package container

import (
	"encoding/json"
	"errors"
	"fmt"
	"os"
	"slices"
	"sort"

	"git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-adm/internal/modules/morph/constants"
	"git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-adm/internal/modules/morph/helper"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
	"github.com/nspcc-dev/neo-go/pkg/io"
	"github.com/nspcc-dev/neo-go/pkg/rpcclient/invoker"
	"github.com/nspcc-dev/neo-go/pkg/rpcclient/management"
	"github.com/nspcc-dev/neo-go/pkg/rpcclient/unwrap"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract/callflag"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/vm/emit"
	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
	"github.com/spf13/cobra"
	"github.com/spf13/viper"
)

var errInvalidContainerResponse = errors.New("invalid response from container contract")

func getContainerContractHash(cmd *cobra.Command, inv *invoker.Invoker) (util.Uint160, error) {
	s, err := cmd.Flags().GetString(containerContractFlag)
	var ch util.Uint160
	if err == nil {
		ch, err = util.Uint160DecodeStringLE(s)
	}
	if err != nil {
		r := management.NewReader(inv)
		nnsCs, err := helper.GetContractByID(r, 1)
		if err != nil {
			return util.Uint160{}, fmt.Errorf("can't get NNS contract state: %w", err)
		}
		ch, err = helper.NNSResolveHash(inv, nnsCs.Hash, helper.DomainOf(constants.ContainerContract))
		if err != nil {
			return util.Uint160{}, err
		}
	}
	return ch, nil
}

func iterateContainerList(inv *invoker.Invoker, ch util.Uint160, f func([]byte) error) error {
	sid, r, err := unwrap.SessionIterator(inv.Call(ch, "containersOf", ""))
	if err != nil {
		return fmt.Errorf("%w: %v", errInvalidContainerResponse, err)
	}
	// Nothing bad, except live session on the server, do not report to the user.
	defer func() { _ = inv.TerminateSession(sid) }()

	items, err := inv.TraverseIterator(sid, &r, 0)
	for err == nil && len(items) != 0 {
		for j := range items {
			b, err := items[j].TryBytes()
			if err != nil {
				return fmt.Errorf("%w: %v", errInvalidContainerResponse, err)
			}
			if err := f(b); err != nil {
				return err
			}
		}
		items, err = inv.TraverseIterator(sid, &r, 0)
	}
	return err
}

func dumpContainers(cmd *cobra.Command, _ []string) error {
	filename, err := cmd.Flags().GetString(containerDumpFlag)
	if err != nil {
		return fmt.Errorf("invalid filename: %w", err)
	}

	c, err := helper.NewRemoteClient(viper.GetViper())
	if err != nil {
		return fmt.Errorf("can't create N3 client: %w", err)
	}

	inv := invoker.New(c, nil)

	ch, err := getContainerContractHash(cmd, inv)
	if err != nil {
		return fmt.Errorf("unable to get contaract hash: %w", err)
	}

	isOK, err := getCIDFilterFunc(cmd)
	if err != nil {
		return err
	}

	f, err := os.OpenFile(filename, os.O_RDWR|os.O_TRUNC|os.O_CREATE, 0o660)
	if err != nil {
		return err
	}
	defer f.Close()

	_, err = f.Write([]byte{'['})
	if err != nil {
		return err
	}

	written := 0
	enc := json.NewEncoder(f)
	bw := io.NewBufBinWriter()
	iterErr := iterateContainerList(inv, ch, func(id []byte) error {
		if !isOK(id) {
			return nil
		}

		cnt, err := dumpSingleContainer(bw, ch, inv, id)
		if err != nil {
			return err
		}

