macltok

use std::sync::Arc;

use futures_util::StreamExt;

use matrix_sdk::{

    Client,

    encryption::{

        VerificationState,

        backups::BackupState,

        recovery::RecoveryState as SdkRecoveryState,

        verification::{

            SasState, SasVerification, Verification, VerificationRequest, VerificationRequestState,

        },

    },

    ruma::events::key::verification::VerificationMethod,

};

use ruma::{OwnedDeviceId, UserId};

use tokio::{sync::Mutex, task::JoinHandle};

use crate::{

    EncryptionState, Error, ErrorKind, Event, KeyBackupState, RecoveryState, VerificationAction,

    VerificationState as UiState, VerificationTarget, model::VerificationFailure,

    transport::EventSender,

};

pub(crate) fn encryption_state(

    device_id: OwnedDeviceId,

    recovery: SdkRecoveryState,

    verification: VerificationState,

    backup: BackupState,

) -> EncryptionState {

    EncryptionState {

        device_id,

        device_verified: matches!(verification, VerificationState::Verified),

        recovery: match recovery {

            SdkRecoveryState::Unknown => RecoveryState::Unknown,

            SdkRecoveryState::Disabled => RecoveryState::Disabled,

            SdkRecoveryState::Incomplete => RecoveryState::Incomplete,

            SdkRecoveryState::Enabled => RecoveryState::Enabled,

        },

        key_backup: match backup {

            BackupState::Unknown => KeyBackupState::Unknown,

            BackupState::Creating => KeyBackupState::Creating,

            BackupState::Enabling => KeyBackupState::Enabling,

            BackupState::Resuming => KeyBackupState::Resuming,

            BackupState::Enabled => KeyBackupState::Enabled,

            BackupState::Downloading => KeyBackupState::Downloading,

            BackupState::Disabling => KeyBackupState::Disabling,

        },

    }

}

#[derive(Default)]

pub(crate) struct VerificationController {

    active: Arc<Mutex<VerificationSession>>,

    task: Option<JoinHandle<()>>,

}

#[derive(Default)]

struct VerificationSession {

    request: Option<VerificationRequest>,

    sas: Option<SasVerification>,

}

impl VerificationController {

    pub(crate) async fn apply(

        &mut self,

        sender: EventSender,

        action: VerificationAction,

    ) -> Result<(), Error> {

        match action {

            VerificationAction::Accept => self.accept().await,

            VerificationAction::Confirm => {

                // Retain a handle across the operation: the watcher clears

                // `active` when it publishes a terminal event, but this clone

                // still observes the shared SDK state afterwards.

                let sas = self.active.lock().await.sas.clone();

                match self.confirm().await {

                    Ok(()) => Ok(()),

                    Err(error) if error.kind == ErrorKind::VerificationInactive => Err(error),

                    // The confirm advanced local SDK state before its send failed,

                    // so the retained session could report success on retry without

                    // network traffic. Best-effort cancel (no lock held across the

                    // network), clear for restart, then report the terminal state.

                    Err(error) => {

                        // Stop the watcher first so it cannot emit a stale

                        // Confirmed from the local transition we are unwinding.

                        self.stop_task().await;

                        // The peer can complete or cancel the verification

                        // while our own Done send fails. The stopped watcher may

                        // already have published that terminal outcome (losing the

                        // claim below); otherwise this path owns it and must emit

                        // it instead of regressing to Cancelled.

                        if sas.as_ref().is_some_and(|sas| sas.is_done()) {

                            if take_verification(&self.active).await {

                                let _ =

                                    sender.send(Event::VerificationChanged(UiState::Done)).await;

                            }

                            return Err(error);

                        }

                        if let Some(reason) = sas

                            .as_ref()

                            .and_then(|sas| sas.cancel_info())

                            .map(|info| info.reason().to_owned())

                        {

                            if take_verification(&self.active).await {

                                let _ = sender

                                    .send(Event::VerificationChanged(UiState::Cancelled(reason)))

                                    .await;

                            }

                            return Err(error);

                        }

                        if let Some(sas) = sas {

                            if sas.cancel().await.is_err() {

                                // The best-effort unwind already advanced

                                // local state; clearing here keeps the failed

                                // cancellation from looking retryable. The

                                // send is owned only if the watcher has not

                                // already claimed the session for its own

                                // terminal outcome.

