package client

import (
	"context"
	"crypto/ecdsa"
	"errors"
	"fmt"
	"io"

	v2object "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object/grpc"
	rpcapi "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc"
	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/rpc/client"
	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/signature"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
)

func (c *Client) objectPutInitRaw(ctx context.Context, prm PrmObjectPutInit) (*objectWriterRaw, error) {
	w := newObjectWriterRaw()
	stream, err := rpcapi.PutObject(&c.c, w.respV2, client.WithContext(ctx))
	if err != nil {
		return nil, fmt.Errorf("open stream: %w", err)
	}

	w.key = &c.prm.key
	if prm.key != nil {
		w.key = prm.key
	}
	w.client = c
	w.stream = stream
	w.partInit = new(v2object.PutRequest_Body_Init)
	w.partInit.SetCopiesNumber(prm.copyNum)
	w.req = new(v2object.PutRequest)
	w.req.SetBody(new(v2object.PutRequest_Body))
	if prm.maxChunkLen > 0 {
		w.maxChunkLen = prm.maxChunkLen
	} else {
		w.maxChunkLen = defaultGRPCPayloadChunkLen
	}
	c.prepareRequest(w.req, prm.meta)
	return &w, nil
}

type objectWriterRaw struct {
	client *Client
	stream interface {
		Write(*v2object.PutRequest) error
		Close() error
	}

	key         *ecdsa.PrivateKey
	res         ResObjectPut
	err         error
	chunkCalled bool
	respV2      *v2object.PutResponse
	req         *v2object.PutRequest
	partInit    *v2object.PutRequest_Body_Init
	partChunk   *v2object.PutRequest_Body_Chunk
	maxChunkLen int
}

func newObjectWriterRaw() objectWriterRaw {
	return objectWriterRaw{
		respV2:    &v2object.PutResponse{},
		req:       &v2object.PutRequest{},
		partInit:  &v2object.PutRequest_Body_Init{},
		partChunk: &v2object.PutRequest_Body_Chunk{},
	}
}

func (x *objectWriterRaw) WriteHeader(_ context.Context, hdr object.Object) bool {
	v2Hdr := hdr.ToV2()

	if x.partInit == nil {
		x.partInit = new(v2object.PutRequest_Body_Init)
	}

	x.partInit.SetObjectId(v2Hdr.GetObjectId())
	x.partInit.SetHeader(v2Hdr.GetHeader())
	x.partInit.SetSignature(v2Hdr.GetSignature())

	x.req.GetBody().SetInit(x.partInit)
	x.req.SetVerifyHeader(nil)

	x.err = signature.SignServiceMessage(x.key, x.req)
	if x.err != nil {
		x.err = fmt.Errorf("sign message: %w", x.err)
		return false
	}

	x.err = x.stream.Write(x.req)
	return x.err == nil
}

func (x *objectWriterRaw) WritePayloadChunk(_ context.Context, chunk []byte) bool {
	if !x.chunkCalled {
		x.chunkCalled = true
		x.req.GetBody().SetChunk(x.partChunk)
	}

	for ln := len(chunk); ln > 0; ln = len(chunk) {
		if ln > x.maxChunkLen {
			ln = x.maxChunkLen
		}

		// we deal with size limit overflow above, but there is another case:
		// what if method is called with "small" chunk many times? We write
		// a message to the stream on each call. Alternatively, we could use buffering.
		// In most cases, the chunk length does not vary between calls. Given this
		// assumption, as well as the length of the payload from the header, it is
		// possible to buffer the data of intermediate chunks, and send a message when
		// the allocated buffer is filled, or when the last chunk is received.
		// It is mentally assumed that allocating and filling the buffer is better than
		// synchronous sending, but this needs to be tested.
		x.partChunk.SetChunk(chunk[:ln])
		x.req.SetVerifyHeader(nil)

		x.err = signature.SignServiceMessage(x.key, x.req)
		if x.err != nil {
			x.err = fmt.Errorf("sign message: %w", x.err)
			return false
		}

		x.err = x.stream.Write(x.req)
		if x.err != nil {
			return false
		}

		chunk = chunk[ln:]
	}

	return true
}

func (x *objectWriterRaw) Close(_ context.Context) (*ResObjectPut, error) {
	// Ignore io.EOF error, because it is expected error for client-side
	// stream termination by the server. E.g. when stream contains invalid
	// message. Server returns an error in response message (in status).
	if x.err != nil && !errors.Is(x.err, io.EOF) {
		return nil, x.err
	}

	if x.err = x.stream.Close(); x.err != nil {
		return nil, x.err
	}

	x.res.st, x.err = x.client.processResponse(x.respV2)
	if x.err != nil {
		return nil, x.err
	}

	if !apistatus.IsSuccessful(x.res.st) {
		return &x.res, nil
	}

	const fieldID = "ID"

	idV2 := x.respV2.GetBody().GetObjectId()
	if idV2 == nil {
		return nil, newErrMissingResponseField(fieldID)
	}

	x.err = x.res.obj.ReadFromV2(idV2)
	if x.err != nil {
		x.err = newErrInvalidResponseField(fieldID, x.err)
	}

	return &x.res, nil
}