// Copyright 2020 The Matrix.org Foundation C.I.C.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Types and traits to implement the storage layer for the [`OlmMachine`]
//!
//! The storage layer for the [`OlmMachine`] can be customized using a trait.
//! Implementing your own [`CryptoStore`]
//!
//! An in-memory only store is provided as well as a Sled based one, depending
//! on your needs and targets a custom store may be implemented, e.g. for
//! `wasm-unknown-unknown` an indexeddb store would be needed
//!
//! ```
//! # use matrix_sdk_crypto::{
//! #     OlmMachine,
//! #     store::MemoryStore,
//! # };
//! # use ruma::{user_id, DeviceIdBox};
//! # let user_id = user_id!("@example:localhost");
//! # let device_id: DeviceIdBox = "TEST".into();
//! let store = Box::new(MemoryStore::new());
//!
//! let machine = OlmMachine::new_with_store(user_id, device_id, store);
//! ```
//!
//! [`OlmMachine`]: /matrix_sdk_crypto/struct.OlmMachine.html
//! [`CryptoStore`]: trait.Cryptostore.html

pub mod caches;
mod memorystore;
mod pickle_key;
#[cfg(feature = "sled_cryptostore")]
pub(crate) mod sled;

use std::{
    collections::{HashMap, HashSet},
    fmt::Debug,
    io::Error as IoError,
    ops::Deref,
    sync::Arc,
};

use base64::DecodeError;
use matrix_sdk_common::{async_trait, locks::Mutex, uuid::Uuid, AsyncTraitDeps};
pub use memorystore::MemoryStore;
use olm_rs::errors::{OlmAccountError, OlmGroupSessionError, OlmSessionError};
pub use pickle_key::{EncryptedPickleKey, PickleKey};
use ruma::{
    events::secret::request::SecretName, identifiers::Error as IdentifierValidationError, DeviceId,
    DeviceIdBox, DeviceKeyAlgorithm, RoomId, UserId,
};
use serde_json::Error as SerdeError;
use thiserror::Error;
use tracing::{info, warn};
use zeroize::Zeroize;

#[cfg(feature = "sled_cryptostore")]
pub use self::sled::SledStore;
use crate::{
    error::SessionUnpicklingError,
    gossiping::{GossipRequest, SecretInfo},
    identities::{
        user::{OwnUserIdentity, UserIdentities, UserIdentity},
        Device, ReadOnlyDevice, ReadOnlyUserIdentities, UserDevices,
    },
    olm::{
        InboundGroupSession, OlmMessageHash, OutboundGroupSession, PrivateCrossSigningIdentity,
        ReadOnlyAccount, Session,
    },
    verification::VerificationMachine,
    CrossSigningStatus,
};

/// A `CryptoStore` specific result type.
pub type Result<T, E = CryptoStoreError> = std::result::Result<T, E>;

/// A wrapper for our CryptoStore trait object.
///
/// This is needed because we want to have a generic interface so we can
/// store/restore objects that we can serialize. Since trait objects and
/// generics don't mix let the CryptoStore store strings and this wrapper
/// adds the generic interface on top.
#[derive(Debug, Clone)]
pub(crate) struct Store {
    user_id: Arc<UserId>,
    identity: Arc<Mutex<PrivateCrossSigningIdentity>>,
    inner: Arc<dyn CryptoStore>,
    verification_machine: VerificationMachine,
}

#[derive(Clone, Debug, Default)]
#[allow(missing_docs)]
pub struct Changes {
    pub account: Option<ReadOnlyAccount>,
    pub private_identity: Option<PrivateCrossSigningIdentity>,
    pub sessions: Vec<Session>,
    pub message_hashes: Vec<OlmMessageHash>,
    pub inbound_group_sessions: Vec<InboundGroupSession>,
    pub outbound_group_sessions: Vec<OutboundGroupSession>,
    pub identities: IdentityChanges,
    pub key_requests: Vec<GossipRequest>,
    pub devices: DeviceChanges,
}

#[derive(Debug, Clone, Default)]
#[allow(missing_docs)]
pub struct IdentityChanges {
    pub new: Vec<ReadOnlyUserIdentities>,
    pub changed: Vec<ReadOnlyUserIdentities>,
}