                                if take_verification(&self.active).await {

                                    let _ = sender

                                        .send(Event::VerificationChanged(UiState::Cancelled(

                                            error.to_string(),

                                        )))

                                        .await;

                                }

                                return Err(error);

                            }

                            // The peer can complete while the unwind cancel is in

                            // flight and the SDK call no-ops; the Done then owns the

                            // terminal outcome, so report it instead of attributing

                            // it to the send failure.

                            if sas.is_done() {

                                if take_verification(&self.active).await {

                                    let _ = sender

                                        .send(Event::VerificationChanged(UiState::Done))

                                        .await;

                                }

                                return Err(error);

                            }

                            if let Some(info) = sas.cancel_info() {

                                // Our own unwind cancel just marked the flow; it does

                                // not own the outcome yet, so fall through and report

                                // the send failure as Cancelled below. Only a peer

                                // cancellation racing the unwind owns it instead.

                                if !info.cancelled_by_us() {

                                    if take_verification(&self.active).await {

                                        let _ = sender

                                            .send(Event::VerificationChanged(UiState::Cancelled(

                                                info.reason().to_owned(),

                                            )))

                                            .await;

                                    }

                                    return Err(Error::new(

                                        ErrorKind::VerificationInactive,

                                        info.reason().to_owned(),

                                    ));

                                }

                            }

                        }

                        if take_verification(&self.active).await {

                            let _ = sender

                                .send(Event::VerificationChanged(UiState::Cancelled(

                                    error.to_string(),

                                )))

                                .await;

                        }

                        Err(error)

                    }

                }

            }

            VerificationAction::Reject => self.reject().await,

            VerificationAction::Cancel => {

                // The SDK no-ops a cancel of an already-settled flow, so a

                // failed claim inside `cancel` already reported the true

                // outcome as an error and owns no event here. Only the claim

                // winner emits the local Cancelled.

                let claimed = self.cancel_claimed(Some(&sender)).await?;

                if claimed {

                    sender

                        .send(Event::VerificationChanged(UiState::Cancelled(

                            "cancelled by this client".to_owned(),

                        )))

                        .await

                        .map_err(|source| {

                            Error::with_source(

                                ErrorKind::Interrupted,

                                "event receiver has closed",

                                source,

                            )

                        })?;

                }

                Ok(())

            }

        }

    }

    pub(crate) async fn start(

        &mut self,

        client: &Client,

        sender: EventSender,

        target: VerificationTarget,

    ) -> Result<(), Error> {

        client

            .encryption()

            .wait_for_e2ee_initialization_tasks()

            .await;

        let own_user_id = client.user_id().ok_or_else(|| {

            Error::new(

                ErrorKind::Unauthenticated,

                "the Matrix client is not authenticated",

            )

        })?;

        if self.has_active_verification().await {

            self.cancel().await?;

        } else {

            self.stop_task().await;

        }

        let request = match &target {

            VerificationTarget::OwnIdentity => {

                request_identity_verification(client, own_user_id).await?

            }

            VerificationTarget::User(user_id) => {

                request_identity_verification(client, user_id).await?

            }

            VerificationTarget::Device { user_id, device_id } => {

                let device = client

                    .encryption()

                    .get_device(user_id, device_id)

                    .await

                    .map_err(|source| {

                        Error::with_source(

                            ErrorKind::Encryption,

                            "reading the verification device failed",

                            source,

                        )

                    })?

                    .ok_or_else(|| {

                        Error::new(

                            ErrorKind::VerificationUnsupported,

                            "the verification device is unavailable",

                        )

                    })?;

                device

                    .request_verification_with_methods(vec![VerificationMethod::SasV1])

                    .await

                    .map_err(|source| {

                        Error::from_sdk("starting device verification failed", source)

                    })?

