package service

import (
	"errors"
	"regexp"
	"strconv"
	"strings"
	"unicode/utf8"

	"github.com/freefire/jiang13-bbs/model"
	"gorm.io/gorm"
)

// 站点设置键
const (
	// SettingKeyAccent 站点主题色（浅色基准，#rrggbb）；为空表示使用内置默认色
	SettingKeyAccent = "theme_accent"
	// SettingKeyTrustReviewedPublish 已过审用户后续发帖/评论免审；缺行视为开启（默认开）
	SettingKeyTrustReviewedPublish = "trust_reviewed_publish"
	SettingKeySiteName             = "site_name"
	SettingKeySiteDescription      = "site_description"
	SettingKeyAllowRegister        = "allow_register"
	// SettingKeyAllowComments 全站开放评论；缺行视为开启（默认开）
	SettingKeyAllowComments = "allow_comments"
	// SettingKeyAllowMessages 全站开放私聊/群聊；缺行视为开启（默认开）
	SettingKeyAllowMessages     = "allow_messages"
	SettingKeyPostCooldownHours = "post_cooldown_hours"
	// SettingKeyCodeBlockAutoFold 代码块自动折叠；缺行视为开启
	SettingKeyCodeBlockAutoFold = "code_block_auto_fold"
	// SettingKeyCodeBlockFoldLines 超过该行数则折叠；0=无预览；缺行=5
	SettingKeyCodeBlockFoldLines = "code_block_fold_lines"
	// SettingKeyUIAnimations 界面动画总开关；缺行视为开启
	SettingKeyUIAnimations = "ui_animations"
	// SettingKeyAnimCodeFold 代码折叠高度/跟滚动画；缺行视为开启
	SettingKeyAnimCodeFold = "anim_code_fold"
	// SettingKeyAnimSmoothScroll 平滑滚动；缺行视为开启
	SettingKeyAnimSmoothScroll = "anim_smooth_scroll"
	// SettingKeyAnimChrome 装饰入场（列表/Toast/点赞等）；缺行视为开启
	SettingKeyAnimChrome = "anim_chrome"
	// SettingKeyPostLinkNewTab 帖子/评论 Markdown 外链是否新标签打开；缺行视为开启（聊天链接始终新开，不受此键控制）
	SettingKeyPostLinkNewTab = "post_link_new_tab"
	// SettingKeyAttachmentExtLimit 是否限制附件扩展名；缺行视为开启
	SettingKeyAttachmentExtLimit = "attachment_ext_limit"
	// SettingKeyAttachmentExts 允许的扩展名（逗号分隔，无点）；缺行=默认列表
	SettingKeyAttachmentExts = "attachment_exts"
	// SettingKeyAttachmentMaxMB 附件单文件上限（MB）；缺行=20
	SettingKeyAttachmentMaxMB = "attachment_max_mb"
	// SettingKeyAttachmentMaxCount 每帖附件个数上限；缺行=10
	SettingKeyAttachmentMaxCount = "attachment_max_count"
	// SettingKeyImageMaxMB 正文插图上限（MB）；缺行=5
	SettingKeyImageMaxMB = "image_max_mb"
	// SettingKeyCustomCSS 全站自定义 CSS（外观页注入，空=无）
	SettingKeyCustomCSS = "custom_css"
	// SettingKeyCustomJS 全站自定义 JS（外观页注入，空=无）
	SettingKeyCustomJS = "custom_js"
)

const (
	DefaultSiteName        = "姜十三论坛"
	DefaultSiteDescription = "姜十三论坛 - 技术分享与讨论社区"
	DefaultCooldownHours   = 24
	DefaultCodeFoldLines   = 5
	MaxSiteNameRunes       = 32
	MaxSiteDescRunes       = 160
	MaxCooldownHours       = 168
	MinCodeFoldLines       = 0
	MaxCodeFoldLines       = 100

	DefaultAttachmentMaxMB    = 20
	DefaultAttachmentMaxCount = 10
	DefaultImageMaxMB         = 5
	MinAttachmentMaxMB        = 1
	MinImageMaxMB             = 1
	MinAttachmentMaxCount     = 1
	MaxAttachmentMaxCount     = 20
	MaxAttachmentExtCount     = 80