#[derive(Debug, Clone, Default)]
#[allow(missing_docs)]
pub struct DeviceChanges {
    pub new: Vec<ReadOnlyDevice>,
    pub changed: Vec<ReadOnlyDevice>,
    pub deleted: Vec<ReadOnlyDevice>,
}

impl DeviceChanges {
    /// Merge the given `DeviceChanges` into this instance of `DeviceChanges`.
    pub fn extend(&mut self, other: DeviceChanges) {
        self.new.extend(other.new);
        self.changed.extend(other.changed);
        self.deleted.extend(other.deleted);
    }
}

/// A struct containing private cross signing keys that can be backed up or
/// uploaded to the secret store.
#[derive(Zeroize)]
#[zeroize(drop)]
pub struct CrossSigningKeyExport {
    /// The seed of the master key encoded as unpadded base64.
    pub master_key: Option<String>,
    /// The seed of the self signing key encoded as unpadded base64.
    pub self_signing_key: Option<String>,
    /// The seed of the user signing key encoded as unpadded base64.
    pub user_signing_key: Option<String>,
}

impl Debug for CrossSigningKeyExport {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        f.debug_struct("CrossSigningKeyExport")
            .field("master_key", &self.master_key.is_some())
            .field("self_signing_key", &self.self_signing_key.is_some())
            .field("user_signing_key", &self.user_signing_key.is_some())
            .finish_non_exhaustive()
    }
}

/// Error describing what went wrong when importing private cross signing keys
/// or the key backup key.
#[derive(Debug, Error)]
pub enum SecretImportError {
    /// The seed for the private key wasn't valid base64.
    #[error(transparent)]
    Base64(#[from] DecodeError),
    /// The public key of the imported private key doesn't match to the public
    /// key that was uploaded to the server.
    #[error(
        "The public key of the imported private key doesn't match to the \
            public key that was uploaded to the server"
    )]
    MissmatchedPublicKeys,
    /// The new version of the identity couldn't be stored.
    #[error(transparent)]
    Store(#[from] CryptoStoreError),
}

impl Store {
    pub fn new(
        user_id: Arc<UserId>,
        identity: Arc<Mutex<PrivateCrossSigningIdentity>>,
        store: Arc<dyn CryptoStore>,
        verification_machine: VerificationMachine,
    ) -> Self {
        Self { user_id, identity, inner: store, verification_machine }
    }

    pub fn user_id(&self) -> &UserId {
        &self.user_id
    }

    pub fn device_id(&self) -> &DeviceId {
        self.verification_machine.own_device_id()
    }

    #[cfg(test)]
    pub async fn reset_cross_signing_identity(&self) {
        self.identity.lock().await.reset().await;
    }

    pub fn private_identity(&self) -> Arc<Mutex<PrivateCrossSigningIdentity>> {
        self.identity.clone()
    }

    pub async fn save_sessions(&self, sessions: &[Session]) -> Result<()> {
        let changes = Changes { sessions: sessions.to_vec(), ..Default::default() };

        self.save_changes(changes).await
    }

    #[cfg(test)]
    pub async fn save_devices(&self, devices: &[ReadOnlyDevice]) -> Result<()> {
        let changes = Changes {
            devices: DeviceChanges { changed: devices.to_vec(), ..Default::default() },
            ..Default::default()
        };

        self.save_changes(changes).await
    }

    #[cfg(test)]
    pub async fn save_inbound_group_sessions(
        &self,
        sessions: &[InboundGroupSession],
    ) -> Result<()> {
        let changes = Changes { inbound_group_sessions: sessions.to_vec(), ..Default::default() };

        self.save_changes(changes).await
    }

    /// Get the display name of our own device.
    pub async fn device_display_name(&self) -> Result<Option<String>, CryptoStoreError> {
        Ok(self
            .inner
            .get_device(self.user_id(), self.device_id())
            .await?
            .and_then(|d| d.display_name().to_owned()))
    }

    /// Get the read-only version of all the devices that the given user has.
    ///
    /// *Note*: This doesn't return our own device.
    pub async fn get_readonly_device(
        &self,
        user_id: &UserId,
        device_id: &DeviceId,
    ) -> Result<Option<ReadOnlyDevice>> {
        if user_id == self.user_id() && device_id == self.device_id() {
            Ok(None)
        } else {
            self.inner.get_device(user_id, device_id).await
        }
    }

