package layer

import (
	"context"
	"crypto/ecdsa"
	"fmt"
	"io"
	"net/url"
	"sort"
	"time"

	"github.com/nspcc-dev/neofs-api-go/pkg/client"
	cid "github.com/nspcc-dev/neofs-api-go/pkg/container/id"
	"github.com/nspcc-dev/neofs-api-go/pkg/netmap"
	"github.com/nspcc-dev/neofs-api-go/pkg/object"
	"github.com/nspcc-dev/neofs-api-go/pkg/owner"
	"github.com/nspcc-dev/neofs-s3-gw/api"
	"github.com/nspcc-dev/neofs-s3-gw/api/cache"
	"github.com/nspcc-dev/neofs-s3-gw/api/errors"
	"github.com/nspcc-dev/neofs-s3-gw/creds/accessbox"
	"github.com/nspcc-dev/neofs-sdk-go/pkg/pool"
	"go.uber.org/zap"
)

type (
	layer struct {
		pool         pool.Pool
		log          *zap.Logger
		listObjCache ObjectsListCache
		objCache     cache.ObjectsCache
	}

	// CacheConfig contains params for caches.
	CacheConfig struct {
		Lifetime            time.Duration
		Size                int
		ListObjectsLifetime time.Duration
	}

	// Params stores basic API parameters.
	Params struct {
		Pool    pool.Pool
		Logger  *zap.Logger
		Timeout time.Duration
		Key     *ecdsa.PrivateKey
	}

	// GetObjectParams stores object get request parameters.
	GetObjectParams struct {
		Range  *RangeParams
		Bucket string
		Object string
		Offset int64
		Length int64
		Writer io.Writer
	}

	// RangeParams stores range header request parameters.
	RangeParams struct {
		Start uint64
		End   uint64
	}

	// PutObjectParams stores object put request parameters.
	PutObjectParams struct {
		Bucket string
		Object string
		Size   int64
		Reader io.Reader
		Header map[string]string
	}

	// CopyObjectParams stores object copy request parameters.
	CopyObjectParams struct {
		SrcBucket string
		DstBucket string
		SrcObject string
		DstObject string
		SrcSize   int64
		Header    map[string]string
	}
	// CreateBucketParams stores bucket create request parameters.
	CreateBucketParams struct {
		Name    string
		ACL     uint32
		Policy  *netmap.PlacementPolicy
		BoxData *accessbox.Box
	}
	// DeleteBucketParams stores delete bucket request parameters.
	DeleteBucketParams struct {
		Name string
	}
	// ListObjectVersionsParams stores list objects versions parameters.
	ListObjectVersionsParams struct {
		Bucket          string
		Delimiter       string
		KeyMarker       string
		MaxKeys         int
		Prefix          string
		VersionIDMarker string
		Encode          string
	}

	// NeoFS provides basic NeoFS interface.
	NeoFS interface {
		Get(ctx context.Context, address *object.Address) (*object.Object, error)
	}

	// Client provides S3 API client interface.
	Client interface {
		NeoFS

		ListBuckets(ctx context.Context) ([]*BucketInfo, error)
		GetBucketInfo(ctx context.Context, name string) (*BucketInfo, error)
		CreateBucket(ctx context.Context, p *CreateBucketParams) (*cid.ID, error)
		DeleteBucket(ctx context.Context, p *DeleteBucketParams) error

		GetObject(ctx context.Context, p *GetObjectParams) error
		GetObjectInfo(ctx context.Context, bucketName, objectName string) (*ObjectInfo, error)

		PutObject(ctx context.Context, p *PutObjectParams) (*ObjectInfo, error)

		CopyObject(ctx context.Context, p *CopyObjectParams) (*ObjectInfo, error)

		ListObjectsV1(ctx context.Context, p *ListObjectsParamsV1) (*ListObjectsInfoV1, error)
		ListObjectsV2(ctx context.Context, p *ListObjectsParamsV2) (*ListObjectsInfoV2, error)
		ListObjectVersions(ctx context.Context, p *ListObjectVersionsParams) (*ListObjectVersionsInfo, error)

		DeleteObject(ctx context.Context, bucket, object string) error
		DeleteObjects(ctx context.Context, bucket string, objects []string) []error
	}
)

const (
	unversionedObjectVersionID = "null"
)

// NewLayer creates instance of layer. It checks credentials
// and establishes gRPC connection with node.
func NewLayer(log *zap.Logger, conns pool.Pool, config *CacheConfig) Client {
	return &layer{
		pool:         conns,
		log:          log,
		listObjCache: newListObjectsCache(config.ListObjectsLifetime),
		objCache:     cache.New(config.Size, config.Lifetime),
	}
}

