//! The `window` module defines data structure for storing the tail of the ledger.
//!
use crate::packet::SharedBlob;
use solana_sdk::pubkey::Pubkey;
use std::cmp;
use std::sync::{Arc, RwLock};

#[derive(Default, Clone)]
pub struct WindowSlot {
    pub data: Option<SharedBlob>,
    pub coding: Option<SharedBlob>,
    pub leader_unknown: bool,
}

impl WindowSlot {
    fn blob_index(&self) -> Option<u64> {
        match self.data {
            Some(ref blob) => Some(blob.read().unwrap().index()),
            None => None,
        }
    }

    fn clear_data(&mut self) {
        self.data.take();
    }
}

type Window = Vec<WindowSlot>;
pub type SharedWindow = Arc<RwLock<Window>>;

#[derive(Debug)]
pub struct WindowIndex {
    pub data: u64,
    pub coding: u64,
}

pub trait WindowUtil {
    /// Finds available slots, clears them, and returns their indices.
    fn clear_slots(&mut self, consumed: u64, received: u64) -> Vec<u64>;

    fn window_size(&self) -> u64;

    fn print(&self, id: &Pubkey, consumed: u64) -> String;

    fn blob_idx_in_window(&self, id: &Pubkey, pix: u64, consumed: u64, received: &mut u64) -> bool;
}

impl WindowUtil for Window {
    fn clear_slots(&mut self, consumed: u64, received: u64) -> Vec<u64> {
        (consumed..received)
            .filter_map(|pix| {
                let i = (pix % self.window_size()) as usize;
                if let Some(blob_idx) = self[i].blob_index() {
                    if blob_idx == pix {
                        return None;
                    }
                }
                self[i].clear_data();
                Some(pix)
            })
            .collect()
    }

    fn blob_idx_in_window(&self, id: &Pubkey, pix: u64, consumed: u64, received: &mut u64) -> bool {
        // Prevent receive window from running over
        // Got a blob which has already been consumed, skip it
        // probably from a repair window request
        if pix < consumed {
            trace!(
                "{}: received: {} but older than consumed: {} skipping..",
                id,
                pix,
                consumed
            );
            false
        } else {
            // received always has to be updated even if we don't accept the packet into
            //  the window.  The worst case here is the server *starts* outside
            //  the window, none of the packets it receives fits in the window
            //  and repair requests (which are based on received) are never generated
            *received = cmp::max(pix, *received);

            if pix >= consumed + self.window_size() {
                trace!(
                    "{}: received: {} will overrun window: {} skipping..",
                    id,
                    pix,
                    consumed + self.window_size()
                );
                false
            } else {
                true
            }
        }
    }

    fn window_size(&self) -> u64 {
        self.len() as u64
    }

    fn print(&self, id: &Pubkey, consumed: u64) -> String {
        let pointer: Vec<_> = self
            .iter()
            .enumerate()
            .map(|(i, _v)| {
                if i == (consumed % self.window_size()) as usize {
                    "V"
                } else {
                    " "
                }
            })
            .collect();

        let buf: Vec<_> = self
            .iter()
            .map(|v| {
                if v.data.is_none() && v.coding.is_none() {
                    "O"
                } else if v.data.is_some() && v.coding.is_some() {
                    "D"
                } else if v.data.is_some() {
                    // coding.is_none()
                    "d"
                } else {
                    // data.is_none()
                    "c"
                }
            })
            .collect();
        format!(
            "\n{}: WINDOW ({}): {}\n{}: WINDOW ({}): {}",
            id,
            consumed,
            pointer.join(""),
            id,
            consumed,
            buf.join("")
        )
    }
}

fn calculate_max_repair(
    num_peers: u64,
    consumed: u64,
    received: u64,
    times: usize,
    is_next_leader: bool,
    window_size: u64,
) -> u64 {
    // Calculate the highest blob index that this node should have already received
    // via avalanche. The avalanche splits data stream into nodes and each node retransmits
    // the data to their peer nodes. So there's a possibility that a blob (with index lower
    // than current received index) is being retransmitted by a peer node.
    let max_repair = if times >= 8 || is_next_leader {
        // if repair backoff is getting high, or if we are the next leader,
        // don't wait for avalanche
        cmp::max(consumed, received)
    } else {
        cmp::max(consumed, received.saturating_sub(num_peers))
    };

    // This check prevents repairing a blob that will cause window to roll over. Even if
    // the highes_lost blob is actually missing, asking to repair it might cause our
    // current window to move past other missing blobs
    cmp::min(consumed + window_size - 1, max_repair)
}

pub fn new_window(window_size: usize) -> Window {
    (0..window_size).map(|_| WindowSlot::default()).collect()
}

pub fn default_window() -> Window {
    (0..2048).map(|_| WindowSlot::default()).collect()
}