    /// Get the read-only version of all the devices that the given user has.
    ///
    /// *Note*: This doesn't return our own device.
    pub async fn get_readonly_devices(
        &self,
        user_id: &UserId,
    ) -> Result<HashMap<DeviceIdBox, ReadOnlyDevice>> {
        self.inner.get_user_devices(user_id).await.map(|mut d| {
            if user_id == self.user_id() {
                d.remove(self.device_id());
            }
            d
        })
    }

    /// Get the read-only version of all the devices that the given user has.
    ///
    /// *Note*: This does also return our own device.
    pub async fn get_readonly_devices_unfiltered(
        &self,
        user_id: &UserId,
    ) -> Result<HashMap<DeviceIdBox, ReadOnlyDevice>> {
        self.inner.get_user_devices(user_id).await
    }

    /// Get a device for the given user with the given curve25519 key.
    ///
    /// *Note*: This doesn't return our own device.
    pub async fn get_device_from_curve_key(
        &self,
        user_id: &UserId,
        curve_key: &str,
    ) -> Result<Option<Device>> {
        self.get_user_devices(user_id).await.map(|d| {
            d.devices().find(|d| {
                d.get_key(DeviceKeyAlgorithm::Curve25519).map_or(false, |k| k == curve_key)
            })
        })
    }

    pub async fn get_user_devices(&self, user_id: &UserId) -> Result<UserDevices> {
        let mut devices = self.inner.get_user_devices(user_id).await?;

        if user_id == self.user_id() {
            devices.remove(self.device_id());
        }

        let own_identity =
            self.inner.get_user_identity(&self.user_id).await?.map(|i| i.own().cloned()).flatten();
        let device_owner_identity = self.inner.get_user_identity(user_id).await.ok().flatten();

        Ok(UserDevices {
            inner: devices,
            private_identity: self.identity.clone(),
            verification_machine: self.verification_machine.clone(),
            own_identity,
            device_owner_identity,
        })
    }

    pub async fn get_device(
        &self,
        user_id: &UserId,
        device_id: &DeviceId,
    ) -> Result<Option<Device>> {
        if user_id == self.user_id() && device_id == self.device_id() {
            Ok(None)
        } else {
            let own_identity = self
                .inner
                .get_user_identity(&self.user_id)
                .await?
                .map(|i| i.own().cloned())
                .flatten();
            let device_owner_identity = self.inner.get_user_identity(user_id).await?;

            Ok(self.inner.get_device(user_id, device_id).await?.map(|d| Device {
                inner: d,
                verification_machine: self.verification_machine.clone(),
                own_identity,
                device_owner_identity,
            }))
        }
    }

    pub async fn get_identity(&self, user_id: &UserId) -> Result<Option<UserIdentities>> {
        // let own_identity =
        // self.inner.get_user_identity(self.user_id()).await?.and_then(|i| i.own());
        Ok(if let Some(identity) = self.inner.get_user_identity(user_id).await? {
            Some(match identity {
                ReadOnlyUserIdentities::Own(i) => OwnUserIdentity {
                    inner: i,
                    verification_machine: self.verification_machine.clone(),
                }
                .into(),
                ReadOnlyUserIdentities::Other(i) => {
                    let own_identity =
                        self.inner.get_user_identity(self.user_id()).await?.and_then(|i| {
                            if let ReadOnlyUserIdentities::Own(i) = i {
                                Some(i)
                            } else {
                                None
                            }
                        });
                    UserIdentity {
                        inner: i,
                        verification_machine: self.verification_machine.clone(),
                        own_identity,
                    }
                    .into()
                }
            })
        } else {
            None
        })
    }

    /// Try to export the secret with the given secret name.
    ///
    /// The exported secret will be encoded as unpadded base64. Returns `Null`
    /// if the secret can't be found.
    ///
    /// # Arguments
    ///
    /// * `secret_name` - The name of the secret that should be exported.
    pub async fn export_secret(&self, secret_name: &SecretName) -> Option<String> {
        match secret_name {
            SecretName::CrossSigningMasterKey
            | SecretName::CrossSigningUserSigningKey
            | SecretName::CrossSigningSelfSigningKey => {
                self.identity.lock().await.export_secret(secret_name).await
            }
            SecretName::RecoveryKey => None,
            name => {
                warn!(secret =? name, "Unknown secret was requested");
                None
            }
        }
    }

