// Copyright 2019 Intel Corporation. All Rights Reserved.
// SPDX-License-Identifier: Apache-2.0

use super::Error as DeviceError;
use super::{
    ActivateResult, EpollHelper, EpollHelperError, EpollHelperHandler, VirtioCommon, VirtioDevice,
    VirtioDeviceType, VirtioInterruptType, EPOLL_HELPER_EVENT_LAST, VIRTIO_F_IOMMU_PLATFORM,
    VIRTIO_F_VERSION_1,
};
use crate::seccomp_filters::Thread;
use crate::thread_helper::spawn_virtio_thread;
use crate::GuestMemoryMmap;
use crate::VirtioInterrupt;
use libc::{EFD_NONBLOCK, TIOCGWINSZ};
use seccompiler::SeccompAction;
use std::cmp;
use std::collections::VecDeque;
use std::fs::File;
use std::io;
use std::io::{Read, Write};
use std::os::unix::io::AsRawFd;
use std::result;
use std::sync::atomic::{AtomicBool, AtomicU64, Ordering};
use std::sync::{Arc, Barrier, Mutex};
use versionize::{VersionMap, Versionize, VersionizeResult};
use versionize_derive::Versionize;
use virtio_queue::Queue;
use vm_memory::{ByteValued, Bytes, GuestMemoryAtomic};
use vm_migration::VersionMapped;
use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};
use vm_virtio::{AccessPlatform, Translatable};
use vmm_sys_util::eventfd::EventFd;

const QUEUE_SIZE: u16 = 256;
const NUM_QUEUES: usize = 2;
const QUEUE_SIZES: &[u16] = &[QUEUE_SIZE; NUM_QUEUES];

// New descriptors are pending on the virtio queue.
const INPUT_QUEUE_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 1;
const OUTPUT_QUEUE_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 2;
// Some input from the VMM is ready to be injected into the VM.
const INPUT_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 3;
// Console configuration change event is triggered.
const CONFIG_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 4;
// File written to (input ready)
const FILE_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 5;
// Console resized
const RESIZE_EVENT: u16 = EPOLL_HELPER_EVENT_LAST + 6;

//Console size feature bit
const VIRTIO_CONSOLE_F_SIZE: u64 = 0;

#[derive(Copy, Clone, Debug, Versionize)]
#[repr(C, packed)]
pub struct VirtioConsoleConfig {
    cols: u16,
    rows: u16,
    max_nr_ports: u32,
    emerg_wr: u32,
}

impl Default for VirtioConsoleConfig {
    fn default() -> Self {
        VirtioConsoleConfig {
            cols: 0,
            rows: 0,
            max_nr_ports: 1,
            emerg_wr: 0,
        }
    }
}

// SAFETY: it only has data and has no implicit padding.
unsafe impl ByteValued for VirtioConsoleConfig {}

struct ConsoleEpollHandler {
    queues: Vec<Queue<GuestMemoryAtomic<GuestMemoryMmap>>>,
    interrupt_cb: Arc<dyn VirtioInterrupt>,
    in_buffer: Arc<Mutex<VecDeque<u8>>>,
    resizer: Arc<ConsoleResizer>,
    endpoint: Endpoint,
    input_queue_evt: EventFd,
    output_queue_evt: EventFd,
    input_evt: EventFd,
    config_evt: EventFd,
    resize_pipe: Option<File>,
    kill_evt: EventFd,
    pause_evt: EventFd,
    access_platform: Option<Arc<dyn AccessPlatform>>,
}

pub enum Endpoint {
    File(File),
    FilePair(File, File),
    Null,
}

impl Endpoint {
    fn out_file(&self) -> Option<&File> {
        match self {
            Self::File(f) => Some(f),
            Self::FilePair(f, _) => Some(f),
            Self::Null => None,
        }
    }

    fn in_file(&self) -> Option<&File> {
        match self {
            Self::File(_) => None,
            Self::FilePair(_, f) => Some(f),
            Self::Null => None,
        }
    }
}

