// newBlockImporter returns a new importer for the provided file reader seeker
// and database.
func newBlockImporter(db database.DB, r io.ReadSeeker) (*blockImporter, error) {
	// Create the transaction and address indexes if needed.
	//
	// CAUTION: the txindex needs to be first in the indexes array because
	// the addrindex uses data from the txindex during catchup.  If the
	// addrindex is run first, it may not have the transactions from the
	// current block indexed.
	var indexes []indexers.Indexer
	if cfg.TxIndex || cfg.AddrIndex {
		// Enable transaction index if address index is enabled since it
		// requires it.
		if !cfg.TxIndex {
			log.Infof("Transaction index enabled because it is " +
				"required by the address index")
			cfg.TxIndex = true
		} else {
			log.Info("Transaction index is enabled")
		}
		indexes = append(indexes, indexers.NewTxIndex(db))
	}
	if cfg.AddrIndex {
		log.Info("Address index is enabled")
		indexes = append(indexes, indexers.NewAddrIndex(db, activeNetParams))
	}

	// Create an index manager if any of the optional indexes are enabled.
	var indexManager blockchain.IndexManager
	if len(indexes) > 0 {
		indexManager = indexers.NewManager(db, indexes)
	}

	chain, err := blockchain.New(&blockchain.Config{
		DB:           db,
		ChainParams:  activeNetParams,
		TimeSource:   blockchain.NewMedianTime(),
		IndexManager: indexManager,
	})
	if err != nil {
		return nil, err
	}

	return &blockImporter{
		db:           db,
		r:            r,
		processQueue: make(chan []byte, 2),
		doneChan:     make(chan bool),
		errChan:      make(chan error),
		quit:         make(chan struct{}),
		chain:        chain,
		lastLogTime:  time.Now(),
	}, nil
}

// newBlockImporter returns a new importer for the provided file reader seeker
// and database.
func newBlockImporter(db database.Db, r io.ReadSeeker) *blockImporter {
	return &blockImporter{
		db:           db,
		r:            r,
		processQueue: make(chan []byte, 2),
		doneChan:     make(chan bool),
		errChan:      make(chan error),
		quit:         make(chan struct{}),
		chain:        blockchain.New(db, activeNetParams, nil),
		medianTime:   blockchain.NewMedianTime(),
		lastLogTime:  time.Now(),
	}
}

func main() {
	// Load configuration and parse command line.
	tcfg, _, err := loadConfig()
	if err != nil {
		return
	}
	cfg = tcfg

	// Load the block database.
	db, err := loadBlockDB()
	if err != nil {
		fmt.Fprintln(os.Stderr, "failed to load database:", err)
		return
	}
	defer db.Close()

	// Setup chain.  Ignore notifications since they aren't needed for this
	// util.
	chain, err := blockchain.New(&blockchain.Config{
		DB:          db,
		ChainParams: activeNetParams,
	})
	if err != nil {
		fmt.Fprintf(os.Stderr, "failed to initialize chain: %v\n", err)
		return
	}

	// Get the latest block hash and height from the database and report
	// status.
	best := chain.BestSnapshot()
	fmt.Printf("Block database loaded with block height %d\n", best.Height)

	// Find checkpoint candidates.
	candidates, err := findCandidates(chain, best.Hash)
	if err != nil {
		fmt.Fprintln(os.Stderr, "Unable to identify candidates:", err)
		return
	}

	// No candidates.
	if len(candidates) == 0 {
		fmt.Println("No candidates found.")
		return
	}

	// Show the candidates.
	for i, checkpoint := range candidates {
		showCandidate(i+1, checkpoint)
	}
}

// This example demonstrates how to create a new chain instance and use
// ProcessBlock to attempt to attempt add a block to the chain.  As the package
// overview documentation describes, this includes all of the Bitcoin consensus
// rules.  This example intentionally attempts to insert a duplicate genesis
// block to illustrate how an invalid block is handled.
func ExampleBlockChain_ProcessBlock() {
	// Create a new database to store the accepted blocks into.  Typically
	// this would be opening an existing database and would not be deleting
	// and creating a new database like this, but it is done here so this is
	// a complete working example and does not leave temporary files laying
	// around.
	dbPath := filepath.Join(os.TempDir(), "exampleprocessblock")
	_ = os.RemoveAll(dbPath)
	db, err := database.Create("ffldb", dbPath, chaincfg.MainNetParams.Net)
	if err != nil {
		fmt.Printf("Failed to create database: %v\n", err)
		return
	}
	defer os.RemoveAll(dbPath)
	defer db.Close()

	// Create a new BlockChain instance using the underlying database for
	// the main bitcoin network.  This example does not demonstrate some
	// of the other available configuration options such as specifying a
	// notification callback and signature cache.
	chain, err := blockchain.New(&blockchain.Config{
		DB:          db,
		ChainParams: &chaincfg.MainNetParams,
	})
	if err != nil {
		fmt.Printf("Failed to create chain instance: %v\n", err)
		return
	}