#[cfg(test)]
mod test {
    use crate::packet::{Blob, Packet, Packets, SharedBlob, PACKET_DATA_SIZE};
    use crate::streamer::{receiver, responder, PacketReceiver};
    use crate::window::{calculate_max_repair, new_window, Window, WindowUtil};
    use solana_sdk::pubkey::Pubkey;
    use std::io;
    use std::io::Write;
    use std::net::UdpSocket;
    use std::sync::atomic::{AtomicBool, Ordering};
    use std::sync::mpsc::channel;
    use std::sync::Arc;
    use std::time::Duration;

    fn get_msgs(r: PacketReceiver, num: &mut usize) {
        for _t in 0..5 {
            let timer = Duration::new(1, 0);
            match r.recv_timeout(timer) {
                Ok(m) => *num += m.read().unwrap().packets.len(),
                e => info!("error {:?}", e),
            }
            if *num == 10 {
                break;
            }
        }
    }
    #[test]
    pub fn streamer_debug() {
        write!(io::sink(), "{:?}", Packet::default()).unwrap();
        write!(io::sink(), "{:?}", Packets::default()).unwrap();
        write!(io::sink(), "{:?}", Blob::default()).unwrap();
    }
    #[test]
    pub fn streamer_send_test() {
        let read = UdpSocket::bind("127.0.0.1:0").expect("bind");
        read.set_read_timeout(Some(Duration::new(1, 0))).unwrap();

        let addr = read.local_addr().unwrap();
        let send = UdpSocket::bind("127.0.0.1:0").expect("bind");
        let exit = Arc::new(AtomicBool::new(false));
        let (s_reader, r_reader) = channel();
        let t_receiver = receiver(Arc::new(read), &exit, s_reader, "window-streamer-test");
        let t_responder = {
            let (s_responder, r_responder) = channel();
            let t_responder = responder("streamer_send_test", Arc::new(send), r_responder);
            let mut msgs = Vec::new();
            for i in 0..10 {
                let b = SharedBlob::default();
                {
                    let mut w = b.write().unwrap();
                    w.data[0] = i as u8;
                    w.meta.size = PACKET_DATA_SIZE;
                    w.meta.set_addr(&addr);
                }
                msgs.push(b);
            }
            s_responder.send(msgs).expect("send");
            t_responder
        };

        let mut num = 0;
        get_msgs(r_reader, &mut num);
        assert_eq!(num, 10);
        exit.store(true, Ordering::Relaxed);
        t_receiver.join().expect("join");
        t_responder.join().expect("join");
    }

    #[test]
    pub fn test_calculate_max_repair() {
        const WINDOW_SIZE: u64 = 200;

        assert_eq!(calculate_max_repair(0, 10, 90, 0, false, WINDOW_SIZE), 90);
        assert_eq!(calculate_max_repair(15, 10, 90, 32, false, WINDOW_SIZE), 90);
        assert_eq!(calculate_max_repair(15, 10, 90, 0, false, WINDOW_SIZE), 75);
        assert_eq!(calculate_max_repair(90, 10, 90, 0, false, WINDOW_SIZE), 10);
        assert_eq!(calculate_max_repair(90, 10, 50, 0, false, WINDOW_SIZE), 10);
        assert_eq!(calculate_max_repair(90, 10, 99, 0, false, WINDOW_SIZE), 10);
        assert_eq!(calculate_max_repair(90, 10, 101, 0, false, WINDOW_SIZE), 11);
        assert_eq!(
            calculate_max_repair(90, 10, 95 + WINDOW_SIZE, 0, false, WINDOW_SIZE),
            WINDOW_SIZE + 5
        );
        assert_eq!(
            calculate_max_repair(90, 10, 99 + WINDOW_SIZE, 0, false, WINDOW_SIZE),
            WINDOW_SIZE + 9
        );
        assert_eq!(
            calculate_max_repair(90, 10, 100 + WINDOW_SIZE, 0, false, WINDOW_SIZE),
            WINDOW_SIZE + 9
        );
        assert_eq!(
            calculate_max_repair(90, 10, 120 + WINDOW_SIZE, 0, false, WINDOW_SIZE),
            WINDOW_SIZE + 9
        );
        assert_eq!(
            calculate_max_repair(50, 100, 50 + WINDOW_SIZE, 0, false, WINDOW_SIZE),
            WINDOW_SIZE
        );
        assert_eq!(
            calculate_max_repair(50, 100, 50 + WINDOW_SIZE, 0, true, WINDOW_SIZE),
            50 + WINDOW_SIZE
        );
    }

    fn wrap_blob_idx_in_window(
        window: &Window,
        id: &Pubkey,
        pix: u64,
        consumed: u64,
        received: u64,
    ) -> (bool, u64) {
        let mut received = received;
        let is_in_window = window.blob_idx_in_window(&id, pix, consumed, &mut received);
        (is_in_window, received)
    }
    #[test]
    pub fn test_blob_idx_in_window() {
        let id = Pubkey::default();
        const WINDOW_SIZE: u64 = 200;
        let window = new_window(WINDOW_SIZE as usize);

        assert_eq!(
            wrap_blob_idx_in_window(&window, &id, 90 + WINDOW_SIZE, 90, 100),
            (false, 90 + WINDOW_SIZE)
        );
        assert_eq!(
            wrap_blob_idx_in_window(&window, &id, 91 + WINDOW_SIZE, 90, 100),
            (false, 91 + WINDOW_SIZE)
        );
        assert_eq!(
            wrap_blob_idx_in_window(&window, &id, 89, 90, 100),
            (false, 100)
        );

        assert_eq!(
            wrap_blob_idx_in_window(&window, &id, 91, 90, 100),
            (true, 100)
        );
        assert_eq!(
            wrap_blob_idx_in_window(&window, &id, 101, 90, 100),
            (true, 101)
        );
    }
}