package cache

import (
	"context"
	"encoding/json"
	"fmt"
	"log"
	"time"

	"soul-api/internal/database"
	"soul-api/internal/model"
	"soul-api/internal/redis"
)

const defaultTimeout = 2 * time.Second

// KeyBookParts 目录接口缓存 key，后台更新章节/内容时需 Del
const KeyBookParts = "soul:book:parts"

// KeyAllChapters 全书章节列表，default 与 excludeFixed 两种
func KeyAllChapters(cacheKey string) string {
	if cacheKey == "excludeFixed" {
		return "soul:book:all-chapters:excludeFixed"
	}
	return "soul:book:all-chapters"
}

// KeyChaptersByPart 篇章内章节，格式 soul:book:chapters-by-part:{partId}
func KeyChaptersByPart(partId string) string {
	return "soul:book:chapters-by-part:" + partId
}

// KeyChaptersByPartPattern 用于批量删除 chapters-by-part 缓存
const KeyChaptersByPartPattern = "soul:book:chapters-by-part:*"

// KeyBookLatestChapters 最新更新章节
const KeyBookLatestChapters = "soul:book:latest-chapters"

// KeyFreeChapterIDs 免费章节 ID 列表（JSON 数组）
const KeyFreeChapterIDs = "soul:config:free-chapters"

// KeyBookHot 热门章节，格式 soul:book:hot:{limit}
func KeyBookHot(limit int) string { return "soul:book:hot:" + fmt.Sprint(limit) }
const KeyBookRecommended = "soul:book:recommended"
const KeyBookStats = "soul:book:stats"
const KeyConfigMiniprogram = "soul:config:miniprogram"
const KeyConfigAuditMode = "soul:config:audit-mode"
const KeyConfigCore = "soul:config:core"
const KeyConfigReadExtras = "soul:config:read-extras"

// Get 从 Redis 读取，未配置或失败返回 nil（调用方回退 DB）
func Get(ctx context.Context, key string, dest interface{}) bool {
	client := redis.Client()
	if client == nil {
		return false
	}
	if ctx == nil {
		ctx = context.Background()
	}
	ctx, cancel := context.WithTimeout(ctx, defaultTimeout)
	defer cancel()
	val, err := client.Get(ctx, key).Bytes()
	if err != nil {
		return false
	}
	if dest != nil && len(val) > 0 {
		_ = json.Unmarshal(val, dest)
	}
	return true
}

// Set 写入 Redis，失败仅打日志不阻塞
func Set(ctx context.Context, key string, val interface{}, ttl time.Duration) {
	client := redis.Client()
	if client == nil {
		return
	}
	if ctx == nil {
		ctx = context.Background()
	}
	ctx, cancel := context.WithTimeout(ctx, defaultTimeout)
	defer cancel()
	data, err := json.Marshal(val)
	if err != nil {
		log.Printf("cache.Set marshal %s: %v", key, err)
		return
	}
	if err := client.Set(ctx, key, data, ttl).Err(); err != nil {
		log.Printf("cache.Set %s: %v (非致命)", key, err)
	}
}

// Del 删除 key，失败仅打日志
func Del(ctx context.Context, key string) {
	client := redis.Client()
	if client == nil {
		return
	}
	if ctx == nil {
		ctx = context.Background()
	}
	ctx, cancel := context.WithTimeout(ctx, defaultTimeout)
	defer cancel()
	if err := client.Del(ctx, key).Err(); err != nil {
		log.Printf("cache.Del %s: %v (非致命)", key, err)
	}
}

// DelPattern 按模式删除 key（如 soul:book:chapters-by-part:*），用于批量失效
func DelPattern(ctx context.Context, pattern string) {
	client := redis.Client()
	if client == nil {
		return
	}
	if ctx == nil {
		ctx = context.Background()
	}
	ctx, cancel := context.WithTimeout(ctx, defaultTimeout*2)
	defer cancel()
	keys, err := client.Keys(ctx, pattern).Result()
	if err != nil || len(keys) == 0 {
		return
	}
	if err := client.Del(ctx, keys...).Err(); err != nil {
		log.Printf("cache.DelPattern %s: %v (非致命)", pattern, err)
	}
}

