package session

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"slices"
	"time"

	"github.com/go-redis/redis/v8"
	"go.mongodb.org/mongo-driver/bson/primitive"
	"repositories.action2quare.com/ayo/gocommon"
	"repositories.action2quare.com/ayo/gocommon/logger"
)

const (
	communication_channel_name_prefix = "_sess_comm_chan_name"
)

type sessionRedis struct {
	*Authorization
	expireAt time.Time
}

type provider_redis struct {
	redisClient   *redis.Client
	deleteChannel string
	ttl           time.Duration
	ctx           context.Context
}

func newProviderWithRedis(ctx context.Context, redisUrl string, ttl time.Duration) (Provider, error) {
	redisClient, err := gocommon.NewRedisClient(redisUrl)
	if err != nil {
		return nil, err
	}

	return &provider_redis{
		redisClient:   redisClient,
		deleteChannel: fmt.Sprintf("%s_%d_d", communication_channel_name_prefix, redisClient.Options().DB),
		ttl:           ttl,
		ctx:           ctx,
	}, nil
}

func (p *provider_redis) New(input *Authorization) (string, error) {
	sks, err := p.RevokeAll(input.Account, false)
	if err != nil {
		return "", err
	}

	var newsk storagekey
	for {
		newsk = make_storagekey(input.Account)
		duplicated := slices.Contains(sks, string(newsk))
		if !duplicated {
			break
		}
	}

	_, err = p.redisClient.HSet(p.ctx, string(newsk), input.ToStrings()).Result()
	if err != nil {
		return "", err
	}
	_, err = p.redisClient.Expire(p.ctx, string(newsk), p.ttl).Result()
	if err != nil {
		return "", err
	}
	pk := storagekey_to_publickey(newsk)
	return string(pk), err
}

func (p *provider_redis) RevokeAll(account primitive.ObjectID, infinite bool) ([]string, error) {
	prefix := account.Hex()
	sks, err := p.redisClient.Keys(p.ctx, prefix+"*").Result()
	if err != nil {
		logger.Println("session provider delete :", sks, err)
		return nil, err
	}

	if len(sks) > 0 {
		p.redisClient.Del(p.ctx, sks...)

		invsess := InvalidatedSession{
			SessionKeys: sks,
			Account:     account,
			Infinite:    infinite,
		}
		data, _ := json.Marshal(invsess)

		p.redisClient.Publish(p.ctx, p.deleteChannel, string(data)).Result()
	}

	return sks, nil
}

func (p *provider_redis) Query(pk string) (Authorization, error) {
	sk := publickey_to_storagekey(publickey(pk))
	src, err := p.redisClient.HGetAll(p.ctx, string(sk)).Result()
	if err == redis.Nil {
		logger.Println("session provider query :", pk, err)
		return Authorization{}, nil
	} else if err != nil {
		logger.Println("session provider query :", pk, err)
		return Authorization{}, err
	}

	auth := MakeAuthrizationFromStringMap(src)
	return auth, nil
}

func (p *provider_redis) Touch(pk string) (bool, error) {
	sk := publickey_to_storagekey(publickey(pk))
	ok, err := p.redisClient.Expire(p.ctx, string(sk), p.ttl).Result()

	if err == redis.Nil {
		// 이미 만료됨
		logger.Println("session provider touch :", pk, err)
		return false, nil
	} else if err != nil {
		logger.Println("session provider touch :", pk, err)
		return false, err
	}

	return ok, nil
}

type consumer_redis struct {
	consumer_common[*sessionRedis]
	redisClient   *redis.Client
	deleteChannel string
}

func newConsumerWithRedis(ctx context.Context, redisUrl string, ttl time.Duration) (Consumer, error) {
	redisClient, err := gocommon.NewRedisClient(redisUrl)
	if err != nil {
		return nil, err
	}

	deleteChannel := fmt.Sprintf("%s_%d_d", communication_channel_name_prefix, redisClient.Options().DB)
	sub := redisClient.Subscribe(ctx, deleteChannel)

	consumer := &consumer_redis{
		consumer_common: consumer_common[*sessionRedis]{
			ttl:       ttl,
			ctx:       ctx,
			stages:    [2]*cache_stage[*sessionRedis]{make_cache_stage[*sessionRedis](), make_cache_stage[*sessionRedis]()},
			startTime: time.Now(),
		},
		redisClient:   redisClient,
		deleteChannel: deleteChannel,
	}

	go func() {
		stageswitch := time.Now().Add(ttl)
		tickTimer := time.After(ttl)

		for {
			select {
			case <-ctx.Done():
				return

			case <-tickTimer:
				consumer.changeStage()
				stageswitch = stageswitch.Add(ttl)
				tempttl := time.Until(stageswitch)
				tickTimer = time.After(tempttl)

			case msg := <-sub.Channel():
				if msg == nil {
					return
				}

				if len(msg.Payload) == 0 {
					continue
				}

				switch msg.Channel {
				case deleteChannel:
					var invsess InvalidatedSession
					if err := json.Unmarshal([]byte(msg.Payload), &invsess); err != nil {
						logger.Println("redis consumer deleteChannel unmarshal failed :", err)
						break
					}

