util.go

// Copyright 2019 dfuse Platform Inc.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package bstream

import (
	"encoding/binary"
	"encoding/hex"
	"fmt"

	pbbstream "github.com/streamingfast/bstream/pb/sf/bstream/v1"
)

// DoForProtocol extra the worker (a lambda) that will be invoked based on the
// received `kind` parameter. If the mapping exists, the worker is invoked and
// the error returned with the call. If the mapping does not exist, an error
// is returned. In all other cases, this function returns `nil`.
func DoForProtocol(kind pbbstream.Protocol, mappings map[pbbstream.Protocol]func() error) error {
	if worker, exists := mappings[kind]; exists {
		return worker()
	}

	return fmt.Errorf("don't know how to handle block kind %s", kind)
}

// MustDoForProtocol perform the same work, but accept only non-error
// lambdas as the worker and an inexistant mapping will panic.
func MustDoForProtocol(kind pbbstream.Protocol, mappings map[pbbstream.Protocol]func()) {
	if worker, exists := mappings[kind]; exists {
		worker()
		return
	}

	panic(fmt.Errorf("don't know how to handle block kind %s", kind))
}

// toBlockNum extracts the block number (or height) from a hex-encoded block ID.
func toBlockNum(blockID string) uint64 {
	if len(blockID) < 8 {
		return 0
	}
	bin, err := hex.DecodeString(blockID[:8])
	if err != nil {
		return 0
	}
	return binary.BigEndian.Uint64(bin)
}

func lowBoundary(i uint64, mod uint64) uint64 {
	return i - (i % mod)
}