/// passthrough: the secret never reaches a browser.
#[utoipa::path(
    get,
    path = "/plugins/{id}/ui-credential",
    tag = "plugins",
    operation_id = "getPluginUiCredential",
    params(("id" = String, Path, description = "The plugin id")),
    responses(
        (status = OK, description = "The proxy credential", body = UiCredential),
        (status = UNAUTHORIZED, description = "Missing or invalid bearer token", body = ApiError),
        (status = NOT_FOUND, description = "No live plugin with that id, or it serves no UI", body = ApiError),
    )
)]
pub(crate) async fn get_ui_credential(Path(id): Path<String>) -> Response {
    match registry().credential(&id) {
        Some(cred) => Json(cred).into_response(),
        None => api_error(StatusCode::NOT_FOUND, "no live plugin UI with that id"),
    }
}

/// Deregister a plugin
///
/// The clean-shutdown path: removes the plugin's directory entry immediately (the SDK helper calls
/// this from its scope finalizer on `SIGTERM`). Emits `plugins.changed` when a live entry was
/// removed. Idempotent — deleting an unknown/expired id is a no-op `204`.
#[utoipa::path(
    delete,
    path = "/plugins/{id}",
    tag = "plugins",
    operation_id = "deregisterPlugin",
    params(("id" = String, Path, description = "The plugin id")),
    responses(
        (status = NO_CONTENT, description = "Deregistered (or already absent)"),
        (status = UNAUTHORIZED, description = "Missing or invalid bearer token", body = ApiError),
    )
)]
pub(crate) async fn delete_plugin(Path(id): Path<String>) -> Response {
    if registry().remove(&id) {
        tracing::info!(plugin = %id, "plugin deregistered");
        emit(EventKind::PluginsChanged { id });
    }
    StatusCode::NO_CONTENT.into_response()
}

#[cfg(test)]
mod tests {
    use super::*;

    fn reg(title: &str, port: u16, secret: &str) -> PluginRegistration {
        PluginRegistration {
            title: title.into(),
            version: None,
            ui: Some(PluginUi {
                port,
                secret: secret.into(),
                icon: Some("gamepad-2".into()),
            }),
        }
    }

    const SECRET: &str = "abcdefghijklmnop0123"; // 20 chars, valid alphabet

    #[test]
    fn id_validation() {
        assert!(valid_plugin_id("rom-manager"));
        assert!(valid_plugin_id("a"));
        assert!(valid_plugin_id("x9"));
        assert!(!valid_plugin_id("")); // empty
        assert!(!valid_plugin_id("9lives")); // must start with a letter
        assert!(!valid_plugin_id("-lead")); // must start with a letter
        assert!(!valid_plugin_id("Rom")); // no uppercase
        assert!(!valid_plugin_id("rom_manager")); // no underscore
        assert!(!valid_plugin_id(&"a".repeat(65))); // too long
    }

    #[test]
    fn registration_validation() {
        assert!(validate(reg("ROM Manager", 49321, SECRET)).is_ok());
        // control chars stripped from the title
        let v = validate(PluginRegistration {
            title: "Ro\u{7}m\n".into(),
            version: None,
            ui: None,
        })
        .unwrap();
        assert_eq!(v.title, "Rom");
        // privileged port rejected
        assert!(validate(reg("x", 80, SECRET)).is_err());
        // short secret rejected
        assert!(validate(reg("x", 49321, "tooshort")).is_err());
        // bad secret alphabet rejected
        assert!(validate(reg("x", 49321, "bad secret with spaces!!")).is_err());
        // empty title rejected
        assert!(validate(reg("   ", 49321, SECRET)).is_err());
    }

    #[test]
    fn upsert_reports_change_but_not_renewal() {
        let r = PluginRegistry::new();
        // first registration is a change
        assert!(r.upsert("p", validate(reg("Title", 49321, SECRET)).unwrap()));
        // identical renewal is not
        assert!(!r.upsert("p", validate(reg("Title", 49321, SECRET)).unwrap()));
        // a new secret (restart) is a change
        assert!(r.upsert(
            "p",
            validate(reg("Title", 49321, "ZZZZZZZZZZZZZZZZ")).unwrap()
        ));
        // a new title (re-scan) is a change
        assert!(r.upsert(
            "p",
            validate(reg("New Title", 49321, "ZZZZZZZZZZZZZZZZ")).unwrap()
        ));
    }

    #[test]
    fn snapshot_lists_secret_free_sorted() {
        let r = PluginRegistry::new();
        r.upsert("zeta", validate(reg("Zeta", 50000, SECRET)).unwrap());
        r.upsert("alpha", validate(reg("Alpha", 50001, SECRET)).unwrap());
        let (plugins, expired) = r.snapshot();
        assert!(expired.is_empty());
        assert_eq!(
            plugins.iter().map(|p| p.id.as_str()).collect::<Vec<_>>(),
            vec!["alpha", "zeta"] // sorted by title
        );
        // the summary type has no secret field at all — check the credential path carries it
        assert_eq!(r.credential("alpha").unwrap().secret, SECRET);
        assert_eq!(r.credential("alpha").unwrap().port, 50001);
    }

    #[test]
    fn credential_absent_for_ui_less_and_unknown() {
        let r = PluginRegistry::new();
        r.upsert(
            "headless",
            validate(PluginRegistration {
                title: "Headless".into(),
                version: None,
                ui: None,
            })
            .unwrap(),
        );
        assert!(r.credential("headless").is_none()); // registered but no UI
        assert!(r.credential("nope").is_none()); // unknown
    }

    #[test]
    fn expired_entries_drop_from_listing_and_credential() {
        let r = PluginRegistry::new();
        r.upsert("p", validate(reg("P", 49321, SECRET)).unwrap());
        // Force the lease into the past.
        {
            let mut map = r.inner.write().unwrap();
            map.get_mut("p").unwrap().expires_at =
                Instant::now().checked_sub(Duration::from_secs(1)).unwrap();
        }
        assert!(r.credential("p").is_none()); // expired → no credential
        let (plugins, expired) = r.snapshot();
        assert!(plugins.is_empty());
        assert_eq!(expired, vec!["p".to_string()]); // reaped + announced once
                                                    // second snapshot no longer reports it as freshly-expired
        assert!(r.snapshot().1.is_empty());
    }

    #[test]
    fn remove_reports_live_only() {
        let r = PluginRegistry::new();
        r.upsert("p", validate(reg("P", 49321, SECRET)).unwrap());
        assert!(r.remove("p")); // live → announced
        assert!(!r.remove("p")); // already gone → silent
    }
}