package auditor

import (
	"sync"
	"time"

	"github.com/nspcc-dev/neofs-api-go/pkg/container"
	"github.com/nspcc-dev/neofs-api-go/pkg/netmap"
	"github.com/nspcc-dev/neofs-api-go/pkg/object"
	"github.com/nspcc-dev/neofs-api-go/pkg/storagegroup"
	"github.com/nspcc-dev/neofs-node/pkg/services/audit"
	"github.com/nspcc-dev/neofs-node/pkg/services/object_manager/placement"
	"github.com/nspcc-dev/neofs-node/pkg/util"
	"github.com/nspcc-dev/neofs-node/pkg/util/logger"
	"go.uber.org/zap"
)

// Context represents container data audit execution context.
type Context struct {
	ContextPrm

	task *audit.Task

	report *audit.Report

	// consider adding mutex to access caches

	sgMembersCache map[int][]*object.ID

	placementCache map[string][]netmap.Nodes

	pairs []gamePair

	pairedMtx   sync.Mutex
	pairedNodes map[uint64]*pairMemberInfo

	counters struct {
		hit, miss, fail uint32
	}

	cnrNodesNum int

	headResponses map[string]shortHeader
}

type pairMemberInfo struct {
	failedPDP, passedPDP bool // at least one

	node *netmap.Node
}

type gamePair struct {
	n1, n2 *netmap.Node

	id *object.ID

	rn1, rn2 []*object.Range

	hh1, hh2 [][]byte
}

type shortHeader struct {
	tzhash []byte

	objectSize uint64
}

// ContextPrm groups components required to conduct data audit checks.
type ContextPrm struct {
	maxPDPSleep uint64

	log *logger.Logger

	cnrCom ContainerCommunicator

	pdpWorkerPool util.WorkerPool
}

// ContainerCommunicator is an interface of
// component of communication with container nodes.
type ContainerCommunicator interface {
	// Must return storage group structure stored in object from container.
	GetSG(*audit.Task, *object.ID) (*storagegroup.StorageGroup, error)

	// Must return object header from the container node.
	GetHeader(*audit.Task, *netmap.Node, *object.ID, bool) (*object.Object, error)

	// Must return homomorphic Tillich-Zemor hash of payload range of the
	// object stored in container node.
	GetRangeHash(*audit.Task, *netmap.Node, *object.ID, *object.Range) ([]byte, error)
}

// NewContext creates, initializes and returns Context.
func NewContext(prm ContextPrm) *Context {
	return &Context{
		ContextPrm: prm,
	}
}

// SetLogger sets logging component.
func (p *ContextPrm) SetLogger(l *logger.Logger) {
	if p != nil {
		p.log = l
	}
}

// SetContainerCommunicator sets component of communication with container nodes.
func (p *ContextPrm) SetContainerCommunicator(cnrCom ContainerCommunicator) {
	if p != nil {
		p.cnrCom = cnrCom
	}
}

// SetMaxPDPSleep sets maximum sleep interval between range hash requests.
// as part of PDP check.
func (p *ContextPrm) SetMaxPDPSleep(dur time.Duration) {
	if p != nil {
		p.maxPDPSleep = uint64(dur)
	}
}

// WithTask sets container audit parameters.
func (c *Context) WithTask(t *audit.Task) *Context {
	if c != nil {
		c.task = t
	}

	return c
}

// WithPDPWorkerPool sets worker pool for PDP pairs processing..
func (c *Context) WithPDPWorkerPool(pool util.WorkerPool) *Context {
	if c != nil {
		c.pdpWorkerPool = pool
	}

	return c
}

func (c *Context) containerID() *container.ID {
	return c.task.ContainerID()
}

func (c *Context) init() {
	c.report = audit.NewReport(c.containerID())

	c.sgMembersCache = make(map[int][]*object.ID)

	c.placementCache = make(map[string][]netmap.Nodes)

	c.cnrNodesNum = len(c.task.ContainerNodes().Flatten())

	c.pairedNodes = make(map[uint64]*pairMemberInfo)

	c.headResponses = make(map[string]shortHeader)

	c.log = c.log.With(
		zap.Stringer("container ID", c.task.ContainerID()),
	)
}

func (c *Context) expired() bool {
	ctx := c.task.AuditContext()

	select {
	case <-ctx.Done():
		c.log.Debug("audit context is done",
			zap.String("error", ctx.Err().Error()),
		)

		return true
	default:
		return false
	}
}

func (c *Context) complete() {
	c.report.Complete()
}

func (c *Context) writeReport() {
	c.log.Debug("writing audit report...")

	if err := c.task.Reporter().WriteReport(c.report); err != nil {
		c.log.Error("could not write audit report")
	}
}

func (c *Context) buildPlacement(id *object.ID) ([]netmap.Nodes, error) {
	strID := id.String()

	if nn, ok := c.placementCache[strID]; ok {
		return nn, nil
	}

	nn, err := placement.BuildObjectPlacement(
		c.task.NetworkMap(),
		c.task.ContainerNodes(),
		id,
	)
	if err != nil {
		return nil, err
	}

	c.placementCache[strID] = nn

	return nn, nil
}

func (c *Context) objectSize(id *object.ID) uint64 {
	strID := id.String()

	if hdr, ok := c.headResponses[strID]; ok {
		return hdr.objectSize
	}

	return 0
}

func (c *Context) objectHomoHash(id *object.ID) []byte {
	strID := id.String()

	if hdr, ok := c.headResponses[strID]; ok {
		return hdr.tzhash
	}

	return nil
}

func (c *Context) updateHeadResponses(hdr *object.Object) {
	strID := hdr.ID().String()

	if _, ok := c.headResponses[strID]; !ok {
		c.headResponses[strID] = shortHeader{
			tzhash:     hdr.PayloadHomomorphicHash().Sum(),
			objectSize: hdr.PayloadSize(),
		}
	}
}