use alloc::{collections::BTreeMap, rc::Rc, string::String};
use core::cell::RefCell;

use io::{Cursor, ProtoRead};
use libboard_artiq::{drtio_routing, pl::csr};
use libboard_zynq::timer::GlobalTimer;
use libconfig::Config;
use libcortex_a9::mutex::Mutex;
use log::warn;

static mut RTIO_DEVICE_MAP: BTreeMap<u32, String> = BTreeMap::new();

#[cfg(has_drtio)]
pub mod drtio {
    use alloc::vec::Vec;

    use embedded_hal::blocking::delay::DelayMs;
    use libasync::{delay, task};
    use libboard_artiq::{drtioaux::Error, drtioaux_async, drtioaux_async::Packet, drtioaux_proto::DMA_TRACE_MAX_SIZE};
    use libboard_zynq::time::Milliseconds;
    use log::{error, info, warn};

    use super::*;
    use crate::{rtio_dma::remote_dma, ASYNC_ERROR_BUSY, ASYNC_ERROR_COLLISION, ASYNC_ERROR_SEQUENCE_ERROR,
                SEEN_ASYNC_ERRORS};

    pub fn startup(
        aux_mutex: &Rc<Mutex<bool>>,
        routing_table: &Rc<RefCell<drtio_routing::RoutingTable>>,
        up_destinations: &Rc<RefCell<[bool; drtio_routing::DEST_COUNT]>>,
        timer: GlobalTimer,
    ) {
        let aux_mutex = aux_mutex.clone();
        let routing_table = routing_table.clone();
        let up_destinations = up_destinations.clone();
        task::spawn(async move {
            let routing_table = routing_table.borrow();
            link_task(&aux_mutex, &routing_table, &up_destinations, timer).await;
        });
    }

    async fn link_rx_up(linkno: u8) -> bool {
        let linkno = linkno as usize;
        unsafe { (csr::DRTIO[linkno].rx_up_read)() == 1 }
    }

    async fn recv_aux_timeout(linkno: u8, timeout: u64, timer: GlobalTimer) -> Result<Packet, &'static str> {
        if !link_rx_up(linkno).await {
            return Err("link went down");
        }
        match drtioaux_async::recv_timeout(linkno, Some(timeout), timer).await {
            Ok(packet) => return Ok(packet),
            Err(Error::TimedOut) => return Err("timed out"),
            Err(_) => return Err("aux packet error"),
        }
    }

    pub async fn aux_transact(
        aux_mutex: &Mutex<bool>,
        linkno: u8,
        request: &Packet,
        timer: GlobalTimer,
    ) -> Result<Packet, &'static str> {
        if !link_rx_up(linkno).await {
            return Err("link went down");
        }
        let _lock = aux_mutex.async_lock().await;
        drtioaux_async::send(linkno, request).await.unwrap();
        loop {
            let reply = recv_aux_timeout(linkno, 200, timer).await;
            match reply {
                Ok(Packet::DmaPlaybackStatus {
                    id,
                    destination,
                    error,
                    channel,
                    timestamp,
                }) => {
                    remote_dma::playback_done(id, destination, error, channel, timestamp).await;
                }
                Ok(packet) => return Ok(packet),
                Err(e) => return Err(e),
            }
        }
    }

    async fn drain_buffer(linkno: u8, draining_time: Milliseconds, timer: GlobalTimer) {
        let max_time = timer.get_time() + draining_time;
        loop {
            if timer.get_time() > max_time {
                return;
            } //could this be cut short?
            let _ = drtioaux_async::recv(linkno).await;
        }
    }

    async fn ping_remote(aux_mutex: &Rc<Mutex<bool>>, linkno: u8, timer: GlobalTimer) -> u32 {
        let mut count = 0;
        loop {
            if !link_rx_up(linkno).await {
                return 0;
            }
            count += 1;
            if count > 100 {
                return 0;
            }
            let reply = aux_transact(aux_mutex, linkno, &Packet::EchoRequest, timer).await;
            match reply {
                Ok(Packet::EchoReply) => {
                    // make sure receive buffer is drained
                    let draining_time = Milliseconds(200);
                    drain_buffer(linkno, draining_time, timer).await;
                    return count;
                }
                _ => {}
            }
        }
    }

    async fn sync_tsc(aux_mutex: &Rc<Mutex<bool>>, linkno: u8, timer: GlobalTimer) -> Result<(), &'static str> {
        let _lock = aux_mutex.async_lock().await;

