import_tx.go

// Copyright (C) 2019-2021, Ava Labs, Inc. All rights reserved.
// See the file LICENSE for licensing terms.

package txs

import (
	"errors"

	"github.com/ava-labs/avalanchego/codec"
	"github.com/ava-labs/avalanchego/ids"
	"github.com/ava-labs/avalanchego/snow"
	"github.com/ava-labs/avalanchego/vms/components/avax"
)

var (
	errNoImportInputs = errors.New("no import inputs")

	_ UnsignedTx = &ImportTx{}
)

// ImportTx is a transaction that imports an asset from another blockchain.
type ImportTx struct {
	BaseTx `serialize:"true"`

	// Which chain to consume the funds from
	SourceChain ids.ID `serialize:"true" json:"sourceChain"`

	// The inputs to this transaction
	ImportedIns []*avax.TransferableInput `serialize:"true" json:"importedInputs"`
}

// InputUTXOs track which UTXOs this transaction is consuming.
func (t *ImportTx) InputUTXOs() []*avax.UTXOID {
	utxos := t.BaseTx.InputUTXOs()
	for _, in := range t.ImportedIns {
		in.Symbol = true
		utxos = append(utxos, &in.UTXOID)
	}
	return utxos
}

// ConsumedAssetIDs returns the IDs of the assets this transaction consumes
func (t *ImportTx) ConsumedAssetIDs() ids.Set {
	assets := t.BaseTx.AssetIDs()
	for _, in := range t.ImportedIns {
		assets.Add(in.AssetID())
	}
	return assets
}

// AssetIDs returns the IDs of the assets this transaction depends on
func (t *ImportTx) AssetIDs() ids.Set {
	assets := t.BaseTx.AssetIDs()
	for _, in := range t.ImportedIns {
		assets.Add(in.AssetID())
	}
	return assets
}

// NumCredentials returns the number of expected credentials
func (t *ImportTx) NumCredentials() int {
	return t.BaseTx.NumCredentials() + len(t.ImportedIns)
}

// SyntacticVerify that this import transaction is well-formed.
func (t *ImportTx) SyntacticVerify(
	ctx *snow.Context,
	c codec.Manager,
	txFeeAssetID ids.ID,
	txFee uint64,
	_ uint64,
	numFxs int,
) error {
	switch {
	case t == nil:
		return errNilTx
	case len(t.ImportedIns) == 0:
		return errNoImportInputs
	}

	if err := t.MetadataVerify(ctx); err != nil {
		return err
	}

	return avax.VerifyTx(
		txFee,
		txFeeAssetID,
		[][]*avax.TransferableInput{
			t.Ins,
			t.ImportedIns,
		},
		[][]*avax.TransferableOutput{t.Outs},
		c,
	)
}

func (t *ImportTx) Visit(v Visitor) error {
	return v.ImportTx(t)
}