package client

import (
	"encoding/hex"
	"errors"
	"fmt"

	"github.com/nspcc-dev/neo-go/pkg/core"
	"github.com/nspcc-dev/neo-go/pkg/core/block"
	"github.com/nspcc-dev/neo-go/pkg/core/state"
	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
	"github.com/nspcc-dev/neo-go/pkg/crypto/hash"
	"github.com/nspcc-dev/neo-go/pkg/encoding/address"
	"github.com/nspcc-dev/neo-go/pkg/io"
	"github.com/nspcc-dev/neo-go/pkg/rpc/request"
	"github.com/nspcc-dev/neo-go/pkg/rpc/response/result"
	"github.com/nspcc-dev/neo-go/pkg/smartcontract"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/wallet"
)

// GetApplicationLog returns the contract log based on the specified txid.
func (c *Client) GetApplicationLog(hash util.Uint256) (*result.ApplicationLog, error) {
	var (
		params = request.NewRawParams(hash.StringLE())
		resp   = &result.ApplicationLog{}
	)
	if err := c.performRequest("getapplicationlog", params, resp); err != nil {
		return nil, err
	}
	return resp, nil
}

// GetBestBlockHash returns the hash of the tallest block in the main chain.
func (c *Client) GetBestBlockHash() (util.Uint256, error) {
	var resp = util.Uint256{}
	if err := c.performRequest("getbestblockhash", request.NewRawParams(), &resp); err != nil {
		return resp, err
	}
	return resp, nil
}

// GetBlockCount returns the number of blocks in the main chain.
func (c *Client) GetBlockCount() (uint32, error) {
	var resp uint32
	if err := c.performRequest("getblockcount", request.NewRawParams(), &resp); err != nil {
		return resp, err
	}
	return resp, nil
}

// GetBlockByIndex returns a block by its height.
func (c *Client) GetBlockByIndex(index uint32) (*block.Block, error) {
	return c.getBlock(request.NewRawParams(index))
}

// GetBlockByHash returns a block by its hash.
func (c *Client) GetBlockByHash(hash util.Uint256) (*block.Block, error) {
	return c.getBlock(request.NewRawParams(hash.StringLE()))
}

func (c *Client) getBlock(params request.RawParams) (*block.Block, error) {
	var (
		resp string
		err  error
		b    *block.Block
	)
	if err = c.performRequest("getblock", params, &resp); err != nil {
		return nil, err
	}
	blockBytes, err := hex.DecodeString(resp)
	if err != nil {
		return nil, err
	}
	r := io.NewBinReaderFromBuf(blockBytes)
	b = block.New(c.opts.Network)
	b.DecodeBinary(r)
	if r.Err != nil {
		return nil, r.Err
	}
	return b, nil
}

// GetBlockByIndexVerbose returns a block wrapper with additional metadata by
// its height.
// NOTE: to get transaction.ID and transaction.Size, use t.Hash() and io.GetVarSize(t) respectively.
func (c *Client) GetBlockByIndexVerbose(index uint32) (*result.Block, error) {
	return c.getBlockVerbose(request.NewRawParams(index, 1))
}

// GetBlockByHashVerbose returns a block wrapper with additional metadata by
// its hash.
func (c *Client) GetBlockByHashVerbose(hash util.Uint256) (*result.Block, error) {
	return c.getBlockVerbose(request.NewRawParams(hash.StringLE(), 1))
}

func (c *Client) getBlockVerbose(params request.RawParams) (*result.Block, error) {
	var (
		resp = &result.Block{}
		err  error
	)
	resp.Network = c.opts.Network
	if err = c.performRequest("getblock", params, resp); err != nil {
		return nil, err
	}
	return resp, nil
}

// GetBlockHash returns the hash value of the corresponding block, based on the specified index.
func (c *Client) GetBlockHash(index uint32) (util.Uint256, error) {
	var (
		params = request.NewRawParams(index)
		resp   = util.Uint256{}
	)
	if err := c.performRequest("getblockhash", params, &resp); err != nil {
		return resp, err
	}
	return resp, nil
}

// GetBlockHeader returns the corresponding block header information from serialized hex string
// according to the specified script hash.
func (c *Client) GetBlockHeader(hash util.Uint256) (*block.Header, error) {
	var (
		params = request.NewRawParams(hash.StringLE())
		resp   string
		h      *block.Header
	)
	if err := c.performRequest("getblockheader", params, &resp); err != nil {
		return nil, err
	}
	headerBytes, err := hex.DecodeString(resp)
	if err != nil {
		return nil, err
	}
	r := io.NewBinReaderFromBuf(headerBytes)
	h = new(block.Header)
	h.Network = c.opts.Network
	h.DecodeBinary(r)
	if r.Err != nil {
		return nil, r.Err
	}
	return h, nil
}