	MaxCustomCSSRunes = 48000
	MaxCustomJSRunes  = 48000
)

// DefaultAttachmentExts 论坛向默认允许扩展名（含安装包/脚本/网页）
var DefaultAttachmentExts = []string{
	"pdf", "txt", "md", "csv", "json",
	"doc", "docx", "xls", "xlsx", "ppt", "pptx",
	"zip", "7z", "rar", "tar", "gz", "tgz",
	"jpg", "jpeg", "png", "webp", "gif",
	"mp3", "wav", "ogg", "mp4", "webm",
	"exe", "msi", "msp", "apk", "dmg", "iso", "deb", "rpm", "dll",
	"html", "htm", "js", "mjs", "css", "svg", "xml", "bat", "cmd", "ps1", "sh",
}

var attachmentExtRe = regexp.MustCompile(`^[a-z0-9]{1,16}$`)

// ErrInvalidAccent 主题色格式非法
var ErrInvalidAccent = errors.New("主题色格式不正确，应为 #RRGGBB")

// ErrInvalidSiteSetting 站点设置字段校验失败
var ErrInvalidSiteSetting = errors.New("站点设置参数无效")

var accentHexRe = regexp.MustCompile(`^#[0-9a-fA-F]{6}$`)

// PublicSiteSettings 对前台公开的站点配置（SEO / 注册入口 / 发帖冷静期提示）
type PublicSiteSettings struct {
	Accent               string   `json:"accent"`
	TrustReviewedPublish bool     `json:"trust_reviewed_publish"`
	SiteName             string   `json:"site_name"`
	SiteDescription      string   `json:"site_description"`
	AllowRegister        bool     `json:"allow_register"`
	AllowComments        bool     `json:"allow_comments"`
	AllowMessages        bool     `json:"allow_messages"`
	PostCooldownHours    int      `json:"post_cooldown_hours"`
	CodeBlockAutoFold    bool     `json:"code_block_auto_fold"`
	CodeBlockFoldLines   int      `json:"code_block_fold_lines"`
	UIAnimations         bool     `json:"ui_animations"`
	AnimCodeFold         bool     `json:"anim_code_fold"`
	AnimSmoothScroll     bool     `json:"anim_smooth_scroll"`
	AnimChrome           bool     `json:"anim_chrome"`
	PostLinkNewTab       bool     `json:"post_link_new_tab"`
	AttachmentExtLimit   bool     `json:"attachment_ext_limit"`
	AttachmentExts       []string `json:"attachment_exts"`
	AttachmentMaxMB      int      `json:"attachment_max_mb"`
	AttachmentMaxCount   int      `json:"attachment_max_count"`
	ImageMaxMB           int      `json:"image_max_mb"`
	CustomCSS            string   `json:"custom_css"`
	CustomJS             string   `json:"custom_js"`
}

// SettingService 站点级键值设置
type SettingService struct {
	db *gorm.DB
}

func NewSettingService(db *gorm.DB) *SettingService {
	return &SettingService{db: db}
}

func (s *SettingService) getValue(key string) (string, bool, error) {
	var st model.SiteSetting
	err := s.db.Where("key = ?", key).First(&st).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return "", false, nil
	}
	if err != nil {
		return "", false, err
	}
	return st.Value, true, nil
}

func (s *SettingService) putValue(key, value string) error {
	st := model.SiteSetting{Key: key, Value: value}
	return s.db.Save(&st).Error
}

func (s *SettingService) deleteKey(key string) error {
	return s.db.Where("key = ?", key).Delete(&model.SiteSetting{}).Error
}

// 缺行或空值视为 on；仅显式 false/0/off/no 为关。不用 GORM bool default:true，避免零值省略。
func parseBoolDefaultTrue(v string, found bool) bool {
	if !found {
		return true
	}
	switch strings.TrimSpace(strings.ToLower(v)) {
	case "false", "0", "off", "no":
		return false
	default:
		return true
	}
}

func (s *SettingService) setBoolDefaultTrue(key string, on bool) error {
	if on {
		return s.deleteKey(key)
	}
	return s.putValue(key, "false")
}

