package snapshotsync

import (
	"context"
	"fmt"

	"github.com/ledgerwatch/erigon-lib/kv"
	"github.com/ledgerwatch/erigon/common"
	"github.com/ledgerwatch/erigon/core/rawdb"
	"github.com/ledgerwatch/erigon/core/types"
)

// BlockReader can read blocks from db and snapshots
type BlockReader struct {
}

func NewBlockReader() *BlockReader {
	return &BlockReader{}
}

func (back *BlockReader) BlockWithSenders(ctx context.Context, tx kv.Tx, hash common.Hash, blockHeight uint64) (block *types.Block, senders []common.Address, err error) {
	canonicalHash, err := rawdb.ReadCanonicalHash(tx, blockHeight)
	if err != nil {
		return nil, nil, fmt.Errorf("requested non-canonical hash %x. canonical=%x", hash, canonicalHash)
	}
	if canonicalHash == hash {
		block, senders, err = rawdb.ReadBlockWithSenders(tx, hash, blockHeight)
		if err != nil {
			return nil, nil, err
		}
		return block, senders, nil
	}

	return rawdb.NonCanonicalBlockWithSenders(tx, hash, blockHeight)
}