package utils

import (
	"context"
	"fmt"
	"math/big"

	"github.com/scroll-tech/go-ethereum/core/types"
	"github.com/scroll-tech/go-ethereum/rpc"
)

type ethClient interface {
	BlockNumber(ctx context.Context) (uint64, error)
	HeaderByNumber(ctx context.Context, number *big.Int) (*types.Header, error)
}

// GetLatestConfirmedBlockNumber get confirmed block number by rpc.BlockNumber type.
func GetLatestConfirmedBlockNumber(ctx context.Context, client ethClient, confirm rpc.BlockNumber) (uint64, error) {
	switch true {
	case confirm == rpc.SafeBlockNumber || confirm == rpc.FinalizedBlockNumber:
		var tag *big.Int
		if confirm == rpc.FinalizedBlockNumber {
			tag = big.NewInt(int64(rpc.FinalizedBlockNumber))
		} else {
			tag = big.NewInt(int64(rpc.SafeBlockNumber))
		}

		header, err := client.HeaderByNumber(ctx, tag)
		if err != nil {
			return 0, err
		}
		if !header.Number.IsInt64() {
			return 0, fmt.Errorf("received invalid block confirm: %v", header.Number)
		}
		return header.Number.Uint64(), nil
	case confirm == rpc.LatestBlockNumber:
		number, err := client.BlockNumber(ctx)
		if err != nil {
			return 0, err
		}
		return number, nil
	case confirm.Int64() >= 0: // If it's positive integer, consider it as a certain confirm value.
		number, err := client.BlockNumber(ctx)
		if err != nil {
			return 0, err
		}
		cfmNum := uint64(confirm.Int64())

		if number >= cfmNum {
			return number - cfmNum, nil
		}
		return 0, nil
	default:
		return 0, fmt.Errorf("unknown confirmation type: %v", confirm)
	}
}