package node

import (
	"bytes"
	"context"
	"errors"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"gitlab.com/NebulousLabs/encoding"
	"go.sia.tech/core/consensus"
	"go.sia.tech/core/types"
	"go.sia.tech/renterd/autopilot"
	"go.sia.tech/renterd/bus"
	"go.sia.tech/renterd/stores"
	"go.sia.tech/renterd/wallet"
	"go.sia.tech/renterd/worker"
	"go.sia.tech/siad/modules"
	mconsensus "go.sia.tech/siad/modules/consensus"
	"go.sia.tech/siad/modules/gateway"
	"go.sia.tech/siad/modules/transactionpool"
	stypes "go.sia.tech/siad/types"
	"go.uber.org/zap"
	"go.uber.org/zap/zapcore"
	"golang.org/x/crypto/blake2b"
	"gorm.io/gorm"
)

type WorkerConfig struct {
	ID                      string
	BusFlushInterval        time.Duration
	ContractLockTimeout     time.Duration
	SessionLockTimeout      time.Duration
	SessionReconnectTimeout time.Duration
	SessionTTL              time.Duration
	DownloadSectorTimeout   time.Duration
	UploadSectorTimeout     time.Duration
	DownloadMaxOverdrive    int
	UploadMaxOverdrive      int
}

type BusConfig struct {
	Bootstrap       bool
	GatewayAddr     string
	Network         *consensus.Network
	Miner           *Miner
	PersistInterval time.Duration

	DBDialector gorm.Dialector
}

type AutopilotConfig struct {
	AccountsRefillInterval   time.Duration
	Heartbeat                time.Duration
	MigrationHealthCutoff    float64
	ScannerInterval          time.Duration
	ScannerBatchSize         uint64
	ScannerMinRecentFailures uint64
	ScannerNumThreads        uint64
}

type ShutdownFn = func(context.Context) error

func convertToSiad(core types.EncoderTo, siad encoding.SiaUnmarshaler) {
	var buf bytes.Buffer
	e := types.NewEncoder(&buf)
	core.EncodeTo(e)
	e.Flush()
	if err := siad.UnmarshalSia(&buf); err != nil {
		panic(err)
	}
}

func convertToCore(siad encoding.SiaMarshaler, core types.DecoderFrom) {
	var buf bytes.Buffer
	siad.MarshalSia(&buf)
	d := types.NewBufDecoder(buf.Bytes())
	core.DecodeFrom(d)
	if d.Err() != nil {
		panic(d.Err())
	}
}

type chainManager struct {
	cs      modules.ConsensusSet
	network *consensus.Network
}

func (cm chainManager) AcceptBlock(ctx context.Context, b types.Block) error {
	var sb stypes.Block
	convertToSiad(b, &sb)
	return cm.cs.AcceptBlock(sb)
}

func (cm chainManager) Synced(ctx context.Context) bool {
	return cm.cs.Synced()
}

func (cm chainManager) TipState(ctx context.Context) consensus.State {
	return consensus.State{
		Network: cm.network,
		Index: types.ChainIndex{
			Height: uint64(cm.cs.Height()),
			ID:     types.BlockID(cm.cs.CurrentBlock().ID()),
		},
	}
}

type syncer struct {
	g  modules.Gateway
	tp modules.TransactionPool
}

func (s syncer) Addr() string {
	return string(s.g.Address())
}

func (s syncer) Peers() []string {
	var peers []string
	for _, p := range s.g.Peers() {
		peers = append(peers, string(p.NetAddress))
	}
	return peers
}

func (s syncer) Connect(addr string) error {
	return s.g.Connect(modules.NetAddress(addr))
}

func (s syncer) BroadcastTransaction(txn types.Transaction, dependsOn []types.Transaction) {
	txnSet := make([]stypes.Transaction, len(dependsOn)+1)
	for i, txn := range dependsOn {
		convertToSiad(txn, &txnSet[i])
	}
	convertToSiad(txn, &txnSet[len(txnSet)-1])
	s.tp.Broadcast(txnSet)
}