impl Clone for Endpoint {
    fn clone(&self) -> Self {
        match self {
            Self::File(f) => Self::File(f.try_clone().unwrap()),
            Self::FilePair(f_out, f_in) => {
                Self::FilePair(f_out.try_clone().unwrap(), f_in.try_clone().unwrap())
            }
            Self::Null => Self::Null,
        }
    }
}

impl ConsoleEpollHandler {
    /*
     * Each port of virtio console device has one receive
     * queue. One or more empty buffers are placed by the
     * driver in the receive queue for incoming data. Here,
     * we place the input data to these empty buffers.
     */
    fn process_input_queue(&mut self) -> bool {
        let mut in_buffer = self.in_buffer.lock().unwrap();
        let recv_queue = &mut self.queues[0]; //receiveq
        let mut used_desc_heads = [(0, 0); QUEUE_SIZE as usize];
        let mut used_count = 0;

        if in_buffer.is_empty() {
            return false;
        }

        let mut avail_iter = recv_queue.iter().unwrap();
        for mut desc_chain in &mut avail_iter {
            let desc = desc_chain.next().unwrap();
            let len = cmp::min(desc.len() as u32, in_buffer.len() as u32);
            let source_slice = in_buffer.drain(..len as usize).collect::<Vec<u8>>();

            if let Err(e) = desc_chain.memory().write_slice(
                &source_slice[..],
                desc.addr()
                    .translate_gva(self.access_platform.as_ref(), desc.len() as usize),
            ) {
                error!("Failed to write slice: {:?}", e);
                avail_iter.go_to_previous_position();
                break;
            }

            used_desc_heads[used_count] = (desc_chain.head_index(), len);
            used_count += 1;

            if in_buffer.is_empty() {
                break;
            }
        }

        for &(desc_index, len) in &used_desc_heads[..used_count] {
            recv_queue.add_used(desc_index, len).unwrap();
        }

        used_count > 0
    }

    /*
     * Each port of virtio console device has one transmit
     * queue. For outgoing data, characters are placed in
     * the transmit queue by the driver. Therefore, here
     * we read data from the transmit queue and flush them
     * to the referenced address.
     */
    fn process_output_queue(&mut self) -> bool {
        let trans_queue = &mut self.queues[1]; //transmitq
        let mut used_desc_heads = [(0, 0); QUEUE_SIZE as usize];
        let mut used_count = 0;

        for mut desc_chain in trans_queue.iter().unwrap() {
            let desc = desc_chain.next().unwrap();
            if let Some(ref mut out) = self.endpoint.out_file() {
                let _ = desc_chain.memory().write_to(
                    desc.addr()
                        .translate_gva(self.access_platform.as_ref(), desc.len() as usize),
                    out,
                    desc.len() as usize,
                );
                let _ = out.flush();
            }
            used_desc_heads[used_count] = (desc_chain.head_index(), desc.len());
            used_count += 1;
        }

        for &(desc_index, len) in &used_desc_heads[..used_count] {
            trans_queue.add_used(desc_index, len).unwrap();
        }
        used_count > 0
    }

    fn signal_used_queue(&self, queue_index: u16) -> result::Result<(), DeviceError> {
        self.interrupt_cb
            .trigger(VirtioInterruptType::Queue(queue_index))
            .map_err(|e| {
                error!("Failed to signal used queue: {:?}", e);
                DeviceError::FailedSignalingUsedQueue(e)
            })
    }

    fn run(
        &mut self,
        paused: Arc<AtomicBool>,
        paused_sync: Arc<Barrier>,
    ) -> result::Result<(), EpollHelperError> {
        let mut helper = EpollHelper::new(&self.kill_evt, &self.pause_evt)?;
        helper.add_event(self.input_queue_evt.as_raw_fd(), INPUT_QUEUE_EVENT)?;
        helper.add_event(self.output_queue_evt.as_raw_fd(), OUTPUT_QUEUE_EVENT)?;
        helper.add_event(self.input_evt.as_raw_fd(), INPUT_EVENT)?;
        helper.add_event(self.config_evt.as_raw_fd(), CONFIG_EVENT)?;
        if let Some(resize_pipe) = self.resize_pipe.as_ref() {
            helper.add_event(resize_pipe.as_raw_fd(), RESIZE_EVENT)?;
        }
        if let Some(in_file) = self.endpoint.in_file() {
            helper.add_event(in_file.as_raw_fd(), FILE_EVENT)?;
        }
        helper.run(paused, paused_sync, self)?;

