package frostfs

import (
	"context"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/layer/frostfs"
	"git.frostfs.info/TrueCloudLab/frostfs-s3-gw/api/middleware"
	cid "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/container/id"
	"git.frostfs.info/TrueCloudLab/frostfs-sdk-go/netmap"
)

type Source struct {
	frostFS *FrostFS
	cache   *layer.Cache
}

func NewSource(frostFS *FrostFS, cache *layer.Cache) *Source {
	return &Source{
		frostFS: frostFS,
		cache:   cache,
	}
}

func (s *Source) NetMapSnapshot(ctx context.Context) (netmap.NetMap, error) {
	cachedNetmap := s.cache.GetNetmap()
	if cachedNetmap != nil {
		return *cachedNetmap, nil
	}

	netmapSnapshot, err := s.frostFS.NetmapSnapshot(ctx)
	if err != nil {
		return netmap.NetMap{}, fmt.Errorf("get netmap: %w", err)
	}

	s.cache.PutNetmap(netmapSnapshot)

	return netmapSnapshot, nil
}

func (s *Source) PlacementPolicy(ctx context.Context, cnrID cid.ID) (netmap.PlacementPolicy, error) {
	cachedPolicy := s.cache.GetPlacementPolicy(cnrID)
	if cachedPolicy != nil {
		return *cachedPolicy, nil
	}

	prm := frostfs.PrmContainer{
		ContainerID: cnrID,
	}
	if bd, err := middleware.GetBoxData(ctx); err == nil && bd.Gate != nil {
		prm.SessionToken = bd.Gate.SessionToken()
	}

	res, err := s.frostFS.Container(ctx, prm)
	if err != nil {
		return netmap.PlacementPolicy{}, fmt.Errorf("get container: %w", err)
	}

	// We don't put container back to the cache to keep cache
	// coherent to the requests made by S3 users. FrostFS Source
	// is being used by SDK Tree Pool and it should not fill cache
	// with possibly irrelevant container values.

	return res.PlacementPolicy(), nil
}