// Public 返回解析后的公开站点设置（缺省已填默认值）
func (s *SettingService) Public() (PublicSiteSettings, error) {
	out := PublicSiteSettings{
		SiteName:             DefaultSiteName,
		SiteDescription:      DefaultSiteDescription,
		TrustReviewedPublish: true,
		AllowRegister:        true,
		AllowComments:        true,
		AllowMessages:        true,
		PostCooldownHours:    DefaultCooldownHours,
		CodeBlockAutoFold:    true,
		CodeBlockFoldLines:   DefaultCodeFoldLines,
		UIAnimations:         true,
		AnimCodeFold:         true,
		AnimSmoothScroll:     true,
		AnimChrome:           true,
		PostLinkNewTab:       true,
		AttachmentExtLimit:   true,
		AttachmentExts:       append([]string(nil), DefaultAttachmentExts...),
		AttachmentMaxMB:      DefaultAttachmentMaxMB,
		AttachmentMaxCount:   DefaultAttachmentMaxCount,
		ImageMaxMB:           DefaultImageMaxMB,
	}
	accent, err := s.AccentColor()
	if err != nil {
		return out, err
	}
	out.Accent = accent

	trust, err := s.TrustReviewedPublish()
	if err != nil {
		return out, err
	}
	out.TrustReviewedPublish = trust

	name, found, err := s.getValue(SettingKeySiteName)
	if err != nil {
		return out, err
	}
	if found {
		name = strings.TrimSpace(name)
		if name != "" {
			out.SiteName = name
		}
	}

	desc, found, err := s.getValue(SettingKeySiteDescription)
	if err != nil {
		return out, err
	}
	if found {
		out.SiteDescription = strings.TrimSpace(desc)
	}

	reg, found, err := s.getValue(SettingKeyAllowRegister)
	if err != nil {
		return out, err
	}
	out.AllowRegister = parseBoolDefaultTrue(reg, found)

	comments, err := s.AllowComments()
	if err != nil {
		return out, err
	}
	out.AllowComments = comments

	messages, err := s.AllowMessages()
	if err != nil {
		return out, err
	}
	out.AllowMessages = messages

	hours, err := s.PostCooldownHours()
	if err != nil {
		return out, err
	}
	out.PostCooldownHours = hours

	fold, err := s.CodeBlockAutoFold()
	if err != nil {
		return out, err
	}
	out.CodeBlockAutoFold = fold

	foldLines, err := s.CodeBlockFoldLines()
	if err != nil {
		return out, err
	}
	out.CodeBlockFoldLines = foldLines

	uiAnim, err := s.UIAnimations()
	if err != nil {
		return out, err
	}
	out.UIAnimations = uiAnim

	animFold, err := s.AnimCodeFold()
	if err != nil {
		return out, err
	}
	out.AnimCodeFold = animFold

	animScroll, err := s.AnimSmoothScroll()
	if err != nil {
		return out, err
	}
	out.AnimSmoothScroll = animScroll

	animChrome, err := s.AnimChrome()
	if err != nil {
		return out, err
	}
	out.AnimChrome = animChrome

	linkNewTab, err := s.PostLinkNewTab()
	if err != nil {
		return out, err
	}
	out.PostLinkNewTab = linkNewTab

	extLimit, err := s.AttachmentExtLimit()
	if err != nil {
		return out, err
	}
	out.AttachmentExtLimit = extLimit

	exts, err := s.AttachmentExts()
	if err != nil {
		return out, err
	}
	out.AttachmentExts = exts

	attMB, err := s.AttachmentMaxMB()
	if err != nil {
		return out, err
	}
	out.AttachmentMaxMB = attMB

	attCount, err := s.AttachmentMaxCount()
	if err != nil {
		return out, err
	}
	out.AttachmentMaxCount = attCount

	imgMB, err := s.ImageMaxMB()
	if err != nil {
		return out, err
	}
	out.ImageMaxMB = imgMB

	css, err := s.CustomCSS()
	if err != nil {
		return out, err
	}
	out.CustomCSS = css

	js, err := s.CustomJS()
	if err != nil {
		return out, err
	}
	out.CustomJS = js
	return out, nil
}

