// Package structs contains RPC wrappers for Notifications contract.
package structs

import (
	"crypto/elliptic"
	"errors"
	"fmt"
	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"github.com/nspcc-dev/neo-go/pkg/neorpc/result"
	"github.com/nspcc-dev/neo-go/pkg/util"
	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
	"math/big"
	"unicode/utf8"
)

// Hash contains contract hash.
var Hash = util.Uint160{0x33, 0x22, 0x11, 0x0, 0xff, 0xee, 0xdd, 0xcc, 0xbb, 0xaa, 0x99, 0x88, 0x77, 0x66, 0x55, 0x44, 0x33, 0x22, 0x11, 0x0}

// LedgerBlock is a contract-specific ledger.Block type used by its methods.
type LedgerBlock struct {
	Hash util.Uint256
	Version *big.Int
	PrevHash util.Uint256
	MerkleRoot util.Uint256
	Timestamp *big.Int
	Nonce *big.Int
	Index *big.Int
	NextConsensus util.Uint160
	TransactionsLength *big.Int
}

// LedgerBlockSR is a contract-specific ledger.BlockSR type used by its methods.
type LedgerBlockSR struct {
	Hash util.Uint256
	Version *big.Int
	PrevHash util.Uint256
	MerkleRoot util.Uint256
	Timestamp *big.Int
	Nonce *big.Int
	Index *big.Int
	NextConsensus util.Uint160
	TransactionsLength *big.Int
	PrevStateRoot util.Uint256
}

// LedgerTransaction is a contract-specific ledger.Transaction type used by its methods.
type LedgerTransaction struct {
	Hash util.Uint256
	Version *big.Int
	Nonce *big.Int
	Sender util.Uint160
	SysFee *big.Int
	NetFee *big.Int
	ValidUntilBlock *big.Int
	Script []byte
}

// LedgerTransactionSigner is a contract-specific ledger.TransactionSigner type used by its methods.
type LedgerTransactionSigner struct {
	Account util.Uint160
	Scopes *big.Int
	AllowedContracts []util.Uint160
	AllowedGroups keys.PublicKeys
	Rules []*LedgerWitnessRule
}

// LedgerWitnessCondition is a contract-specific ledger.WitnessCondition type used by its methods.
type LedgerWitnessCondition struct {
	Type *big.Int
	Value any
}

// LedgerWitnessRule is a contract-specific ledger.WitnessRule type used by its methods.
type LedgerWitnessRule struct {
	Action *big.Int
	Condition *LedgerWitnessCondition
}

// ComplicatedNameEvent represents "! complicated name %$#" event emitted by the contract.
type ComplicatedNameEvent struct {
	ComplicatedParam string
}

// Actor is used by Contract to call state-changing methods.
type Actor interface {
	MakeCall(contract util.Uint160, method string, params ...any) (*transaction.Transaction, error)
	MakeRun(script []byte) (*transaction.Transaction, error)
	MakeUnsignedCall(contract util.Uint160, method string, attrs []transaction.Attribute, params ...any) (*transaction.Transaction, error)
	MakeUnsignedRun(script []byte, attrs []transaction.Attribute) (*transaction.Transaction, error)
	SendCall(contract util.Uint160, method string, params ...any) (util.Uint256, uint32, error)
	SendRun(script []byte) (util.Uint256, uint32, error)
}

// Contract implements all contract methods.
type Contract struct {
	actor Actor
}

// New creates an instance of Contract using Hash and the given Actor.
func New(actor Actor) *Contract {
	return &Contract{actor}
}

// Main creates a transaction invoking `main` method of the contract.
// This transaction is signed and immediately sent to the network.
// The values returned are its hash, ValidUntilBlock value and error if any.
func (c *Contract) Main() (util.Uint256, uint32, error) {
	return c.actor.SendCall(Hash, "main")
}

// MainTransaction creates a transaction invoking `main` method of the contract.
// This transaction is signed, but not sent to the network, instead it's
// returned to the caller.
func (c *Contract) MainTransaction() (*transaction.Transaction, error) {
	return c.actor.MakeCall(Hash, "main")
}

// MainUnsigned creates a transaction invoking `main` method of the contract.
// This transaction is not signed, it's simply returned to the caller.
// Any fields of it that do not affect fees can be changed (ValidUntilBlock,
// Nonce), fee values (NetworkFee, SystemFee) can be increased as well.
func (c *Contract) MainUnsigned() (*transaction.Transaction, error) {
	return c.actor.MakeUnsignedCall(Hash, "main", nil)
}