// GetBlockHeaderVerbose returns the corresponding block header information from Json format string
// according to the specified script hash.
func (c *Client) GetBlockHeaderVerbose(hash util.Uint256) (*result.Header, error) {
	var (
		params = request.NewRawParams(hash.StringLE(), 1)
		resp   = &result.Header{}
	)
	if err := c.performRequest("getblockheader", params, resp); err != nil {
		return nil, err
	}
	return resp, nil
}

// GetBlockSysFee returns the system fees of the block, based on the specified index.
func (c *Client) GetBlockSysFee(index uint32) (util.Fixed8, error) {
	var (
		params = request.NewRawParams(index)
		resp   util.Fixed8
	)
	if err := c.performRequest("getblocksysfee", params, &resp); err != nil {
		return resp, err
	}
	return resp, nil
}

// GetConnectionCount returns the current number of connections for the node.
func (c *Client) GetConnectionCount() (int, error) {
	var (
		params = request.NewRawParams()
		resp   int
	)
	if err := c.performRequest("getconnectioncount", params, &resp); err != nil {
		return resp, err
	}
	return resp, nil
}

// GetContractState queries contract information, according to the contract script hash.
func (c *Client) GetContractState(hash util.Uint160) (*state.Contract, error) {
	var (
		params = request.NewRawParams(hash.StringLE())
		resp   = &state.Contract{}
	)
	if err := c.performRequest("getcontractstate", params, resp); err != nil {
		return resp, err
	}
	return resp, nil
}

// GetNEP5Balances is a wrapper for getnep5balances RPC.
func (c *Client) GetNEP5Balances(address util.Uint160) (*result.NEP5Balances, error) {
	params := request.NewRawParams(address.StringLE())
	resp := new(result.NEP5Balances)
	if err := c.performRequest("getnep5balances", params, resp); err != nil {
		return nil, err
	}
	return resp, nil
}

// GetNEP5Transfers is a wrapper for getnep5transfers RPC.
func (c *Client) GetNEP5Transfers(address string) (*result.NEP5Transfers, error) {
	params := request.NewRawParams(address)
	resp := new(result.NEP5Transfers)
	if err := c.performRequest("getnep5transfers", params, resp); err != nil {
		return nil, err
	}
	return resp, nil
}

// GetPeers returns the list of nodes that the node is currently connected/disconnected from.
func (c *Client) GetPeers() (*result.GetPeers, error) {
	var (
		params = request.NewRawParams()
		resp   = &result.GetPeers{}
	)
	if err := c.performRequest("getpeers", params, resp); err != nil {
		return resp, err
	}
	return resp, nil
}

// GetRawMemPool returns the list of unconfirmed transactions in memory.
func (c *Client) GetRawMemPool() ([]util.Uint256, error) {
	var (
		params = request.NewRawParams()
		resp   = new([]util.Uint256)
	)
	if err := c.performRequest("getrawmempool", params, resp); err != nil {
		return *resp, err
	}
	return *resp, nil
}

// GetRawTransaction returns a transaction by hash.
func (c *Client) GetRawTransaction(hash util.Uint256) (*transaction.Transaction, error) {
	var (
		params = request.NewRawParams(hash.StringLE())
		resp   string
		err    error
	)
	if err = c.performRequest("getrawtransaction", params, &resp); err != nil {
		return nil, err
	}
	txBytes, err := hex.DecodeString(resp)
	if err != nil {
		return nil, err
	}
	tx, err := transaction.NewTransactionFromBytes(c.opts.Network, txBytes)
	if err != nil {
		return nil, err
	}
	return tx, nil
}

// GetRawTransactionVerbose returns a transaction wrapper with additional
// metadata by transaction's hash.
// NOTE: to get transaction.ID and transaction.Size, use t.Hash() and io.GetVarSize(t) respectively.
func (c *Client) GetRawTransactionVerbose(hash util.Uint256) (*result.TransactionOutputRaw, error) {
	var (
		params = request.NewRawParams(hash.StringLE(), 1)
		resp   = &result.TransactionOutputRaw{}
		err    error
	)
	resp.Network = c.opts.Network
	if err = c.performRequest("getrawtransaction", params, resp); err != nil {
		return nil, err
	}
	return resp, nil
}

// GetStorageByID returns the stored value, according to the contract ID and the stored key.
func (c *Client) GetStorageByID(id int32, key []byte) ([]byte, error) {
	return c.getStorage(request.NewRawParams(id, hex.EncodeToString(key)))
}