        unsafe {
            (csr::DRTIO[linkno as usize].set_time_write)(1);
            while (csr::DRTIO[linkno as usize].set_time_read)() == 1 {}
        }
        // TSCAck is the only aux packet that is sent spontaneously
        // by the satellite, in response to a TSC set on the RT link.
        let reply = recv_aux_timeout(linkno, 10000, timer).await?;
        if reply == Packet::TSCAck {
            return Ok(());
        } else {
            return Err("unexpected reply");
        }
    }

    async fn load_routing_table(
        aux_mutex: &Rc<Mutex<bool>>,
        linkno: u8,
        routing_table: &drtio_routing::RoutingTable,
        timer: GlobalTimer,
    ) -> Result<(), &'static str> {
        for i in 0..drtio_routing::DEST_COUNT {
            let reply = aux_transact(
                aux_mutex,
                linkno,
                &Packet::RoutingSetPath {
                    destination: i as u8,
                    hops: routing_table.0[i],
                },
                timer,
            )
            .await?;
            if reply != Packet::RoutingAck {
                return Err("unexpected reply");
            }
        }
        Ok(())
    }

    async fn set_rank(
        aux_mutex: &Rc<Mutex<bool>>,
        linkno: u8,
        rank: u8,
        timer: GlobalTimer,
    ) -> Result<(), &'static str> {
        let reply = aux_transact(aux_mutex, linkno, &Packet::RoutingSetRank { rank: rank }, timer).await?;
        if reply != Packet::RoutingAck {
            return Err("unexpected reply");
        }
        Ok(())
    }

    async fn init_buffer_space(destination: u8, linkno: u8) {
        let linkno = linkno as usize;
        unsafe {
            (csr::DRTIO[linkno].destination_write)(destination);
            (csr::DRTIO[linkno].force_destination_write)(1);
            (csr::DRTIO[linkno].o_get_buffer_space_write)(1);
            while (csr::DRTIO[linkno].o_wait_read)() == 1 {}
            info!(
                "[DEST#{}] buffer space is {}",
                destination,
                (csr::DRTIO[linkno].o_dbg_buffer_space_read)()
            );
            (csr::DRTIO[linkno].force_destination_write)(0);
        }
    }

    async fn process_unsolicited_aux(aux_mutex: &Rc<Mutex<bool>>, linkno: u8) {
        let _lock = aux_mutex.async_lock().await;
        match drtioaux_async::recv(linkno).await {
            Ok(Some(Packet::DmaPlaybackStatus {
                id,
                destination,
                error,
                channel,
                timestamp,
            })) => remote_dma::playback_done(id, destination, error, channel, timestamp).await,
            Ok(Some(packet)) => warn!("[LINK#{}] unsolicited aux packet: {:?}", linkno, packet),
            Ok(None) => (),
            Err(_) => warn!("[LINK#{}] aux packet error", linkno),
        }
    }

    async fn process_local_errors(linkno: u8) {
        let errors;
        let linkidx = linkno as usize;
        unsafe {
            errors = (csr::DRTIO[linkidx].protocol_error_read)();
            (csr::DRTIO[linkidx].protocol_error_write)(errors);
        }
        if errors != 0 {
            error!("[LINK#{}] error(s) found (0x{:02x}):", linkno, errors);
            if errors & 1 != 0 {
                error!("[LINK#{}] received packet of an unknown type", linkno);
            }
            if errors & 2 != 0 {
                error!("[LINK#{}] received truncated packet", linkno);
            }
            if errors & 4 != 0 {
                error!("[LINK#{}] timeout attempting to get remote buffer space", linkno);
            }
        }
    }

    async fn destination_set_up(
        routing_table: &drtio_routing::RoutingTable,
        up_destinations: &Rc<RefCell<[bool; drtio_routing::DEST_COUNT]>>,
        destination: u8,
        up: bool,
    ) {
        let mut up_destinations = up_destinations.borrow_mut();
        up_destinations[destination as usize] = up;
        if up {
            drtio_routing::interconnect_enable(routing_table, 0, destination);
            info!("[DEST#{}] destination is up", destination);
        } else {
            drtio_routing::interconnect_disable(destination);
            info!("[DEST#{}] destination is down", destination);
        }
    }

