package getsvc

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

	coreclient "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/client"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/netmap"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/engine"
	internal "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/internal/client"
	internalclient "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/internal/client"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
)

type SimpleObjectWriter struct {
	obj *object.Object

	pld []byte
}

type clientCacheWrapper struct {
	cache ClientConstructor
}

type clientWrapper struct {
	client coreclient.MultiAddressClient
}

type storageEngineWrapper struct {
	engine *engine.StorageEngine
}

type partWriter struct {
	ObjectWriter

	headWriter HeaderWriter

	chunkWriter ChunkWriter
}

type hasherWrapper struct {
	hash io.Writer
}

type nmSrcWrapper struct {
	nmSrc netmap.Source
}

func NewSimpleObjectWriter() *SimpleObjectWriter {
	return &SimpleObjectWriter{
		obj: object.New(),
	}
}

func (s *SimpleObjectWriter) WriteHeader(_ context.Context, obj *object.Object) error {
	s.obj = obj

	s.pld = make([]byte, 0, obj.PayloadSize())

	return nil
}

func (s *SimpleObjectWriter) WriteChunk(_ context.Context, p []byte) error {
	s.pld = append(s.pld, p...)
	return nil
}

func (s *SimpleObjectWriter) Object() *object.Object {
	if len(s.pld) > 0 {
		s.obj.SetPayload(s.pld)
	}

	return s.obj
}

func (c *clientCacheWrapper) get(info coreclient.NodeInfo) (getClient, error) {
	clt, err := c.cache.Get(info)
	if err != nil {
		return nil, err
	}

	return &clientWrapper{
		client: clt,
	}, nil
}

func (c *clientWrapper) getObject(ctx context.Context, exec *execCtx, info coreclient.NodeInfo) (*object.Object, error) {
	if exec.isForwardingEnabled() {
		return exec.prm.forwarder(ctx, info, c.client)
	}

	key, err := exec.key()
	if err != nil {
		return nil, err
	}

	if exec.headOnly() {
		return c.getHeadOnly(ctx, exec, key)
	}
	// we don't specify payload writer because we accumulate
	// the object locally (even huge).
	if rng := exec.ctxRange(); rng != nil {
		// Current spec allows other storage node to deny access,
		// fallback to GET here.
		return c.getRange(ctx, exec, key, rng)
	}

	return c.get(ctx, exec, key)
}

func (c *clientWrapper) getRange(ctx context.Context, exec *execCtx, key *ecdsa.PrivateKey, rng *object.Range) (*object.Object, error) {
	var prm internalclient.PayloadRangePrm

	prm.SetContext(ctx)
	prm.SetClient(c.client)
	prm.SetTTL(exec.prm.common.TTL())
	prm.SetNetmapEpoch(exec.curProcEpoch)
	prm.SetAddress(exec.address())
	prm.SetPrivateKey(key)
	prm.SetSessionToken(exec.prm.common.SessionToken())
	prm.SetBearerToken(exec.prm.common.BearerToken())
	prm.SetXHeaders(exec.prm.common.XHeaders())
	prm.SetRange(rng)

	if exec.isRaw() {
		prm.SetRawFlag()
	}

	res, err := internalclient.PayloadRange(prm)
	if err != nil {
		var errAccessDenied *apistatus.ObjectAccessDenied
		if errors.As(err, &errAccessDenied) {
			obj, err := c.get(ctx, exec, key)
			if err != nil {
				return nil, err
			}

			payload := obj.Payload()
			from := rng.GetOffset()
			to := from + rng.GetLength()

			if pLen := uint64(len(payload)); to < from || pLen < from || pLen < to {
				return nil, new(apistatus.ObjectOutOfRange)
			}

			return payloadOnlyObject(payload[from:to]), nil
		}
		return nil, err
	}

	return payloadOnlyObject(res.PayloadRange()), nil
}

func (c *clientWrapper) getHeadOnly(ctx context.Context, exec *execCtx, key *ecdsa.PrivateKey) (*object.Object, error) {
	var prm internalclient.HeadObjectPrm

	prm.SetContext(ctx)
	prm.SetClient(c.client)
	prm.SetTTL(exec.prm.common.TTL())
	prm.SetNetmapEpoch(exec.curProcEpoch)
	prm.SetAddress(exec.address())
	prm.SetPrivateKey(key)
	prm.SetSessionToken(exec.prm.common.SessionToken())
	prm.SetBearerToken(exec.prm.common.BearerToken())
	prm.SetXHeaders(exec.prm.common.XHeaders())

	if exec.isRaw() {
		prm.SetRawFlag()
	}

	res, err := internalclient.HeadObject(prm)
	if err != nil {
		return nil, err
	}

	return res.Header(), nil
}

func (c *clientWrapper) get(ctx context.Context, exec *execCtx, key *ecdsa.PrivateKey) (*object.Object, error) {
	var prm internalclient.GetObjectPrm

	prm.SetContext(ctx)
	prm.SetClient(c.client)
	prm.SetTTL(exec.prm.common.TTL())
	prm.SetNetmapEpoch(exec.curProcEpoch)
	prm.SetAddress(exec.address())
	prm.SetPrivateKey(key)
	prm.SetSessionToken(exec.prm.common.SessionToken())
	prm.SetBearerToken(exec.prm.common.BearerToken())
	prm.SetXHeaders(exec.prm.common.XHeaders())

	if exec.isRaw() {
		prm.SetRawFlag()
	}

	res, err := internal.GetObject(prm)
	if err != nil {
		return nil, err
	}

	return res.Object(), nil
}

func (e *storageEngineWrapper) get(exec *execCtx) (*object.Object, error) {
	if exec.headOnly() {
		var headPrm engine.HeadPrm
		headPrm.WithAddress(exec.address())
		headPrm.WithRaw(exec.isRaw())

		r, err := e.engine.Head(headPrm)
		if err != nil {
			return nil, err
		}

		return r.Header(), nil
	} else if rng := exec.ctxRange(); rng != nil {
		var getRange engine.RngPrm
		getRange.WithAddress(exec.address())
		getRange.WithPayloadRange(rng)

		r, err := e.engine.GetRange(getRange)
		if err != nil {
			return nil, err
		}

		return r.Object(), nil
	} else {
		var getPrm engine.GetPrm
		getPrm.WithAddress(exec.address())

		r, err := e.engine.Get(getPrm)
		if err != nil {
			return nil, err
		}

		return r.Object(), nil
	}
}

func (w *partWriter) WriteChunk(ctx context.Context, p []byte) error {
	return w.chunkWriter.WriteChunk(ctx, p)
}

func (w *partWriter) WriteHeader(ctx context.Context, o *object.Object) error {
	return w.headWriter.WriteHeader(ctx, o)
}

func payloadOnlyObject(payload []byte) *object.Object {
	obj := object.New()
	obj.SetPayload(payload)

	return obj
}

func (h *hasherWrapper) WriteChunk(_ context.Context, p []byte) error {
	_, err := h.hash.Write(p)
	return err
}

func (n *nmSrcWrapper) currentEpoch() (uint64, error) {
	return n.nmSrc.Epoch()
}