// Owner returns owner id from BearerToken (context) or from client owner.
func (n *layer) Owner(ctx context.Context) *owner.ID {
	if data, ok := ctx.Value(api.BoxData).(*accessbox.Box); ok && data != nil && data.Gate != nil {
		return data.Gate.BearerToken.Issuer()
	}

	return n.pool.OwnerID()
}

// BearerOpt returns client.WithBearer call option with token from context or with nil token.
func (n *layer) BearerOpt(ctx context.Context) client.CallOption {
	if data, ok := ctx.Value(api.BoxData).(*accessbox.Box); ok && data != nil && data.Gate != nil {
		return client.WithBearer(data.Gate.BearerToken)
	}

	return client.WithBearer(nil)
}

// SessionOpt returns client.WithSession call option with token from context or with nil token.
func (n *layer) SessionOpt(ctx context.Context) client.CallOption {
	if data, ok := ctx.Value(api.BoxData).(*accessbox.Box); ok && data != nil && data.Gate != nil {
		return client.WithSession(data.Gate.SessionToken)
	}

	return client.WithSession(nil)
}

// Get NeoFS Object by refs.Address (should be used by auth.Center).
func (n *layer) Get(ctx context.Context, address *object.Address) (*object.Object, error) {
	ops := new(client.GetObjectParams).WithAddress(address)
	return n.pool.GetObject(ctx, ops, n.BearerOpt(ctx))
}

// GetBucketInfo returns bucket info by name.
func (n *layer) GetBucketInfo(ctx context.Context, name string) (*BucketInfo, error) {
	name, err := url.QueryUnescape(name)
	if err != nil {
		return nil, err
	}

	containerID := new(cid.ID)
	if err := containerID.Parse(name); err != nil {
		list, err := n.containerList(ctx)
		if err != nil {
			return nil, err
		}
		for _, bkt := range list {
			if bkt.Name == name {
				return bkt, nil
			}
		}

		return nil, errors.GetAPIError(errors.ErrNoSuchBucket)
	}

	return n.containerInfo(ctx, containerID)
}

// ListBuckets returns all user containers. Name of the bucket is a container
// id. Timestamp is omitted since it is not saved in neofs container.
func (n *layer) ListBuckets(ctx context.Context) ([]*BucketInfo, error) {
	return n.containerList(ctx)
}

// GetObject from storage.
func (n *layer) GetObject(ctx context.Context, p *GetObjectParams) error {
	var (
		err error
		oid *object.ID
		bkt *BucketInfo
	)

	if bkt, err = n.GetBucketInfo(ctx, p.Bucket); err != nil {
		return fmt.Errorf("couldn't find bucket: %s : %w", p.Bucket, err)
	} else if oid, err = n.objectFindID(ctx, &findParams{cid: bkt.CID, val: p.Object}); err != nil {
		return fmt.Errorf("search of the object failed: cid: %s, val: %s : %w", bkt.CID, p.Object, err)
	}

	addr := object.NewAddress()
	addr.SetObjectID(oid)
	addr.SetContainerID(bkt.CID)

	params := &getParams{
		Writer:  p.Writer,
		address: addr,
		offset:  p.Offset,
		length:  p.Length,
	}

	if p.Range != nil {
		objRange := object.NewRange()
		objRange.SetOffset(p.Range.Start)
		// Range header is inclusive
		objRange.SetLength(p.Range.End - p.Range.Start + 1)
		params.Range = objRange
		_, err = n.objectRange(ctx, params)
	} else {
		_, err = n.objectGet(ctx, params)
	}

	if err != nil {
		n.objCache.Delete(addr)
		return fmt.Errorf("couldn't get object, cid: %s : %w", bkt.CID, err)
	}

	return nil
}

func (n *layer) checkObject(ctx context.Context, cid *cid.ID, filename string) error {
	var err error

	if _, err = n.objectFindID(ctx, &findParams{cid: cid, val: filename}); err == nil {
		return new(errors.ObjectAlreadyExists)
	}

	return err
}

// GetObjectInfo returns meta information about the object.
func (n *layer) GetObjectInfo(ctx context.Context, bucketName, filename string) (*ObjectInfo, error) {
	var (
		err  error
		oid  *object.ID
		bkt  *BucketInfo
		meta *object.Object
	)

	if bkt, err = n.GetBucketInfo(ctx, bucketName); err != nil {
		n.log.Error("could not fetch bucket info", zap.Error(err))
		return nil, err
	} else if oid, err = n.objectFindID(ctx, &findParams{cid: bkt.CID, val: filename}); err != nil {
		n.log.Error("could not find object id", zap.Error(err))
		return nil, err
	}

	addr := object.NewAddress()
	addr.SetObjectID(oid)
	addr.SetContainerID(bkt.CID)

	/* todo: now we get an address via request to NeoFS and try to find the object with the address in cache
	 but it will be resolved after implementation of local cache with nicenames and address of objects
	for get/head requests */
	meta = n.objCache.Get(addr)
	if meta == nil {
		meta, err = n.objectHead(ctx, addr)
		if err != nil {
			n.log.Error("could not fetch object head", zap.Error(err))
			return nil, err
		}
		if err = n.objCache.Put(addr, *meta); err != nil {
			n.log.Error("couldn't cache an object", zap.Error(err))
		}
	}
	return objectInfoFromMeta(bkt, meta, "", ""), nil
}

// PutObject into storage.
func (n *layer) PutObject(ctx context.Context, p *PutObjectParams) (*ObjectInfo, error) {
	return n.objectPut(ctx, p)
}

