package contract

import (
	"context"
	"fmt"
	"math/big"

	policycontract "git.frostfs.info/TrueCloudLab/frostfs-contract/policy"
	policyclient "git.frostfs.info/TrueCloudLab/frostfs-contract/rpcclient/policy"
	frostfsutil "git.frostfs.info/TrueCloudLab/frostfs-s3-gw/internal/frostfs/util"
	"git.frostfs.info/TrueCloudLab/policy-engine/pkg/chain"
	"git.frostfs.info/TrueCloudLab/policy-engine/pkg/engine"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"github.com/nspcc-dev/neo-go/pkg/rpcclient"
	"github.com/nspcc-dev/neo-go/pkg/rpcclient/actor"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/wallet"
)

type Client struct {
	actor          *actor.Actor
	policyContract *policyclient.Contract
}

type Config struct {
	// RPCAddress is an endpoint to connect to neo rpc.
	RPCAddress string

	// Contract is hash of contract or its name in NNS.
	Contract string

	// Key is used to interact with policy contract.
	// If this is nil than random key will be generated.
	Key *keys.PrivateKey
}

var _ engine.MorphRuleChainStorage = (*Client)(nil)

// New creates new Policy contract wrapper.
func New(ctx context.Context, cfg Config) (*Client, error) {
	contractHash, err := frostfsutil.ResolveContractHash(cfg.Contract, cfg.RPCAddress)
	if err != nil {
		return nil, fmt.Errorf("resolve frostfs contract hash: %w", err)
	}

	key := cfg.Key
	if key == nil {
		if key, err = keys.NewPrivateKey(); err != nil {
			return nil, fmt.Errorf("generate anon private key for policy: %w", err)
		}
	}

	rpcCli, err := rpcclient.New(ctx, cfg.RPCAddress, rpcclient.Options{})
	if err != nil {
		return nil, fmt.Errorf("create policy rpc client: %w", err)
	}

	acc := wallet.NewAccountFromPrivateKey(key)
	act, err := actor.NewSimple(rpcCli, acc)
	if err != nil {
		return nil, fmt.Errorf("create new actor: %w", err)
	}

	return &Client{
		actor:          act,
		policyContract: policyclient.New(act, contractHash),
	}, nil
}

func (c *Client) AddMorphRuleChain(name chain.Name, target engine.Target, policyChain *chain.Chain) (util.Uint256, uint32, error) {
	chainName := append([]byte(name), []byte(policyChain.ID)...)
	return c.policyContract.AddChain(getKind(target), target.Name, chainName, policyChain.Bytes())
}

func (c *Client) RemoveMorphRuleChain(name chain.Name, target engine.Target, chainID chain.ID) (util.Uint256, uint32, error) {
	chainName := append([]byte(name), []byte(chainID)...)
	return c.policyContract.RemoveChain(getKind(target), target.Name, chainName)
}

func (c *Client) ListMorphRuleChains(name chain.Name, target engine.Target) ([]*chain.Chain, error) {
	items, err := c.policyContract.ListChainsByPrefix(getKind(target), target.Name, []byte(name))
	if err != nil {
		return nil, err
	}

	res := make([]*chain.Chain, len(items))
	for i, item := range items {
		data, err := item.TryBytes()
		if err != nil {
			return nil, err
		}

		var policyChain chain.Chain
		if err = policyChain.DecodeBytes(data); err != nil {
			return nil, err
		}

		res[i] = &policyChain
	}

	return res, nil
}

func getKind(target engine.Target) *big.Int {
	var kind int64 = policycontract.Container
	if target.Type != engine.Container {
		kind = policycontract.Namespace
	}

	return big.NewInt(kind)
}