// AccentColor 返回配置的主题色（小写 #rrggbb）；未配置时返回空串，表示走前端默认色
func (s *SettingService) AccentColor() (string, error) {
	v, found, err := s.getValue(SettingKeyAccent)
	if err != nil || !found {
		return "", err
	}
	return strings.ToLower(v), nil
}

// SetAccent 校验并保存主题色；hex 传空串表示恢复默认（删除该键）
func (s *SettingService) SetAccent(hex string) error {
	hex = strings.TrimSpace(strings.ToLower(hex))
	if hex == "" {
		return s.deleteKey(SettingKeyAccent)
	}
	if !accentHexRe.MatchString(hex) {
		return ErrInvalidAccent
	}
	return s.putValue(SettingKeyAccent, hex)
}

// TrustReviewedPublish 是否对「已有过审内容」的用户免审。
func (s *SettingService) TrustReviewedPublish() (bool, error) {
	v, found, err := s.getValue(SettingKeyTrustReviewedPublish)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

// SetTrustReviewedPublish 持久化免审开关；开启时删除键以保持「缺行=默认开」语义
func (s *SettingService) SetTrustReviewedPublish(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyTrustReviewedPublish, on)
}

func (s *SettingService) SetSiteName(name string) error {
	name = strings.TrimSpace(name)
	if name == "" || name == DefaultSiteName {
		return s.deleteKey(SettingKeySiteName)
	}
	if utf8.RuneCountInString(name) > MaxSiteNameRunes {
		return ErrInvalidSiteSetting
	}
	return s.putValue(SettingKeySiteName, name)
}

func (s *SettingService) SetSiteDescription(desc string) error {
	desc = strings.TrimSpace(desc)
	if utf8.RuneCountInString(desc) > MaxSiteDescRunes {
		return ErrInvalidSiteSetting
	}
	if desc == "" || desc == DefaultSiteDescription {
		return s.deleteKey(SettingKeySiteDescription)
	}
	return s.putValue(SettingKeySiteDescription, desc)
}

func (s *SettingService) AllowRegister() (bool, error) {
	v, found, err := s.getValue(SettingKeyAllowRegister)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

func (s *SettingService) SetAllowRegister(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyAllowRegister, on)
}

// AllowComments 是否允许全站发表评论/回复。缺行视为开启。
func (s *SettingService) AllowComments() (bool, error) {
	v, found, err := s.getValue(SettingKeyAllowComments)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

// SetAllowComments 持久化评论开关；开启时删键保持「缺行=默认开」。
func (s *SettingService) SetAllowComments(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyAllowComments, on)
}

// AllowMessages 是否允许全站私聊/群聊。缺行视为开启。
func (s *SettingService) AllowMessages() (bool, error) {
	v, found, err := s.getValue(SettingKeyAllowMessages)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

// SetAllowMessages 持久化消息开关；开启时删键保持「缺行=默认开」。
func (s *SettingService) SetAllowMessages(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyAllowMessages, on)
}

// PostCooldownHours 新用户发帖冷静期（小时）。缺行=24；0 表示关闭。
func (s *SettingService) PostCooldownHours() (int, error) {
	v, found, err := s.getValue(SettingKeyPostCooldownHours)
	if err != nil {
		return DefaultCooldownHours, err
	}
	if !found {
		return DefaultCooldownHours, nil
	}
	n, convErr := strconv.Atoi(strings.TrimSpace(v))
	if convErr != nil || n < 0 {
		return DefaultCooldownHours, nil
	}
	if n > MaxCooldownHours {
		return MaxCooldownHours, nil
	}
	return n, nil
}

func (s *SettingService) SetPostCooldownHours(hours int) error {
	if hours < 0 || hours > MaxCooldownHours {
		return ErrInvalidSiteSetting
	}
	if hours == DefaultCooldownHours {
		return s.deleteKey(SettingKeyPostCooldownHours)
	}
	return s.putValue(SettingKeyPostCooldownHours, strconv.Itoa(hours))
}

// CodeBlockAutoFold 是否对超过阈值行数的 Markdown 代码块默认折叠。缺行视为开启。
func (s *SettingService) CodeBlockAutoFold() (bool, error) {
	v, found, err := s.getValue(SettingKeyCodeBlockAutoFold)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