    async fn destination_up(up_destinations: &Rc<RefCell<[bool; drtio_routing::DEST_COUNT]>>, destination: u8) -> bool {
        let up_destinations = up_destinations.borrow();
        up_destinations[destination as usize]
    }

    async fn destination_survey(
        aux_mutex: &Rc<Mutex<bool>>,
        routing_table: &drtio_routing::RoutingTable,
        up_links: &[bool],
        up_destinations: &Rc<RefCell<[bool; drtio_routing::DEST_COUNT]>>,
        timer: GlobalTimer,
    ) {
        for destination in 0..drtio_routing::DEST_COUNT {
            let hop = routing_table.0[destination][0];
            let destination = destination as u8;

            if hop == 0 {
                /* local RTIO */
                if !destination_up(up_destinations, destination).await {
                    destination_set_up(routing_table, up_destinations, destination, true).await;
                }
            } else if hop as usize <= csr::DRTIO.len() {
                let linkno = hop - 1;
                if destination_up(up_destinations, destination).await {
                    if up_links[linkno as usize] {
                        let reply = aux_transact(
                            aux_mutex,
                            linkno,
                            &Packet::DestinationStatusRequest {
                                destination: destination,
                            },
                            timer,
                        )
                        .await;
                        match reply {
                            Ok(Packet::DestinationDownReply) => {
                                destination_set_up(routing_table, up_destinations, destination, false).await;
                                remote_dma::destination_changed(aux_mutex, routing_table, timer, destination, false)
                                    .await;
                            }
                            Ok(Packet::DestinationOkReply) => (),
                            Ok(Packet::DestinationSequenceErrorReply { channel }) => {
                                error!(
                                    "[DEST#{}] RTIO sequence error involving channel 0x{:04x}:{}",
                                    destination,
                                    channel,
                                    resolve_channel_name(channel as u32)
                                );
                                unsafe { SEEN_ASYNC_ERRORS |= ASYNC_ERROR_SEQUENCE_ERROR };
                            }
                            Ok(Packet::DestinationCollisionReply { channel }) => {
                                error!(
                                    "[DEST#{}] RTIO collision involving channel 0x{:04x}:{}",
                                    destination,
                                    channel,
                                    resolve_channel_name(channel as u32)
                                );
                                unsafe { SEEN_ASYNC_ERRORS |= ASYNC_ERROR_COLLISION };
                            }
                            Ok(Packet::DestinationBusyReply { channel }) => {
                                error!(
                                    "[DEST#{}] RTIO busy error involving channel 0x{:04x}:{}",
                                    destination,
                                    channel,
                                    resolve_channel_name(channel as u32)
                                );
                                unsafe { SEEN_ASYNC_ERRORS |= ASYNC_ERROR_BUSY };
                            }
                            Ok(packet) => error!("[DEST#{}] received unexpected aux packet: {:?}", destination, packet),
                            Err(e) => error!("[DEST#{}] communication failed ({})", destination, e),
                        }
                    } else {
                        destination_set_up(routing_table, up_destinations, destination, false).await;
                        remote_dma::destination_changed(aux_mutex, routing_table, timer, destination, false).await;
                    }
                } else {
                    if up_links[linkno as usize] {
                        let reply = aux_transact(
                            aux_mutex,
                            linkno,
                            &Packet::DestinationStatusRequest {
                                destination: destination,
                            },
                            timer,
                        )
                        .await;
                        match reply {
                            Ok(Packet::DestinationDownReply) => (),
                            Ok(Packet::DestinationOkReply) => {
                                destination_set_up(routing_table, up_destinations, destination, true).await;
                                init_buffer_space(destination as u8, linkno).await;
                                remote_dma::destination_changed(aux_mutex, routing_table, timer, destination, true)
                                    .await;
                            }
                            Ok(packet) => error!("[DEST#{}] received unexpected aux packet: {:?}", destination, packet),
                            Err(e) => error!("[DEST#{}] communication failed ({})", destination, e),
                        }
                    }
                }
            }
        }
    }