func (s syncer) SyncerAddress(ctx context.Context) (string, error) {
	return string(s.g.Address()), nil
}

type txpool struct {
	tp modules.TransactionPool
}

func (tp txpool) RecommendedFee() (fee types.Currency) {
	_, max := tp.tp.FeeEstimation()
	convertToCore(&max, &fee)
	return
}

func (tp txpool) Transactions() []types.Transaction {
	stxns := tp.tp.Transactions()
	txns := make([]types.Transaction, len(stxns))
	for i := range txns {
		convertToCore(&stxns[i], &txns[i])
	}
	return txns
}

func (tp txpool) AddTransactionSet(txns []types.Transaction) error {
	stxns := make([]stypes.Transaction, len(txns))
	for i := range stxns {
		convertToSiad(&txns[i], &stxns[i])
	}
	return tp.tp.AcceptTransactionSet(stxns)
}

func (tp txpool) UnconfirmedParents(txn types.Transaction) ([]types.Transaction, error) {
	pool := tp.Transactions()
	outputToParent := make(map[types.SiacoinOutputID]*types.Transaction)
	for i, txn := range pool {
		for j := range txn.SiacoinOutputs {
			outputToParent[txn.SiacoinOutputID(j)] = &pool[i]
		}
	}
	var parents []types.Transaction
	seen := make(map[types.TransactionID]bool)
	for _, sci := range txn.SiacoinInputs {
		if parent, ok := outputToParent[sci.ParentID]; ok {
			if txid := parent.ID(); !seen[txid] {
				seen[txid] = true
				parents = append(parents, *parent)
			}
		}
	}
	return parents, nil
}

func NewBus(cfg BusConfig, dir string, seed types.PrivateKey, l *zap.Logger) (http.Handler, ShutdownFn, error) {
	gatewayDir := filepath.Join(dir, "gateway")
	if err := os.MkdirAll(gatewayDir, 0700); err != nil {
		return nil, nil, err
	}
	g, err := gateway.New(cfg.GatewayAddr, cfg.Bootstrap, gatewayDir)
	if err != nil {
		return nil, nil, err
	}
	consensusDir := filepath.Join(dir, "consensus")
	if err := os.MkdirAll(consensusDir, 0700); err != nil {
		return nil, nil, err
	}
	cs, errCh := mconsensus.New(g, cfg.Bootstrap, consensusDir)
	select {
	case err := <-errCh:
		if err != nil {
			return nil, nil, err
		}
	default:
		go func() {
			if err := <-errCh; err != nil {
				log.Println("WARNING: consensus initialization returned an error:", err)
			}
		}()
	}
	tpoolDir := filepath.Join(dir, "transactionpool")
	if err := os.MkdirAll(tpoolDir, 0700); err != nil {
		return nil, nil, err
	}
	tp, err := transactionpool.New(cs, g, tpoolDir)
	if err != nil {
		return nil, nil, err
	}

	walletDir := filepath.Join(dir, "wallet")
	if err := os.MkdirAll(walletDir, 0700); err != nil {
		return nil, nil, err
	}
	walletAddr := wallet.StandardAddress(seed.PublicKey())
	ws, ccid, err := stores.NewJSONWalletStore(walletDir, walletAddr)
	if err != nil {
		return nil, nil, err
	} else if err := cs.ConsensusSetSubscribe(ws, ccid, nil); err != nil {
		return nil, nil, err
	}
	w := wallet.NewSingleAddressWallet(seed, ws)

	// If no DB dialector was provided, use SQLite.
	dbConn := cfg.DBDialector
	if dbConn == nil {
		dbDir := filepath.Join(dir, "db")
		if err := os.MkdirAll(dbDir, 0700); err != nil {
			return nil, nil, err
		}
		dbConn = stores.NewSQLiteConnection(filepath.Join(dbDir, "db.sqlite"))
	}

	sqlLogger := stores.NewSQLLogger(l.Named("db"), nil)
	sqlStore, ccid, err := stores.NewSQLStore(dbConn, true, cfg.PersistInterval, sqlLogger)
	if err != nil {
		return nil, nil, err
	} else if err := cs.ConsensusSetSubscribe(sqlStore, ccid, nil); err != nil {
		return nil, nil, err
	}

