// ABOUTME: fprintd D-Bus integration for fingerprint authentication.
// ABOUTME: Provides FingerprintListener that connects to fprintd via Gio.DBusProxy.

use gio::prelude::*;
use gtk4::gio;
use std::cell::RefCell;
use std::rc::Rc;

const FPRINTD_BUS_NAME: &str = "net.reactivated.Fprint";
const FPRINTD_MANAGER_PATH: &str = "/net/reactivated/Fprint/Manager";
const FPRINTD_MANAGER_IFACE: &str = "net.reactivated.Fprint.Manager";
const FPRINTD_DEVICE_IFACE: &str = "net.reactivated.Fprint.Device";

const MAX_FP_ATTEMPTS: u32 = 10;

/// Retry-able statuses — finger not read properly, try again.
const RETRY_STATUSES: &[&str] = &[
    "verify-swipe-too-short",
    "verify-finger-not-centered",
    "verify-remove-and-retry",
    "verify-retry-scan",
];

/// Fingerprint listener state.
pub struct FingerprintListener {
    device_proxy: Option<gio::DBusProxy>,
    signal_id: Option<glib::SignalHandlerId>,
    running: bool,
    failed_attempts: u32,
    on_success: Option<Box<dyn Fn() + 'static>>,
    on_failure: Option<Box<dyn Fn() + 'static>>,
}

impl FingerprintListener {
    /// Create a new FingerprintListener.
    /// Connects to fprintd synchronously — call before creating GTK windows.
    pub fn new() -> Self {
        let mut listener = FingerprintListener {
            device_proxy: None,
            signal_id: None,
            running: false,
            failed_attempts: 0,
            on_success: None,
            on_failure: None,
        };
        listener.init_device();
        listener
    }

    /// Connect to fprintd and get the default device.
    fn init_device(&mut self) {
        let manager = match gio::DBusProxy::for_bus_sync(
            gio::BusType::System,
            gio::DBusProxyFlags::NONE,
            None,
            FPRINTD_BUS_NAME,
            FPRINTD_MANAGER_PATH,
            FPRINTD_MANAGER_IFACE,
            gio::Cancellable::NONE,
        ) {
            Ok(m) => m,
            Err(e) => {
                log::debug!("fprintd manager not available: {e}");
                return;
            }
        };

        // Call GetDefaultDevice
        let result = match manager.call_sync(
            "GetDefaultDevice",
            None,
            gio::DBusCallFlags::NONE,
            -1,
            gio::Cancellable::NONE,
        ) {
            Ok(r) => r,
            Err(e) => {
                log::debug!("fprintd GetDefaultDevice failed: {e}");
                return;
            }
        };

        // Extract device path from variant tuple
        let device_path: String = result.child_get::<String>(0);
        if device_path.is_empty() {
            return;
        }

        match gio::DBusProxy::for_bus_sync(
            gio::BusType::System,
            gio::DBusProxyFlags::NONE,
            None,
            FPRINTD_BUS_NAME,
            &device_path,
            FPRINTD_DEVICE_IFACE,
            gio::Cancellable::NONE,
        ) {
            Ok(proxy) => {
                self.device_proxy = Some(proxy);
            }
            Err(e) => {
                log::debug!("fprintd device proxy failed: {e}");
            }
        }
    }

    /// Check if fprintd is available and the user has enrolled fingerprints.
    pub fn is_available(&self, username: &str) -> bool {
        let proxy = match &self.device_proxy {
            Some(p) => p,
            None => return false,
        };

        let args = glib::Variant::from((&username,));
        match proxy.call_sync(
            "ListEnrolledFingers",
            Some(&args),
            gio::DBusCallFlags::NONE,
            -1,
            gio::Cancellable::NONE,
        ) {
            Ok(result) => {
                // Result is a tuple of (array of strings)
                let fingers: Vec<String> = result.child_get::<Vec<String>>(0);
                !fingers.is_empty()
            }
            Err(_) => false,
        }
    }

    /// Start listening for fingerprint verification.
    /// Connects the D-Bus g-signal handler internally. The `listener` parameter
    /// must be the same `Rc<RefCell<FingerprintListener>>` that owns `self`.
    pub fn start<F, G>(
        listener: &Rc<RefCell<FingerprintListener>>,
        username: &str,
        on_success: F,
        on_failure: G,
    ) where
        F: Fn() + 'static,
        G: Fn() + 'static,
    {
        let proxy = {
            let inner = listener.borrow();
            match inner.device_proxy.clone() {
                Some(p) => p,
                None => return,
            }
        };

        {
            let mut inner = listener.borrow_mut();
            inner.on_success = Some(Box::new(on_success));
            inner.on_failure = Some(Box::new(on_failure));
        }

