const (
	ExitFile       = "exit"
	ExitStatusFile = "exitStatus"
	StateFile      = "state.json"
	ControlFile    = "control"
	InitProcessID  = "init"
)

const (
	Paused  = State("paused")
	Stopped = State("stopped")
	Running = State("running")
)

var (
	ErrNotChildProcess       = errors.New("containerd: not a child process for container")
	ErrInvalidContainerType  = errors.New("containerd: invalid container type for runtime")
	ErrCheckpointNotExists   = errors.New("containerd: checkpoint does not exist for container")
	ErrCheckpointExists      = errors.New("containerd: checkpoint already exists")
	ErrContainerExited       = errors.New("containerd: container has exited")
	ErrTerminalsNotSupported = errors.New("containerd: terminals are not supported for runtime")
	ErrProcessNotExited      = errors.New("containerd: process has not exited")
	ErrProcessExited         = errors.New("containerd: process has exited")
	ErrContainerNotStarted   = errors.New("containerd: container not started")
)

type Container interface {
	// ID returns the container ID
	ID() string
	// Path returns the path to the bundle
	Path() string
	// Start starts the init process of the container
	Start(checkpoint string, s Stdio) (Process, error)
	// Exec starts another process in an existing container
	Exec(string, specs.ProcessSpec, Stdio) (Process, error)
	// Delete removes the container's state and any resources
	Delete() error
	// Processes returns all the containers processes that have been added
	Processes() ([]Process, error)
	// State returns the containers runtime state
	State() State
	// Resume resumes a paused container
	Resume() error
	// Pause pauses a running container
	Pause() error
	// RemoveProcess removes the specified process from the container
	RemoveProcess(string) error
	// Checkpoints returns all the checkpoints for a container
	Checkpoints() ([]Checkpoint, error)
	// Checkpoint creates a new checkpoint
	Checkpoint(Checkpoint) error
	// DeleteCheckpoint deletes the checkpoint for the provided name
	DeleteCheckpoint(name string) error
	// Labels are user provided labels for the container
	Labels() []string
	// Pids returns all pids inside the container
	Pids() ([]int, error)
	// Stats returns realtime container stats and resource information
	Stats() (*Stat, error)
	// Name or path of the OCI compliant runtime used to execute the container
	Runtime() string
	// OOM signals the channel if the container received an OOM notification
	OOM() (OOM, error)
	// UpdateResource updates the containers resources to new values
	UpdateResources(*Resource) error
}

type OOM interface {
	io.Closer
	FD() int
	ContainerID() string
	Flush()
	Removed() bool
}

type Process interface {
	io.Closer

	// ID of the process.
	// This is either "init" when it is the container's init process or
	// it is a user provided id for the process similar to the container id
	ID() string
	CloseStdin() error
	Resize(int, int) error
	// ExitFD returns the fd the provides an event when the process exits
	ExitFD() int
	// ExitStatus returns the exit status of the process or an error if it
	// has not exited
	ExitStatus() (int, error)
	// Spec returns the process spec that created the process
	Spec() specs.ProcessSpec
	// Signal sends the provided signal to the process
	Signal(os.Signal) error
	// Container returns the container that the process belongs to
	Container() Container
	// Stdio of the container
	Stdio() Stdio
	// SystemPid is the pid on the system
	SystemPid() int
	// State returns if the process is running or not
	State() State
}

type ProcessState struct {
	specs.ProcessSpec
	Exec   bool   `json:"exec"`
	Stdin  string `json:"containerdStdin"`
	Stdout string `json:"containerdStdout"`
	Stderr string `json:"containerdStderr"`

	PlatformProcessState
}

type Resource struct {
	CPUShares         int64
	BlkioWeight       uint16
	CPUPeriod         int64
	CPUQuota          int64
	CpusetCpus        string
	CpusetMems        string
	KernelMemory      int64
	Memory            int64
	MemoryReservation int64
	MemorySwap        int64
}

type Stat struct {
	// Timestamp is the time that the statistics where collected
	Timestamp time.Time
	// Data is the raw stats
	// TODO: it is currently an interface because we don't know what type of exec drivers
	// we will have or what the structure should look like at the moment os the containers
	// can return what they want and we could marshal to json or whatever.
	Data interface{}
}

type State string

type Stdio struct {
	Stdin  string
	Stdout string
	Stderr string
}