	if m := cfg.Miner; m != nil {
		if err := cs.ConsensusSetSubscribe(m, ccid, nil); err != nil {
			return nil, nil, err
		}
		tp.TransactionPoolSubscribe(m)
	}

	b, err := bus.New(syncer{g, tp}, chainManager{cs: cs, network: cfg.Network}, txpool{tp}, w, sqlStore, sqlStore, sqlStore, sqlStore, l)
	if err != nil {
		return nil, nil, err
	}

	shutdownFn := func(ctx context.Context) error {
		return joinErrors([]error{
			g.Close(),
			cs.Close(),
			tp.Close(),
			b.Shutdown(ctx),
			sqlStore.Close(),
		})
	}
	return b.Handler(), shutdownFn, nil
}

func NewWorker(cfg WorkerConfig, b worker.Bus, seed types.PrivateKey, l *zap.Logger) (http.Handler, ShutdownFn, error) {
	workerKey := blake2b.Sum256(append([]byte("worker"), seed...))
	w := worker.New(workerKey, cfg.ID, b, cfg.ContractLockTimeout, cfg.SessionLockTimeout, cfg.SessionReconnectTimeout, cfg.SessionTTL, cfg.BusFlushInterval, cfg.DownloadSectorTimeout, cfg.UploadSectorTimeout, cfg.DownloadMaxOverdrive, cfg.UploadMaxOverdrive, l)
	return w.Handler(), w.Shutdown, nil
}

func NewAutopilot(cfg AutopilotConfig, s autopilot.Store, b autopilot.Bus, workers []autopilot.Worker, l *zap.Logger) (http.Handler, func() error, ShutdownFn, error) {
	ap, err := autopilot.New(s, b, workers, l, cfg.Heartbeat, cfg.ScannerInterval, cfg.ScannerBatchSize, cfg.ScannerMinRecentFailures, cfg.ScannerNumThreads, cfg.MigrationHealthCutoff, cfg.AccountsRefillInterval)
	if err != nil {
		return nil, nil, nil, err
	}
	return ap.Handler(), ap.Run, ap.Shutdown, nil
}

func NewLogger(path string) (*zap.Logger, func(context.Context) error, error) {
	writer, closeFn, err := zap.Open(path)
	if err != nil {
		return nil, nil, err
	}

	// console
	config := zap.NewProductionEncoderConfig()
	config.EncodeTime = zapcore.RFC3339TimeEncoder
	config.EncodeLevel = zapcore.CapitalColorLevelEncoder
	config.StacktraceKey = ""
	consoleEncoder := zapcore.NewConsoleEncoder(config)

	// file
	config = zap.NewProductionEncoderConfig()
	config.EncodeTime = zapcore.RFC3339TimeEncoder
	config.CallerKey = ""     // hide
	config.StacktraceKey = "" // hide
	config.NameKey = "component"
	config.TimeKey = "date"
	fileEncoder := zapcore.NewJSONEncoder(config)

	core := zapcore.NewTee(
		zapcore.NewCore(fileEncoder, writer, zapcore.DebugLevel),
		zapcore.NewCore(consoleEncoder, zapcore.AddSync(os.Stdout), zapcore.DebugLevel),
	)

	logger := zap.New(
		core,
		zap.AddCaller(),
		zap.AddStacktrace(zapcore.ErrorLevel),
	)

	return logger, func(_ context.Context) error {
		_ = logger.Sync() // ignore Error
		closeFn()
		return nil
	}, nil
}

func joinErrors(errs []error) error {
	filtered := errs[:0]
	for _, err := range errs {
		if err != nil {
			filtered = append(filtered, err)
		}
	}

	switch len(filtered) {
	case 0:
		return nil
	case 1:
		return filtered[0]
	default:
		strs := make([]string, len(filtered))
		for i := range strs {
			strs[i] = filtered[i].Error()
		}
		return errors.New(strings.Join(strs, ";"))
	}
}