        Ok(())
    }
}

impl EpollHelperHandler for ConsoleEpollHandler {
    fn handle_event(&mut self, _helper: &mut EpollHelper, event: &epoll::Event) -> bool {
        let ev_type = event.data as u16;
        match ev_type {
            INPUT_QUEUE_EVENT => {
                if let Err(e) = self.input_queue_evt.read() {
                    error!("Failed to get queue event: {:?}", e);
                    return true;
                } else if self.process_input_queue() {
                    if let Err(e) = self.signal_used_queue(0) {
                        error!("Failed to signal used queue: {:?}", e);
                        return true;
                    }
                }
            }
            OUTPUT_QUEUE_EVENT => {
                if let Err(e) = self.output_queue_evt.read() {
                    error!("Failed to get queue event: {:?}", e);
                    return true;
                } else if self.process_output_queue() {
                    if let Err(e) = self.signal_used_queue(1) {
                        error!("Failed to signal used queue: {:?}", e);
                        return true;
                    }
                }
            }
            INPUT_EVENT => {
                if let Err(e) = self.input_evt.read() {
                    error!("Failed to get input event: {:?}", e);
                    return true;
                } else if self.process_input_queue() {
                    if let Err(e) = self.signal_used_queue(0) {
                        error!("Failed to signal used queue: {:?}", e);
                        return true;
                    }
                }
            }
            CONFIG_EVENT => {
                if let Err(e) = self.config_evt.read() {
                    error!("Failed to get config event: {:?}", e);
                    return true;
                } else if let Err(e) = self.interrupt_cb.trigger(VirtioInterruptType::Config) {
                    error!("Failed to signal console driver: {:?}", e);
                    return true;
                }
            }
            RESIZE_EVENT => {
                if let Err(e) = self.resize_pipe.as_ref().unwrap().read_exact(&mut [0]) {
                    error!("Failed to get resize event: {:?}", e);
                    return true;
                }

                self.resizer.update_console_size();
            }
            FILE_EVENT => {
                let mut input = [0u8; 64];
                if let Some(ref mut in_file) = self.endpoint.in_file() {
                    if let Ok(count) = in_file.read(&mut input) {
                        let mut in_buffer = self.in_buffer.lock().unwrap();
                        in_buffer.extend(&input[..count]);
                    }

                    if self.process_input_queue() {
                        if let Err(e) = self.signal_used_queue(0) {
                            error!("Failed to signal used queue: {:?}", e);
                            return true;
                        }
                    }
                }
            }
            _ => {
                error!("Unknown event for virtio-console");
                return true;
            }
        }
        false
    }
}

/// Resize handler
pub struct ConsoleResizer {
    config_evt: EventFd,
    tty: Option<File>,
    config: Arc<Mutex<VirtioConsoleConfig>>,
    acked_features: AtomicU64,
}

impl ConsoleResizer {
    pub fn update_console_size(&self) {
        if let Some(tty) = self.tty.as_ref() {
            let (cols, rows) = get_win_size(tty);
            self.config.lock().unwrap().update_console_size(cols, rows);
            if self
                .acked_features
                .fetch_and(1u64 << VIRTIO_CONSOLE_F_SIZE, Ordering::AcqRel)
                != 0
            {
                // Send the interrupt to the driver
                let _ = self.config_evt.write(1);
            }
        }
    }
}

impl VirtioConsoleConfig {
    pub fn update_console_size(&mut self, cols: u16, rows: u16) {
        self.cols = cols;
        self.rows = rows;
    }
}