            }

        };

        // subscribed before anything can wait on the event channel, or a quick peer's

        // answer lands while we're blocked and nobody ever hears it

        let changes = request.changes();

        self.active.lock().await.request = Some(request.clone());

        sender

            .send(Event::VerificationTargetChanged(target))

            .await

            .map_err(|source| {

                Error::with_source(ErrorKind::Interrupted, "event receiver has closed", source)

            })?;

        sender

            .send(Event::VerificationChanged(UiState::Waiting))

            .await

            .map_err(|source| {

                Error::with_source(ErrorKind::Interrupted, "event receiver has closed", source)

            })?;

        let active = self.active.clone();

        self.task = Some(tokio::spawn(async move {

            follow_request(request, changes, active, sender).await;

        }));

        Ok(())

    }

    /// another device asked us. only taken when nothing else is in flight, and not accepted

    /// until the user says so with `VerificationAction::Accept`

    pub(crate) async fn adopt_incoming(

        &mut self,

        sender: EventSender,

        request: VerificationRequest,

    ) {

        if request.we_started() || request.is_done() || request.cancel_info().is_some() {

            return;

        }

        if self.has_active_verification().await {

            tracing::debug!("ignoring a verification request while another is in flight");

            return;

        }

        self.stop_task().await;

        let changes = request.changes();

        self.active.lock().await.request = Some(request.clone());

        let incoming = UiState::Incoming {

            user_id: request.other_user_id().to_owned(),

            device_id: match request.state() {

                VerificationRequestState::Requested {

                    other_device_data, ..

                }

                | VerificationRequestState::Ready {

                    other_device_data, ..

                } => Some(other_device_data.device_id().to_owned()),

                _ => None,

            },

        };

        let target = VerificationTarget::User(request.other_user_id().to_owned());

        for event in [

            Event::VerificationTargetChanged(target),

            Event::VerificationChanged(incoming),

        ] {

            if sender.send(event).await.is_err() {

                return;

            }

        }

        let active = self.active.clone();

        self.task = Some(tokio::spawn(async move {

            follow_request(request, changes, active, sender).await;

        }));

    }

    async fn accept(&self) -> Result<(), Error> {

        let inactive = |message: &str| Error::new(ErrorKind::VerificationInactive, message);

        let (request, sas) = {

            let active = self.active.lock().await;

            (active.request.clone(), active.sas.is_some())

        };

        let request = request.ok_or_else(|| inactive("no verification request is pending"))?;

        if request.we_started() {

            return Err(inactive("nobody asked us, we asked them"));

        }

        if request.is_done() {

            return Err(inactive("verification is already complete"));

        }

        if let Some(info) = request.cancel_info() {

            return Err(inactive(info.reason()));

        }

        if sas {

            return Err(inactive("verification has already started"));

        }

        request

            .accept_with_methods(vec![VerificationMethod::SasV1])

            .await

            .map_err(|source| Error::from_sdk("accepting verification request failed", source))

    }

    async fn confirm(&self) -> Result<(), Error> {

        let sas = self.active.lock().await.sas.clone().ok_or_else(|| {

            Error::new(

                ErrorKind::VerificationInactive,

                "verification has not reached comparison",

            )

        })?;

        // Report a settled flow truthfully instead of as "not reached

        // comparison": the SDK would no-op the confirm with success.

        if sas.is_done() {

            return Err(Error::new(

                ErrorKind::VerificationInactive,

                "verification is already complete",

            ));

        }

        if let Some(info) = sas.cancel_info() {

            return Err(Error::new(

                ErrorKind::VerificationInactive,

                info.reason().to_owned(),

            ));

        }

        // Only the short-auth-string stage is confirmable. The SDK reports the

        // remote-MAC-arrived state through the same presentable flag, while an

        // early confirm would locally no-op and falsely report success.

        if !sas.can_be_presented() {

            return Err(Error::new(

                ErrorKind::VerificationInactive,

                "verification has not reached comparison",

            ));

        }

        // Our own confirm can move the flow to Done, so only Done that predates

        // the send means the SDK no-op'd on a stale session; a cancellation

        // racing the send must not report success.

