// Copyright (C) 2019 Storj Labs, Inc.
// See LICENSE for copying information.

package psserver

import (
	"github.com/zeebo/errs"

	"storj.io/storj/pkg/pb"
	"storj.io/storj/pkg/utils"
)

// StreamWriterError is a type of error for failures in StreamWriter
var StreamWriterError = errs.Class("stream writer error")

// StreamWriter -- Struct for writing piece to server upload stream
type StreamWriter struct {
	server *Server
	stream pb.PieceStoreRoutes_RetrieveServer
}

// NewStreamWriter returns a new StreamWriter
func NewStreamWriter(s *Server, stream pb.PieceStoreRoutes_RetrieveServer) *StreamWriter {
	return &StreamWriter{server: s, stream: stream}
}

// Write -- Write method for piece upload to stream for Server.Retrieve
func (s *StreamWriter) Write(b []byte) (int, error) {
	// Write the buffer to the stream we opened earlier
	if err := s.stream.Send(&pb.PieceRetrievalStream{PieceSize: int64(len(b)), Content: b}); err != nil {
		return 0, err
	}

	return len(b), nil
}

// StreamReader is a struct for Retrieving data from server
type StreamReader struct {
	src                 *utils.ReaderSource
	bandwidthAllocation *pb.Order
	currentTotal        int64
	bandwidthRemaining  int64
	spaceRemaining      int64
	sofar               int64
}

// NewStreamReader returns a new StreamReader for Server.Store
func NewStreamReader(s *Server, stream pb.PieceStoreRoutes_StoreServer, bandwidthRemaining, spaceRemaining int64) *StreamReader {
	sr := &StreamReader{
		bandwidthRemaining: bandwidthRemaining,
		spaceRemaining:     spaceRemaining,
	}
	sr.src = utils.NewReaderSource(func() ([]byte, error) {

		recv, err := stream.Recv()
		if err != nil {
			return nil, err
		}

		pd := recv.GetPieceData()
		rba := recv.BandwidthAllocation

		if err = s.verifySignature(stream.Context(), rba); err != nil {
			return nil, err
		}
		pba := rba.PayerAllocation
		if err = s.verifyPayerAllocation(&pba, "PUT"); err != nil {
			return nil, err
		}
		// if whitelist does not contain PBA satellite ID, reject storage request
		if len(s.whitelist) != 0 {
			if !s.isWhitelisted(pba.SatelliteId) {
				return nil, StoreError.New("Satellite ID not approved")
			}
		}
		// Update bandwidthallocation to be stored
		if rba.Total > sr.currentTotal {
			sr.bandwidthAllocation = rba
			sr.currentTotal = rba.Total
		}
		return pd.GetContent(), nil
	})

	return sr
}

// Read -- Read method for piece download from stream
func (s *StreamReader) Read(b []byte) (int, error) {
	if s.sofar >= s.bandwidthRemaining {
		return 0, StreamWriterError.New("out of bandwidth")
	}
	if s.sofar >= s.spaceRemaining {
		return 0, StreamWriterError.New("out of space")
	}

	n, err := s.src.Read(b)
	s.sofar += int64(n)
	if err != nil {
		return n, err
	}
	if s.sofar >= s.spaceRemaining {
		return n, StreamWriterError.New("out of space")
	}

	return n, nil
}