package result

import (
	"encoding/json"
	"errors"

	"github.com/nspcc-dev/neo-go/pkg/core/block"
	"github.com/nspcc-dev/neo-go/pkg/core/blockchainer"
	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
	"github.com/nspcc-dev/neo-go/pkg/util"
)

// TransactionOutputRaw is used as a wrapper to represents
// a Transaction.
type TransactionOutputRaw struct {
	*transaction.Transaction
	TransactionMetadata
}

// TransactionMetadata is an auxilliary struct for proper TransactionOutputRaw marshaling.
type TransactionMetadata struct {
	Blockhash     util.Uint256 `json:"blockhash,omitempty"`
	Confirmations int          `json:"confirmations,omitempty"`
	Timestamp     uint64       `json:"blocktime,omitempty"`
}

// NewTransactionOutputRaw returns a new ransactionOutputRaw object.
func NewTransactionOutputRaw(tx *transaction.Transaction, header *block.Header, chain blockchainer.Blockchainer) TransactionOutputRaw {
	// confirmations formula
	confirmations := int(chain.BlockHeight() - header.Base.Index + 1)
	// set index position
	for i, o := range tx.Outputs {
		o.Position = i
	}
	return TransactionOutputRaw{
		Transaction: tx,
		TransactionMetadata: TransactionMetadata{
			Blockhash:     header.Hash(),
			Confirmations: confirmations,
			Timestamp:     header.Timestamp,
		},
	}
}

// MarshalJSON implements json.Marshaler interface.
func (t TransactionOutputRaw) MarshalJSON() ([]byte, error) {
	output, err := json.Marshal(TransactionMetadata{
		Blockhash:     t.Blockhash,
		Confirmations: t.Confirmations,
		Timestamp:     t.Timestamp,
	})
	if err != nil {
		return nil, err
	}
	txBytes, err := json.Marshal(t.Transaction)
	if err != nil {
		return nil, err
	}

	// We have to keep both transaction.Transaction and tranactionOutputRaw at the same level in json
	// in order to match C# API, so there's no way to marshall Tx correctly with standard json.Marshaller tool.
	if output[len(output)-1] != '}' || txBytes[0] != '{' {
		return nil, errors.New("can't merge internal jsons")
	}
	output[len(output)-1] = ','
	output = append(output, txBytes[1:]...)
	return output, nil
}

// UnmarshalJSON implements json.Marshaler interface.
func (t *TransactionOutputRaw) UnmarshalJSON(data []byte) error {
	// As transaction.Transaction and tranactionOutputRaw are at the same level in json,
	// do unmarshalling separately for both structs.
	output := new(TransactionMetadata)
	err := json.Unmarshal(data, output)
	if err != nil {
		return err
	}
	t.Blockhash = output.Blockhash
	t.Confirmations = output.Confirmations
	t.Timestamp = output.Timestamp

	transaction := new(transaction.Transaction)
	err = json.Unmarshal(data, transaction)
	if err != nil {
		return err
	}
	t.Transaction = transaction
	return nil
}