package cache

import (
	"context"
	"time"

	json "github.com/goccy/go-json"
	"github.com/redis/go-redis/v9"
	"github.com/router-for-me/CLIProxyAPI/v6/internal/config"
	log "github.com/sirupsen/logrus"
)

type redisResponseCache struct {
	cfg    config.ResponseCacheConfig
	client redis.UniversalClient
	prefix string
	stats  responseCacheStats
}

func newRedisResponseCache(cfg config.ResponseCacheConfig, client redis.UniversalClient) *redisResponseCache {
	prefix := cfg.RedisKeyPrefix
	if prefix == "" {
		prefix = "respcache"
	}
	return &redisResponseCache{
		cfg:    cfg,
		client: client,
		prefix: "cliproxy:" + prefix,
	}
}

func (r *redisResponseCache) Get(ctx context.Context, key string) (*CachedResponse, bool) {
	data, err := r.client.Get(ctx, r.formatKey(key)).Bytes()
	if err != nil {
		r.stats.recordMiss()
		return nil, false
	}
	var entry CachedResponse
	if err := json.Unmarshal(data, &entry); err != nil {
		log.Warnf("response cache: unmarshal error: %v", err)
		r.stats.recordMiss()
		return nil, false
	}
	r.stats.recordHit()
	return &entry, true
}

func (r *redisResponseCache) Set(ctx context.Context, key string, resp *CachedResponse, ttl time.Duration) error {
	data, err := json.Marshal(resp)
	if err != nil {
		return err
	}
	return r.client.Set(ctx, r.formatKey(key), data, ttl).Err()
}

func (r *redisResponseCache) Delete(ctx context.Context, pattern string) error {
	fullPattern := r.prefix + ":" + pattern
	var cursor uint64
	for {
		keys, next, err := r.client.Scan(ctx, cursor, fullPattern, 100).Result()
		if err != nil {
			return err
		}
		if len(keys) > 0 {
			r.client.Del(ctx, keys...)
		}
		cursor = next
		if cursor == 0 {
			break
		}
	}
	return nil
}

func (r *redisResponseCache) Stats() CacheStats {
	return CacheStats{
		Hits:   r.stats.hits.Load(),
		Misses: r.stats.misses.Load(),
	}
}

func (r *redisResponseCache) Close() error {
	return nil
}

func (r *redisResponseCache) formatKey(key string) string {
	return r.prefix + ":" + key
}