package layer

import (
	"bytes"
	"context"
	"crypto/rand"
	"crypto/sha256"
	"fmt"
	"io"
	"strings"
	"time"

	objectv2 "github.com/nspcc-dev/neofs-api-go/v2/object"
	"github.com/nspcc-dev/neofs-sdk-go/checksum"
	"github.com/nspcc-dev/neofs-sdk-go/container"
	cid "github.com/nspcc-dev/neofs-sdk-go/container/id"
	"github.com/nspcc-dev/neofs-sdk-go/object"
	oid "github.com/nspcc-dev/neofs-sdk-go/object/id"
	"github.com/nspcc-dev/neofs-sdk-go/session"
	"github.com/nspcc-dev/neofs-sdk-go/user"
)

type TestNeoFS struct {
	NeoFS

	objects      map[string]*object.Object
	containers   map[string]*container.Container
	currentEpoch uint64
}

const objectSystemAttributeName = "S3-System-name"

func NewTestNeoFS() *TestNeoFS {
	return &TestNeoFS{
		objects:    make(map[string]*object.Object),
		containers: make(map[string]*container.Container),
	}
}

func (t *TestNeoFS) CurrentEpoch() uint64 {
	return t.currentEpoch
}

func (t *TestNeoFS) Objects() []*object.Object {
	res := make([]*object.Object, 0, len(t.objects))

	for _, obj := range t.objects {
		res = append(res, obj)
	}

	return res
}

func (t *TestNeoFS) AddObject(key string, obj *object.Object) {
	t.objects[key] = obj
}

func (t *TestNeoFS) ContainerID(name string) (cid.ID, error) {
	for id, cnr := range t.containers {
		if container.Name(*cnr) == name {
			var cnrID cid.ID
			return cnrID, cnrID.DecodeString(id)
		}
	}
	return cid.ID{}, fmt.Errorf("not found")
}

func (t *TestNeoFS) CreateContainer(_ context.Context, prm PrmContainerCreate) (cid.ID, error) {
	var cnr container.Container
	cnr.Init()
	cnr.SetOwner(prm.Creator)
	cnr.SetPlacementPolicy(prm.Policy)
	cnr.SetBasicACL(prm.BasicACL)
	container.SetCreationTime(&cnr, time.Now())

	if prm.Name != "" {
		var d container.Domain
		d.SetName(prm.Name)

		container.WriteDomain(&cnr, d)
		container.SetName(&cnr, prm.Name)
	}

	for i := range prm.AdditionalAttributes {
		cnr.SetAttribute(prm.AdditionalAttributes[i][0], prm.AdditionalAttributes[i][1])
	}

	b := make([]byte, 32)
	if _, err := io.ReadFull(rand.Reader, b); err != nil {
		return cid.ID{}, err
	}

	var id cid.ID
	id.SetSHA256(sha256.Sum256(b))
	t.containers[id.EncodeToString()] = &cnr

	return id, nil
}

func (t *TestNeoFS) DeleteContainer(_ context.Context, cnrID cid.ID, _ *session.Container) error {
	delete(t.containers, cnrID.EncodeToString())

	return nil
}

func (t *TestNeoFS) Container(_ context.Context, id cid.ID) (*container.Container, error) {
	for k, v := range t.containers {
		if k == id.EncodeToString() {
			return v, nil
		}
	}

	return nil, fmt.Errorf("container not found %s", id)
}

func (t *TestNeoFS) UserContainers(_ context.Context, _ user.ID) ([]cid.ID, error) {
	var res []cid.ID
	for k := range t.containers {
		var idCnr cid.ID
		if err := idCnr.DecodeString(k); err != nil {
			return nil, err
		}
		res = append(res, idCnr)
	}

	return res, nil
}

func (t *TestNeoFS) SelectObjects(_ context.Context, prm PrmObjectSelect) ([]oid.ID, error) {
	filters := object.NewSearchFilters()
	filters.AddRootFilter()

	if prm.FilePrefix != "" {
		filters.AddFilter(object.AttributeFileName, prm.FilePrefix, object.MatchCommonPrefix)
	}

	if prm.ExactAttribute[0] != "" {
		filters.AddFilter(prm.ExactAttribute[0], prm.ExactAttribute[1], object.MatchStringEqual)
	}

