const InitProcessName = "init"

type Backend interface {
	ProcessEvent(containerID string, event EventType, ei EventInfo) error
}

type Client interface {
	Version(ctx context.Context) (containerd.Version, error)

	Restore(ctx context.Context, containerID string, attachStdio StdioCallback) (alive bool, pid int, p Process, err error)

	Create(ctx context.Context, containerID string, spec *specs.Spec, shim string, runtimeOptions interface{}, opts ...containerd.NewContainerOpts) error
	Start(ctx context.Context, containerID, checkpointDir string, withStdin bool, attachStdio StdioCallback) (pid int, err error)
	SignalProcess(ctx context.Context, containerID, processID string, signal syscall.Signal) error
	Exec(ctx context.Context, containerID, processID string, spec *specs.Process, withStdin bool, attachStdio StdioCallback) (int, error)
	ResizeTerminal(ctx context.Context, containerID, processID string, width, height int) error
	CloseStdin(ctx context.Context, containerID, processID string) error
	Pause(ctx context.Context, containerID string) error
	Resume(ctx context.Context, containerID string) error
	Stats(ctx context.Context, containerID string) (*Stats, error)
	ListPids(ctx context.Context, containerID string) ([]uint32, error)
	Summary(ctx context.Context, containerID string) ([]Summary, error)
	DeleteTask(ctx context.Context, containerID string) (uint32, time.Time, error)
	Delete(ctx context.Context, containerID string) error
	Status(ctx context.Context, containerID string) (containerd.ProcessStatus, error)

	UpdateResources(ctx context.Context, containerID string, resources *Resources) error
	CreateCheckpoint(ctx context.Context, containerID, checkpointDir string, exit bool) error
}

type EventInfo struct {
	ContainerID string
	ProcessID   string
	Pid         uint32
	ExitCode    uint32
	ExitedAt    time.Time
	OOMKilled   bool
	Error       error
}

type EventType string

const (
	EventUnknown     EventType = "unknown"
	EventExit        EventType = "exit"
	EventOOM         EventType = "oom"
	EventCreate      EventType = "create"
	EventStart       EventType = "start"
	EventExecAdded   EventType = "exec-added"
	EventExecStarted EventType = "exec-started"
	EventPaused      EventType = "paused"
	EventResumed     EventType = "resumed"
)

type Process interface {
	Delete(context.Context) (uint32, time.Time, error)
}

type StdioCallback func(io *cio.DirectIO) (cio.IO, error)