// Copyright © 2023 Cyberus Technology

//

// SPDX-License-Identifier: Apache-2.0

//

//! Module for [`DebugconState`].

use std::io;

use std::io::Write;

use std::sync::{Arc, Barrier};

use log::error;

use vm_device::BusDevice;

use vm_migration::{Migratable, MigratableError, Pausable, Snapshot, Snapshottable, Transportable};

/// I/O-port.

pub const DEFAULT_PORT: u64 = 0xe9;

#[derive(Default)]

pub struct DebugconState {}

/// Emulates a debug console similar to the QEMU debugcon device. This device

/// is stateless and only prints the bytes (usually text) that are written to

/// it.

///

/// This device is only available on x86.

///

/// Reference:

/// - https://github.com/qemu/qemu/blob/master/hw/char/debugcon.c

/// - https://phip1611.de/blog/how-to-use-qemus-debugcon-feature-and-write-to-a-file/

pub struct DebugConsole {

    id: String,

    out: Box<dyn io::Write + Send>,

}

impl DebugConsole {

    pub fn new(id: String, out: Box<dyn io::Write + Send>) -> Self {

        Self { id, out }

    }

}

impl BusDevice for DebugConsole {

    fn read(&mut self, _base: u64, _offset: u64, _data: &mut [u8]) {}

    fn write(&mut self, _base: u64, _offset: u64, data: &[u8]) -> Option<Arc<Barrier>> {

        if let Err(e) = self.out.write_all(data) {

            // unlikely

            error!("debug-console: failed writing data: {e:?}");

        }

        None

    }

}

impl Snapshottable for DebugConsole {

    fn id(&self) -> String {

        self.id.clone()

    }

    fn snapshot(&mut self) -> Result<Snapshot, MigratableError> {

        Snapshot::new_from_state(&())

    }

}

impl Pausable for DebugConsole {}

impl Transportable for DebugConsole {}

impl Migratable for DebugConsole {}