/*
 * SPDX-FileCopyrightText: 2020 Stalwart Labs LLC <hello@stalw.art>
 *
 * SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-SEL
 */

use std::{
    collections::BTreeMap,
    net::IpAddr,
    sync::{Arc, atomic::AtomicU32},
};

use ahash::AHashMap;
use common::{
    Inner, Server,
    auth::AccessToken,
    listener::{ServerInstance, SessionStream, limiter::InFlight},
};

use imap_proto::{
    Command,
    protocol::{ProtocolVersion, list::Attribute},
    receiver::Receiver,
};
use tokio::{
    io::{ReadHalf, WriteHalf},
    sync::watch,
};
use trc::AddContext;

pub mod client;
pub mod mailbox;
pub mod message;
pub mod session;

#[derive(Clone)]
pub struct ImapSessionManager {
    pub inner: Arc<Inner>,
}

impl ImapSessionManager {
    pub fn new(inner: Arc<Inner>) -> Self {
        Self { inner }
    }
}

pub struct Session<T: SessionStream> {
    pub server: Server,
    pub instance: Arc<ServerInstance>,
    pub receiver: Receiver<Command>,
    pub version: ProtocolVersion,
    pub state: State<T>,
    pub is_tls: bool,
    pub is_condstore: bool,
    pub is_qresync: bool,
    pub is_utf8: bool,
    pub stream_rx: ReadHalf<T>,
    pub stream_tx: Arc<tokio::sync::Mutex<WriteHalf<T>>>,
    pub in_flight: InFlight,
    pub remote_addr: IpAddr,
    pub session_id: u64,
}

pub struct SessionData<T: SessionStream> {
    pub account_id: u32,
    pub access_token: Arc<AccessToken>,
    pub server: Server,
    pub session_id: u64,
    pub mailboxes: parking_lot::Mutex<Vec<Account>>,
    pub stream_tx: Arc<tokio::sync::Mutex<WriteHalf<T>>>,
    pub state: AtomicU32,
    pub in_flight: Option<InFlight>,
}

pub struct SelectedMailbox {
    pub id: MailboxId,
    pub state: parking_lot::Mutex<MailboxState>,
    pub saved_search: parking_lot::Mutex<SavedSearch>,
    pub is_select: bool,
    pub is_condstore: bool,
}

#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)]
pub struct AccountId {
    pub account_id: u32,
    pub primary_id: u32,
}

#[derive(Debug, PartialEq, Eq, Hash, Clone, Copy)]
pub struct MailboxId {
    pub account_id: u32,
    pub mailbox_id: u32,
}

#[derive(Debug, Clone, Default)]
pub struct Account {
    pub account_id: u32,
    pub prefix: Option<String>,
    pub mailbox_names: BTreeMap<String, u32>,
    pub mailbox_state: AHashMap<u32, Mailbox>,
    pub last_change_id: u64,
}

#[derive(Debug, Default, Clone)]
pub struct Mailbox {
    pub has_children: bool,
    pub is_subscribed: bool,
    pub special_use: Option<Attribute>,
    pub total_messages: u64,
    pub total_unseen: u64,
    pub total_deleted: u64,
    pub total_deleted_storage: Option<u64>,
    pub uid_validity: u64,
    pub uid_next: u64,
    pub size: Option<u64>,
}

#[derive(Debug, Clone, Default)]
pub struct MailboxState {
    pub uid_max: u32,
    pub id_to_imap: AHashMap<u32, ImapId>,
    pub uid_to_id: AHashMap<u32, u32>,
    pub total_messages: usize,
    pub modseq: u64,
    pub next_state: Option<Box<NextMailboxState>>,
}

#[derive(Debug, Clone)]
pub struct NextMailboxState {
    pub next_state: MailboxState,
    pub deletions: Vec<ImapId>,
}

#[derive(Debug, Clone, Copy, Default)]
pub struct ImapId {
    pub uid: u32,
    pub seqnum: u32,
}

#[derive(Debug, Default)]
pub struct MailboxSync {
    pub added: Vec<String>,
    pub changed: Vec<String>,
    pub deleted: Vec<String>,
}

pub enum SavedSearch {
    InFlight {
        rx: watch::Receiver<Arc<Vec<ImapId>>>,
    },
    Results {
        items: Arc<Vec<ImapId>>,
    },
    None,
}

#[derive(Debug, Clone, Copy, Default)]
pub struct ImapUidToId {
    pub uid: u32,
    pub id: u32,
}

pub enum State<T: SessionStream> {
    NotAuthenticated {
        auth_failures: u32,
    },
    Authenticated {
        data: Arc<SessionData<T>>,
    },
    Selected {
        data: Arc<SessionData<T>>,
        mailbox: Arc<SelectedMailbox>,
    },
}

impl<T: SessionStream> State<T> {
    pub fn try_replace_stream_tx<U: SessionStream>(
        self,
        new_stream: Arc<tokio::sync::Mutex<WriteHalf<U>>>,
    ) -> Option<State<U>> {
        match self {
            State::NotAuthenticated { auth_failures } => {
                State::NotAuthenticated { auth_failures }.into()
            }
            State::Authenticated { data } => {
                Arc::try_unwrap(data).ok().map(|data| State::Authenticated {
                    data: Arc::new(data.replace_stream_tx(new_stream)),
                })
            }
            State::Selected { data, mailbox } => {
                Arc::try_unwrap(data).ok().map(|data| State::Selected {
                    data: Arc::new(data.replace_stream_tx(new_stream)),
                    mailbox,
                })
            }
        }
    }
}

impl<T: SessionStream> SessionData<T> {
    pub async fn get_access_token(&self) -> trc::Result<Arc<AccessToken>> {
        self.server
            .get_access_token(self.account_id)
            .await
            .caused_by(trc::location!())
    }

    pub fn replace_stream_tx<U: SessionStream>(
        self,
        new_stream: Arc<tokio::sync::Mutex<WriteHalf<U>>>,
    ) -> SessionData<U> {
        SessionData {
            account_id: self.account_id,
            server: self.server,
            session_id: self.session_id,
            mailboxes: self.mailboxes,
            stream_tx: new_stream,
            state: self.state,
            in_flight: self.in_flight,
            access_token: self.access_token,
        }
    }
}

impl MailboxState {
    pub fn map_result_id(&self, document_id: u32, is_uid: bool) -> Option<(u32, ImapId)> {
        if let Some(imap_id) = self.id_to_imap.get(&document_id) {
            Some((if is_uid { imap_id.uid } else { imap_id.seqnum }, *imap_id))
        } else if is_uid {
            self.next_state.as_ref().and_then(|s| {
                s.next_state
                    .id_to_imap
                    .get(&document_id)
                    .map(|imap_id| (imap_id.uid, *imap_id))
            })
        } else {
            None
        }
    }
}