	// Create a new median time source that is required by the upcoming
	// call to ProcessBlock.  Ordinarily this would also add time values
	// obtained from other peers on the network so the local time is
	// adjusted to be in agreement with other peers.
	timeSource := blockchain.NewMedianTime()

	// Process a block.  For this example, we are going to intentionally
	// cause an error by trying to process the genesis block which already
	// exists.
	genesisBlock := btcutil.NewBlock(chaincfg.MainNetParams.GenesisBlock)
	isOrphan, err := chain.ProcessBlock(genesisBlock, timeSource, blockchain.BFNone)
	if err != nil {
		fmt.Printf("Failed to process block: %v\n", err)
		return
	}
	fmt.Printf("Block accepted. Is it an orphan?: %v", isOrphan)

	// Output:
	// Failed to process block: already have block 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
}

// This example demonstrates how to create a new chain instance and use
// ProcessBlock to attempt to attempt add a block to the chain.  As the package
// overview documentation describes, this includes all of the Bitcoin consensus
// rules.  This example intentionally attempts to insert a duplicate genesis
// block to illustrate how an invalid block is handled.
func ExampleBlockChain_ProcessBlock() {
	// Create a new database to store the accepted blocks into.  Typically
	// this would be opening an existing database and would not use memdb
	// which is a memory-only database backend, but we create a new db
	// here so this is a complete working example.
	db, err := database.CreateDB("memdb")
	if err != nil {
		fmt.Printf("Failed to create database: %v\n", err)
		return
	}
	defer db.Close()

	// Insert the main network genesis block.  This is part of the initial
	// database setup.  Like above, this typically would not be needed when
	// opening an existing database.
	genesisBlock := btcutil.NewBlock(chaincfg.MainNetParams.GenesisBlock)
	_, err = db.InsertBlock(genesisBlock)
	if err != nil {
		fmt.Printf("Failed to insert genesis block: %v\n", err)
		return
	}

	// Create a new BlockChain instance without an initialized signature
	// verification cache, using the underlying database for the main
	// bitcoin network and ignore notifications.
	chain := blockchain.New(db, &chaincfg.MainNetParams, nil, nil)

	// Create a new median time source that is required by the upcoming
	// call to ProcessBlock.  Ordinarily this would also add time values
	// obtained from other peers on the network so the local time is
	// adjusted to be in agreement with other peers.
	timeSource := blockchain.NewMedianTime()

	// Process a block.  For this example, we are going to intentionally
	// cause an error by trying to process the genesis block which already
	// exists.
	isOrphan, err := chain.ProcessBlock(genesisBlock, timeSource, blockchain.BFNone)
	if err != nil {
		fmt.Printf("Failed to process block: %v\n", err)
		return
	}
	fmt.Printf("Block accepted. Is it an orphan?: %v", isOrphan)

	// Output:
	// Failed to process block: already have block 000000000019d6689c085ae165831e934ff763ae46a2a6c172b3f1b60a8ce26f
}

// newBlockManager returns a new bitcoin block manager.
// Use Start to begin processing asynchronous block and inv updates.
func newBlockManager(s *server, indexManager blockchain.IndexManager) (*blockManager, error) {
	bm := blockManager{
		server:          s,
		rejectedTxns:    make(map[chainhash.Hash]struct{}),
		requestedTxns:   make(map[chainhash.Hash]struct{}),
		requestedBlocks: make(map[chainhash.Hash]struct{}),
		progressLogger:  newBlockProgressLogger("Processed", bmgrLog),
		msgChan:         make(chan interface{}, cfg.MaxPeers*3),
		headerList:      list.New(),
		quit:            make(chan struct{}),
	}

	// Create a new block chain instance with the appropriate configuration.
	var err error
	bm.chain, err = blockchain.New(&blockchain.Config{
		DB:            s.db,
		ChainParams:   s.chainParams,
		TimeSource:    s.timeSource,
		Notifications: bm.handleNotifyMsg,
		SigCache:      s.sigCache,
		IndexManager:  indexManager,
	})
	if err != nil {
		return nil, err
	}
	best := bm.chain.BestSnapshot()
	bm.chain.DisableCheckpoints(cfg.DisableCheckpoints)
	if !cfg.DisableCheckpoints {
		// Initialize the next checkpoint based on the current height.
		bm.nextCheckpoint = bm.findNextHeaderCheckpoint(best.Height)
		if bm.nextCheckpoint != nil {
			bm.resetHeaderState(best.Hash, best.Height)
		}
	} else {
		bmgrLog.Info("Checkpoints are disabled")
	}

