package main

import (
	"strings"
	"time"

	"git.frostfs.info/TrueCloudLab/frostfs-contract/frostfsid/client"
	frostfsidcore "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/frostfsid"
	"github.com/hashicorp/golang-lru/v2/expirable"
	"github.com/nspcc-dev/neo-go/pkg/util"
)

type subjectWithError struct {
	subject *client.Subject
	err     error
}

type subjectExtWithError struct {
	subject *client.SubjectExtended
	err     error
}

type morphFrostfsIDCache struct {
	subjProvider frostfsidcore.SubjectProvider

	subjCache *expirable.LRU[util.Uint160, subjectWithError]

	subjExtCache *expirable.LRU[util.Uint160, subjectExtWithError]

	metrics cacheMetrics
}

func newMorphFrostfsIDCache(subjProvider frostfsidcore.SubjectProvider, size int, ttl time.Duration, metrics cacheMetrics) frostfsidcore.SubjectProvider {
	return &morphFrostfsIDCache{
		subjProvider: subjProvider,

		subjCache: expirable.NewLRU(size, func(util.Uint160, subjectWithError) {}, ttl),

		subjExtCache: expirable.NewLRU(size, func(util.Uint160, subjectExtWithError) {}, ttl),

		metrics: metrics,
	}
}

func (m *morphFrostfsIDCache) GetSubject(addr util.Uint160) (*client.Subject, error) {
	hit := false
	startedAt := time.Now()
	defer func() {
		m.metrics.AddMethodDuration("GetSubject", time.Since(startedAt), hit)
	}()

	result, found := m.subjCache.Get(addr)
	if found {
		hit = true
		return result.subject, result.err
	}

	subj, err := m.subjProvider.GetSubject(addr)
	if err != nil {
		if m.isCacheableError(err) {
			m.subjCache.Add(addr, subjectWithError{
				err: err,
			})
		}
		return nil, err
	}

	m.subjCache.Add(addr, subjectWithError{subject: subj})
	return subj, nil
}

func (m *morphFrostfsIDCache) GetSubjectExtended(addr util.Uint160) (*client.SubjectExtended, error) {
	hit := false
	startedAt := time.Now()
	defer func() {
		m.metrics.AddMethodDuration("GetSubjectExtended", time.Since(startedAt), hit)
	}()

	result, found := m.subjExtCache.Get(addr)
	if found {
		hit = true
		return result.subject, result.err
	}

	subjExt, err := m.subjProvider.GetSubjectExtended(addr)
	if err != nil {
		if m.isCacheableError(err) {
			m.subjExtCache.Add(addr, subjectExtWithError{
				err: err,
			})
			m.subjCache.Add(addr, subjectWithError{
				err: err,
			})
		}
		return nil, err
	}

	m.subjExtCache.Add(addr, subjectExtWithError{subject: subjExt})
	m.subjCache.Add(addr, subjectWithError{subject: subjectFromSubjectExtended(subjExt)})

	return subjExt, nil
}

func (m *morphFrostfsIDCache) isCacheableError(err error) bool {
	return strings.Contains(err.Error(), frostfsidcore.SubjectNotFoundErrorMessage)
}

func subjectFromSubjectExtended(subjExt *client.SubjectExtended) *client.Subject {
	return &client.Subject{
		PrimaryKey:     subjExt.PrimaryKey,
		AdditionalKeys: subjExt.AdditionalKeys,
		Namespace:      subjExt.Namespace,
		Name:           subjExt.Name,
		KV:             subjExt.KV,
	}
}