package history

import (
	"log"

	"github.com/vulcanize/vulcanizedb/pkg/core"
	"github.com/vulcanize/vulcanizedb/pkg/datastore"
	"github.com/vulcanize/vulcanizedb/pkg/datastore/postgres/repositories"
	"github.com/vulcanize/vulcanizedb/pkg/transformers"
)

func PopulateMissingHeaders(blockchain core.BlockChain, headerRepository datastore.HeaderRepository, startingBlockNumber int64, transformers []transformers.Transformer) (int, error) {
	lastBlock := blockchain.LastBlock().Int64()
	blockRange := headerRepository.MissingBlockNumbers(startingBlockNumber, lastBlock, blockchain.Node().ID)
	log.SetPrefix("")
	log.Printf("Backfilling %d blocks\n\n", len(blockRange))
	_, err := RetrieveAndUpdateHeaders(blockchain, headerRepository, blockRange, transformers)
	if err != nil {
		return 0, err
	}
	return len(blockRange), nil
}

func RetrieveAndUpdateHeaders(chain core.BlockChain, headerRepository datastore.HeaderRepository, blockNumbers []int64, transformers []transformers.Transformer) (int, error) {
	for _, blockNumber := range blockNumbers {
		header, err := chain.GetHeaderByNumber(blockNumber)
		if err != nil {
			return 0, err
		}
		id, err := headerRepository.CreateOrUpdateHeader(header)
		if err != nil {
			if err == repositories.ErrValidHeaderExists {
				continue
			}
			return 0, err
		}
		for _, transformer := range transformers {
			err := transformer.Execute(header, id)
			if err != nil {
				return 0, err
			}
		}
	}
	return len(blockNumbers), nil
}