package cache

import (
	"context"
	"encoding/json"
	"errors"
	"strings"
	"time"

	"github.com/redis/go-redis/v9"

	"server/internal/config"
)

type Caches struct {
	rdb       *redis.Client
	keyPrefix string
}

func NewCaches(rdb *redis.Client, cfg *config.Config) *Caches {
	return &Caches{
		rdb:       rdb,
		keyPrefix: cfg.Redis.KeyPrefix,
	}
}

func (c *Caches) key(key string) string {
	if c.keyPrefix == "" {
		return key
	}
	return c.keyPrefix + key
}

func (c *Caches) Set(ctx context.Context, key string, value any, expiration time.Duration) error {
	return c.rdb.Set(ctx, c.key(key), value, expiration).Err()
}

func (c *Caches) Get(ctx context.Context, key string) (string, bool, error) {
	val, err := c.rdb.Get(ctx, c.key(key)).Result()
	if errors.Is(err, redis.Nil) {
		return "", false, nil
	}

	if err != nil {
		return "", false, err
	}

	return val, true, nil
}

func (c *Caches) SetJSON(ctx context.Context, key string, value any, expiration time.Duration) error {
	b, err := json.Marshal(value)
	if err != nil {
		return err
	}
	return c.rdb.Set(ctx, c.key(key), b, expiration).Err()
}

func GetJSON[T any](ctx context.Context, c *Caches, key string) (*T, bool, error) {
	val, err := c.rdb.Get(ctx, c.key(key)).Bytes()
	if errors.Is(err, redis.Nil) {
		return nil, false, nil
	}
	if err != nil {
		return nil, false, err
	}

	var result T
	if err = json.Unmarshal(val, &result); err != nil {
		return nil, false, err
	}
	return &result, true, nil
}

func GetOrSetJSON[T any](ctx context.Context, c *Caches, key string, expiration time.Duration, fetch func() (T, error)) (T, error) {
	var zero T

	cacheKey := c.key(key)

	val, err := c.rdb.Get(ctx, cacheKey).Bytes()
	if err == nil {
		var result T
		if err = json.Unmarshal(val, &result); err == nil {
			return result, nil
		}
	}
	if !errors.Is(err, redis.Nil) {
		return zero, err
	}

	result, err := fetch()
	if err != nil {
		return zero, err
	}

	b, err := json.Marshal(result)
	if err != nil {
		return zero, err
	}
	_ = c.rdb.Set(ctx, cacheKey, b, expiration).Err()

	return result, nil
}

func (c *Caches) Del(ctx context.Context, keys ...string) error {
	for i := range keys {
		keys[i] = c.key(keys[i])
	}
	return c.rdb.Del(ctx, keys...).Err()
}

func (c *Caches) Exists(ctx context.Context, key string) (bool, error) {
	n, err := c.rdb.Exists(ctx, c.key(key)).Result()
	if err != nil {
		return false, err
	}

	return n > 0, nil
}

// SAdd 向 Set 中添加成员
func (c *Caches) SAdd(ctx context.Context, key string, members ...any) error {
	return c.rdb.SAdd(ctx, c.key(key), members...).Err()
}

// SMembers 获取 Set 中所有成员
func (c *Caches) SMembers(ctx context.Context, key string) ([]string, error) {
	return c.rdb.SMembers(ctx, c.key(key)).Result()
}

// DelSetMembers 删除 Set 中记录的所有成员对应的缓存 key，并删除 Set 本身
func (c *Caches) DelSetMembers(ctx context.Context, key string) error {
	members, err := c.SMembers(ctx, key)
	if err != nil {
		return err
	}

	keys := append(members, key)
	return c.Del(ctx, keys...)
}

// SRem 从 Set 中移除成员
func (c *Caches) SRem(ctx context.Context, key string, members ...any) error {
	return c.rdb.SRem(ctx, c.key(key), members...).Err()
}

// SIsMember 判断 member 是否在 Set 中
func (c *Caches) SIsMember(ctx context.Context, key string, member any) (bool, error) {
	return c.rdb.SIsMember(ctx, c.key(key), member).Result()
}

// MGet 批量获取多个 key 的值
func (c *Caches) MGet(ctx context.Context, keys ...string) (map[string]string, error) {
	if len(keys) == 0 {
		return map[string]string{}, nil
	}

	redisKeys := make([]string, len(keys))
	for i, key := range keys {
		redisKeys[i] = c.key(key)
	}

	values, err := c.rdb.MGet(ctx, redisKeys...).Result()
	if err != nil {
		return nil, err
	}

	result := make(map[string]string, len(keys))
	for i, value := range values {
		if value == nil {
			continue
		}

		str, ok := value.(string)
		if !ok {
			continue
		}

		result[keys[i]] = str
	}

	return result, nil
}

// DelByPrefix 批量删除指定前缀的缓存键
func (c *Caches) DelByPrefix(ctx context.Context, prefix string) error {
	prefix = c.key(prefix)

	if !strings.HasSuffix(prefix, "*") {
		prefix += "*"
	}

	var cursor uint64
	var keys []string
	var err error

	for {
		keys, cursor, err = c.rdb.Scan(ctx, cursor, prefix, 100).Result()
		if err != nil {
			return err
		}

		if len(keys) > 0 {
			if err = c.rdb.Del(ctx, keys...).Err(); err != nil {
				return err
			}
		}

		if cursor == 0 {
			break
		}
	}

	return nil
}

func (c *Caches) Expire(ctx context.Context, key string, expiration time.Duration) error {
	return c.rdb.Expire(ctx, c.keyPrefix+key, expiration).Err()
}