package service

import (
	"errors"
	"strings"

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

// 公告标签允许使用的预设色（服务端白名单，禁止透传任意颜色值）
var allowedTagColors = map[string]bool{
	"blue": true, "green": true, "orange": true,
	"red": true, "purple": true, "gray": true,
	"teal": true, "cyan": true, "pink": true,
	"amber": true, "indigo": true, "rose": true,
}

// AnnouncementService 站点公告服务
type AnnouncementService struct {
	db *gorm.DB
}

func NewAnnouncementService(db *gorm.DB) *AnnouncementService {
	return &AnnouncementService{db: db}
}

// AnnouncementInput 创建/更新公告的入参
type AnnouncementInput struct {
	Title     string `json:"title"`
	Content   string `json:"content"`
	Tag       string `json:"tag"`
	TagColor  string `json:"tag_color"`
	Published *bool  `json:"published"`
	Pinned    *bool  `json:"pinned"`
}

// normalize 清洗并校验入参，返回可直接落库的字段
func (in *AnnouncementInput) normalize(existing *model.Announcement) error {
	in.Title = strings.TrimSpace(in.Title)
	if in.Title == "" {
		return errors.New("标题不能为空")
	}
	if len([]rune(in.Title)) > 200 {
		return errors.New("标题不能超过 200 字")
	}
	in.Content = strings.TrimSpace(in.Content)
	if in.Content == "" {
		return errors.New("内容不能为空")
	}
	if err := markdown.ValidateHideContent(in.Content); err != nil {
		return err
	}
	if err := rejectReplyHideBlocks(in.Content, ErrAnnouncementReplyHideNotAllowed); err != nil {
		return err
	}

	in.Tag = strings.TrimSpace(in.Tag)
	if in.Tag == "" {
		in.Tag = "公告"
	}
	if len([]rune(in.Tag)) > 32 {
		return errors.New("标签不能超过 32 字")
	}

	in.TagColor = strings.ToLower(strings.TrimSpace(in.TagColor))
	if in.TagColor == "" {
		if existing != nil && existing.TagColor != "" {
			in.TagColor = existing.TagColor
		} else {
			in.TagColor = "blue"
		}
	}
	if !allowedTagColors[in.TagColor] {
		return errors.New("不支持的标签颜色")
	}
	return nil
}

// applyTo 把入参写入模型（Published/Pinned 为指针以区分"未传"与"显式 false"）
func (in *AnnouncementInput) applyTo(a *model.Announcement) {
	a.Title = in.Title
	a.Content = in.Content
	a.Tag = in.Tag
	a.TagColor = in.TagColor
	if in.Published != nil {
		a.Published = *in.Published
	}
	if in.Pinned != nil {
		a.Pinned = *in.Pinned
	}
}

// 写入字段须为独立 Select 参数；逗号拼成一串会被 GORM 当成单个非法字段名
var announcementWriteFields = []string{
	"Title", "Content", "Tag", "TagColor", "Published", "Pinned",
}

// ListPublished 已发布公告（首页右栏），置顶优先再按发布时间倒序
func (s *AnnouncementService) ListPublished(limit int) ([]model.Announcement, error) {
	if limit <= 0 {
		limit = 5
	}
	var list []model.Announcement
	err := s.db.Where("published = ?", true).
		Order("pinned DESC, created_at DESC, id DESC").Limit(limit).Find(&list).Error
	return list, err
}

// ListPublishedPage 已发布公告分页（全部公告页）
func (s *AnnouncementService) ListPublishedPage(page, size int) ([]model.Announcement, int64, error) {
	if page < 1 {
		page = 1
	}
	if size < 1 || size > 50 {
		size = 20
	}
	q := s.db.Model(&model.Announcement{}).Where("published = ?", true)
	var total int64
	if err := q.Count(&total).Error; err != nil {
		return nil, 0, err
	}
	var list []model.Announcement
	err := q.Order("pinned DESC, created_at DESC, id DESC").
		Offset((page - 1) * size).Limit(size).Find(&list).Error
	return list, total, err
}

// GetPublished 取单条已发布公告（详情页）；草稿/不存在返回 gorm.ErrRecordNotFound
func (s *AnnouncementService) GetPublished(id uint) (*model.Announcement, error) {
	var a model.Announcement
	err := s.db.Where("published = ?", true).First(&a, id).Error
	if err != nil {
		return nil, err
	}
	return &a, nil
}

// ListAll 管理后台：含草稿，置顶优先
func (s *AnnouncementService) ListAll() ([]model.Announcement, error) {
	var list []model.Announcement
	err := s.db.Order("pinned DESC, created_at DESC, id DESC").Limit(100).Find(&list).Error
	return list, err
}

// Create 创建公告
func (s *AnnouncementService) Create(in *AnnouncementInput) (*model.Announcement, error) {
	if err := in.normalize(nil); err != nil {
		return nil, err
	}
	a := &model.Announcement{Published: true, Pinned: false}
	in.applyTo(a)
	if err := s.db.Select(announcementWriteFields).Create(a).Error; err != nil {
		return nil, err
	}
	return a, nil
}

// Update 更新公告
func (s *AnnouncementService) Update(id uint, in *AnnouncementInput) (*model.Announcement, error) {
	var a model.Announcement
	if err := s.db.First(&a, id).Error; err != nil {
		return nil, err
	}
	if err := in.normalize(&a); err != nil {
		return nil, err
	}
	in.applyTo(&a)
	if err := s.db.Model(&model.Announcement{}).Where("id = ?", a.ID).Updates(map[string]interface{}{
		"title":     a.Title,
		"content":   a.Content,
		"tag":       a.Tag,
		"tag_color": a.TagColor,
		"published": a.Published,
		"pinned":    a.Pinned,
	}).Error; err != nil {
		return nil, err
	}
	return &a, nil
}

// TogglePin 切换置顶状态
func (s *AnnouncementService) TogglePin(id uint) (*model.Announcement, error) {
	var a model.Announcement
	if err := s.db.First(&a, id).Error; err != nil {
		return nil, err
	}
	a.Pinned = !a.Pinned
	if err := s.db.Model(&a).Select("Pinned").Update("pinned", a.Pinned).Error; err != nil {
		return nil, err
	}
	return &a, nil
}

// Delete 删除公告（软删除）
func (s *AnnouncementService) Delete(id uint) error {
	result := s.db.Delete(&model.Announcement{}, id)
	if result.Error != nil {
		return result.Error
	}
	if result.RowsAffected == 0 {
		return gorm.ErrRecordNotFound
	}
	return nil
}