		// Writing directly to the file is ok, because json.Encoder does no internal buffering.
		if written != 0 {
			_, err = f.Write([]byte{','})
			if err != nil {
				return err
			}
		}

		written++
		return enc.Encode(cnt)
	})
	if iterErr != nil {
		return iterErr
	}

	_, err = f.Write([]byte{']'})
	return err
}

func dumpSingleContainer(bw *io.BufBinWriter, ch util.Uint160, inv *invoker.Invoker, id []byte) (*Container, error) {
	bw.Reset()
	emit.AppCall(bw.BinWriter, ch, "get", callflag.All, id)
	res, err := inv.Run(bw.Bytes())
	if err != nil {
		return nil, fmt.Errorf("can't get container info: %w", err)
	}
	if len(res.Stack) != 1 {
		return nil, fmt.Errorf("%w: expected 1 items on stack", errInvalidContainerResponse)
	}

	cnt := new(Container)
	err = cnt.FromStackItem(res.Stack[0])
	if err != nil {
		return nil, fmt.Errorf("%w: %v", errInvalidContainerResponse, err)
	}

	return cnt, nil
}

func listContainers(cmd *cobra.Command, _ []string) error {
	c, err := helper.NewRemoteClient(viper.GetViper())
	if err != nil {
		return fmt.Errorf("can't create N3 client: %w", err)
	}

	inv := invoker.New(c, nil)

	ch, err := getContainerContractHash(cmd, inv)
	if err != nil {
		return fmt.Errorf("unable to get contaract hash: %w", err)
	}

	return iterateContainerList(inv, ch, func(id []byte) error {
		var idCnr cid.ID
		err = idCnr.Decode(id)
		if err != nil {
			return fmt.Errorf("unable to decode container id: %w", err)
		}
		cmd.Println(idCnr)
		return nil
	})
}

func restoreContainers(cmd *cobra.Command, _ []string) error {
	filename, err := cmd.Flags().GetString(containerDumpFlag)
	if err != nil {
		return fmt.Errorf("invalid filename: %w", err)
	}

	wCtx, err := helper.NewInitializeContext(cmd, viper.GetViper())
	if err != nil {
		return err
	}
	defer wCtx.Close()

	containers, err := parseContainers(filename)
	if err != nil {
		return err
	}

	ch, err := fetchContainerContractHash(wCtx)
	if err != nil {
		return err
	}

	isOK, err := getCIDFilterFunc(cmd)
	if err != nil {
		return err
	}

	err = restoreOrPutContainers(containers, isOK, cmd, wCtx, ch)
	if err != nil {
		return err
	}

	return wCtx.AwaitTx()
}

func restoreOrPutContainers(containers []Container, isOK func([]byte) bool, cmd *cobra.Command, wCtx *helper.InitializeContext, ch util.Uint160) error {
	bw := io.NewBufBinWriter()
	for _, cnt := range containers {
		hv := hash.Sha256(cnt.Value)
		if !isOK(hv[:]) {
			continue
		}
		bw.Reset()
		restored, err := isContainerRestored(cmd, wCtx, ch, bw, hv)
		if err != nil {
			return err
		}
		if restored {
			continue
		}

		bw.Reset()

		putContainer(bw, ch, cnt)

		if bw.Err != nil {
			panic(bw.Err)
		}

		if err := wCtx.SendConsensusTx(bw.Bytes()); err != nil {
			return err
		}
	}
	return nil
}

func putContainer(bw *io.BufBinWriter, ch util.Uint160, cnt Container) {
	emit.AppCall(bw.BinWriter, ch, "put", callflag.All,
		cnt.Value, cnt.Signature, cnt.PublicKey, cnt.Token)
}

func isContainerRestored(cmd *cobra.Command, wCtx *helper.InitializeContext, containerHash util.Uint160, bw *io.BufBinWriter, hashValue util.Uint256) (bool, error) {
	emit.AppCall(bw.BinWriter, containerHash, "get", callflag.All, hashValue.BytesBE())
	res, err := wCtx.Client.InvokeScript(bw.Bytes(), nil)
	if err != nil {
		return false, fmt.Errorf("can't check if container is already restored: %w", err)
	}
	if len(res.Stack) == 0 {
		return false, errors.New("empty stack")
	}

