// Copyright (C) 2018 Storj Labs, Inc.
// See LICENSE for copying information.

package ranger

import (
	"bytes"
	"io"
	"io/ioutil"

	"storj.io/storj/internal/pkg/readcloser"
	"storj.io/storj/pkg/piecestore/rpc/client"
)

type grpcRanger struct {
	c    *client.Client
	id   string
	size int64
}

// GRPCRanger turns a gRPC connection to piece store into a Ranger
func GRPCRanger(c *client.Client, id string) (Ranger, error) {
	piece, err := c.PieceMetaRequest(id)
	if err != nil {
		return nil, err
	}
	return &grpcRanger{c: c, id: id, size: piece.Size}, nil
}

// GRPCRangerSize creates a GRPCRanger with known size.
// Use it if you know the piece size. This will safe the extra request for
// retrieving the piece size from the piece storage.
func GRPCRangerSize(c *client.Client, id string, size int64) Ranger {
	return &grpcRanger{c: c, id: id, size: size}
}

// Size implements Ranger.Size
func (r *grpcRanger) Size() int64 {
	return r.size
}

// Range implements Ranger.Range
func (r *grpcRanger) Range(offset, length int64) io.ReadCloser {
	if offset < 0 {
		return readcloser.FatalReadCloser(Error.New("negative offset"))
	}
	if length < 0 {
		return readcloser.FatalReadCloser(Error.New("negative length"))
	}
	if offset+length > r.size {
		return readcloser.FatalReadCloser(Error.New("range beyond end"))
	}
	if length == 0 {
		return ioutil.NopCloser(bytes.NewReader([]byte{}))
	}
	reader, err := r.c.RetrievePieceRequest(r.id, offset, length)
	if err != nil {
		return readcloser.FatalReadCloser(Error.Wrap(err))
	}
	return reader
}