// CopyObject from one bucket into another bucket.
func (n *layer) CopyObject(ctx context.Context, p *CopyObjectParams) (*ObjectInfo, error) {
	pr, pw := io.Pipe()

	go func() {
		err := n.GetObject(ctx, &GetObjectParams{
			Bucket: p.SrcBucket,
			Object: p.SrcObject,
			Writer: pw,
		})

		if err = pw.CloseWithError(err); err != nil {
			n.log.Error("could not get object", zap.Error(err))
		}
	}()

	return n.PutObject(ctx, &PutObjectParams{
		Bucket: p.DstBucket,
		Object: p.DstObject,
		Size:   p.SrcSize,
		Reader: pr,
		Header: p.Header,
	})
}

// DeleteObject removes all objects with passed nice name.
func (n *layer) DeleteObject(ctx context.Context, bucket, filename string) error {
	var (
		err error
		ids []*object.ID
		bkt *BucketInfo
	)

	if bkt, err = n.GetBucketInfo(ctx, bucket); err != nil {
		return &errors.DeleteError{
			Err:    err,
			Object: filename,
		}
	} else if ids, err = n.objectSearch(ctx, &findParams{cid: bkt.CID, val: filename}); err != nil {
		return &errors.DeleteError{
			Err:    err,
			Object: filename,
		}
	}

	for _, id := range ids {
		addr := object.NewAddress()
		addr.SetObjectID(id)
		addr.SetContainerID(bkt.CID)

		if err = n.objectDelete(ctx, addr); err != nil {
			return &errors.DeleteError{
				Err:    err,
				Object: filename,
			}
		}
	}

	return nil
}

// DeleteObjects from the storage.
func (n *layer) DeleteObjects(ctx context.Context, bucket string, objects []string) []error {
	var errs = make([]error, 0, len(objects))

	for i := range objects {
		if err := n.DeleteObject(ctx, bucket, objects[i]); err != nil {
			errs = append(errs, err)
		}
	}

	return errs
}

func (n *layer) CreateBucket(ctx context.Context, p *CreateBucketParams) (*cid.ID, error) {
	_, err := n.GetBucketInfo(ctx, p.Name)
	if err != nil {
		if errors.IsS3Error(err, errors.ErrNoSuchBucket) {
			return n.createContainer(ctx, p)
		}
		return nil, err
	}

	return nil, errors.GetAPIError(errors.ErrBucketAlreadyExists)
}

func (n *layer) DeleteBucket(ctx context.Context, p *DeleteBucketParams) error {
	bucketInfo, err := n.GetBucketInfo(ctx, p.Name)
	if err != nil {
		return err
	}

	return n.deleteContainer(ctx, bucketInfo.CID)
}

func (n *layer) ListObjectVersions(ctx context.Context, p *ListObjectVersionsParams) (*ListObjectVersionsInfo, error) {
	var (
		res       = ListObjectVersionsInfo{}
		err       error
		bkt       *BucketInfo
		ids       []*object.ID
		uniqNames = make(map[string]bool)
	)

	if bkt, err = n.GetBucketInfo(ctx, p.Bucket); err != nil {
		return nil, err
	} else if ids, err = n.objectSearch(ctx, &findParams{cid: bkt.CID}); err != nil {
		return nil, err
	}

	versions := make([]*ObjectVersionInfo, 0, len(ids))
	// todo: deletemarkers is empty now, we will use it after proper realization of versioning
	deleted := make([]*DeletedObjectInfo, 0, len(ids))
	res.DeleteMarker = deleted

	for _, id := range ids {
		addr := object.NewAddress()
		addr.SetObjectID(id)
		addr.SetContainerID(bkt.CID)

		meta, err := n.objectHead(ctx, addr)
		if err != nil {
			n.log.Warn("could not fetch object meta", zap.Error(err))
			continue
		}
		if ov := objectVersionInfoFromMeta(bkt, meta, p.Prefix, p.Delimiter); ov != nil {
			if _, ok := uniqNames[ov.Object.Name]; ok {
				continue
			}
			if len(p.KeyMarker) > 0 && ov.Object.Name <= p.KeyMarker {
				continue
			}
			uniqNames[ov.Object.Name] = ov.Object.isDir
			versions = append(versions, ov)
		}
	}

	sort.Slice(versions, func(i, j int) bool {
		return versions[i].Object.Name < versions[j].Object.Name
	})

	if len(versions) > p.MaxKeys {
		res.IsTruncated = true

		lastVersion := versions[p.MaxKeys-1]
		res.KeyMarker = lastVersion.Object.Name
		res.VersionIDMarker = lastVersion.VersionID

		nextVersion := versions[p.MaxKeys]
		res.NextKeyMarker = nextVersion.Object.Name
		res.NextVersionIDMarker = nextVersion.VersionID

		versions = versions[:p.MaxKeys]
	}

	for _, ov := range versions {
		if isDir := uniqNames[ov.Object.Name]; isDir {
			res.CommonPrefixes = append(res.CommonPrefixes, &ov.Object.Name)
		} else {
			res.Version = append(res.Version, ov)
		}
	}
	return &res, nil
}