    pub async fn import_cross_signing_keys(
        &self,
        export: CrossSigningKeyExport,
    ) -> Result<CrossSigningStatus, SecretImportError> {
        if let Some(public_identity) = self.get_identity(&self.user_id).await?.and_then(|i| i.own())
        {
            let identity = self.identity.lock().await;

            identity
                .import_secrets(
                    public_identity,
                    export.master_key.as_deref(),
                    export.self_signing_key.as_deref(),
                    export.user_signing_key.as_deref(),
                )
                .await?;

            let status = identity.status().await;
            info!(status =? status, "Successfully imported the private cross signing keys");

            let changes =
                Changes { private_identity: Some(identity.clone()), ..Default::default() };

            self.save_changes(changes).await?;
        }

        Ok(self.identity.lock().await.status().await)
    }

    pub async fn import_secret(
        &self,
        secret_name: &SecretName,
        secret: String,
    ) -> Result<(), SecretImportError> {
        let secret = zeroize::Zeroizing::new(secret);

        match secret_name {
            SecretName::CrossSigningMasterKey
            | SecretName::CrossSigningUserSigningKey
            | SecretName::CrossSigningSelfSigningKey => {
                if let Some(public_identity) =
                    self.get_identity(&self.user_id).await?.and_then(|i| i.own())
                {
                    let identity = self.identity.lock().await;

                    identity.import_secret(public_identity, secret_name, &secret).await?;
                    info!(
                        secret_name = secret_name.as_ref(),
                        "Successfully imported a private cross signing key"
                    );

                    let changes =
                        Changes { private_identity: Some(identity.clone()), ..Default::default() };

                    self.save_changes(changes).await?;
                }
            }
            SecretName::RecoveryKey => (),
            name => {
                warn!(secret =? name, "Tried to import an unknown secret");
            }
        }

        Ok(())
    }
}

impl Deref for Store {
    type Target = dyn CryptoStore;

    fn deref(&self) -> &Self::Target {
        &*self.inner
    }
}

#[derive(Debug, Error)]
/// The crypto store's error type.
pub enum CryptoStoreError {
    /// The account that owns the sessions, group sessions, and devices wasn't
    /// found.
    #[error("can't save/load sessions or group sessions in the store before an account is stored")]
    AccountUnset,

    /// Error in the internal database
    #[cfg(feature = "sled_cryptostore")]
    #[error(transparent)]
    Database(#[from] sled::Error),

    /// An IO error occurred.
    #[error(transparent)]
    Io(#[from] IoError),

    /// The underlying Olm Account operation returned an error.
    #[error(transparent)]
    OlmAccount(#[from] OlmAccountError),

    /// The underlying Olm session operation returned an error.
    #[error(transparent)]
    OlmSession(#[from] OlmSessionError),

    /// The underlying Olm group session operation returned an error.
    #[error(transparent)]
    OlmGroupSession(#[from] OlmGroupSessionError),

    /// A session time-stamp couldn't be loaded.
    #[error(transparent)]
    SessionUnpickling(#[from] SessionUnpicklingError),

    /// Failed to decrypt an pickled object.
    #[error("An object failed to be decrypted while unpickling")]
    UnpicklingError,

    /// A Matrix identifier failed to be validated.
    #[error(transparent)]
    IdentifierValidation(#[from] IdentifierValidationError),

    /// The store failed to (de)serialize a data type.
    #[error(transparent)]
    Serialization(#[from] SerdeError),
}

/// Trait abstracting a store that the `OlmMachine` uses to store cryptographic
/// keys.
#[cfg_attr(target_arch = "wasm32", async_trait(?Send))]
#[cfg_attr(not(target_arch = "wasm32"), async_trait)]
pub trait CryptoStore: AsyncTraitDeps {
    /// Load an account that was previously stored.
    async fn load_account(&self) -> Result<Option<ReadOnlyAccount>>;

    /// Save the given account in the store.
    ///
    /// # Arguments
    ///
    /// * `account` - The account that should be stored.
    async fn save_account(&self, account: ReadOnlyAccount) -> Result<()>;

    /// Try to load a private cross signing identity, if one is stored.
    async fn load_identity(&self) -> Result<Option<PrivateCrossSigningIdentity>>;