        // Claim the device
        let args = glib::Variant::from((&username,));
        if let Err(e) = proxy.call_sync(
            "Claim",
            Some(&args),
            gio::DBusCallFlags::NONE,
            -1,
            gio::Cancellable::NONE,
        ) {
            log::error!("Failed to claim fingerprint device: {e}");
            return;
        }

        // Start verification
        let start_args = glib::Variant::from((&"any",));
        if let Err(e) = proxy.call_sync(
            "VerifyStart",
            Some(&start_args),
            gio::DBusCallFlags::NONE,
            -1,
            gio::Cancellable::NONE,
        ) {
            log::error!("Failed to start fingerprint verification: {e}");
            let _ = proxy.call_sync(
                "Release",
                None,
                gio::DBusCallFlags::NONE,
                -1,
                gio::Cancellable::NONE,
            );
            return;
        }

        // Connect the g-signal handler on the proxy to dispatch VerifyStatus
        let listener_weak = Rc::downgrade(listener);
        let signal_id = proxy.connect_local("g-signal", false, move |values| {
            // g-signal arguments: (proxy, sender_name, signal_name, parameters)
            let signal_name: String = match values[2].get() {
                Ok(v) => v,
                Err(_) => return None,
            };
            if signal_name.as_str() != "VerifyStatus" {
                return None;
            }

            let params = match values[3].get::<glib::Variant>() {
                Ok(v) => v,
                Err(_) => return None,
            };

            let status = params
                .child_value(0)
                .get::<String>()
                .unwrap_or_default();
            let done = params
                .child_value(1)
                .get::<bool>()
                .unwrap_or(false);

            if let Some(listener_rc) = listener_weak.upgrade() {
                listener_rc.borrow_mut().on_verify_status(&status, done);
            }

            None
        });

        let mut inner = listener.borrow_mut();
        inner.signal_id = Some(signal_id);
        inner.running = true;
    }

    /// Process a VerifyStatus signal from fprintd.
    pub fn on_verify_status(&mut self, status: &str, done: bool) {
        if !self.running {
            return;
        }

        if status == "verify-match" {
            if let Some(ref cb) = self.on_success {
                cb();
            }
            return;
        }

        if RETRY_STATUSES.contains(&status) {
            if done {
                self.restart_verify();
            }
            return;
        }

        if status == "verify-no-match" {
            self.failed_attempts += 1;
            if let Some(ref cb) = self.on_failure {
                cb();
            }
            if self.failed_attempts >= MAX_FP_ATTEMPTS {
                log::warn!("Fingerprint max attempts ({MAX_FP_ATTEMPTS}) reached, stopping");
                self.stop();
                return;
            }
            if done {
                self.restart_verify();
            }
            return;
        }

        log::debug!("Unhandled fprintd status: {status}");
    }

    /// Restart fingerprint verification after a completed attempt.
    fn restart_verify(&self) {
        if let Some(ref proxy) = self.device_proxy {
            // VerifyStop before VerifyStart to avoid D-Bus errors
            let _ = proxy.call_sync(
                "VerifyStop",
                None,
                gio::DBusCallFlags::NONE,
                -1,
                gio::Cancellable::NONE,
            );
            let args = glib::Variant::from((&"any",));
            if let Err(e) = proxy.call_sync(
                "VerifyStart",
                Some(&args),
                gio::DBusCallFlags::NONE,
                -1,
                gio::Cancellable::NONE,
            ) {
                log::error!("Failed to restart fingerprint verification: {e}");
            }
        }
    }

    /// Stop listening and release the device.
    pub fn stop(&mut self) {
        if !self.running {
            return;
        }
        self.running = false;

        if let Some(ref proxy) = self.device_proxy {
            if let Some(id) = self.signal_id.take() {
                proxy.disconnect(id);
            }
            let _ = proxy.call_sync(
                "VerifyStop",
                None,
                gio::DBusCallFlags::NONE,
                -1,
                gio::Cancellable::NONE,
            );
            let _ = proxy.call_sync(
                "Release",
                None,
                gio::DBusCallFlags::NONE,
                -1,
                gio::Cancellable::NONE,
            );
        }
    }

}

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

    #[test]
    fn retry_statuses_are_defined() {
        assert!(RETRY_STATUSES.contains(&"verify-swipe-too-short"));
        assert!(RETRY_STATUSES.contains(&"verify-finger-not-centered"));
        assert!(!RETRY_STATUSES.contains(&"verify-match"));
        assert!(!RETRY_STATUSES.contains(&"verify-no-match"));
    }

    #[test]
    fn max_attempts_constant() {
        assert_eq!(MAX_FP_ATTEMPTS, 10);
    }
}