// itemToLedgerBlock converts stack item into *LedgerBlock.
func itemToLedgerBlock(item stackitem.Item, err error) (*LedgerBlock, error) {
	if err != nil {
		return nil, err
	}
	var res = new(LedgerBlock)
	err = res.FromStackItem(item)
	return res, err
}

// FromStackItem retrieves fields of LedgerBlock from the given stack item
// and returns an error if so.
func (res *LedgerBlock) FromStackItem(item stackitem.Item) error {
	arr, ok := item.Value().([]stackitem.Item)
	if !ok {
		return errors.New("not an array")
	}
	if len(arr) != 9 {
		return errors.New("wrong number of structure elements")
	}

	var (
		index = -1
		err error
	)
	index++
	res.Hash, err = func (item stackitem.Item) (util.Uint256, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint256{}, err
		}
		u, err := util.Uint256DecodeBytesBE(b)
		if err != nil {
			return util.Uint256{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field Hash: %w", err)
	}

	index++
	res.Version, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Version: %w", err)
	}

	index++
	res.PrevHash, err = func (item stackitem.Item) (util.Uint256, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint256{}, err
		}
		u, err := util.Uint256DecodeBytesBE(b)
		if err != nil {
			return util.Uint256{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field PrevHash: %w", err)
	}

	index++
	res.MerkleRoot, err = func (item stackitem.Item) (util.Uint256, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint256{}, err
		}
		u, err := util.Uint256DecodeBytesBE(b)
		if err != nil {
			return util.Uint256{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field MerkleRoot: %w", err)
	}

	index++
	res.Timestamp, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Timestamp: %w", err)
	}

	index++
	res.Nonce, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Nonce: %w", err)
	}

	index++
	res.Index, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Index: %w", err)
	}

	index++
	res.NextConsensus, err = func (item stackitem.Item) (util.Uint160, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint160{}, err
		}
		u, err := util.Uint160DecodeBytesBE(b)
		if err != nil {
			return util.Uint160{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field NextConsensus: %w", err)
	}

	index++
	res.TransactionsLength, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field TransactionsLength: %w", err)
	}

	return nil
}

// itemToLedgerBlockSR converts stack item into *LedgerBlockSR.
func itemToLedgerBlockSR(item stackitem.Item, err error) (*LedgerBlockSR, error) {
	if err != nil {
		return nil, err
	}
	var res = new(LedgerBlockSR)
	err = res.FromStackItem(item)
	return res, err
}

// FromStackItem retrieves fields of LedgerBlockSR from the given stack item
// and returns an error if so.
func (res *LedgerBlockSR) FromStackItem(item stackitem.Item) error {
	arr, ok := item.Value().([]stackitem.Item)
	if !ok {
		return errors.New("not an array")
	}
	if len(arr) != 10 {
		return errors.New("wrong number of structure elements")
	}

	var (
		index = -1
		err error
	)
	index++
	res.Hash, err = func (item stackitem.Item) (util.Uint256, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint256{}, err
		}
		u, err := util.Uint256DecodeBytesBE(b)
		if err != nil {
			return util.Uint256{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field Hash: %w", err)
	}

	index++
	res.Version, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Version: %w", err)
	}

	index++
	res.PrevHash, err = func (item stackitem.Item) (util.Uint256, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint256{}, err
		}
		u, err := util.Uint256DecodeBytesBE(b)
		if err != nil {
			return util.Uint256{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field PrevHash: %w", err)
	}

	index++
	res.MerkleRoot, err = func (item stackitem.Item) (util.Uint256, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint256{}, err
		}
		u, err := util.Uint256DecodeBytesBE(b)
		if err != nil {
			return util.Uint256{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field MerkleRoot: %w", err)
	}

	index++
	res.Timestamp, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Timestamp: %w", err)
	}

	index++
	res.Nonce, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Nonce: %w", err)
	}

	index++
	res.Index, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Index: %w", err)
	}

	index++
	res.NextConsensus, err = func (item stackitem.Item) (util.Uint160, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint160{}, err
		}
		u, err := util.Uint160DecodeBytesBE(b)
		if err != nil {
			return util.Uint160{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field NextConsensus: %w", err)
	}

	index++
	res.TransactionsLength, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field TransactionsLength: %w", err)
	}

	index++
	res.PrevStateRoot, err = func (item stackitem.Item) (util.Uint256, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint256{}, err
		}
		u, err := util.Uint256DecodeBytesBE(b)
		if err != nil {
			return util.Uint256{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field PrevStateRoot: %w", err)
	}

	return nil
}

// itemToLedgerTransaction converts stack item into *LedgerTransaction.
func itemToLedgerTransaction(item stackitem.Item, err error) (*LedgerTransaction, error) {
	if err != nil {
		return nil, err
	}
	var res = new(LedgerTransaction)
	err = res.FromStackItem(item)
	return res, err
}

