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"
	SettingKeyPostCooldownHours    = "post_cooldown_hours"
)

const (
	DefaultSiteName        = "姜十三论坛"
	DefaultSiteDescription = "姜十三论坛 - 技术分享与讨论社区"
	DefaultCooldownHours   = 24
	MaxSiteNameRunes       = 32
	MaxSiteDescRunes       = 160
	MaxCooldownHours       = 168
)

// 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"`
	PostCooldownHours     int    `json:"post_cooldown_hours"`
}

// 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,
		PostCooldownHours:    DefaultCooldownHours,
	}
	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)

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

// 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))
}