package service

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

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

// SummaryCache 封装 summary 接口的 Redis 缓存。
type SummaryCache struct {
	rc        *redis.Client
	keyPrefix string
	ttl       time.Duration
}

func NewSummaryCache(rc *redis.Client, keyPrefix string, ttl time.Duration) *SummaryCache {
	if ttl <= 0 {
		ttl = 5 * time.Minute
	}
	return &SummaryCache{
		rc:        rc,
		keyPrefix: keyPrefix,
		ttl:       ttl,
	}
}

func (c *SummaryCache) Get(ctx context.Context, userID uint) (*SummaryResponse, bool, error) {
	if c == nil || c.rc == nil || userID == 0 {
		return nil, false, nil
	}

	val, err := c.rc.Get(ctx, c.summaryKey(userID)).Bytes()
	if err != nil {
		if errors.Is(err, redis.Nil) {
			return nil, false, nil
		}
		return nil, false, fmt.Errorf("redis get summary: %w", err)
	}

	var summary SummaryResponse
	if err := json.Unmarshal(val, &summary); err != nil {
		_ = c.rc.Del(ctx, c.summaryKey(userID)).Err()
		return nil, false, nil
	}

	return &summary, true, nil
}

func (c *SummaryCache) Set(ctx context.Context, userID uint, summary *SummaryResponse) error {
	if c == nil || c.rc == nil || userID == 0 || summary == nil {
		return nil
	}
	body, err := json.Marshal(summary)
	if err != nil {
		return fmt.Errorf("marshal summary: %w", err)
	}
	if err := c.rc.Set(ctx, c.summaryKey(userID), body, c.ttl).Err(); err != nil {
		return fmt.Errorf("redis set summary: %w", err)
	}
	return nil
}

func (c *SummaryCache) Delete(ctx context.Context, userID uint) error {
	if c == nil || c.rc == nil || userID == 0 {
		return nil
	}
	if err := c.rc.Del(ctx, c.summaryKey(userID)).Err(); err != nil {
		return fmt.Errorf("redis del summary: %w", err)
	}
	return nil
}

func (c *SummaryCache) summaryKey(userID uint) string {
	prefix := c.keyPrefix
	if prefix != "" && !strings.HasSuffix(prefix, ":") {
		prefix += ":"
	}
	return fmt.Sprintf("%sexpiry_summary:%d", prefix, userID)
}