// BookPartsTTL 目录接口缓存 TTL，后台更新时主动 Del，此为兜底时长
const BookPartsTTL = 10 * time.Minute

// AllChaptersTTL 全书章节列表 TTL
const AllChaptersTTL = 10 * time.Minute

// ChaptersByPartTTL 篇章内章节 TTL
const ChaptersByPartTTL = 10 * time.Minute

// FreeChapterIDsTTL 免费章节配置 TTL
const FreeChapterIDsTTL = 5 * time.Minute

// InvalidateBookParts 后台更新章节/内容时调用，使目录、章节列表等缓存失效
func InvalidateBookParts() {
	ctx := context.Background()
	Del(ctx, KeyBookParts)
	Del(ctx, KeyAllChapters("default"))
	Del(ctx, KeyAllChapters("excludeFixed"))
	Del(ctx, KeyBookLatestChapters)
	Del(ctx, KeyFreeChapterIDs)
	DelPattern(ctx, KeyChaptersByPartPattern)
}

// InvalidateBookCache 使热门、推荐、统计等书籍相关缓存失效（与 InvalidateBookParts 同时调用）
func InvalidateBookCache() {
	ctx := context.Background()
	Del(ctx, KeyBookRecommended)
	Del(ctx, KeyBookStats)
	for _, limit := range []int{3, 10, 20, 50} {
		Del(ctx, KeyBookHot(limit))
	}
}

// InvalidateConfig 配置变更时调用，使小程序 config 及拆分接口缓存失效
func InvalidateConfig() {
	ctx := context.Background()
	Del(ctx, KeyConfigMiniprogram)
	Del(ctx, KeyConfigAuditMode)
	Del(ctx, KeyConfigCore)
	Del(ctx, KeyConfigReadExtras)
}

// BookRelatedTTL 书籍相关接口 TTL（hot/recommended/stats）
const BookRelatedTTL = 5 * time.Minute

// ConfigTTL 配置接口 TTL
const ConfigTTL = 10 * time.Minute

// AuditModeTTL 审核模式 TTL，管理端开关后需较快生效
const AuditModeTTL = 1 * time.Minute

// KeyChapterContent 章节正文缓存，格式 soul:chapter:content:{mid}，存原始 HTML 字符串
func KeyChapterContent(mid int) string { return "soul:chapter:content:" + fmt.Sprint(mid) }

// ChapterContentTTL 章节正文 TTL，后台更新时主动 Del
const ChapterContentTTL = 30 * time.Minute

// GetString 读取字符串（不经过 JSON，适合大文本 content）
func GetString(ctx context.Context, key string) (string, bool) {
	client := redis.Client()
	if client == nil {
		return "", false
	}
	if ctx == nil {
		ctx = context.Background()
	}
	ctx, cancel := context.WithTimeout(ctx, defaultTimeout)
	defer cancel()
	val, err := client.Get(ctx, key).Result()
	if err != nil {
		return "", false
	}
	return val, true
}

// SetString 写入字符串（不经过 JSON，适合大文本 content）
func SetString(ctx context.Context, key string, val string, ttl time.Duration) {
	client := redis.Client()
	if client == nil {
		return
	}
	if ctx == nil {
		ctx = context.Background()
	}
	ctx, cancel := context.WithTimeout(ctx, defaultTimeout)
	defer cancel()
	if err := client.Set(ctx, key, val, ttl).Err(); err != nil {
		log.Printf("cache.SetString %s: %v (非致命)", key, err)
	}
}

// InvalidateChapterContent 章节内容更新时调用，mid<=0 时忽略
func InvalidateChapterContent(mid int) {
	if mid <= 0 {
		return
	}
	Del(context.Background(), KeyChapterContent(mid))
}

// InvalidateChapterContentByID 按业务 id 使章节内容缓存失效（内部查 mid 后调用 InvalidateChapterContent）
func InvalidateChapterContentByID(id string) {
	if id == "" {
		return
	}
	var mid int
	if err := database.DB().Model(&model.Chapter{}).Where("id = ?", id).Pluck("mid", &mid).Error; err != nil || mid <= 0 {
		return
	}
	InvalidateChapterContent(mid)
}