package cache

import (
	"context"
	"joybuywork/internal/app"
	"joybuywork/internal/consts/ckey"
	"joybuywork/internal/plugins/jsonm"
	"errors"
	"fmt"
	"math/rand"
	"sync"
	"sync/atomic"
	"time"

	grds "github.com/go-redis/redis/v8"
	"gorm.io/gorm/schema"
)

var keyPrefix = "dbcache:"

var (
	cacheHits   atomic.Int64
	cacheMisses atomic.Int64
)

func init() {
	machineIP := app.GetLocalIP()

	app.GoSafe(func() {
		ticker := time.NewTicker(4 * time.Hour)
		defer ticker.Stop()

		for range ticker.C {
			hits := cacheHits.Swap(0)
			misses := cacheMisses.Swap(0)
			total := hits + misses

			if total == 0 {
				continue
			}

			hitRate := float64(hits) / float64(total) * 100

			app.FeishuNormalSend(fmt.Sprintf(
				"db cache hit rate in the last minute: ip=%s, rate=%.2f%% (%d/%d)",
				machineIP,
				hitRate,
				hits,
				total,
			))
		}
	})
}

func recordCacheResult(err error) {
	if err == nil {
		cacheHits.Add(1)
		return
	}
	cacheMisses.Add(1)
}

type Option func(cache *Cache)

type Cache struct {
	ctx    context.Context
	tabler schema.Tabler
	rdb    *grds.Client
}

func (c *Cache) init(ctx context.Context, tabler schema.Tabler, opts ...Option) {
	c.ctx = ctx
	c.tabler = tabler
	c.rdb = app.Redis.Cache

	for _, opt := range opts {
		opt(c)
	}

}

func (c *Cache) getIdxInt64(key string, find func() ([]byte, error), opts ...Event) (idx int64, err error) {
	event := redisEvent{}
	for _, opt := range opts {
		opt(&event)
	}

	data, err := c.redis(c.ctx, key, find, event)
	if err != nil || len(data) == 0 {
		return
	}

	err = jsonm.Unmarshal(data, &idx)

	return
}

func (c *Cache) get(key string, find func() ([]byte, error), opts ...Event) (entry []byte, err error) {
	event := redisEvent{}
	for _, opt := range opts {
		opt(&event)
	}

	return c.redis(c.ctx, key, find, event)
}

func (c *Cache) getKeys(keys []string, find func(idKeys []string) (map[string][]byte, error), opts ...Event) (entrys [][]byte, err error) {
	event := redisEvent{}
	for _, opt := range opts {
		opt(&event)
	}

	return c.redisKeys(c.ctx, keys, find, event)
}

// Redis 获取数据
func (c *Cache) redis(ctx context.Context, idKey string, find func() ([]byte, error), event redisEvent) (data []byte, err error) {
	data, err = c.rdb.Get(ctx, idKey).Bytes()
	recordCacheResult(err)
	if err == nil || !errors.Is(err, grds.Nil) {
		return
	}

	//锁
	idKeyLock := ckey.ForLock(idKey)
	lock := app.NewFollower(ctx, idKeyLock).Lock()
	defer lock.Release()
	if lock.Error() != nil {
		err = lock.Error()
		return
	}

	data, err = c.rdb.Get(ctx, idKey).Bytes()
	if err == nil || !errors.Is(err, grds.Nil) {
		return
	}

	data, err = find()
	if err != nil {
		return
	}

	// 不存数据就设置成某个数据
	if data == nil && event.NilSet != nil {
		data, err = event.NilSet()
		if err != nil {
			return
		}
	}

	err = c.set(ctx, idKey, data, event)
	if err != nil {
		return nil, err
	}

	return
}

// Redis 获取数据
func (c *Cache) redisKeys(ctx context.Context, idKeys []string, find func(idKeys []string) (map[string][]byte, error), event redisEvent) (list [][]byte, err error) {
	type state struct {
		ok    bool
		idKey string
	}

	wg := sync.WaitGroup{}
	ch := make(chan state, 1)
	var lcAppend = func(idKey string) (err1 error) {
		//锁
		var one []byte
		idKeyLock := ckey.ForLock(idKey)
		lock := app.NewFollower(ctx, idKeyLock).Lock()
		defer lock.Release()
		if lock.Error() != nil {
			return lock.Error()
		}

		one, err1 = c.rdb.Get(ctx, idKey).Bytes()
		if err1 == nil {
			list = append(list, one)
			ch <- state{
				ok:    true,
				idKey: idKey,
			}
		}

		if !errors.Is(err1, grds.Nil) {
			return
		}

		err1 = nil

		wg.Add(1)
		ch <- state{
			ok:    false,
			idKey: idKey,
		}
		return
	}

	app.GoSafe(func() {
		var memIdKeys, aLen []string
		defer func() {

			if len(memIdKeys) == 0 {
				return
			}
			dm, _ := find(memIdKeys)

			for idKey, data := range dm {
				if data == nil {
					return
				}

				list = append(list, data)

				_ = c.set(ctx, idKey, data, event)
			}

			for range memIdKeys {
				wg.Done()
			}
		}()

		for {
			idKey, ok := <-ch
			if !ok {
				return
			}

			aLen = append(aLen, idKey.idKey)
			if !idKey.ok {
				memIdKeys = append(memIdKeys, idKey.idKey)
			}

			if len(aLen) == len(idKeys) {
				return
			}
		}

	})

	for _, idKey := range idKeys {
		var one []byte
		one, err = c.rdb.Get(ctx, idKey).Bytes()
		recordCacheResult(err)
		if err == nil {
			list = append(list, one)
			ch <- state{
				ok:    true,
				idKey: idKey,
			}
			continue
		}

		if !errors.Is(err, grds.Nil) {
			return
		}

		err = nil

		key := idKey
		wg.Add(1)
		app.GoSafe(func() {
			defer wg.Done()
			_ = lcAppend(key)
		})
	}

	wg.Wait()
	return
}

func (c *Cache) Prefix() string {
	return fmt.Sprintf("%s%s%s", ckey.ProjectPrefix, keyPrefix, c.tabler.TableName())
}

func (c *Cache) TTLRand() time.Duration {
	return time.Duration(rand.Intn(60)+60) * time.Minute
}

func (c *Cache) set(ctx context.Context, key string, data []byte, event redisEvent) (err error) {
	if data != nil {
		//1小时~2小时随机
		return c.rdb.Set(ctx, key, data, c.TTLRand()).Err()
	}

	// 如果是nil也存
	if event.NilSetLimit > 0 {
		return c.rdb.Set(ctx, key, data, event.NilSetLimit).Err()
	}

	return
}

type LocalLogger struct {
}

func (l LocalLogger) Printf(format string, v ...interface{}) {
	app.Logger.Info(context.Background(), fmt.Sprintf(format, v...))
}

const idxSplit = "||"

func (c *Cache) IdxKey(values ...any) string {
	var suffix string
	var idxL = len(values) / 2
	var idx int

	for i := 0; i < idxL; i++ {
		if i == 0 {
			suffix += fmt.Sprintf("%v_%v", values[idx], values[idx+1])
		} else {
			suffix += fmt.Sprintf("%s%v_%v", idxSplit, values[idx], values[idx+1])
		}
		idx += 2
	}

	return fmt.Sprintf("%s%s%s:idx:%s", ckey.ProjectPrefix, keyPrefix, c.tabler.TableName(), suffix)
}