// FromStackItem retrieves fields of LedgerTransaction from the given stack item
// and returns an error if so.
func (res *LedgerTransaction) FromStackItem(item stackitem.Item) error {
	arr, ok := item.Value().([]stackitem.Item)
	if !ok {
		return errors.New("not an array")
	}
	if len(arr) != 8 {
		return errors.New("wrong number of structure elements")
	}

	var (
		index = -1
		err error
	)
	index++
	res.Hash, err = func (item stackitem.Item) (util.Uint256, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint256{}, err
		}
		u, err := util.Uint256DecodeBytesBE(b)
		if err != nil {
			return util.Uint256{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field Hash: %w", err)
	}

	index++
	res.Version, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Version: %w", err)
	}

	index++
	res.Nonce, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Nonce: %w", err)
	}

	index++
	res.Sender, err = func (item stackitem.Item) (util.Uint160, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint160{}, err
		}
		u, err := util.Uint160DecodeBytesBE(b)
		if err != nil {
			return util.Uint160{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field Sender: %w", err)
	}

	index++
	res.SysFee, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field SysFee: %w", err)
	}

	index++
	res.NetFee, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field NetFee: %w", err)
	}

	index++
	res.ValidUntilBlock, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field ValidUntilBlock: %w", err)
	}

	index++
	res.Script, err = arr[index].TryBytes()
	if err != nil {
		return fmt.Errorf("field Script: %w", err)
	}

	return nil
}

// itemToLedgerTransactionSigner converts stack item into *LedgerTransactionSigner.
func itemToLedgerTransactionSigner(item stackitem.Item, err error) (*LedgerTransactionSigner, error) {
	if err != nil {
		return nil, err
	}
	var res = new(LedgerTransactionSigner)
	err = res.FromStackItem(item)
	return res, err
}

// FromStackItem retrieves fields of LedgerTransactionSigner from the given stack item
// and returns an error if so.
func (res *LedgerTransactionSigner) FromStackItem(item stackitem.Item) error {
	arr, ok := item.Value().([]stackitem.Item)
	if !ok {
		return errors.New("not an array")
	}
	if len(arr) != 5 {
		return errors.New("wrong number of structure elements")
	}

	var (
		index = -1
		err error
	)
	index++
	res.Account, err = func (item stackitem.Item) (util.Uint160, error) {
		b, err := item.TryBytes()
		if err != nil {
			return util.Uint160{}, err
		}
		u, err := util.Uint160DecodeBytesBE(b)
		if err != nil {
			return util.Uint160{}, err
		}
		return u, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field Account: %w", err)
	}

	index++
	res.Scopes, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Scopes: %w", err)
	}

	index++
	res.AllowedContracts, err = func (item stackitem.Item) ([]util.Uint160, error) {
		arr, ok := item.Value().([]stackitem.Item)
		if !ok {
			return nil, errors.New("not an array")
		}
		res := make([]util.Uint160, len(arr))
		for i := range res {
			res[i], err = func (item stackitem.Item) (util.Uint160, error) {
				b, err := item.TryBytes()
				if err != nil {
					return util.Uint160{}, err
				}
				u, err := util.Uint160DecodeBytesBE(b)
				if err != nil {
					return util.Uint160{}, err
				}
				return u, nil
			} (arr[i])
			if err != nil {
				return nil, fmt.Errorf("item %d: %w", i, err)
			}
		}
		return res, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field AllowedContracts: %w", err)
	}

	index++
	res.AllowedGroups, err = func (item stackitem.Item) (keys.PublicKeys, error) {
		arr, ok := item.Value().([]stackitem.Item)
		if !ok {
			return nil, errors.New("not an array")
		}
		res := make(keys.PublicKeys, len(arr))
		for i := range res {
			res[i], err = func (item stackitem.Item) (*keys.PublicKey, error) {
				b, err := item.TryBytes()
				if err != nil {
					return nil, err
				}
				k, err := keys.NewPublicKeyFromBytes(b, elliptic.P256())
				if err != nil {
					return nil, err
				}
				return k, nil
			} (arr[i])
			if err != nil {
				return nil, fmt.Errorf("item %d: %w", i, err)
			}
		}
		return res, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field AllowedGroups: %w", err)
	}

