package control

import (
	"context"
	"crypto/ecdsa"
	"sync/atomic"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/container"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/netmap"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/local_object_storage/engine"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/control"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/replicator"
	policyengine "git.frostfs.info/TrueCloudLab/policy-engine/pkg/engine"
)

// Server is an entity that serves
// Control service on storage node.
type Server struct {
	*cfg

	// TODO (aarifullin): this counter is used to assign id for rule chains
	// added as local overrides and will be removed as soon as in-memory
	// implementation will be replaced.
	apeChainCounter atomic.Uint32
}

// HealthChecker is component interface for calculating
// the current health status of a node.
type HealthChecker interface {
	// NetmapStatus must calculate and return current status of the node in FrostFS network map.
	//
	// If status can not be calculated for any reason,
	// control.netmapStatus_STATUS_UNDEFINED should be returned.
	NetmapStatus() control.NetmapStatus

	// HealthStatus must calculate and return current health status of the node application.
	//
	// If status can not be calculated for any reason,
	// control.HealthStatus_HEALTH_STATUS_UNDEFINED should be returned.
	HealthStatus() control.HealthStatus
}

// NodeState is an interface of storage node network state.
type NodeState interface {
	// SetNetmapStatus switches the storage node to the given network status.
	//
	// If status is control.NetmapStatus_MAINTENANCE and maintenance is allowed
	// in the network settings, the node additionally starts local maintenance.
	SetNetmapStatus(ctx context.Context, st control.NetmapStatus) error

	// ForceMaintenance works like SetNetmapStatus(control.NetmapStatus_MAINTENANCE)
	// but starts local maintenance regardless of the network settings.
	ForceMaintenance(ctx context.Context) error

	GetNetmapStatus() (control.NetmapStatus, uint64, error)
}

// LocalOverrideStorageDecorator interface provides methods to decorate LocalOverrideEngine
// interface methods.
type LocalOverrideStorageDecorator interface {
	// LocalStorage method can be decorated by using sync primitives in the case if the local
	// override storage state should be consistent for chain router.
	LocalStorage() policyengine.LocalOverrideStorage
}

// Option of the Server's constructor.
type Option func(*cfg)

type cfg struct {
	key *ecdsa.PrivateKey

	allowedKeys [][]byte

	healthChecker HealthChecker

	netMapSrc netmap.Source

	cnrSrc container.Source

	localOverrideStorage LocalOverrideStorageDecorator

	replicator *replicator.Replicator

	nodeState NodeState

	treeService TreeService

	s *engine.StorageEngine
}

func defaultCfg() *cfg {
	return &cfg{}
}

// New creates, initializes and returns new Server instance.
func New(opts ...Option) *Server {
	c := defaultCfg()

	for _, opt := range opts {
		opt(c)
	}

	return &Server{
		cfg: c,
	}
}

// WithKey returns option to set private key
// used for signing responses.
func WithKey(key *ecdsa.PrivateKey) Option {
	return func(c *cfg) {
		c.key = key
	}
}

// WithAuthorizedKeys returns option to add list of public
// keys that have rights to use Control service.
func WithAuthorizedKeys(keys [][]byte) Option {
	return func(c *cfg) {
		c.allowedKeys = append(c.allowedKeys, keys...)
	}
}

// WithHealthChecker returns option to set component
// to calculate node health status.
func WithHealthChecker(hc HealthChecker) Option {
	return func(c *cfg) {
		c.healthChecker = hc
	}
}

// WithNetMapSource returns option to set network map storage.
func WithNetMapSource(netMapSrc netmap.Source) Option {
	return func(c *cfg) {
		c.netMapSrc = netMapSrc
	}
}

// WithContainerSource returns option to set container storage.
func WithContainerSource(cnrSrc container.Source) Option {
	return func(c *cfg) {
		c.cnrSrc = cnrSrc
	}
}

// WithReplicator returns option to set network map storage.
func WithReplicator(r *replicator.Replicator) Option {
	return func(c *cfg) {
		c.replicator = r
	}
}

// WithNodeState returns option to set node network state component.
func WithNodeState(state NodeState) Option {
	return func(c *cfg) {
		c.nodeState = state
	}
}

// WithLocalStorage returns option to set local storage engine that
// contains information about shards.
func WithLocalStorage(engine *engine.StorageEngine) Option {
	return func(c *cfg) {
		c.s = engine
	}
}

// WithTreeService returns an option to set tree service.
func WithTreeService(s TreeService) Option {
	return func(c *cfg) {
		c.treeService = s
	}
}

// WithLocalOverrideStorage returns the option to set access policy engine
// chain override storage.
func WithLocalOverrideStorage(localOverrideStorage LocalOverrideStorageDecorator) Option {
	return func(c *cfg) {
		c.localOverrideStorage = localOverrideStorage
	}
}