	cidStr := prm.Container.EncodeToString()

	var res []oid.ID

	if len(filters) == 1 {
		for k, v := range t.objects {
			if strings.Contains(k, cidStr) {
				id, _ := v.ID()
				res = append(res, id)
			}
		}
		return res, nil
	}

	filter := filters[1]
	if len(filters) != 2 || filter.Operation() != object.MatchStringEqual ||
		(filter.Header() != object.AttributeFileName && filter.Header() != objectSystemAttributeName) {
		return nil, fmt.Errorf("usupported filters")
	}

	for k, v := range t.objects {
		if strings.Contains(k, cidStr) && isMatched(v.Attributes(), filter) {
			id, _ := v.ID()
			res = append(res, id)
		}
	}

	return res, nil
}

func (t *TestNeoFS) ReadObject(_ context.Context, prm PrmObjectRead) (*ObjectPart, error) {
	var addr oid.Address
	addr.SetContainer(prm.Container)
	addr.SetObject(prm.Object)

	sAddr := addr.EncodeToString()

	if obj, ok := t.objects[sAddr]; ok {
		payload := obj.Payload()

		if prm.PayloadRange[0]+prm.PayloadRange[1] > 0 {
			off := prm.PayloadRange[0]
			payload = payload[off : off+prm.PayloadRange[1]]
		}

		return &ObjectPart{
			Head:    obj,
			Payload: io.NopCloser(bytes.NewReader(payload)),
		}, nil
	}

	return nil, fmt.Errorf("object not found %s", addr)
}

func (t *TestNeoFS) CreateObject(_ context.Context, prm PrmObjectCreate) (oid.ID, error) {
	b := make([]byte, 32)
	if _, err := io.ReadFull(rand.Reader, b); err != nil {
		return oid.ID{}, err
	}
	var id oid.ID
	id.SetSHA256(sha256.Sum256(b))

	attrs := make([]object.Attribute, 0)

	if prm.Filename != "" {
		a := object.NewAttribute()
		a.SetKey(object.AttributeFileName)
		a.SetValue(prm.Filename)
		attrs = append(attrs, *a)
	}

	for i := range prm.Attributes {
		a := object.NewAttribute()
		a.SetKey(prm.Attributes[i][0])
		a.SetValue(prm.Attributes[i][1])
		attrs = append(attrs, *a)
	}

	obj := object.New()
	obj.SetContainerID(prm.Container)
	obj.SetID(id)
	obj.SetPayloadSize(prm.PayloadSize)
	obj.SetAttributes(attrs...)
	obj.SetCreationEpoch(t.currentEpoch)
	t.currentEpoch++

	if len(prm.Locks) > 0 {
		lock := new(object.Lock)
		lock.WriteMembers(prm.Locks)
		objectv2.WriteLock(obj.ToV2(), (objectv2.Lock)(*lock))
	}

	if prm.Payload != nil {
		all, err := io.ReadAll(prm.Payload)
		if err != nil {
			return oid.ID{}, err
		}
		obj.SetPayload(all)
		obj.SetPayloadSize(uint64(len(all)))
		var hash checksum.Checksum
		checksum.Calculate(&hash, checksum.SHA256, all)
		obj.SetPayloadChecksum(hash)
	}

	cnrID, _ := obj.ContainerID()
	objID, _ := obj.ID()

	addr := newAddress(cnrID, objID)
	t.objects[addr.EncodeToString()] = obj
	return objID, nil
}

func (t *TestNeoFS) DeleteObject(_ context.Context, prm PrmObjectDelete) error {
	var addr oid.Address
	addr.SetContainer(prm.Container)
	addr.SetObject(prm.Object)

	delete(t.objects, addr.EncodeToString())

	return nil
}

func (t *TestNeoFS) TimeToEpoch(_ context.Context, futureTime time.Time) (uint64, uint64, error) {
	return t.currentEpoch, t.currentEpoch + uint64(futureTime.Second()), nil
}

func isMatched(attributes []object.Attribute, filter object.SearchFilter) bool {
	for _, attr := range attributes {
		if attr.Key() == filter.Header() && attr.Value() == filter.Value() {
			return true
		}
	}

	return false
}