// SetCodeBlockAutoFold 持久化代码折叠开关；开启时删键保持「缺行=默认开」。
func (s *SettingService) SetCodeBlockAutoFold(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyCodeBlockAutoFold, on)
}

// CodeBlockFoldLines 超过该行数则折叠（折叠预览约同高；0=无预览）。缺行=5。
func (s *SettingService) CodeBlockFoldLines() (int, error) {
	v, found, err := s.getValue(SettingKeyCodeBlockFoldLines)
	if err != nil {
		return DefaultCodeFoldLines, err
	}
	if !found {
		return DefaultCodeFoldLines, nil
	}
	n, convErr := strconv.Atoi(strings.TrimSpace(v))
	if convErr != nil || n < MinCodeFoldLines {
		return DefaultCodeFoldLines, nil
	}
	if n > MaxCodeFoldLines {
		return MaxCodeFoldLines, nil
	}
	return n, nil
}

func (s *SettingService) SetCodeBlockFoldLines(lines int) error {
	if lines < MinCodeFoldLines || lines > MaxCodeFoldLines {
		return ErrInvalidSiteSetting
	}
	if lines == DefaultCodeFoldLines {
		return s.deleteKey(SettingKeyCodeBlockFoldLines)
	}
	return s.putValue(SettingKeyCodeBlockFoldLines, strconv.Itoa(lines))
}

// UIAnimations 界面动画总开关。缺行视为开启；关闭后全站减少动态效果。
func (s *SettingService) UIAnimations() (bool, error) {
	v, found, err := s.getValue(SettingKeyUIAnimations)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

func (s *SettingService) SetUIAnimations(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyUIAnimations, on)
}

// AnimCodeFold 代码折叠动画子开关（总开关开启时生效）。
func (s *SettingService) AnimCodeFold() (bool, error) {
	v, found, err := s.getValue(SettingKeyAnimCodeFold)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

func (s *SettingService) SetAnimCodeFold(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyAnimCodeFold, on)
}

// AnimSmoothScroll 平滑滚动子开关（总开关开启时生效）。
func (s *SettingService) AnimSmoothScroll() (bool, error) {
	v, found, err := s.getValue(SettingKeyAnimSmoothScroll)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

func (s *SettingService) SetAnimSmoothScroll(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyAnimSmoothScroll, on)
}

// AnimChrome 装饰入场子开关（列表/Toast/点赞等；总开关开启时生效）。
func (s *SettingService) AnimChrome() (bool, error) {
	v, found, err := s.getValue(SettingKeyAnimChrome)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

func (s *SettingService) SetAnimChrome(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyAnimChrome, on)
}

// PostLinkNewTab 帖子/评论 Markdown 外链是否新标签打开。缺行视为开启。
func (s *SettingService) PostLinkNewTab() (bool, error) {
	v, found, err := s.getValue(SettingKeyPostLinkNewTab)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

func (s *SettingService) SetPostLinkNewTab(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyPostLinkNewTab, on)
}

// AttachmentExtLimit 是否限制附件扩展名。缺行视为开启。
func (s *SettingService) AttachmentExtLimit() (bool, error) {
	v, found, err := s.getValue(SettingKeyAttachmentExtLimit)
	if err != nil {
		return true, err
	}
	return parseBoolDefaultTrue(v, found), nil
}

func (s *SettingService) SetAttachmentExtLimit(on bool) error {
	return s.setBoolDefaultTrue(SettingKeyAttachmentExtLimit, on)
}

// NormalizeAttachmentExts 规范化扩展名列表：去点、小写、去重、校验格式。
func NormalizeAttachmentExts(raw []string) ([]string, error) {
	seen := make(map[string]struct{}, len(raw))
	out := make([]string, 0, len(raw))
	for _, item := range raw {
		e := strings.TrimSpace(strings.ToLower(item))
		e = strings.TrimPrefix(e, ".")
		if e == "" {
			continue
		}
		if !attachmentExtRe.MatchString(e) {
			return nil, ErrInvalidSiteSetting
		}
		if _, ok := seen[e]; ok {
			continue
		}
		seen[e] = struct{}{}
		out = append(out, e)
		if len(out) > MaxAttachmentExtCount {
			return nil, ErrInvalidSiteSetting
		}
	}
	return out, nil
}