					for _, sk := range invsess.SessionKeys {
						consumer.delete(storagekey(sk))
					}

					for _, f := range consumer.onSessionInvalidated {
						f(invsess)
					}
				}
			}
		}
	}()

	return consumer, nil
}

func (c *consumer_redis) query_internal(sk storagekey) (*sessionRedis, error) {
	if old, deleted := c.stages[0].deleted[sk]; deleted {
		return old, nil
	}

	if old, deleted := c.stages[1].deleted[sk]; deleted {
		return old, nil
	}

	found, ok := c.stages[0].cache[sk]
	if !ok {
		found, ok = c.stages[1].cache[sk]
	}

	if ok {
		if time.Now().Before(found.expireAt) {
			// 만료전 세션
			return found, nil
		}

		// 다른 Consumer가 Touch했을 수도 있으므로 redis에서 읽어본다.
	}

	payload, err := c.redisClient.HGetAll(c.ctx, string(sk)).Result()
	if err != nil && err != redis.Nil {
		logger.Println("consumer Query :", err)
		return nil, err
	}

	if len(payload) == 0 {
		return nil, nil
	}

	ttl, err := c.redisClient.TTL(c.ctx, string(sk)).Result()
	if err != nil {
		logger.Println("consumer Query :", err)
		return nil, err
	}
	if ttl < 0 {
		ttl = time.Duration(time.Hour * 24)
	}

	auth := MakeAuthrizationFromStringMap(payload)
	si := &sessionRedis{
		Authorization: &auth,
		expireAt:      time.Now().Add(ttl),
	}

	if auth.Valid() {
		c.add_internal(sk, si)
	} else {
		c.stages[0].deleted[sk] = si
	}

	return si, nil
}

var errRevoked = errors.New("session revoked")
var errExpired = errors.New("session expired")

func (c *consumer_redis) Query(pk string) Authorization {
	c.lock.Lock()
	defer c.lock.Unlock()

	sk := publickey_to_storagekey(publickey(pk))

	if _, deleted := c.stages[0].deleted[sk]; deleted {
		return Authorization{}
	}

	if _, deleted := c.stages[1].deleted[sk]; deleted {
		return Authorization{}
	}

	si, err := c.query_internal(sk)
	if err != nil {
		logger.Println("session consumer query :", pk, err)
		return Authorization{}
	}

	if si == nil {
		logger.Println("session consumer query(si nil) :", pk, nil)
		return Authorization{}
	}

	if time.Now().After(si.expireAt) {
		logger.Println("session consumer query(expired):", pk, nil)
		return Authorization{}
	}

	return *si.Authorization
}

func (c *consumer_redis) Touch(pk string) (Authorization, error) {
	c.lock.Lock()
	defer c.lock.Unlock()

	sk := publickey_to_storagekey(publickey(pk))

	if _, deleted := c.stages[0].deleted[sk]; deleted {
		return Authorization{}, nil
	}

	if _, deleted := c.stages[1].deleted[sk]; deleted {
		return Authorization{}, nil
	}

	ok, err := c.redisClient.Expire(c.ctx, string(sk), c.ttl).Result()
	if err == redis.Nil {
		logger.Println("session consumer touch :", pk, err)

		return Authorization{}, nil
	} else if err != nil {
		logger.Println("session consumer touch :", pk, err)
		return Authorization{}, err
	}

	if ok {
		// redis에 살아있다.
		si, err := c.query_internal(sk)
		if err != nil {
			logger.Println("session consumer touch(ok) :", pk, err)
			return Authorization{}, err
		}

		if si == nil {
			logger.Println("session consumer touch(ok, si nil) :", pk)
			return Authorization{}, nil
		}

		return *si.Authorization, nil
	}

	return Authorization{}, nil
}

func (c *consumer_redis) Revoke(pk string) {
	sk := publickey_to_storagekey(publickey(pk))

	c.redisClient.Del(c.ctx, string(sk))

	c.lock.Lock()
	defer c.lock.Unlock()

	if sr, ok := c.stages[0].cache[sk]; ok {
		c.stages[0].deleted[sk] = sr
	}

	if sr, ok := c.stages[1].cache[sk]; ok {
		c.stages[1].deleted[sk] = sr
	}
}

func (c *consumer_redis) IsRevoked(accid primitive.ObjectID) bool {
	sk := make_storagekey(accid)

	c.lock.Lock()
	defer c.lock.Unlock()

	if _, deleted := c.stages[0].deleted[sk]; deleted {
		return true
	}

	if _, deleted := c.stages[1].deleted[sk]; deleted {
		return true
	}

	return false
}

func (c *consumer_redis) RegisterOnSessionInvalidated(cb func(InvalidatedSession)) {
	c.onSessionInvalidated = append(c.onSessionInvalidated, cb)
}