package transfer

import "time"

type Channel string

const (
	ControlChannel Channel = "control"
	DataChannel    Channel = "data"
)

type Direction uint8

const (
	DirectionSend Direction = iota
	DirectionReceive
)

type State uint8

const (
	StateInit State = iota
	StateNegotiating
	StatePrepared
	StateActive
	StatePaused
	StateCommitting
	StateVerifying
	StateDone
	StateAborted
	StateFailed
)

func (s State) Terminal() bool {
	switch s {
	case StateDone, StateAborted, StateFailed:
		return true
	default:
		return false
	}
}

type Range struct {
	Offset int64
	Length int64
}

type Metadata map[string]string

type TelemetryDelta struct {
	SourceReadDuration  time.Duration
	StreamWriteDuration time.Duration
	SinkWriteDuration   time.Duration
	SyncDuration        time.Duration
	VerifyDuration      time.Duration
	CommitDuration      time.Duration
	CommitWaitDuration  time.Duration
	SourceReadCount     int
	StreamWriteCount    int
	SinkWriteCount      int
}

type Descriptor struct {
	ID        string
	Direction Direction
	Channel   Channel
	Size      int64
	Checksum  string
	Metadata  Metadata
}

type Snapshot struct {
	ID                  string
	Direction           Direction
	Channel             Channel
	State               State
	Stage               string
	LastFailureStage    string
	Size                int64
	Checksum            string
	Metadata            Metadata
	SentBytes           int64
	AckedBytes          int64
	ReceivedBytes       int64
	InflightBytes       int64
	RetryCount          int
	TimeoutCount        int
	LastError           string
	SourceReadDuration  time.Duration
	StreamWriteDuration time.Duration
	SinkWriteDuration   time.Duration
	SyncDuration        time.Duration
	VerifyDuration      time.Duration
	CommitDuration      time.Duration
	CommitWaitDuration  time.Duration
	SourceReadCount     int
	StreamWriteCount    int
	SinkWriteCount      int
	StartedAt           int64
	UpdatedAt           int64
	CompletedAt         int64
}

type Begin struct {
	TransferID string
	Channel    Channel
	Size       int64
	Checksum   string
	Metadata   Metadata
}

type BeginAck struct {
	TransferID string
	Accepted   bool
	NextOffset int64
	Missing    []Range
	Error      string
}

type Resume struct {
	TransferID string
}

type ResumeAck struct {
	TransferID string
	Accepted   bool
	NextOffset int64
	Missing    []Range
	Error      string
}

type Commit struct {
	TransferID string
	Size       int64
	Checksum   string
}

type CommitAck struct {
	TransferID string
	Accepted   bool
	Error      string
}

type Abort struct {
	TransferID string
	Stage      string
	Offset     int64
	Error      string
}

type Segment struct {
	TransferID string
	Channel    Channel
	Offset     int64
	Payload    []byte
	Flags      uint32
}

type Ack struct {
	TransferID string
	NextOffset int64
	Missing    []Range
	Final      bool
	Error      string
}

func normalizeChannel(channel Channel) Channel {
	if channel == "" {
		return DataChannel
	}
	return channel
}

func cloneMetadata(src Metadata) Metadata {
	if len(src) == 0 {
		return nil
	}
	dst := make(Metadata, len(src))
	for key, value := range src {
		dst[key] = value
	}
	return dst
}

func cloneSnapshot(src Snapshot) Snapshot {
	src.Metadata = cloneMetadata(src.Metadata)
	return src
}