package notify

import (
	"context"
	"errors"
	"io"
)

type TransferReaderAt interface {
	io.ReaderAt
	Size() int64
}

type TransferWriterAt interface {
	io.WriterAt
}

type TransferCommitter interface {
	Commit(context.Context) error
}

type TransferSyncer interface {
	Sync(context.Context) error
}

type TransferCloser interface {
	Close() error
}

type TransferDescriptor struct {
	ID       string
	Channel  TransferChannel
	Size     int64
	Checksum string
	Metadata map[string]string
}

type TransferSendOptions struct {
	Descriptor       TransferDescriptor
	Source           TransferReaderAt
	ChunkSize        int
	Parallelism      int
	MaxInflightBytes int64
	VerifyChecksum   bool
}

type TransferReceiveOptions struct {
	Descriptor       TransferDescriptor
	Sink             TransferWriterAt
	SyncOnCheckpoint bool
	VerifyChecksum   bool
}

type TransferAcceptInfo struct {
	Descriptor          TransferDescriptor
	LogicalConn         *LogicalConn
	TransportConn       *TransportConn
	TransportGeneration uint64
}

type TransferHandle interface {
	ID() string
	LogicalConn() *LogicalConn
	TransportConn() *TransportConn
	Snapshot() (TransferSnapshot, bool)
	Wait(context.Context) error
	Abort(context.Context, error) error
}

var (
	errTransferIDEmpty              = errors.New("transfer id is empty")
	errTransferSourceNil            = errors.New("transfer source is nil")
	errTransferSinkNil              = errors.New("transfer sink is nil")
	errTransferHandlerNotConfigured = errors.New("transfer handler is not configured")
	errTransferSizeInvalid          = errors.New("transfer size must be non-negative")
	errTransferSessionNotFound      = errors.New("transfer session not found")
	errTransferSessionExists        = errors.New("transfer session already exists")
	errTransferStreamAlreadyActive  = errors.New("transfer stream already active")
	errTransferSegmentOffset        = errors.New("transfer segment offset mismatch")
	errTransferSizeMismatch         = errors.New("transfer size mismatch")
	errTransferChecksumMismatch     = errors.New("transfer checksum mismatch")
	errTransferChecksumUnsupported  = errors.New("transfer checksum verification requires io.ReaderAt")
	errTransferSequenceEncodeNil    = errors.New("transfer sequence encoder is nil")
	errTransferSequenceDecodeNil    = errors.New("transfer sequence decoder is nil")
	errTransferAlreadyCompleted     = errors.New("transfer already completed")
	errTransferAlreadyAborted       = errors.New("transfer already aborted")
)