package local

import (
	"context"
	"errors"
	"fmt"
	"sync"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-node/config"
	engineconfig "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-node/config/engine"
	shardconfig "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-node/config/engine/shard"
	blobovniczaconfig "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-node/config/engine/shard/blobstor/blobovnicza"
	fstreeconfig "git.frostfs.info/TrueCloudLab/frostfs-node/cmd/frostfs-node/config/engine/shard/blobstor/fstree"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/blobovniczatree"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/blobstor/fstree"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/engine"
	metabase "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/metabase"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/pilorama"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/shard"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/writecache"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	"git.frostfs.info/TrueCloudLab/xk6-frostfs/internal/local/rawclient"
	"git.frostfs.info/TrueCloudLab/xk6-frostfs/internal/stats"
	"github.com/nspcc-dev/neo-go/pkg/crypto/keys"
	"github.com/panjf2000/ants/v2"
	"go.etcd.io/bbolt"
	"go.k6.io/k6/js/modules"
	"go.k6.io/k6/metrics"
	"go.uber.org/zap"
	"golang.org/x/sys/unix"
)

// RootModule is the global module object type. It is instantiated once per test
// run and will be used to create k6/x/frostfs/local module instances for each VU.
type RootModule struct {
	mu sync.Mutex
	// configFile is the name of the configuration file used during one test.
	configFile string
	// ng is the engine instance used during one test, corresponding to the configFile. Each VU
	// gets the same engine instance.
	ng *engine.StorageEngine
}

// Local represents an instance of the module for every VU.
type Local struct {
	vu            modules.VU
	ResolveEngine func(context.Context, string, bool) (*engine.StorageEngine, error)
}

// Ensure the interfaces are implemented correctly.
var (
	_ modules.Module   = &RootModule{}
	_ modules.Instance = &Local{}

	objPutTotal, objPutFails, objPutDuration          *metrics.Metric
	objGetTotal, objGetFails, objGetDuration          *metrics.Metric
	objDeleteTotal, objDeleteFails, objDeleteDuration *metrics.Metric
)

func init() {
	modules.Register("k6/x/frostfs/local", &RootModule{})
}

// NewModuleInstance implements the modules.Module interface and returns
// a new instance for each VU.
func (r *RootModule) NewModuleInstance(vu modules.VU) modules.Instance {
	return NewLocalModuleInstance(vu, r.GetOrCreateEngine)
}

func NewLocalModuleInstance(vu modules.VU, resolveEngine func(context.Context, string, bool) (*engine.StorageEngine, error)) *Local {
	return &Local{
		vu:            vu,
		ResolveEngine: resolveEngine,
	}
}

// checkResourceLimits checks the current limit on NOFILE.
//
// The usual default is around 1024 and this is too low for production clusters where a value of
// about 65536 is needed in order to not run into errors because of attempting to open too many files.
// This is needed for the local storage engine scenarios, where the user running the scenario is not
// necessarily the service user, for which the limits are preconfigured correctly.
//
// See: https://k6.io/docs/misc/fine-tuning-os/
func checkResourceLimits() error {
	const (
		minNofileLimit = 1 << 16
	)
	rlimit := &unix.Rlimit{}
	if err := unix.Getrlimit(unix.RLIMIT_NOFILE, rlimit); err != nil {
		return fmt.Errorf("getting resource limits: %v", err)
	}
	if rlimit.Cur < minNofileLimit {
		return fmt.Errorf("nofile limit is too low: %d", rlimit.Cur)
	}
	return nil
}

// GetOrCreateEngine returns the current engine instance for the given configuration file,
// creating a new one if none exists. Note that the identity of configuration files is their
// file name for the purposes of test runs.
func (r *RootModule) GetOrCreateEngine(ctx context.Context, configFile string, debug bool) (*engine.StorageEngine, error) {
	r.mu.Lock()
	defer r.mu.Unlock()

	if len(configFile) == 0 {
		return nil, errors.New("configFile cannot be empty")
	}

	// Create and initialize engine for the given configFile if it doesn't exist already
	if r.ng == nil {
		r.configFile = configFile
		appCfg := config.New(configFile, "", "")
		ngOpts, shardOpts, err := storageEngineOptionsFromConfig(appCfg, debug)
		if err != nil {
			return nil, fmt.Errorf("creating engine options from config: %v", err)
		}
		if err := checkResourceLimits(); err != nil {
			return nil, err
		}
		r.ng = engine.New(ngOpts...)
		for i, opts := range shardOpts {
			if _, err := r.ng.AddShard(opts...); err != nil {
				return nil, fmt.Errorf("adding shard %d: %v", i, err)
			}
		}
		if err := r.ng.Open(); err != nil {
			return nil, fmt.Errorf("opening engine: %v", err)
		}
		if err := r.ng.Init(ctx); err != nil {
			return nil, fmt.Errorf("initializing engine: %v", err)
		}
	} else if configFile != r.configFile {
		return nil, fmt.Errorf("GetOrCreateEngine called with mismatching configFile after engine was initialized: got %q, want %q", configFile, r.configFile)
	}

