// Copyright 2022 The ChromiumOS Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

//! Trait to suspend virtual hardware.

use anyhow::anyhow;
use serde::Deserialize;
use serde::Serialize;

#[derive(Copy, Clone, Serialize, Deserialize)]
pub enum DeviceState {
    Awake,
    Sleep,
}

/// This trait provides the functions required for a device to implement to successfully
/// suspend/resume in crosvm.
pub trait Suspendable {
    /// Save the device state in an image that can be restored.
    fn snapshot(&mut self) -> anyhow::Result<serde_json::Value> {
        Err(anyhow!(
            "Suspendable::snapshot not implemented for {}",
            std::any::type_name::<Self>()
        ))
    }
    /// Load a saved snapshot of an image.
    fn restore(&mut self, _data: serde_json::Value) -> anyhow::Result<()> {
        Err(anyhow!(
            "Suspendable::restore not implemented for {}",
            std::any::type_name::<Self>()
        ))
    }
    /// Stop all threads related to the device.
    /// Sleep should be idempotent.
    fn sleep(&mut self) -> anyhow::Result<()> {
        Err(anyhow!(
            "Suspendable::sleep not implemented for {}",
            std::any::type_name::<Self>()
        ))
    }
    /// Create/Resume all threads related to the device.
    /// Wake should be idempotent.
    fn wake(&mut self) -> anyhow::Result<()> {
        Err(anyhow!(
            "Suspendable::wake not implemented for {}",
            std::any::type_name::<Self>()
        ))
    }
}

// General tests that should pass on all suspendables.
// Do implement device-specific tests to validate the functionality of the device.
// Those tests are not a replacement for regular tests. Only an extension specific to the trait's
// basic functionality.
/// `dev` is the device.
/// `modfun` is the function name of the function that would modify the device. The function call
/// should modify the device so that a snapshot taken after the function call would be different
/// from a snapshot taken before the function call.
#[macro_export]
macro_rules! suspendable_tests {
    ($name:ident, $dev:expr, $modfun:ident) => {
        mod $name {
            use super::*;

            #[test]
            fn test_sleep_idempotent() {
                let unit = &mut $dev;
                let res = unit.sleep();
                let res2 = unit.sleep();
                match res {
                    Ok(()) => (),
                    Err(e) => println!("{}", e),
                }
                match res2 {
                    Ok(()) => (),
                    Err(e) => println!("idempotent: {}", e),
                }
            }

            #[test]
            fn test_snapshot_restore() {
                let unit = &mut $dev;
                let snap = unit.snapshot();
                match snap {
                    Ok(snap_res) => {
                        let res = unit.restore(snap_res);
                        match res {
                            Ok(()) => (),
                            Err(e) => println!("{}", e),
                        }
                    }
                    Err(e) => println!("{}", e),
                }
            }

            #[test]
            fn test_sleep_snapshot() {
                let unit = &mut $dev;
                let sleep_result = unit.sleep();
                let snap_result = unit.snapshot();
                match sleep_result {
                    Ok(()) => (),
                    Err(e) => println!("{}", e),
                }
                match snap_result {
                    Ok(_res) => (),
                    Err(e) => println!("{}", e),
                }
            }

            #[test]
            fn test_sleep_snapshot_restore_wake() {
                let unit = &mut $dev;
                let sleep_result = unit.sleep();
                let snap_result = unit.snapshot();
                match sleep_result {
                    Ok(()) => (),
                    Err(e) => println!("{}", e),
                }
                match snap_result {
                    Ok(snap_res) => {
                        let res = unit.restore(snap_res);
                        match res {
                            Ok(()) => (),
                            Err(e) => println!("{}", e),
                        }
                    }
                    Err(e) => println!("{}", e),
                }
                let wake_res = unit.wake();
                match wake_res {
                    Ok(()) => (),
                    Err(e) => println!("{}", e),
                }
            }

            #[test]
            fn test_sleep_snapshot_wake() {
                let unit = &mut $dev;
                let sleep_result = unit.sleep();
                let snap_result = unit.snapshot();
                match sleep_result {
                    Ok(()) => (),
                    Err(e) => println!("{}", e),
                }
                match snap_result {
                    Ok(_snap_res) => (),
                    Err(e) => println!("{}", e),
                }
                let wake_res = unit.wake();
                match wake_res {
                    Ok(()) => (),
                    Err(e) => println!("{}", e),
                }
            }

            #[test]
            fn test_snapshot() {
                let unit = &mut $dev;
                let snap_result = unit.snapshot();
                match snap_result {
                    Ok(_snap_res) => (),
                    Err(e) => println!("{}", e),
                }
            }

            #[test]
            fn test_suspend_mod_restore() {
                let unit = &mut $dev;
                let snap_result = unit.snapshot().expect("failed to take initial snapshot");
                $modfun(unit);
                unit.restore(snap_result.clone())
                    .expect("failed to restore snapshot");
                let snap2_result = unit
                    .snapshot()
                    .expect("failed to take snapshot after modification");
                assert_eq!(snap_result, snap2_result);
            }

            #[test]
            fn test_suspend_mod() {
                let unit = &mut $dev;
                let snap_result = unit.snapshot().expect("failed to take initial snapshot");
                $modfun(unit);
                let snap2_result = unit
                    .snapshot()
                    .expect("failed to take snapshot after modification");
                assert_ne!(snap_result, snap2_result)
            }
        }
    };
}