func parseExtList(v string) []string {
	parts := strings.FieldsFunc(v, func(r rune) bool {
		return r == ',' || r == ' ' || r == ';' || r == '\n' || r == '\t'
	})
	out, err := NormalizeAttachmentExts(parts)
	if err != nil || len(out) == 0 {
		return append([]string(nil), DefaultAttachmentExts...)
	}
	return out
}

func extsEqualDefault(exts []string) bool {
	if len(exts) != len(DefaultAttachmentExts) {
		return false
	}
	for i := range exts {
		if exts[i] != DefaultAttachmentExts[i] {
			return false
		}
	}
	return true
}

// AttachmentExts 允许的扩展名（无点）。缺行=默认列表；显式空串=空列表。
func (s *SettingService) AttachmentExts() ([]string, error) {
	v, found, err := s.getValue(SettingKeyAttachmentExts)
	if err != nil {
		return append([]string(nil), DefaultAttachmentExts...), err
	}
	if !found {
		return append([]string(nil), DefaultAttachmentExts...), nil
	}
	if strings.TrimSpace(v) == "" {
		return []string{}, nil
	}
	return parseExtList(v), nil
}

// SetAttachmentExts 保存扩展名列表；与默认完全一致时删键。空列表写入空串（限制开启时表示禁止上传）。
func (s *SettingService) SetAttachmentExts(exts []string) error {
	norm, err := NormalizeAttachmentExts(exts)
	if err != nil {
		return err
	}
	if len(norm) == 0 {
		return s.putValue(SettingKeyAttachmentExts, "")
	}
	if extsEqualDefault(norm) {
		return s.deleteKey(SettingKeyAttachmentExts)
	}
	return s.putValue(SettingKeyAttachmentExts, strings.Join(norm, ","))
}

// AttachmentExtAllowed 当前设置下扩展名（含点或不含点）是否允许上传。
func (s *SettingService) AttachmentExtAllowed(ext string) (bool, error) {
	limit, err := s.AttachmentExtLimit()
	if err != nil {
		return false, err
	}
	if !limit {
		return true, nil
	}
	e := strings.TrimPrefix(strings.ToLower(strings.TrimSpace(ext)), ".")
	if e == "" {
		return false, nil
	}
	list, err := s.AttachmentExts()
	if err != nil {
		return false, err
	}
	for _, x := range list {
		if x == e {
			return true, nil
		}
	}
	return false, nil
}

// AttachmentMaxMB 附件单文件上限（MB）。缺行=20；最小 1，无硬顶。
func (s *SettingService) AttachmentMaxMB() (int, error) {
	v, found, err := s.getValue(SettingKeyAttachmentMaxMB)
	if err != nil {
		return DefaultAttachmentMaxMB, err
	}
	if !found {
		return DefaultAttachmentMaxMB, nil
	}
	n, convErr := strconv.Atoi(strings.TrimSpace(v))
	if convErr != nil || n < MinAttachmentMaxMB {
		return DefaultAttachmentMaxMB, nil
	}
	return n, nil
}

func (s *SettingService) SetAttachmentMaxMB(mb int) error {
	if mb < MinAttachmentMaxMB {
		return ErrInvalidSiteSetting
	}
	if mb == DefaultAttachmentMaxMB {
		return s.deleteKey(SettingKeyAttachmentMaxMB)
	}
	return s.putValue(SettingKeyAttachmentMaxMB, strconv.Itoa(mb))
}

// AttachmentMaxBytes 附件字节上限（按当前 MB 设置）。
func (s *SettingService) AttachmentMaxBytes() (int64, error) {
	mb, err := s.AttachmentMaxMB()
	if err != nil {
		return int64(DefaultAttachmentMaxMB) << 20, err
	}
	return int64(mb) << 20, nil
}