	return r.ng, nil
}

// Exports implements the modules.Instance interface and returns the exports
// of the JS module.
func (s *Local) Exports() modules.Exports {
	return modules.Exports{Default: s}
}

func (s *Local) VU() modules.VU { return s.vu }

func (s *Local) Connect(configFile, hexKey string, debug bool) (*Client, error) {
	ng, err := s.ResolveEngine(s.VU().Context(), configFile, debug)
	if err != nil {
		return nil, fmt.Errorf("connecting to engine for config %q: %v", configFile, err)
	}

	key, err := ParseOrCreateKey(hexKey)
	if err != nil {
		return nil, fmt.Errorf("creating key: %v", err)
	}

	// Register metrics.
	registry := metrics.NewRegistry()
	objPutTotal, _ = registry.NewMetric("local_obj_put_total", metrics.Counter)
	objPutFails, _ = registry.NewMetric("local_obj_put_fails", metrics.Counter)
	objPutDuration, _ = registry.NewMetric("local_obj_put_duration", metrics.Trend, metrics.Time)

	objGetTotal, _ = registry.NewMetric("local_obj_get_total", metrics.Counter)
	objGetFails, _ = registry.NewMetric("local_obj_get_fails", metrics.Counter)
	objGetDuration, _ = registry.NewMetric("local_obj_get_duration", metrics.Trend, metrics.Time)

	objDeleteTotal, _ = registry.NewMetric("local_obj_delete_total", metrics.Counter)
	objDeleteFails, _ = registry.NewMetric("local_obj_delete_fails", metrics.Counter)
	objDeleteDuration, _ = registry.NewMetric("local_obj_delete_duration", metrics.Trend, metrics.Time)

	// Create raw client backed by local storage engine.
	rc := rawclient.New(ng,
		rawclient.WithKey(key.PrivateKey),
		rawclient.WithPutHandler(func(sz uint64, err error, dt time.Duration) {
			if err != nil {
				stats.Report(s.vu, objPutFails, 1)
			} else {
				stats.Report(s.vu, objPutTotal, 1)
				stats.ReportDataSent(s.vu, float64(sz))
				stats.Report(s.vu, objPutDuration, metrics.D(dt))
			}
		}),
		rawclient.WithGetHandler(func(sz uint64, err error, dt time.Duration) {
			if err != nil {
				stats.Report(s.vu, objGetFails, 1)
			} else {
				stats.Report(s.vu, objGetTotal, 1)
				stats.Report(s.vu, objGetDuration, metrics.D(dt))
				stats.ReportDataReceived(s.vu, float64(sz))
			}
		}),
		rawclient.WithDeleteHandler(func(err error, dt time.Duration) {
			if err != nil {
				stats.Report(s.vu, objDeleteFails, 1)
			} else {
				stats.Report(s.vu, objDeleteTotal, 1)
				stats.Report(s.vu, objDeleteDuration, metrics.D(dt))
			}
		}),
	)
	return &Client{vu: s.vu, rc: rc}, nil
}

type epochState struct{}

func (epochState) CurrentEpoch() uint64 { return 0 }

// storageEngineOptionsFromConfig loads a configuration file and returns the corresponding
// engine and shard options to recreate an engine usable with an existing storage instance.
// This makes sure that the local loader uses the same engine configuration as the one that
// preloaded the storage (if any), by using the same configuration file.
//
// Note that the configuration file only needs to contain the storage-specific sections.
func storageEngineOptionsFromConfig(c *config.Config, debug bool) ([]engine.Option, [][]shard.Option, error) {
	log := zap.L()
	if debug {
		var err error
		log, err = zap.NewDevelopment()
		if err != nil {
			return nil, nil, fmt.Errorf("creating development logger: %v", err)
		}
	}

	ngOpts := []engine.Option{
		engine.WithErrorThreshold(engineconfig.ShardErrorThreshold(c)),
		engine.WithShardPoolSize(engineconfig.ShardPoolSize(c)),
		engine.WithLogger(&logger.Logger{Logger: log}),
	}

	var shOpts [][]shard.Option

	engineconfig.IterateShards(c, false, func(sc *shardconfig.Config) error {
		opts := []shard.Option{
			shard.WithRefillMetabase(sc.RefillMetabase()),
			shard.WithMode(sc.Mode()),
			shard.WithLogger(&logger.Logger{Logger: log}),
		}