	index++
	res.Rules, err = func (item stackitem.Item) ([]*LedgerWitnessRule, error) {
		arr, ok := item.Value().([]stackitem.Item)
		if !ok {
			return nil, errors.New("not an array")
		}
		res := make([]*LedgerWitnessRule, len(arr))
		for i := range res {
			res[i], err = itemToLedgerWitnessRule(arr[i], nil)
			if err != nil {
				return nil, fmt.Errorf("item %d: %w", i, err)
			}
		}
		return res, nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field Rules: %w", err)
	}

	return nil
}

// itemToLedgerWitnessCondition converts stack item into *LedgerWitnessCondition.
func itemToLedgerWitnessCondition(item stackitem.Item, err error) (*LedgerWitnessCondition, error) {
	if err != nil {
		return nil, err
	}
	var res = new(LedgerWitnessCondition)
	err = res.FromStackItem(item)
	return res, err
}

// FromStackItem retrieves fields of LedgerWitnessCondition from the given stack item
// and returns an error if so.
func (res *LedgerWitnessCondition) FromStackItem(item stackitem.Item) error {
	arr, ok := item.Value().([]stackitem.Item)
	if !ok {
		return errors.New("not an array")
	}
	if len(arr) != 2 {
		return errors.New("wrong number of structure elements")
	}

	var (
		index = -1
		err error
	)
	index++
	res.Type, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Type: %w", err)
	}

	index++
	res.Value, err = arr[index].Value(), error(nil)
	if err != nil {
		return fmt.Errorf("field Value: %w", err)
	}

	return nil
}

// itemToLedgerWitnessRule converts stack item into *LedgerWitnessRule.
func itemToLedgerWitnessRule(item stackitem.Item, err error) (*LedgerWitnessRule, error) {
	if err != nil {
		return nil, err
	}
	var res = new(LedgerWitnessRule)
	err = res.FromStackItem(item)
	return res, err
}

// FromStackItem retrieves fields of LedgerWitnessRule from the given stack item
// and returns an error if so.
func (res *LedgerWitnessRule) FromStackItem(item stackitem.Item) error {
	arr, ok := item.Value().([]stackitem.Item)
	if !ok {
		return errors.New("not an array")
	}
	if len(arr) != 2 {
		return errors.New("wrong number of structure elements")
	}

	var (
		index = -1
		err error
	)
	index++
	res.Action, err = arr[index].TryInteger()
	if err != nil {
		return fmt.Errorf("field Action: %w", err)
	}

	index++
	res.Condition, err = itemToLedgerWitnessCondition(arr[index], nil)
	if err != nil {
		return fmt.Errorf("field Condition: %w", err)
	}

	return nil
}

// ComplicatedNameEventsFromApplicationLog retrieves a set of all emitted events
// with "! complicated name %$#" name from the provided ApplicationLog.
func ComplicatedNameEventsFromApplicationLog(log *result.ApplicationLog) ([]*ComplicatedNameEvent, error) {
	if log == nil {
		return nil, errors.New("nil application log")
	}

	var res []*ComplicatedNameEvent
	for i, ex := range log.Executions {
		for j, e := range ex.Events {
			if e.Name != "! complicated name %$#" {
				continue
			}
			event := new(ComplicatedNameEvent)
			err := event.FromStackItem(e.Item)
			if err != nil {
				return nil, fmt.Errorf("failed to deserialize ComplicatedNameEvent from stackitem (execution %d, event %d): %w", i, j, err)
			}
			res = append(res, event)
		}
	}

	return res, nil
}

// FromStackItem converts provided stackitem.Array to ComplicatedNameEvent and
// returns an error if so.
func (e *ComplicatedNameEvent) FromStackItem(item *stackitem.Array) error {
	if item == nil {
		return errors.New("nil item")
	}
	arr, ok := item.Value().([]stackitem.Item)
	if !ok {
		return errors.New("not an array")
	}
	if len(arr) != 1 {
		return errors.New("wrong number of structure elements")
	}

	var (
		index = -1
		err error
	)
	index++
	e.ComplicatedParam, err = func (item stackitem.Item) (string, error) {
		b, err := item.TryBytes()
		if err != nil {
			return "", err
		}
		if !utf8.Valid(b) {
			return "", errors.New("not a UTF-8 string")
		}
		return string(b), nil
	} (arr[index])
	if err != nil {
		return fmt.Errorf("field ComplicatedParam: %w", err)
	}

	return nil
}