package fastbridge

import (
	"bytes"
	"github.com/ethereum/go-ethereum/accounts/abi"
	"github.com/ethereum/go-ethereum/common"
	"strings"
)

// TODO: consider not exporting to avoid accidental mutation.
var (
	// BridgeRequestedTopic is the event topic for a bridge request.
	BridgeRequestedTopic common.Hash
	// BridgeRelayedTopic is the topic emitted by a bridge relay.
	BridgeRelayedTopic common.Hash
	// BridgeProofProvidedTopic is the topic emitted by a bridge relay.
	BridgeProofProvidedTopic common.Hash
	// BridgeDepositClaimedTopic is the topic emitted by a bridge relay.
	BridgeDepositClaimedTopic common.Hash
	// BridgeProofDisputedTopic is the topic emitted by a bridge dispute.
	BridgeProofDisputedTopic common.Hash
)

// static checks to make sure topics actually exist.
func init() {
	var err error

	parsedABI, err := abi.JSON(strings.NewReader(FastBridgeMetaData.ABI))
	if err != nil {
		panic(err)
	}

	BridgeRequestedTopic = parsedABI.Events["BridgeRequested"].ID
	BridgeRelayedTopic = parsedABI.Events["BridgeRelayed"].ID
	BridgeProofProvidedTopic = parsedABI.Events["BridgeProofProvided"].ID
	BridgeDepositClaimedTopic = parsedABI.Events["BridgeDepositClaimed"].ID
	BridgeProofDisputedTopic = parsedABI.Events["BridgeProofDisputed"].ID

	_, err = parsedABI.EventByID(BridgeRequestedTopic)
	if err != nil {
		panic(err)
	}

	_, err = parsedABI.EventByID(BridgeRelayedTopic)
	if err != nil {
		panic(err)
	}

	_, err = parsedABI.EventByID(BridgeProofProvidedTopic)
	if err != nil {
		panic(err)
	}

	_, err = parsedABI.EventByID(BridgeProofDisputedTopic)
	if err != nil {
		panic(err)
	}
}

// topicMap maps events to topics.
// this is returned as a function to assert immutability.
func topicMap() map[EventType]common.Hash {
	return map[EventType]common.Hash{
		BridgeRequestedEvent:      BridgeRequestedTopic,
		BridgeRelayedEvent:        BridgeRelayedTopic,
		BridgeProofProvidedEvent:  BridgeProofProvidedTopic,
		BridgeDepositClaimedEvent: BridgeDepositClaimedTopic,
		BridgeDisputeEvent:        BridgeProofDisputedTopic,
	}
}

// eventTypeFromTopic gets the event type from the topic
// returns nil if the topic is not found.
func eventTypeFromTopic(ogTopic common.Hash) *EventType {
	for eventType, topic := range topicMap() {
		if bytes.Equal(ogTopic.Bytes(), topic.Bytes()) {
			return &eventType
		}
	}
	return nil
}