        let was_done = sas.is_done();

        sas.confirm()

            .await

            .map_err(|source| Error::from_sdk("confirming verification failed", source))?;

        if sas.is_done() {

            if was_done {

                return Err(Error::new(

                    ErrorKind::VerificationInactive,

                    "verification is already complete",

                ));

            }

        } else if sas.is_cancelled() {

            let reason = sas

                .cancel_info()

                .map(|info| info.reason().to_owned())

                .unwrap_or_else(|| "verification was cancelled".to_owned());

            return Err(Error::new(ErrorKind::VerificationInactive, reason));

        }

        Ok(())

    }

    async fn reject(&self) -> Result<(), Error> {

        let sas = self.active.lock().await.sas.clone().ok_or_else(|| {

            Error::new(

                ErrorKind::VerificationInactive,

                "verification has not reached comparison",

            )

        })?;

        // Report a settled flow truthfully instead of as "not reached

        // comparison": the SDK would no-op the mismatch with success.

        if sas.is_done() {

            return Err(Error::new(

                ErrorKind::VerificationInactive,

                "verification is already complete",

            ));

        }

        if let Some(info) = sas.cancel_info() {

            return Err(Error::new(

                ErrorKind::VerificationInactive,

                info.reason().to_owned(),

            ));

        }

        // Rejecting before the comparison stage would cancel a flow the user

        // never compared, so it requires the same presentable state.

        if !sas.can_be_presented() {

            return Err(Error::new(

                ErrorKind::VerificationInactive,

                "verification has not reached comparison",

            ));

        }

        sas.mismatch()

            .await

            .map_err(|source| Error::from_sdk("rejecting verification failed", source))?;

        // A peer completing the flow concurrently must not be reported as

        // rejected. A remote cancellation racing the send turns the SDK call

        // into a no-op success, so report it instead of a false success.

        if sas.is_done() {

            return Err(Error::new(

                ErrorKind::VerificationInactive,

                "verification is already complete",

            ));

        }

        if let Some(info) = sas.cancel_info() {

            // Our own mismatch just marked the flow cancelled-by-us; that is the

            // expected reject path and stays Ok. Only a peer cancel reports an

            // error.

            if !info.cancelled_by_us() {

                return Err(Error::new(

                    ErrorKind::VerificationInactive,

                    info.reason().to_owned(),

                ));

            }

        }

        Ok(())

    }

    pub(crate) async fn cancel(&mut self) -> Result<(), Error> {

        self.cancel_claimed(None).await.map(|_| ())

    }

    /// Return whether this action won the claim for a local cancellation.

    /// The optional sender reports a peer terminal outcome when it races after

    /// the claim; starting a replacement verification does not publish it.

    async fn cancel_claimed(&mut self, sender: Option<&EventSender>) -> Result<bool, Error> {

        let (sas, request) = {

            let active = self.active.lock().await;

            (active.sas.clone(), active.request.clone())

        };

        if sas.is_none() && request.is_none() {

            return Err(Error::new(

                ErrorKind::VerificationInactive,

                "no verification is active",

            ));

        }

        // The watcher owns terminal emission and claims the session when it

        // publishes. If the SDK is already terminal, the watcher either already

        // reported it or is about to: leave session and watcher alone so the

        // outcome is emitted exactly once, and report it instead of letting the

        // SDK no-op success regress Done to "cancelled by this client".

        if let Some(sas) = sas.as_ref() {

            if sas.is_done() {

                return Err(Error::new(

                    ErrorKind::VerificationInactive,

                    "verification is already complete",

                ));

            }

            if let Some(info) = sas.cancel_info() {

                return Err(Error::new(

                    ErrorKind::VerificationInactive,

                    info.reason().to_owned(),

                ));

            }

        } else if let Some(request) = request.as_ref() {

            if request.is_done() {

                return Err(Error::new(

                    ErrorKind::VerificationInactive,

                    "verification is already complete",

                ));

            }

            if let Some(info) = request.cancel_info() {

                return Err(Error::new(

                    ErrorKind::VerificationInactive,

                    info.reason().to_owned(),