// GetStorageByHash returns the stored value, according to the contract script hash and the stored key.
func (c *Client) GetStorageByHash(hash util.Uint160, key []byte) ([]byte, error) {
	return c.getStorage(request.NewRawParams(hash.StringLE(), hex.EncodeToString(key)))
}

func (c *Client) getStorage(params request.RawParams) ([]byte, error) {
	var resp string
	if err := c.performRequest("getstorage", params, &resp); err != nil {
		return nil, err
	}
	res, err := hex.DecodeString(resp)
	if err != nil {
		return nil, err
	}
	return res, nil
}

// GetTransactionHeight returns the block index in which the transaction is found.
func (c *Client) GetTransactionHeight(hash util.Uint256) (uint32, error) {
	var (
		params = request.NewRawParams(hash.StringLE())
		resp   uint32
	)
	if err := c.performRequest("gettransactionheight", params, &resp); err != nil {
		return resp, err
	}
	return resp, nil
}

// GetUnclaimedGas returns unclaimed GAS amount for the specified address.
func (c *Client) GetUnclaimedGas(address string) (result.UnclaimedGas, error) {
	var (
		params = request.NewRawParams(address)
		resp   result.UnclaimedGas
	)
	if err := c.performRequest("getunclaimedgas", params, &resp); err != nil {
		return resp, err
	}
	return resp, nil
}

// GetValidators returns the current NEO consensus nodes information and voting status.
func (c *Client) GetValidators() ([]result.Validator, error) {
	var (
		params = request.NewRawParams()
		resp   = new([]result.Validator)
	)
	if err := c.performRequest("getvalidators", params, resp); err != nil {
		return nil, err
	}
	return *resp, nil
}

// GetVersion returns the version information about the queried node.
func (c *Client) GetVersion() (*result.Version, error) {
	var (
		params = request.NewRawParams()
		resp   = &result.Version{}
	)
	if err := c.performRequest("getversion", params, resp); err != nil {
		return nil, err
	}
	return resp, nil
}

// InvokeScript returns the result of the given script after running it true the VM.
// NOTE: This is a test invoke and will not affect the blockchain.
func (c *Client) InvokeScript(script []byte, signers []transaction.Signer) (*result.Invoke, error) {
	var p = request.NewRawParams(hex.EncodeToString(script))
	return c.invokeSomething("invokescript", p, signers)
}

// InvokeFunction returns the results after calling the smart contract scripthash
// with the given operation and parameters.
// NOTE: this is test invoke and will not affect the blockchain.
func (c *Client) InvokeFunction(contract util.Uint160, operation string, params []smartcontract.Parameter, signers []transaction.Signer) (*result.Invoke, error) {
	var p = request.NewRawParams(contract.StringLE(), operation, params)
	return c.invokeSomething("invokefunction", p, signers)
}

// invokeSomething is an inner wrapper for Invoke* functions
func (c *Client) invokeSomething(method string, p request.RawParams, signers []transaction.Signer) (*result.Invoke, error) {
	var resp = new(result.Invoke)
	if signers != nil {
		p.Values = append(p.Values, signers)
	}
	if err := c.performRequest(method, p, resp); err != nil {
		// Retry with old-fashioned hashes (see neo/neo-modules#260).
		if signers != nil {
			var hashes = make([]util.Uint160, len(signers))
			for i := range signers {
				hashes[i] = signers[i].Account
			}
			p.Values[len(p.Values)-1] = hashes
			err = c.performRequest(method, p, resp)
			if err == nil {
				return resp, nil
			}
		}
		return nil, err
	}
	return resp, nil
}

// SendRawTransaction broadcasts a transaction over the NEO network.
// The given hex string needs to be signed with a keypair.
// When the result of the response object is true, the TX has successfully
// been broadcasted to the network.
func (c *Client) SendRawTransaction(rawTX *transaction.Transaction) (util.Uint256, error) {
	var (
		params = request.NewRawParams(hex.EncodeToString(rawTX.Bytes()))
		resp   = new(result.RelayResult)
	)
	if err := c.performRequest("sendrawtransaction", params, resp); err != nil {
		return util.Uint256{}, err
	}
	return resp.Hash, nil
}

// SubmitBlock broadcasts a raw block over the NEO network.
func (c *Client) SubmitBlock(b block.Block) (util.Uint256, error) {
	var (
		params request.RawParams
		resp   = new(result.RelayResult)
	)
	buf := io.NewBufBinWriter()
	b.EncodeBinary(buf.BinWriter)
	if err := buf.Err; err != nil {
		return util.Uint256{}, err
	}
	params = request.NewRawParams(hex.EncodeToString(buf.Bytes()))

	if err := c.performRequest("submitblock", params, resp); err != nil {
		return util.Uint256{}, err
	}
	return resp.Hash, nil
}