/// Virtio device for exposing console to the guest OS through virtio.
pub struct Console {
    common: VirtioCommon,
    id: String,
    config: Arc<Mutex<VirtioConsoleConfig>>,
    resizer: Arc<ConsoleResizer>,
    resize_pipe: Option<File>,
    endpoint: Endpoint,
    seccomp_action: SeccompAction,
    in_buffer: Arc<Mutex<VecDeque<u8>>>,
    exit_evt: EventFd,
}

#[derive(Versionize)]
pub struct ConsoleState {
    avail_features: u64,
    acked_features: u64,
    config: VirtioConsoleConfig,
    in_buffer: Vec<u8>,
}

fn get_win_size(tty: &dyn AsRawFd) -> (u16, u16) {
    #[repr(C)]
    #[derive(Default)]
    struct WindowSize {
        rows: u16,
        cols: u16,
        xpixel: u16,
        ypixel: u16,
    }
    let ws: WindowSize = WindowSize::default();

    unsafe {
        libc::ioctl(tty.as_raw_fd(), TIOCGWINSZ, &ws);
    }

    (ws.cols, ws.rows)
}

impl VersionMapped for ConsoleState {}

impl Console {
    /// Create a new virtio console device that gets random data from /dev/urandom.
    pub fn new(
        id: String,
        endpoint: Endpoint,
        resize_pipe: Option<File>,
        iommu: bool,
        seccomp_action: SeccompAction,
        exit_evt: EventFd,
    ) -> io::Result<(Console, Arc<ConsoleResizer>)> {
        let mut avail_features = 1u64 << VIRTIO_F_VERSION_1 | 1u64 << VIRTIO_CONSOLE_F_SIZE;

        if iommu {
            avail_features |= 1u64 << VIRTIO_F_IOMMU_PLATFORM;
        }

        let config_evt = EventFd::new(EFD_NONBLOCK).unwrap();
        let console_config = Arc::new(Mutex::new(VirtioConsoleConfig::default()));
        let resizer = Arc::new(ConsoleResizer {
            config_evt,
            config: console_config.clone(),
            tty: endpoint.out_file().as_ref().map(|t| t.try_clone().unwrap()),
            acked_features: AtomicU64::new(0),
        });

        resizer.update_console_size();

        Ok((
            Console {
                common: VirtioCommon {
                    device_type: VirtioDeviceType::Console as u32,
                    queue_sizes: QUEUE_SIZES.to_vec(),
                    avail_features,
                    paused_sync: Some(Arc::new(Barrier::new(2))),
                    min_queues: NUM_QUEUES as u16,
                    ..Default::default()
                },
                id,
                config: console_config,
                resizer: resizer.clone(),
                resize_pipe,
                endpoint,
                seccomp_action,
                in_buffer: Arc::new(Mutex::new(VecDeque::new())),
                exit_evt,
            },
            resizer,
        ))
    }

    fn state(&self) -> ConsoleState {
        ConsoleState {
            avail_features: self.common.avail_features,
            acked_features: self.common.acked_features,
            config: *(self.config.lock().unwrap()),
            in_buffer: self.in_buffer.lock().unwrap().clone().into(),
        }
    }

    fn set_state(&mut self, state: &ConsoleState) {
        self.common.avail_features = state.avail_features;
        self.common.acked_features = state.acked_features;
        *(self.config.lock().unwrap()) = state.config;
        *(self.in_buffer.lock().unwrap()) = state.in_buffer.clone().into();
    }
}

impl Drop for Console {
    fn drop(&mut self) {
        if let Some(kill_evt) = self.common.kill_evt.take() {
            // Ignore the result because there is nothing we can do about it.
            let _ = kill_evt.write(1);
        }
    }
}

impl VirtioDevice for Console {
    fn device_type(&self) -> u32 {
        self.common.device_type
    }