	old := new(Container)
	if err := old.FromStackItem(res.Stack[0]); err != nil {
		return false, fmt.Errorf("%w: %v", errInvalidContainerResponse, err)
	}
	if len(old.Value) != 0 {
		var id cid.ID
		id.SetSHA256(hashValue)
		cmd.Printf("Container %s is already deployed.\n", id)
		return true, nil
	}

	return false, nil
}

func parseContainers(filename string) ([]Container, error) {
	data, err := os.ReadFile(filename)
	if err != nil {
		return nil, fmt.Errorf("can't read dump file: %w", err)
	}

	var containers []Container
	err = json.Unmarshal(data, &containers)
	if err != nil {
		return nil, fmt.Errorf("can't parse dump file: %w", err)
	}
	return containers, nil
}

func fetchContainerContractHash(wCtx *helper.InitializeContext) (util.Uint160, error) {
	r := management.NewReader(wCtx.ReadOnlyInvoker)
	nnsCs, err := helper.GetContractByID(r, 1)
	if err != nil {
		return util.Uint160{}, fmt.Errorf("can't get NNS contract state: %w", err)
	}

	ch, err := helper.NNSResolveHash(wCtx.ReadOnlyInvoker, nnsCs.Hash, helper.DomainOf(constants.ContainerContract))
	if err != nil {
		return util.Uint160{}, fmt.Errorf("can't fetch container contract hash: %w", err)
	}
	return ch, nil
}

// Container represents container struct in contract storage.
type Container struct {
	Value     []byte `json:"value"`
	Signature []byte `json:"signature"`
	PublicKey []byte `json:"public_key"`
	Token     []byte `json:"token"`
}

// ToStackItem implements stackitem.Convertible.
func (c *Container) ToStackItem() (stackitem.Item, error) {
	return stackitem.NewStruct([]stackitem.Item{
		stackitem.NewByteArray(c.Value),
		stackitem.NewByteArray(c.Signature),
		stackitem.NewByteArray(c.PublicKey),
		stackitem.NewByteArray(c.Token),
	}), nil
}

// FromStackItem implements stackitem.Convertible.
func (c *Container) FromStackItem(item stackitem.Item) error {
	arr, ok := item.Value().([]stackitem.Item)
	if !ok || len(arr) != 4 {
		return errors.New("invalid stack item type")
	}

	value, err := arr[0].TryBytes()
	if err != nil {
		return errors.New("invalid container value")
	}

	sig, err := arr[1].TryBytes()
	if err != nil {
		return errors.New("invalid container signature")
	}

	pub, err := arr[2].TryBytes()
	if err != nil {
		return errors.New("invalid container public key")
	}

	tok, err := arr[3].TryBytes()
	if err != nil {
		return errors.New("invalid container token")
	}

	c.Value = value
	c.Signature = sig
	c.PublicKey = pub
	c.Token = tok
	return nil
}

// getCIDFilterFunc returns filtering function for container IDs.
// Raw byte slices are used because it works with structures returned
// from contract.
func getCIDFilterFunc(cmd *cobra.Command) (func([]byte) bool, error) {
	rawIDs, err := cmd.Flags().GetStringSlice(containerIDsFlag)
	if err != nil {
		return nil, err
	}
	if len(rawIDs) == 0 {
		return func([]byte) bool { return true }, nil
	}

	for i := range rawIDs {
		err := new(cid.ID).DecodeString(rawIDs[i])
		if err != nil {
			return nil, fmt.Errorf("can't parse CID %s: %w", rawIDs[i], err)
		}
	}
	sort.Strings(rawIDs)
	return func(rawID []byte) bool {
		var v [32]byte
		copy(v[:], rawID)

		var id cid.ID
		id.SetSHA256(v)
		idStr := id.EncodeToString()
		_, found := slices.BinarySearch(rawIDs, idStr)
		return found
	}, nil
}