    pub async fn link_task(
        aux_mutex: &Rc<Mutex<bool>>,
        routing_table: &drtio_routing::RoutingTable,
        up_destinations: &Rc<RefCell<[bool; drtio_routing::DEST_COUNT]>>,
        timer: GlobalTimer,
    ) {
        let mut up_links = [false; csr::DRTIO.len()];
        loop {
            for linkno in 0..csr::DRTIO.len() {
                let linkno = linkno as u8;
                if up_links[linkno as usize] {
                    /* link was previously up */
                    if link_rx_up(linkno).await {
                        process_unsolicited_aux(aux_mutex, linkno).await;
                        process_local_errors(linkno).await;
                    } else {
                        info!("[LINK#{}] link is down", linkno);
                        up_links[linkno as usize] = false;
                    }
                } else {
                    /* link was previously down */
                    if link_rx_up(linkno).await {
                        info!("[LINK#{}] link RX became up, pinging", linkno);
                        let ping_count = ping_remote(aux_mutex, linkno, timer).await;
                        if ping_count > 0 {
                            info!("[LINK#{}] remote replied after {} packets", linkno, ping_count);
                            up_links[linkno as usize] = true;
                            if let Err(e) = sync_tsc(aux_mutex, linkno, timer).await {
                                error!("[LINK#{}] failed to sync TSC ({})", linkno, e);
                            }
                            if let Err(e) = load_routing_table(aux_mutex, linkno, routing_table, timer).await {
                                error!("[LINK#{}] failed to load routing table ({})", linkno, e);
                            }
                            if let Err(e) = set_rank(aux_mutex, linkno, 1 as u8, timer).await {
                                error!("[LINK#{}] failed to set rank ({})", linkno, e);
                            }
                            info!("[LINK#{}] link initialization completed", linkno);
                        } else {
                            error!("[LINK#{}] ping failed", linkno);
                        }
                    }
                }
            }
            destination_survey(aux_mutex, routing_table, &up_links, up_destinations, timer).await;
            let mut countdown = timer.countdown();
            delay(&mut countdown, Milliseconds(200)).await;
        }
    }

    #[allow(dead_code)]
    pub fn reset(aux_mutex: Rc<Mutex<bool>>, mut timer: GlobalTimer) {
        for linkno in 0..csr::DRTIO.len() {
            unsafe {
                (csr::DRTIO[linkno].reset_write)(1);
            }
        }
        timer.delay_ms(1);
        for linkno in 0..csr::DRTIO.len() {
            unsafe {
                (csr::DRTIO[linkno].reset_write)(0);
            }
        }

        for linkno in 0..csr::DRTIO.len() {
            let linkno = linkno as u8;
            if task::block_on(link_rx_up(linkno)) {
                let reply = task::block_on(aux_transact(&aux_mutex, linkno, &Packet::ResetRequest, timer));
                match reply {
                    Ok(Packet::ResetAck) => (),
                    Ok(_) => error!("[LINK#{}] reset failed, received unexpected aux packet", linkno),
                    Err(e) => error!("[LINK#{}] reset failed, aux packet error ({})", linkno, e),
                }
            }
        }
    }

    pub async fn ddma_upload_trace(
        aux_mutex: &Rc<Mutex<bool>>,
        routing_table: &drtio_routing::RoutingTable,
        timer: GlobalTimer,
        id: u32,
        destination: u8,
        trace: &Vec<u8>,
    ) -> Result<(), &'static str> {
        let linkno = routing_table.0[destination as usize][0] - 1;
        let mut i = 0;
        while i < trace.len() {
            let mut trace_slice: [u8; DMA_TRACE_MAX_SIZE] = [0; DMA_TRACE_MAX_SIZE];
            let len: usize = if i + DMA_TRACE_MAX_SIZE < trace.len() {
                DMA_TRACE_MAX_SIZE
            } else {
                trace.len() - i
            } as usize;
            let last = i + len == trace.len();
            trace_slice[..len].clone_from_slice(&trace[i..i + len]);
            i += len;
            let reply = aux_transact(
                aux_mutex,
                linkno,
                &Packet::DmaAddTraceRequest {
                    id: id,
                    destination: destination,
                    last: last,
                    length: len as u16,
                    trace: trace_slice,
                },
                timer,
            )
            .await;
            match reply {
                Ok(Packet::DmaAddTraceReply { succeeded: true }) => (),
                Ok(Packet::DmaAddTraceReply { succeeded: false }) => {
                    return Err("error adding trace on satellite");
                }
                Ok(_) => {
                    return Err("adding DMA trace failed, unexpected aux packet");
                }
                Err(_) => {
                    return Err("adding DMA trace failed, aux error");
                }
            }
        }
        Ok(())
    }

