package getsvc

import (
	"context"

	objectSDK "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object"
	oid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/object/id"
)

func (a *assembler) assembleHeader(ctx context.Context, writer ObjectWriter) (*objectSDK.Object, error) {
	var sourceObjectIDs []oid.ID
	sourceObjectID, ok := a.splitInfo.Link()
	if ok {
		sourceObjectIDs = append(sourceObjectIDs, sourceObjectID)
	}
	sourceObjectID, ok = a.splitInfo.LastPart()
	if ok {
		sourceObjectIDs = append(sourceObjectIDs, sourceObjectID)
	}
	if len(sourceObjectIDs) == 0 {
		return nil, objectSDK.NewSplitInfoError(a.splitInfo)
	}
	for _, sourceObjectID = range sourceObjectIDs {
		obj, err := a.getParent(ctx, sourceObjectID, writer)
		if err == nil {
			return obj, nil
		}
	}
	return nil, objectSDK.NewSplitInfoError(a.splitInfo)
}

func (a *assembler) getParent(ctx context.Context, sourceObjectID oid.ID, writer ObjectWriter) (*objectSDK.Object, error) {
	obj, err := a.objGetter.HeadObject(ctx, sourceObjectID)
	if err != nil {
		return nil, err
	}
	parent := obj.Parent()
	if parent == nil {
		return nil, objectSDK.NewSplitInfoError(a.splitInfo)
	}
	if err := writer.WriteHeader(ctx, parent); err != nil {
		return nil, err
	}
	return obj, nil
}