	// Initialize the chain state now that the initial block node index has
	// been generated.
	bm.updateChainState(best.Hash, best.Height)

	return &bm, nil
}

// newBlockManager returns a new bitcoin block manager.
// Use Start to begin processing asynchronous block and inv updates.
func newBlockManager(s *server) (*blockManager, error) {
	newestHash, height, err := s.db.NewestSha()
	if err != nil {
		return nil, err
	}

	bm := blockManager{
		server:          s,
		requestedTxns:   make(map[wire.ShaHash]struct{}),
		requestedBlocks: make(map[wire.ShaHash]struct{}),
		progressLogger:  newBlockProgressLogger("Processed", bmgrLog),
		msgChan:         make(chan interface{}, cfg.MaxPeers*3),
		headerList:      list.New(),
		quit:            make(chan struct{}),
	}
	bm.progressLogger = newBlockProgressLogger("Processed", bmgrLog)
	bm.blockChain = blockchain.New(s.db, s.chainParams, bm.handleNotifyMsg)
	bm.blockChain.DisableCheckpoints(cfg.DisableCheckpoints)
	if !cfg.DisableCheckpoints {
		// Initialize the next checkpoint based on the current height.
		bm.nextCheckpoint = bm.findNextHeaderCheckpoint(height)
		if bm.nextCheckpoint != nil {
			bm.resetHeaderState(newestHash, height)
		}
	} else {
		bmgrLog.Info("Checkpoints are disabled")
	}

	bmgrLog.Infof("Generating initial block node index.  This may " +
		"take a while...")
	err = bm.blockChain.GenerateInitialIndex()
	if err != nil {
		return nil, err
	}
	bmgrLog.Infof("Block index generation complete")

	// Initialize the chain state now that the intial block node index has
	// been generated.
	bm.updateChainState(newestHash, height)

	return &bm, nil
}

// newBlockImporter returns a new importer for the provided file reader seeker
// and database.
func newBlockImporter(db database.DB, r io.ReadSeeker) (*blockImporter, error) {
	chain, err := blockchain.New(&blockchain.Config{
		DB:          db,
		ChainParams: activeNetParams,
	})
	if err != nil {
		return nil, err
	}

	return &blockImporter{
		db:           db,
		r:            r,
		processQueue: make(chan []byte, 2),
		doneChan:     make(chan bool),
		errChan:      make(chan error),
		quit:         make(chan struct{}),
		chain:        chain,
		medianTime:   blockchain.NewMedianTime(),
		lastLogTime:  time.Now(),
	}, nil
}

// findCandidates searches the chain backwards for checkpoint candidates and
// returns a slice of found candidates, if any.  It also stops searching for
// candidates at the last checkpoint that is already hard coded into btcchain
// since there is no point in finding candidates before already existing
// checkpoints.
func findCandidates(db database.Db, latestHash *wire.ShaHash) ([]*chaincfg.Checkpoint, error) {
	// Start with the latest block of the main chain.
	block, err := db.FetchBlockBySha(latestHash)
	if err != nil {
		return nil, err
	}

	// Setup chain and get the latest checkpoint.  Ignore notifications
	// since they aren't needed for this util.
	chain := blockchain.New(db, activeNetParams, nil, nil)
	latestCheckpoint := chain.LatestCheckpoint()
	if latestCheckpoint == nil {
		return nil, fmt.Errorf("unable to retrieve latest checkpoint")
	}

	// The latest known block must be at least the last known checkpoint
	// plus required checkpoint confirmations.
	checkpointConfirmations := int32(blockchain.CheckpointConfirmations)
	requiredHeight := latestCheckpoint.Height + checkpointConfirmations
	if block.Height() < requiredHeight {
		return nil, fmt.Errorf("the block database is only at height "+
			"%d which is less than the latest checkpoint height "+
			"of %d plus required confirmations of %d",
			block.Height(), latestCheckpoint.Height,
			checkpointConfirmations)
	}

	// Indeterminate progress setup.
	numBlocksToTest := block.Height() - requiredHeight
	progressInterval := (numBlocksToTest / 100) + 1 // min 1
	fmt.Print("Searching for candidates")
	defer fmt.Println()

	// Loop backwards through the chain to find checkpoint candidates.
	candidates := make([]*chaincfg.Checkpoint, 0, cfg.NumCandidates)
	numTested := int32(0)
	for len(candidates) < cfg.NumCandidates && block.Height() > requiredHeight {
		// Display progress.
		if numTested%progressInterval == 0 {
			fmt.Print(".")
		}

		// Determine if this block is a checkpoint candidate.
		isCandidate, err := chain.IsCheckpointCandidate(block)
		if err != nil {
			return nil, err
		}