    pub async fn ddma_send_erase(
        aux_mutex: &Rc<Mutex<bool>>,
        routing_table: &drtio_routing::RoutingTable,
        timer: GlobalTimer,
        id: u32,
        destination: u8,
    ) -> Result<(), &'static str> {
        let linkno = routing_table.0[destination as usize][0] - 1;
        let reply = aux_transact(
            aux_mutex,
            linkno,
            &Packet::DmaRemoveTraceRequest {
                id: id,
                destination: destination,
            },
            timer,
        )
        .await;
        match reply {
            Ok(Packet::DmaRemoveTraceReply { succeeded: true }) => Ok(()),
            Ok(Packet::DmaRemoveTraceReply { succeeded: false }) => Err("satellite DMA erase error"),
            Ok(_) => Err("adding trace failed, unexpected aux packet"),
            Err(_) => Err("erasing trace failed, aux error"),
        }
    }

    pub async fn ddma_send_playback(
        aux_mutex: &Rc<Mutex<bool>>,
        routing_table: &drtio_routing::RoutingTable,
        timer: GlobalTimer,
        id: u32,
        destination: u8,
        timestamp: u64,
    ) -> Result<(), &'static str> {
        let linkno = routing_table.0[destination as usize][0] - 1;
        let reply = aux_transact(
            aux_mutex,
            linkno,
            &Packet::DmaPlaybackRequest {
                id: id,
                destination: destination,
                timestamp: timestamp,
            },
            timer,
        )
        .await;
        match reply {
            Ok(Packet::DmaPlaybackReply { succeeded: true }) => Ok(()),
            Ok(Packet::DmaPlaybackReply { succeeded: false }) => Err("error on DMA playback request"),
            Ok(_) => Err("received unexpected aux packet during DMA playback"),
            Err(_) => Err("aux error on DMA playback"),
        }
    }
}

fn read_device_map(cfg: &Config) -> BTreeMap<u32, String> {
    let mut device_map: BTreeMap<u32, String> = BTreeMap::new();
    let _ = cfg
        .read("device_map")
        .and_then(|raw_bytes| {
            let mut bytes_cr = Cursor::new(raw_bytes);
            let size = bytes_cr.read_u32().unwrap();
            for _ in 0..size {
                let channel = bytes_cr.read_u32().unwrap();
                let device_name = bytes_cr.read_string().unwrap();
                if let Some(old_entry) = device_map.insert(channel, device_name.clone()) {
                    warn!(
                        "conflicting device map entries for RTIO channel {}: '{}' and '{}'",
                        channel, old_entry, device_name
                    );
                }
            }
            Ok(())
        })
        .or_else(|err| {
            warn!(
                "error reading device map ({}), device names will not be available in RTIO error messages",
                err
            );
            Err(err)
        });
    device_map
}

fn _resolve_channel_name(channel: u32, device_map: &BTreeMap<u32, String>) -> String {
    match device_map.get(&channel) {
        Some(val) => val.clone(),
        None => String::from("unknown"),
    }
}

pub fn resolve_channel_name(channel: u32) -> String {
    _resolve_channel_name(channel, unsafe { &RTIO_DEVICE_MAP })
}

#[cfg(not(has_drtio))]
pub mod drtio {
    use super::*;

    pub fn startup(
        _aux_mutex: &Rc<Mutex<bool>>,
        _routing_table: &Rc<RefCell<drtio_routing::RoutingTable>>,
        _up_destinations: &Rc<RefCell<[bool; drtio_routing::DEST_COUNT]>>,
        _timer: GlobalTimer,
    ) {
    }

    #[allow(dead_code)]
    pub fn reset(_aux_mutex: Rc<Mutex<bool>>, mut _timer: GlobalTimer) {}
}

pub fn startup(
    aux_mutex: &Rc<Mutex<bool>>,
    routing_table: &Rc<RefCell<drtio_routing::RoutingTable>>,
    up_destinations: &Rc<RefCell<[bool; drtio_routing::DEST_COUNT]>>,
    timer: GlobalTimer,
    cfg: &Config,
) {
    unsafe {
        RTIO_DEVICE_MAP = read_device_map(cfg);
    }
    drtio::startup(aux_mutex, routing_table, up_destinations, timer);
    unsafe {
        csr::rtio_core::reset_phy_write(1);
    }
}

#[allow(dead_code)]
pub fn reset(aux_mutex: Rc<Mutex<bool>>, timer: GlobalTimer) {
    unsafe {
        csr::rtio_core::reset_write(1);
    }
    drtio::reset(aux_mutex, timer)
}