    /// Save the set of changes to the store.
    ///
    /// # Arguments
    ///
    /// * `changes` - The set of changes that should be stored.
    async fn save_changes(&self, changes: Changes) -> Result<()>;

    /// Get all the sessions that belong to the given sender key.
    ///
    /// # Arguments
    ///
    /// * `sender_key` - The sender key that was used to establish the sessions.
    async fn get_sessions(&self, sender_key: &str) -> Result<Option<Arc<Mutex<Vec<Session>>>>>;

    /// Get the inbound group session from our store.
    ///
    /// # Arguments
    /// * `room_id` - The room id of the room that the session belongs to.
    ///
    /// * `sender_key` - The sender key that sent us the session.
    ///
    /// * `session_id` - The unique id of the session.
    async fn get_inbound_group_session(
        &self,
        room_id: &RoomId,
        sender_key: &str,
        session_id: &str,
    ) -> Result<Option<InboundGroupSession>>;

    /// Get all the inbound group sessions we have stored.
    async fn get_inbound_group_sessions(&self) -> Result<Vec<InboundGroupSession>>;

    /// Get the outbound group sessions we have stored that is used for the
    /// given room.
    async fn get_outbound_group_sessions(
        &self,
        room_id: &RoomId,
    ) -> Result<Option<OutboundGroupSession>>;

    /// Is the given user already tracked.
    fn is_user_tracked(&self, user_id: &UserId) -> bool;

    /// Are there any tracked users that are marked as dirty.
    fn has_users_for_key_query(&self) -> bool;

    /// Set of users that we need to query keys for. This is a subset of
    /// the tracked users.
    fn users_for_key_query(&self) -> HashSet<UserId>;

    /// Get all tracked users we know about.
    fn tracked_users(&self) -> HashSet<UserId>;

    /// Add an user for tracking.
    ///
    /// Returns true if the user wasn't already tracked, false otherwise.
    ///
    /// # Arguments
    ///
    /// * `user` - The user that should be marked as tracked.
    ///
    /// * `dirty` - Should the user be also marked for a key query.
    async fn update_tracked_user(&self, user: &UserId, dirty: bool) -> Result<bool>;

    /// Get the device for the given user with the given device id.
    ///
    /// # Arguments
    ///
    /// * `user_id` - The user that the device belongs to.
    ///
    /// * `device_id` - The unique id of the device.
    async fn get_device(
        &self,
        user_id: &UserId,
        device_id: &DeviceId,
    ) -> Result<Option<ReadOnlyDevice>>;

    /// Get all the devices of the given user.
    ///
    /// # Arguments
    ///
    /// * `user_id` - The user for which we should get all the devices.
    async fn get_user_devices(
        &self,
        user_id: &UserId,
    ) -> Result<HashMap<DeviceIdBox, ReadOnlyDevice>>;

    /// Get the user identity that is attached to the given user id.
    ///
    /// # Arguments
    ///
    /// * `user_id` - The user for which we should get the identity.
    async fn get_user_identity(&self, user_id: &UserId) -> Result<Option<ReadOnlyUserIdentities>>;

    /// Check if a hash for an Olm message stored in the database.
    async fn is_message_known(&self, message_hash: &OlmMessageHash) -> Result<bool>;

    /// Get an outgoing secret request that we created that matches the given
    /// request id.
    ///
    /// # Arguments
    ///
    /// * `request_id` - The unique request id that identifies this outgoing
    /// secret request.
    async fn get_outgoing_secret_requests(&self, request_id: Uuid)
        -> Result<Option<GossipRequest>>;

    /// Get an outgoing key request that we created that matches the given
    /// requested key info.
    ///
    /// # Arguments
    ///
    /// * `key_info` - The key info of an outgoing secret request.
    async fn get_secret_request_by_info(
        &self,
        secret_info: &SecretInfo,
    ) -> Result<Option<GossipRequest>>;

    /// Get all outgoing secret requests that we have in the store.
    async fn get_unsent_secret_requests(&self) -> Result<Vec<GossipRequest>>;

    /// Delete an outgoing key request that we created that matches the given
    /// request id.
    ///
    /// # Arguments
    ///
    /// * `request_id` - The unique request id that identifies this outgoing key
    /// request.
    async fn delete_outgoing_secret_requests(&self, request_id: Uuid) -> Result<()>;
}