// AttachmentMaxCount 每帖/草稿附件个数上限。缺行=10；范围 1–20。
func (s *SettingService) AttachmentMaxCount() (int, error) {
	v, found, err := s.getValue(SettingKeyAttachmentMaxCount)
	if err != nil {
		return DefaultAttachmentMaxCount, err
	}
	if !found {
		return DefaultAttachmentMaxCount, nil
	}
	n, convErr := strconv.Atoi(strings.TrimSpace(v))
	if convErr != nil || n < MinAttachmentMaxCount {
		return DefaultAttachmentMaxCount, nil
	}
	if n > MaxAttachmentMaxCount {
		return MaxAttachmentMaxCount, nil
	}
	return n, nil
}

func (s *SettingService) SetAttachmentMaxCount(n int) error {
	if n < MinAttachmentMaxCount || n > MaxAttachmentMaxCount {
		return ErrInvalidSiteSetting
	}
	if n == DefaultAttachmentMaxCount {
		return s.deleteKey(SettingKeyAttachmentMaxCount)
	}
	return s.putValue(SettingKeyAttachmentMaxCount, strconv.Itoa(n))
}

// ImageMaxMB 正文插图上限（MB）。缺行=5；最小 1，无硬顶。
func (s *SettingService) ImageMaxMB() (int, error) {
	v, found, err := s.getValue(SettingKeyImageMaxMB)
	if err != nil {
		return DefaultImageMaxMB, err
	}
	if !found {
		return DefaultImageMaxMB, nil
	}
	n, convErr := strconv.Atoi(strings.TrimSpace(v))
	if convErr != nil || n < MinImageMaxMB {
		return DefaultImageMaxMB, nil
	}
	return n, nil
}

func (s *SettingService) SetImageMaxMB(mb int) error {
	if mb < MinImageMaxMB {
		return ErrInvalidSiteSetting
	}
	if mb == DefaultImageMaxMB {
		return s.deleteKey(SettingKeyImageMaxMB)
	}
	return s.putValue(SettingKeyImageMaxMB, strconv.Itoa(mb))
}

// ImageMaxBytes 插图像素字节上限。
func (s *SettingService) ImageMaxBytes() (int64, error) {
	mb, err := s.ImageMaxMB()
	if err != nil {
		return int64(DefaultImageMaxMB) << 20, err
	}
	return int64(mb) << 20, nil
}

func sanitizeCustomSnippet(s, closer string, maxRunes int) (string, error) {
	s = strings.TrimSpace(s)
	if strings.ContainsRune(s, 0) {
		return "", ErrInvalidSiteSetting
	}
	if utf8.RuneCountInString(s) > maxRunes {
		return "", ErrInvalidSiteSetting
	}
	if closer != "" && strings.Contains(strings.ToLower(s), closer) {
		return "", ErrInvalidSiteSetting
	}
	return s, nil
}

// CustomCSS 全站自定义 CSS。缺行/空=无。
func (s *SettingService) CustomCSS() (string, error) {
	v, found, err := s.getValue(SettingKeyCustomCSS)
	if err != nil || !found {
		return "", err
	}
	out, nerr := sanitizeCustomSnippet(v, "</style", MaxCustomCSSRunes)
	if nerr != nil {
		return "", nil
	}
	return out, nil
}

func (s *SettingService) SetCustomCSS(css string) error {
	normalized, err := sanitizeCustomSnippet(css, "</style", MaxCustomCSSRunes)
	if err != nil {
		return err
	}
	if normalized == "" {
		return s.deleteKey(SettingKeyCustomCSS)
	}
	return s.putValue(SettingKeyCustomCSS, normalized)
}

// CustomJS 全站自定义 JS。缺行/空=无。
func (s *SettingService) CustomJS() (string, error) {
	v, found, err := s.getValue(SettingKeyCustomJS)
	if err != nil || !found {
		return "", err
	}
	out, nerr := sanitizeCustomSnippet(v, "</script", MaxCustomJSRunes)
	if nerr != nil {
		return "", nil
	}
	return out, nil
}

func (s *SettingService) SetCustomJS(js string) error {
	normalized, err := sanitizeCustomSnippet(js, "</script", MaxCustomJSRunes)
	if err != nil {
		return err
	}
	if normalized == "" {
		return s.deleteKey(SettingKeyCustomJS)
	}
	return s.putValue(SettingKeyCustomJS, normalized)
}