		// All checks passed, so this node seems like a reasonable
		// checkpoint candidate.
		if isCandidate {
			checkpoint := chaincfg.Checkpoint{
				Height: block.Height(),
				Hash:   block.Sha(),
			}
			candidates = append(candidates, &checkpoint)
		}

		prevHash := &block.MsgBlock().Header.PrevBlock
		block, err = db.FetchBlockBySha(prevHash)
		if err != nil {
			return nil, err
		}
		numTested++
	}
	return candidates, nil
}

// chainSetup is used to create a new db and chain instance with the genesis
// block already inserted.  In addition to the new chain instnce, it returns
// a teardown function the caller should invoke when done testing to clean up.
func chainSetup(dbName string) (*blockchain.BlockChain, func(), error) {
	if !isSupportedDbType(testDbType) {
		return nil, nil, fmt.Errorf("unsupported db type %v", testDbType)
	}

	// Handle memory database specially since it doesn't need the disk
	// specific handling.
	var db database.Db
	var teardown func()
	if testDbType == "memdb" {
		ndb, err := database.CreateDB(testDbType)
		if err != nil {
			return nil, nil, fmt.Errorf("error creating db: %v", err)
		}
		db = ndb

		// Setup a teardown function for cleaning up.  This function is
		// returned to the caller to be invoked when it is done testing.
		teardown = func() {
			db.Close()
		}
	} else {
		// Create the root directory for test databases.
		if !fileExists(testDbRoot) {
			if err := os.MkdirAll(testDbRoot, 0700); err != nil {
				err := fmt.Errorf("unable to create test db "+
					"root: %v", err)
				return nil, nil, err
			}
		}

		// Create a new database to store the accepted blocks into.
		dbPath := filepath.Join(testDbRoot, dbName)
		_ = os.RemoveAll(dbPath)
		ndb, err := database.CreateDB(testDbType, dbPath)
		if err != nil {
			return nil, nil, fmt.Errorf("error creating db: %v", err)
		}
		db = ndb

		// Setup a teardown function for cleaning up.  This function is
		// returned to the caller to be invoked when it is done testing.
		teardown = func() {
			dbVersionPath := filepath.Join(testDbRoot, dbName+".ver")
			db.Sync()
			db.Close()
			os.RemoveAll(dbPath)
			os.Remove(dbVersionPath)
			os.RemoveAll(testDbRoot)
		}
	}

	// Insert the main network genesis block.  This is part of the initial
	// database setup.
	genesisBlock := btcutil.NewBlock(chaincfg.MainNetParams.GenesisBlock)
	_, err := db.InsertBlock(genesisBlock)
	if err != nil {
		teardown()
		err := fmt.Errorf("failed to insert genesis block: %v", err)
		return nil, nil, err
	}

	chain := blockchain.New(db, &chaincfg.MainNetParams, nil)
	return chain, teardown, nil
}

// chainSetup is used to create a new db and chain instance with the genesis
// block already inserted.  In addition to the new chain instnce, it returns
// a teardown function the caller should invoke when done testing to clean up.
func chainSetup(dbName string) (*blockchain.BlockChain, func(), error) {
	if !isSupportedDbType(testDbType) {
		return nil, nil, fmt.Errorf("unsupported db type %v", testDbType)
	}

	// Handle memory database specially since it doesn't need the disk
	// specific handling.
	var db database.DB
	var teardown func()
	if testDbType == "memdb" {
		ndb, err := database.Create(testDbType)
		if err != nil {
			return nil, nil, fmt.Errorf("error creating db: %v", err)
		}
		db = ndb

		// Setup a teardown function for cleaning up.  This function is
		// returned to the caller to be invoked when it is done testing.
		teardown = func() {
			db.Close()
		}
	} else {
		// Create the root directory for test databases.
		if !fileExists(testDbRoot) {
			if err := os.MkdirAll(testDbRoot, 0700); err != nil {
				err := fmt.Errorf("unable to create test db "+
					"root: %v", err)
				return nil, nil, err
			}
		}

		// Create a new database to store the accepted blocks into.
		dbPath := filepath.Join(testDbRoot, dbName)
		_ = os.RemoveAll(dbPath)
		ndb, err := database.Create(testDbType, dbPath, blockDataNet)
		if err != nil {
			return nil, nil, fmt.Errorf("error creating db: %v", err)
		}
		db = ndb

		// Setup a teardown function for cleaning up.  This function is
		// returned to the caller to be invoked when it is done testing.
		teardown = func() {
			db.Close()
			os.RemoveAll(dbPath)
			os.RemoveAll(testDbRoot)
		}
	}

	// Create the main chain instance.
	chain, err := blockchain.New(&blockchain.Config{
		DB:          db,
		ChainParams: &chaincfg.MainNetParams,
	})
	if err != nil {
		teardown()
		err := fmt.Errorf("failed to create chain instance: %v", err)
		return nil, nil, err
	}
	return chain, teardown, nil
}