// SignAndPushInvocationTx signs and pushes given script as an invocation
// transaction  using given wif to sign it and spending the amount of gas
// specified. It returns a hash of the invocation transaction and an error.
func (c *Client) SignAndPushInvocationTx(script []byte, acc *wallet.Account, sysfee int64, netfee util.Fixed8, cosigners []transaction.Signer) (util.Uint256, error) {
	var txHash util.Uint256
	var err error

	tx := transaction.New(c.opts.Network, script, sysfee)
	tx.SystemFee = sysfee

	addr, err := address.StringToUint160(acc.Address)
	if err != nil {
		return txHash, fmt.Errorf("failed to get address: %w", err)
	}
	tx.Signers = getSigners(addr, cosigners)

	validUntilBlock, err := c.CalculateValidUntilBlock()
	if err != nil {
		return txHash, fmt.Errorf("failed to add validUntilBlock to transaction: %w", err)
	}
	tx.ValidUntilBlock = validUntilBlock

	err = c.AddNetworkFee(tx, int64(netfee), acc)
	if err != nil {
		return txHash, fmt.Errorf("failed to add network fee: %w", err)
	}

	if err = acc.SignTx(tx); err != nil {
		return txHash, fmt.Errorf("failed to sign tx: %w", err)
	}
	txHash = tx.Hash()
	actualHash, err := c.SendRawTransaction(tx)
	if err != nil {
		return txHash, fmt.Errorf("failed to send tx: %w", err)
	}
	if !actualHash.Equals(txHash) {
		return actualHash, fmt.Errorf("sent and actual tx hashes mismatch:\n\tsent: %v\n\tactual: %v", txHash.StringLE(), actualHash.StringLE())
	}
	return txHash, nil
}

// getSigners returns an array of transaction signers from given sender and cosigners.
// If cosigners list already contains sender, the sender will be placed at the start of
// the list.
func getSigners(sender util.Uint160, cosigners []transaction.Signer) []transaction.Signer {
	s := transaction.Signer{
		Account: sender,
		Scopes:  transaction.FeeOnly,
	}
	for i, c := range cosigners {
		if c.Account == sender {
			if i == 0 {
				return cosigners
			}
			s.Scopes = c.Scopes
			cosigners = append(cosigners[:i], cosigners[i+1:]...)
			break
		}
	}
	return append([]transaction.Signer{s}, cosigners...)
}

// ValidateAddress verifies that the address is a correct NEO address.
func (c *Client) ValidateAddress(address string) error {
	var (
		params = request.NewRawParams(address)
		resp   = &result.ValidateAddress{}
	)

	if err := c.performRequest("validateaddress", params, resp); err != nil {
		return err
	}
	if !resp.IsValid {
		return errors.New("validateaddress returned false")
	}
	return nil
}

// CalculateValidUntilBlock calculates ValidUntilBlock field for tx as
// current blockchain height + number of validators. Number of validators
// is the length of blockchain validators list got from GetValidators()
// method. Validators count is being cached and updated every 100 blocks.
func (c *Client) CalculateValidUntilBlock() (uint32, error) {
	var (
		result          uint32
		validatorsCount uint32
	)
	blockCount, err := c.GetBlockCount()
	if err != nil {
		return result, fmt.Errorf("can't get block count: %w", err)
	}

	if c.cache.calculateValidUntilBlock.expiresAt > blockCount {
		validatorsCount = c.cache.calculateValidUntilBlock.validatorsCount
	} else {
		validators, err := c.GetValidators()
		if err != nil {
			return result, fmt.Errorf("can't get validators: %w", err)
		}
		validatorsCount = uint32(len(validators))
		c.cache.calculateValidUntilBlock = calculateValidUntilBlockCache{
			validatorsCount: validatorsCount,
			expiresAt:       blockCount + cacheTimeout,
		}
	}
	return blockCount + validatorsCount, nil
}

// AddNetworkFee adds network fee for each witness script and optional extra
// network fee to transaction.
func (c *Client) AddNetworkFee(tx *transaction.Transaction, extraFee int64, acc *wallet.Account) error {
	size := io.GetVarSize(tx)
	if acc.Contract != nil {
		netFee, sizeDelta := core.CalculateNetworkFee(acc.Contract.Script)
		tx.NetworkFee += netFee
		size += sizeDelta
	}
	for _, cosigner := range tx.Signers {
		script := acc.Contract.Script
		if !cosigner.Account.Equals(hash.Hash160(acc.Contract.Script)) {
			contract, err := c.GetContractState(cosigner.Account)
			if err != nil {
				return err
			}
			if contract == nil {
				continue
			}
			script = contract.Script
		}
		netFee, sizeDelta := core.CalculateNetworkFee(script)
		tx.NetworkFee += netFee
		size += sizeDelta
	}
	fee, err := c.GetFeePerByte()
	if err != nil {
		return err
	}
	tx.NetworkFee += int64(size)*fee + extraFee
	return nil
}