		// substorages
		{
			var substorages []blobstor.SubStorage
			for _, scfg := range sc.BlobStor().Storages() {
				switch scfg.Type() {
				case blobovniczatree.Type:
					cfg := blobovniczaconfig.From((*config.Config)(scfg))
					ss := blobstor.SubStorage{
						Storage: blobovniczatree.NewBlobovniczaTree(
							blobovniczatree.WithRootPath(scfg.Path()),
							blobovniczatree.WithPermissions(scfg.Perm()),
							blobovniczatree.WithBlobovniczaSize(cfg.Size()),
							blobovniczatree.WithBlobovniczaShallowDepth(cfg.ShallowDepth()),
							blobovniczatree.WithBlobovniczaShallowWidth(cfg.ShallowWidth()),
							blobovniczatree.WithOpenedCacheSize(cfg.OpenedCacheSize()),
							blobovniczatree.WithLogger(&logger.Logger{Logger: log}),
						),
						Policy: func(_ *objectSDK.Object, data []byte) bool {
							return uint64(len(data)) < sc.SmallSizeLimit()
						},
					}
					substorages = append(substorages, ss)
				case fstree.Type:
					cfg := fstreeconfig.From((*config.Config)(scfg))
					ss := blobstor.SubStorage{
						Storage: fstree.New(
							fstree.WithPath(scfg.Path()),
							fstree.WithPerm(scfg.Perm()),
							fstree.WithDepth(cfg.Depth()),
							fstree.WithNoSync(cfg.NoSync()),
						),
						Policy: func(_ *objectSDK.Object, data []byte) bool {
							return true
						},
					}
					substorages = append(substorages, ss)
				default:
					return fmt.Errorf("invalid storage type: %s", scfg.Type())
				}
			}
			opts = append(opts, shard.WithBlobStorOptions(
				blobstor.WithCompressObjects(sc.Compress()),
				blobstor.WithUncompressableContentTypes(sc.UncompressableContentTypes()),
				blobstor.WithStorages(substorages),
				blobstor.WithLogger(&logger.Logger{Logger: log}),
			))
		}

		// write cache
		if wc := sc.WriteCache(); wc.Enabled() {
			opts = append(opts, shard.WithWriteCacheOptions(
				writecache.WithPath(wc.Path()),
				writecache.WithMaxBatchSize(wc.BoltDB().MaxBatchSize()),
				writecache.WithMaxBatchDelay(wc.BoltDB().MaxBatchDelay()),
				writecache.WithMaxObjectSize(wc.MaxObjectSize()),
				writecache.WithSmallObjectSize(wc.SmallObjectSize()),
				writecache.WithFlushWorkersCount(wc.WorkersNumber()),
				writecache.WithMaxCacheSize(wc.SizeLimit()),
				writecache.WithNoSync(wc.NoSync()),
				writecache.WithLogger(&logger.Logger{Logger: log}),
			))
		}

		// tree
		if config.BoolSafe(c.Sub("tree"), "enabled") {
			pr := sc.Pilorama()
			opts = append(opts, shard.WithPiloramaOptions(
				pilorama.WithPath(pr.Path()),
				pilorama.WithPerm(pr.Perm()),
				pilorama.WithMaxBatchSize(pr.MaxBatchSize()),
				pilorama.WithMaxBatchDelay(pr.MaxBatchDelay()),
				pilorama.WithNoSync(pr.NoSync()),
			))
		}

		// metabase
		{
			mb := sc.Metabase()
			opts = append(opts, shard.WithMetaBaseOptions(
				metabase.WithPath(mb.Path()),
				metabase.WithPermissions(mb.BoltDB().Perm()),
				metabase.WithMaxBatchSize(mb.BoltDB().MaxBatchSize()),
				metabase.WithMaxBatchDelay(mb.BoltDB().MaxBatchDelay()),
				metabase.WithBoltDBOptions(&bbolt.Options{
					Timeout: 1 * time.Second,
				}),
				metabase.WithEpochState(epochState{}),
				metabase.WithLogger(&logger.Logger{Logger: log}),
			))
		}

		// GC
		{
			gc := sc.GC()
			opts = append(opts,
				shard.WithGCRemoverSleepInterval(gc.RemoverSleepInterval()),
				shard.WithRemoverBatchSize(gc.RemoverBatchSize()),
				shard.WithGCWorkerPoolInitializer(func(sz int) util.WorkerPool {
					pool, err := ants.NewPool(sz)
					if err != nil {
						panic(err)
					}

					return pool
				}),
			)
		}

		shOpts = append(shOpts, opts)

		return nil
	})

	return ngOpts, shOpts, nil
}

// ParseOrCreateKey parses the provided key as a hex string or creates a fresh one if empty.
func ParseOrCreateKey(hexKeyStr string) (*keys.PrivateKey, error) {
	if hexKeyStr != "" {
		return keys.NewPrivateKeyFromHex(hexKeyStr)
	}
	return keys.NewPrivateKey()
}