package putsvc

import (
	"context"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/object"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object_manager/placement"
	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/transformer"
)

type preparedObjectTarget interface {
	WriteObject(context.Context, *objectSDK.Object, object.ContentMeta) error
}

type distributedTarget struct {
	placementOpts         []placement.Option
	extraBroadcastEnabled bool

	obj     *objectSDK.Object
	objMeta object.ContentMeta

	*cfg

	payload *payload

	nodeTargetInitializer func(nodeDesc) preparedObjectTarget

	relay func(context.Context, nodeDesc) error
}

// parameters and state of container traversal.
type traversal struct {
	opts []placement.Option

	// need of additional broadcast after the object is saved
	extraBroadcastEnabled bool

	// container nodes which was processed during the primary object placement
	mExclude map[string]*bool
}

// updates traversal parameters after the primary placement finish and
// returns true if additional container broadcast is needed.
func (x *traversal) submitPrimaryPlacementFinish() bool {
	if x.extraBroadcastEnabled {
		// do not track success during container broadcast (best-effort)
		x.opts = append(x.opts, placement.WithoutSuccessTracking())

		// avoid 2nd broadcast
		x.extraBroadcastEnabled = false

		return true
	}

	return false
}

// marks the container node as processed during the primary object placement.
func (x *traversal) submitProcessed(n placement.Node, item *bool) {
	if x.extraBroadcastEnabled {
		key := string(n.PublicKey())

		if x.mExclude == nil {
			x.mExclude = make(map[string]*bool, 1)
		}

		x.mExclude[key] = item
	}
}

type nodeDesc struct {
	local bool

	info placement.Node
}

// errIncompletePut is returned if processing on a container fails.
type errIncompletePut struct {
	singleErr error // error from the last responding node
}

func (x errIncompletePut) Error() string {
	const commonMsg = "incomplete object PUT by placement"

	if x.singleErr != nil {
		return fmt.Sprintf("%s: %v", commonMsg, x.singleErr)
	}

	return commonMsg
}

func (t *distributedTarget) WriteHeader(_ context.Context, obj *objectSDK.Object) error {
	t.obj = obj

	return nil
}

func (t *distributedTarget) Write(_ context.Context, p []byte) (n int, err error) {
	t.payload.Data = append(t.payload.Data, p...)

	return len(p), nil
}

func (t *distributedTarget) Close(ctx context.Context) (*transformer.AccessIdentifiers, error) {
	defer func() {
		putPayload(t.payload)
		t.payload = nil
	}()

	t.obj.SetPayload(t.payload.Data)

	if err := t.WriteObject(ctx, t.obj); err != nil {
		return nil, err
	}

	id, _ := t.obj.ID()
	return &transformer.AccessIdentifiers{
		SelfID: id,
	}, nil
}

// WriteObject implements the transformer.ObjectWriter interface.
func (t *distributedTarget) WriteObject(ctx context.Context, obj *objectSDK.Object) error {
	t.obj = obj

	var err error

	if t.objMeta, err = t.fmtValidator.ValidateContent(t.obj); err != nil {
		return fmt.Errorf("(%T) could not validate payload content: %w", t, err)
	}

	if len(t.obj.Children()) > 0 {
		// enabling extra broadcast for linking objects
		t.extraBroadcastEnabled = true
	}

	return t.iteratePlacement(ctx)
}

func (t *distributedTarget) sendObject(ctx context.Context, node nodeDesc) error {
	if !node.local && t.relay != nil {
		return t.relay(ctx, node)
	}

	target := t.nodeTargetInitializer(node)

	err := target.WriteObject(ctx, t.obj, t.objMeta)
	if err != nil {
		return fmt.Errorf("could not write header: %w", err)
	}
	return nil
}

func (t *distributedTarget) iteratePlacement(ctx context.Context) error {
	id, _ := t.obj.ID()

	iter := t.cfg.newNodeIterator(append(t.placementOpts, placement.ForObject(id)))
	iter.extraBroadcastEnabled = t.extraBroadcastEnabled
	return iter.forEachNode(ctx, t.sendObject)
}