package getsvc

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

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/client"
	coreclient "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/client"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/engine"
	internalclient "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/internal/client"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/util"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
)

type epochSource interface {
	Epoch() (uint64, error)
}

type traverserGenerator interface {
	GenerateTraverser(cid.ID, *oid.ID, uint64) (*placement.Traverser, error)
}

type keyStorage interface {
	GetKey(info *util.SessionInfo) (*ecdsa.PrivateKey, error)
}

type localStorageEngine interface {
	Head(ctx context.Context, p engine.HeadPrm) (engine.HeadRes, error)
	GetRange(ctx context.Context, p engine.RngPrm) (engine.RngRes, error)
	Get(ctx context.Context, p engine.GetPrm) (engine.GetRes, error)
}

type clientConstructor interface {
	Get(client.NodeInfo) (client.MultiAddressClient, error)
}

type remoteStorageConstructor interface {
	Get(client.NodeInfo) (remoteStorage, error)
}

type multiclientRemoteStorageConstructor struct {
	clientConstructor clientConstructor
}

func (c *multiclientRemoteStorageConstructor) Get(info client.NodeInfo) (remoteStorage, error) {
	clt, err := c.clientConstructor.Get(info)
	if err != nil {
		return nil, err
	}

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

type remoteStorage interface {
	GetObject(context.Context, *execCtx, client.NodeInfo) (*objectSDK.Object, error)
}

type localStorage interface {
	Head(ctx context.Context, address oid.Address, isRaw bool) (*objectSDK.Object, error)
	Range(ctx context.Context, address oid.Address, rng *objectSDK.Range) (*objectSDK.Object, error)
	Get(ctx context.Context, address oid.Address) (*objectSDK.Object, error)
}

type engineLocalStorage struct {
	engine localStorageEngine
}

func (s *engineLocalStorage) Head(ctx context.Context, address oid.Address, isRaw bool) (*objectSDK.Object, error) {
	var headPrm engine.HeadPrm
	headPrm.WithAddress(address)
	headPrm.WithRaw(isRaw)

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

	return r.Header(), nil
}

func (s *engineLocalStorage) Range(ctx context.Context, address oid.Address, rng *objectSDK.Range) (*objectSDK.Object, error) {
	var getRange engine.RngPrm
	getRange.WithAddress(address)
	getRange.WithPayloadRange(rng)

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

	return r.Object(), nil
}

func (s *engineLocalStorage) Get(ctx context.Context, address oid.Address) (*objectSDK.Object, error) {
	var getPrm engine.GetPrm
	getPrm.WithAddress(address)

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

	return r.Object(), nil
}

type multiaddressRemoteStorage struct {
	client coreclient.MultiAddressClient
}

func (s *multiaddressRemoteStorage) GetObject(ctx context.Context, exec *execCtx, info coreclient.NodeInfo) (*objectSDK.Object, error) {
	if exec.isForwardingEnabled() {
		return exec.prm.forwarder(ctx, info, s.client)
	}

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

	if exec.headOnly() {
		return s.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 s.getRange(ctx, exec, key, rng)
	}

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

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

	prm.SetClient(s.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(ctx, prm)
	if err != nil {
		var errAccessDenied *apistatus.ObjectAccessDenied
		if errors.As(err, &errAccessDenied) {
			obj, err := s.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 (s *multiaddressRemoteStorage) getHeadOnly(ctx context.Context, exec *execCtx, key *ecdsa.PrivateKey) (*object.Object, error) {
	var prm internalclient.HeadObjectPrm

	prm.SetClient(s.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(ctx, prm)
	if err != nil {
		return nil, err
	}

	return res.Header(), nil
}

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

	prm.SetClient(s.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.GetObject(ctx, prm)
	if err != nil {
		return nil, err
	}

	return res.Object(), nil
}