    fn queue_max_sizes(&self) -> &[u16] {
        &self.common.queue_sizes
    }

    fn features(&self) -> u64 {
        self.common.avail_features
    }

    fn ack_features(&mut self, value: u64) {
        self.common.ack_features(value)
    }

    fn read_config(&self, offset: u64, data: &mut [u8]) {
        self.read_config_from_slice(self.config.lock().unwrap().as_slice(), offset, data);
    }

    fn activate(
        &mut self,
        _mem: GuestMemoryAtomic<GuestMemoryMmap>,
        interrupt_cb: Arc<dyn VirtioInterrupt>,
        mut queues: Vec<(usize, Queue<GuestMemoryAtomic<GuestMemoryMmap>>, EventFd)>,
    ) -> ActivateResult {
        self.common.activate(&queues, &interrupt_cb)?;
        self.resizer
            .acked_features
            .store(self.common.acked_features, Ordering::Relaxed);

        if self.common.feature_acked(VIRTIO_CONSOLE_F_SIZE) {
            if let Err(e) = interrupt_cb.trigger(VirtioInterruptType::Config) {
                error!("Failed to signal console driver: {:?}", e);
            }
        }

        let (kill_evt, pause_evt) = self.common.dup_eventfds();
        let input_evt = EventFd::new(EFD_NONBLOCK).unwrap();

        let mut virtqueues = Vec::new();
        let (_, queue, queue_evt) = queues.remove(0);
        virtqueues.push(queue);
        let input_queue_evt = queue_evt;
        let (_, queue, queue_evt) = queues.remove(0);
        virtqueues.push(queue);
        let output_queue_evt = queue_evt;

        let mut handler = ConsoleEpollHandler {
            queues: virtqueues,
            interrupt_cb,
            in_buffer: self.in_buffer.clone(),
            endpoint: self.endpoint.clone(),
            input_queue_evt,
            output_queue_evt,
            input_evt,
            config_evt: self.resizer.config_evt.try_clone().unwrap(),
            resize_pipe: self.resize_pipe.as_ref().map(|p| p.try_clone().unwrap()),
            resizer: Arc::clone(&self.resizer),
            kill_evt,
            pause_evt,
            access_platform: self.common.access_platform.clone(),
        };

        let paused = self.common.paused.clone();
        let paused_sync = self.common.paused_sync.clone();
        let mut epoll_threads = Vec::new();

        spawn_virtio_thread(
            &self.id,
            &self.seccomp_action,
            Thread::VirtioConsole,
            &mut epoll_threads,
            &self.exit_evt,
            move || {
                if let Err(e) = handler.run(paused, paused_sync.unwrap()) {
                    error!("Error running worker: {:?}", e);
                }
            },
        )?;

        self.common.epoll_threads = Some(epoll_threads);

        event!("virtio-device", "activated", "id", &self.id);
        Ok(())
    }

    fn reset(&mut self) -> Option<Arc<dyn VirtioInterrupt>> {
        let result = self.common.reset();
        event!("virtio-device", "reset", "id", &self.id);
        result
    }

    fn set_access_platform(&mut self, access_platform: Arc<dyn AccessPlatform>) {
        self.common.set_access_platform(access_platform)
    }
}

impl Pausable for Console {
    fn pause(&mut self) -> result::Result<(), MigratableError> {
        self.common.pause()
    }

    fn resume(&mut self) -> result::Result<(), MigratableError> {
        self.common.resume()
    }
}

impl Snapshottable for Console {
    fn id(&self) -> String {
        self.id.clone()
    }

    fn snapshot(&mut self) -> std::result::Result<Snapshot, MigratableError> {
        Snapshot::new_from_versioned_state(&self.id, &self.state())
    }

    fn restore(&mut self, snapshot: Snapshot) -> std::result::Result<(), MigratableError> {
        self.set_state(&snapshot.to_versioned_state(&self.id)?);
        Ok(())
    }
}
impl Transportable for Console {}
impl Migratable for Console {}