ferogram 0.3.8

// Copyright (c) Ankit Chaubey <ankitchaubey.dev@gmail.com>
//
// ferogram: async Telegram MTProto client in Rust
// https://github.com/ankit-chaubey/ferogram
//
// Licensed under either the MIT License or the Apache License 2.0.
// See the LICENSE-MIT or LICENSE-APACHE file in this repository:
// https://github.com/ankit-chaubey/ferogram
//
// Feel free to use, modify, and share this code.
// Please keep this notice when redistributing.

use std::time::Duration;

// ---------- Instant (real vs test-time fake) ----------

#[cfg(not(test))]
pub(super) use std::time::Instant;

/// Thread-local fake clock used in tests so we never need `thread::sleep`.
///
/// The production code in mod.rs simply calls `Instant::now()`; under
/// `cfg(test)` that resolves to the controlled fake below.
#[cfg(test)]
pub(super) mod fake_clock {
    use std::cell::RefCell;
    use std::ops::Add;
    use std::time::Duration;

    thread_local! {
        static NOW: RefCell<Duration> = const { RefCell::new(Duration::ZERO) };
    }

    /// A fake `Instant` backed by a thread-local counter.
    #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
    pub struct Instant(pub Duration);

    impl Instant {
        pub fn now() -> Self {
            NOW.with_borrow(|d| Self(*d))
        }

        /// Helper used only in tests to observe the raw duration.
        pub fn elapsed_secs(&self) -> u64 {
            self.0.as_secs()
        }
    }

    impl Add<Duration> for Instant {
        type Output = Instant;
        fn add(self, rhs: Duration) -> Instant {
            Instant(self.0 + rhs)
        }
    }

    /// Reset the fake clock to zero.  Call at the start of every test.
    pub fn reset_time() {
        NOW.with_borrow_mut(|d| *d = Duration::ZERO);
    }

    /// Advance the fake clock by `dur`.
    pub fn advance_time_by(dur: Duration) {
        NOW.with_borrow_mut(|d| *d += dur);
    }
}

#[cfg(test)]
pub(super) use fake_clock::Instant;

// Allow reader_loop code (which calls `check_deadlines().into()`) to compile
// under `cfg(test)`.  The reader loop never actually runs in unit-tests, so
// this conversion just returns a reasonable stand-in.
#[cfg(test)]
impl From<fake_clock::Instant> for tokio::time::Instant {
    fn from(i: fake_clock::Instant) -> Self {
        tokio::time::Instant::now()
            .checked_add(i.0)
            .unwrap_or_else(tokio::time::Instant::now)
    }
}

use ferogram_tl_types as tl;

/// Telegram sends `seq` equal to `0` when "it doesn't matter", so we use that value too.
pub(super) const NO_SEQ: i32 = 0;

/// `qts` of `0` means "ordering should be ignored" for that update.
pub(super) const NO_PTS: i32 = 0;

/// Sentinel `date` value when constructing dummy Updates containers.
pub(super) const NO_DATE: i32 = 0;

/// Wait up to 0.5 s before declaring a gap a real gap.
pub(super) const POSSIBLE_GAP_TIMEOUT: Duration = Duration::from_millis(500);

/// After how long without updates the client will proactively fetch updates.
///
/// Documentation recommends 15 minutes without updates.
pub(super) const NO_UPDATES_TIMEOUT: Duration = Duration::from_secs(15 * 60);

// Keys

/// A sortable message-box entry key.
#[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord)]
pub(crate) enum Key {
    Common,
    Secondary,
    Channel(i64),
}

// Live entry

/// A single live entry inside [`MessageBoxes`].
#[derive(Debug)]
pub(super) struct LiveEntry {
    pub(super) key: Key,
    pub(super) pts: i32,
    /// Next instant when we forcibly fetch difference if no updates arrived by then.
    pub(super) deadline: Instant,
    /// If set, we detected a possible gap and are waiting to see if it resolves itself.
    pub(super) possible_gap: Option<PossibleGap>,
}

impl LiveEntry {
    pub(super) fn effective_deadline(&self) -> Instant {
        match &self.possible_gap {
            Some(gap) => gap.deadline.min(self.deadline),
            None => self.deadline,
        }
    }
}

// PossibleGap

#[derive(Debug)]
pub(super) struct PossibleGap {
    pub(super) deadline: Instant,
    /// Pending updates (those with a higher pts that are creating the gap).
    pub(super) updates: Vec<tl::enums::Update>,
}

// MessageBoxes (container)

/// All live message boxes.  The single authority for update-gap detection.
///
/// See <https://core.telegram.org/api/updates#message-related-event-sequences>.
#[derive(Debug)]
pub struct MessageBoxes {
    /// Live entries sorted by key.
    pub(super) entries: Vec<LiveEntry>,

    pub(super) date: i32,
    pub(super) seq: i32,

    /// Entries for which we must currently fetch difference.
    pub(super) getting_diff_for: Vec<Key>,

    /// Cached minimum deadline across all entries.
    pub(super) next_deadline: Instant,
}

// PtsInfo – per-update pts metadata

#[derive(Debug)]
pub(super) struct PtsInfo {
    pub(super) key: Key,
    pub(super) pts: i32,
    pub(super) count: i32,
}

// Gap error

/// Returned by [`MessageBoxes::process_updates`] when a gap is detected.
#[derive(Debug, PartialEq, Eq)]
pub struct Gap;

// UpdatesLike

/// Anything that should be treated as an update batch.
#[derive(Debug)]
pub enum UpdatesLike {
    /// Normal push update from the socket.
    Updates(Box<tl::enums::Updates>),
    /// The connection was closed; a gap may now exist.
    ConnectionClosed,
    /// A received update could not be parsed (unknown constructor, truncation).
    MalformedUpdates,
    /// RPC response for `messages.deleteMessages` / `messages.readHistory` etc.
    AffectedMessages(tl::types::messages::AffectedMessages),
    /// Same as above but channel-specific.
    AffectedChannelMessages {
        affected: tl::types::messages::AffectedMessages,
        channel_id: i64,
    },
}

// Public update state types (for persisting)

/// Per-channel pts snapshot.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ChannelState {
    pub id: i64,
    pub pts: i32,
}

/// Full snapshot of the update state for session persistence.
#[derive(Debug, Clone, Default, PartialEq, Eq)]
pub struct UpdatesStateSnap {
    pub pts: i32,
    pub qts: i32,
    pub date: i32,
    pub seq: i32,
    pub channels: Vec<ChannelState>,
}

// Pair type

pub(super) type UpdateAndPeers = (
    Vec<tl::enums::Update>,
    Vec<tl::enums::User>,
    Vec<tl::enums::Chat>,
);