package s3local

import (
	"context"
	"flag"
	"fmt"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/pkg/service/tree"
	"git.frostfs.info/TrueCloudLab/xk6-frostfs/internal/local"
	"git.frostfs.info/TrueCloudLab/xk6-frostfs/internal/local/rawclient"
	"git.frostfs.info/TrueCloudLab/xk6-frostfs/internal/stats"
	"go.k6.io/k6/js/modules"
	"go.k6.io/k6/metrics"
	"go.uber.org/zap"
)

// RootModule is the global module object type. It is instantiated once per test
// run and will be used to create k6/x/frostfs/s3local module instances for each VU.
type RootModule struct {
	m *local.RootModule
}

// Local represents an instance of the module for every VU.
type Local struct {
	l *local.Local
}

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

	internalObjPutTotal, internalObjPutFails, internalObjPutDuration *metrics.Metric
	internalObjGetTotal, internalObjGetFails, internalObjGetDuration *metrics.Metric
	objPutTotal, objPutFails, objPutDuration                         *metrics.Metric
	objGetTotal, objGetFails, objGetDuration                         *metrics.Metric
)

func init() {
	modules.Register("k6/x/frostfs/s3local", &RootModule{
		m: &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 &Local{local.NewLocalModuleInstance(vu, r.m.GetOrCreateEngine)}
}

// 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) Connect(configFile string, configDir string, params map[string]string, bucketMapping map[string]string, maxSizeGB int64) (*Client, error) {
	// Parse configuration flags.
	fs := flag.NewFlagSet("s3local", flag.ContinueOnError)

	hexKey := fs.String("hex_key", "", "Private key to use as a hexadecimal string. A random one is created if none is provided")
	nodePosition := fs.Int("node_position", 0, "Position of this node in the node array if loading multiple nodes independently")
	nodeCount := fs.Int("node_count", 1, "Number of nodes in the node array if loading multiple nodes independently")
	debugLogger := fs.Bool("debug_logger", false, "Whether to use the development logger instead of the default one for debugging purposes")

	{
		args := make([]string, 0, len(params))
		for k, v := range params {
			args = append(args, fmt.Sprintf("-%s=%s", k, v))
		}
		if err := fs.Parse(args); err != nil {
			return nil, fmt.Errorf("parsing parameters: %v", err)
		}
	}

	// Validate and read configuration flags.
	key, err := local.ParseOrCreateKey(*hexKey)
	if err != nil {
		return nil, fmt.Errorf("parsing hex_key: %v", err)
	}
	if *nodeCount <= 0 {
		return nil, fmt.Errorf("node_count must be positive")
	}
	if *nodePosition < 0 || *nodePosition >= *nodeCount {
		return nil, fmt.Errorf("node_position must be in the range [0, node_count-1]")
	}

	// Register metrics.
	internalObjPutTotal, _ = stats.Registry.NewMetric("s3local_internal_obj_put_total", metrics.Counter)
	internalObjPutFails, _ = stats.Registry.NewMetric("s3local_internal_obj_put_fails", metrics.Counter)
	internalObjPutDuration, _ = stats.Registry.NewMetric("s3local_internal_obj_put_duration", metrics.Trend, metrics.Time)

	internalObjGetTotal, _ = stats.Registry.NewMetric("s3local_internal_obj_get_total", metrics.Counter)
	internalObjGetFails, _ = stats.Registry.NewMetric("s3local_internal_obj_get_fails", metrics.Counter)
	internalObjGetDuration, _ = stats.Registry.NewMetric("s3local_internal_obj_get_duration", metrics.Trend, metrics.Time)

	objPutTotal, _ = stats.Registry.NewMetric("s3local_obj_put_total", metrics.Counter)
	objPutFails, _ = stats.Registry.NewMetric("s3local_obj_put_fails", metrics.Counter)
	objPutDuration, _ = stats.Registry.NewMetric("s3local_obj_put_duration", metrics.Trend, metrics.Time)

	objGetTotal, _ = stats.Registry.NewMetric("s3local_obj_get_total", metrics.Counter)
	objGetFails, _ = stats.Registry.NewMetric("s3local_obj_get_fails", metrics.Counter)
	objGetDuration, _ = stats.Registry.NewMetric("s3local_obj_get_duration", metrics.Trend, metrics.Time)

	// Create S3 layer backed by local storage engine and tree service.
	ng, limiter, err := s.l.ResolveEngine(s.l.VU().Context(), configFile, configDir, *debugLogger, maxSizeGB)
	if err != nil {
		return nil, fmt.Errorf("connecting to engine for config - file %q dir %q: %v", configFile, configDir, err)
	}

	treeSvc := tree.NewTree(treeServiceEngineWrapper{
		ng:   ng,
		pos:  *nodePosition,
		size: *nodeCount,
	}, zap.L())

	rc := rawclient.New(ng,
		rawclient.WithKey(key.PrivateKey),
		rawclient.WithPutHandler(func(sz uint64, err error, dt time.Duration) {
			if err != nil {
				stats.Report(s.l.VU(), internalObjPutFails, 1)
			} else {
				stats.Report(s.l.VU(), internalObjPutTotal, 1)
				stats.Report(s.l.VU(), internalObjPutDuration, metrics.D(dt))
			}
		}),
		rawclient.WithGetHandler(func(sz uint64, err error, dt time.Duration) {
			if err != nil {
				stats.Report(s.l.VU(), internalObjGetFails, 1)
			} else {
				stats.Report(s.l.VU(), internalObjGetTotal, 1)
				stats.Report(s.l.VU(), internalObjGetDuration, metrics.D(dt))
			}
		}),
	)

	resolver, err := newFixedBucketResolver(bucketMapping)
	if err != nil {
		return nil, fmt.Errorf("creating bucket resolver: %v", err)
	}

	cfg := &layer.Config{
		Caches:      layer.DefaultCachesConfigs(zap.L()),
		AnonKey:     layer.AnonymousKey{Key: key},
		Resolver:    resolver,
		TreeService: treeSvc,
	}

	l := layer.NewLayer(zap.L(), &frostfs{rc}, cfg)
	err = l.Initialize(s.l.VU().Context(), nopEventListener{})
	if err != nil {
		return nil, fmt.Errorf("initialize: %w", err)
	}

	return &Client{
		vu:       s.l.VU(),
		l:        l,
		ownerID:  rc.OwnerID(),
		resolver: resolver,
		limiter:  limiter,
	}, nil
}

type nopEventListener struct{}

func (nopEventListener) Subscribe(context.Context, string, layer.MsgHandler) error { return nil }
func (nopEventListener) Listen(context.Context)                                    {}