package v2

import (
	"context"
	"errors"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/acl"
	objectV2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/object"
	refsV2 "git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/refs"
	"git.frostfs.info/TrueCloudLab/frostfs-api-go/v2/session"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	eaclSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/eacl"
	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/user"
)

type Option func(*cfg)

type cfg struct {
	storage ObjectStorage

	msg XHeaderSource

	cnr cid.ID
	obj *oid.ID
}

type ObjectStorage interface {
	Head(context.Context, oid.Address) (*objectSDK.Object, error)
}

type Request interface {
	GetMetaHeader() *session.RequestMetaHeader
}

type Response interface {
	GetMetaHeader() *session.ResponseMetaHeader
}

type headerSource struct {
	requestHeaders []eaclSDK.Header
	objectHeaders  []eaclSDK.Header

	incompleteObjectHeaders bool
}

func NewMessageHeaderSource(os ObjectStorage, xhs XHeaderSource, cnrID cid.ID, opts ...Option) (eaclSDK.TypedHeaderSource, error) {
	cfg := &cfg{
		storage: os,
		cnr:     cnrID,
		msg:     xhs,
	}

	for i := range opts {
		opts[i](cfg)
	}

	if cfg.msg == nil {
		return nil, errors.New("message is not provided")
	}

	var res headerSource

	err := cfg.readObjectHeaders(&res)
	if err != nil {
		return nil, err
	}

	res.requestHeaders = cfg.msg.GetXHeaders()

	return res, nil
}

func (h headerSource) HeadersOfType(typ eaclSDK.FilterHeaderType) ([]eaclSDK.Header, bool) {
	switch typ {
	default:
		return nil, true
	case eaclSDK.HeaderFromRequest:
		return h.requestHeaders, true
	case eaclSDK.HeaderFromObject:
		return h.objectHeaders, !h.incompleteObjectHeaders
	}
}

type xHeader session.XHeader

func (x xHeader) Key() string {
	return (*session.XHeader)(&x).GetKey()
}

func (x xHeader) Value() string {
	return (*session.XHeader)(&x).GetValue()
}

var errMissingOID = errors.New("object ID is missing")

func (h *cfg) readObjectHeaders(dst *headerSource) error {
	switch m := h.msg.(type) {
	default:
		panic(fmt.Sprintf("unexpected message type %T", h.msg))
	case requestXHeaderSource:
		return h.readObjectHeadersFromRequestXHeaderSource(m, dst)
	case responseXHeaderSource:
		return h.readObjectHeadersResponseXHeaderSource(m, dst)
	}
}

func (h *cfg) readObjectHeadersFromRequestXHeaderSource(m requestXHeaderSource, dst *headerSource) error {
	switch req := m.req.(type) {
	case
		*objectV2.GetRequest,
		*objectV2.HeadRequest:
		if h.obj == nil {
			return errMissingOID
		}

		objHeaders, completed := h.localObjectHeaders(h.cnr, h.obj)

		dst.objectHeaders = objHeaders
		dst.incompleteObjectHeaders = !completed
	case
		*objectV2.GetRangeRequest,
		*objectV2.GetRangeHashRequest,
		*objectV2.DeleteRequest:
		if h.obj == nil {
			return errMissingOID
		}

		dst.objectHeaders = addressHeaders(h.cnr, h.obj)
	case *objectV2.PutRequest:
		if v, ok := req.GetBody().GetObjectPart().(*objectV2.PutObjectPartInit); ok {
			oV2 := new(objectV2.Object)
			oV2.SetObjectID(v.GetObjectID())
			oV2.SetHeader(v.GetHeader())

			dst.objectHeaders = headersFromObject(objectSDK.NewFromV2(oV2), h.cnr, h.obj)
		}
	case *objectV2.SearchRequest:
		cnrV2 := req.GetBody().GetContainerID()
		var cnr cid.ID

		if cnrV2 != nil {
			if err := cnr.ReadFromV2(*cnrV2); err != nil {
				return fmt.Errorf("can't parse container ID: %w", err)
			}
		}

		dst.objectHeaders = []eaclSDK.Header{cidHeader(cnr)}
	}
	return nil
}

func (h *cfg) readObjectHeadersResponseXHeaderSource(m responseXHeaderSource, dst *headerSource) error {
	switch resp := m.resp.(type) {
	default:
		objectHeaders, completed := h.localObjectHeaders(h.cnr, h.obj)

		dst.objectHeaders = objectHeaders
		dst.incompleteObjectHeaders = !completed
	case *objectV2.GetResponse:
		if v, ok := resp.GetBody().GetObjectPart().(*objectV2.GetObjectPartInit); ok {
			oV2 := new(objectV2.Object)
			oV2.SetObjectID(v.GetObjectID())
			oV2.SetHeader(v.GetHeader())

			dst.objectHeaders = headersFromObject(objectSDK.NewFromV2(oV2), h.cnr, h.obj)
		}
	case *objectV2.HeadResponse:
		oV2 := new(objectV2.Object)

		var hdr *objectV2.Header

		switch v := resp.GetBody().GetHeaderPart().(type) {
		case *objectV2.ShortHeader:
			hdr = new(objectV2.Header)

			var idV2 refsV2.ContainerID
			h.cnr.WriteToV2(&idV2)

			hdr.SetContainerID(&idV2)
			hdr.SetVersion(v.GetVersion())
			hdr.SetCreationEpoch(v.GetCreationEpoch())
			hdr.SetOwnerID(v.GetOwnerID())
			hdr.SetObjectType(v.GetObjectType())
			hdr.SetPayloadLength(v.GetPayloadLength())
		case *objectV2.HeaderWithSignature:
			hdr = v.GetHeader()
		}

		oV2.SetHeader(hdr)

		dst.objectHeaders = headersFromObject(objectSDK.NewFromV2(oV2), h.cnr, h.obj)
	}
	return nil
}

func (h *cfg) localObjectHeaders(cnr cid.ID, idObj *oid.ID) ([]eaclSDK.Header, bool) {
	if idObj != nil {
		var addr oid.Address
		addr.SetContainer(cnr)
		addr.SetObject(*idObj)

		obj, err := h.storage.Head(context.TODO(), addr)
		if err == nil {
			return headersFromObject(obj, cnr, idObj), true
		}
	}

	return addressHeaders(cnr, idObj), false
}

func cidHeader(idCnr cid.ID) sysObjHdr {
	return sysObjHdr{
		k: acl.FilterObjectContainerID,
		v: idCnr.EncodeToString(),
	}
}

func oidHeader(obj oid.ID) sysObjHdr {
	return sysObjHdr{
		k: acl.FilterObjectID,
		v: obj.EncodeToString(),
	}
}

func ownerIDHeader(ownerID user.ID) sysObjHdr {
	return sysObjHdr{
		k: acl.FilterObjectOwnerID,
		v: ownerID.EncodeToString(),
	}
}

func addressHeaders(cnr cid.ID, oid *oid.ID) []eaclSDK.Header {
	hh := make([]eaclSDK.Header, 0, 2)
	hh = append(hh, cidHeader(cnr))

	if oid != nil {
		hh = append(hh, oidHeader(*oid))
	}

	return hh
}