package announcement

import (
	"context"
	"errors"
	"strings"
	"time"

	"hfb_sys/backend/internal/model"

	"gorm.io/gorm"
)

type Repository struct {
	db *gorm.DB
}

func NewRepository(db *gorm.DB) *Repository {
	return &Repository{db: db}
}

// ResolvePublicSiteScope 解析前台请求应看到的公告归属站点集合。
//
//   - 主站（无站点编码）：只看主站公告 [0]
//   - 分站 inherit：主站公告 + 本站公告 [0, siteID]
//   - 分站 own_only：仅本站公告 [siteID]
//   - 站点编码无效/已停用：回落主站，与前台站点探测失败的兜底一致
func (r *Repository) ResolvePublicSiteScope(ctx context.Context, siteCode string) ([]uint64, error) {
	code := strings.TrimSpace(siteCode)
	if code == "" {
		return []uint64{0}, nil
	}
	var site model.DistributionSite
	err := r.db.WithContext(ctx).Select("id", "announcement_mode").
		Where("site_code = ? AND status = ?", code, "active").First(&site).Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return []uint64{0}, nil
		}
		return nil, err
	}
	if strings.TrimSpace(site.AnnouncementMode) == model.AnnouncementModeOwnOnly {
		return []uint64{site.ID}, nil
	}
	return []uint64{0, site.ID}, nil
}

// List 获取公告列表（前台用户）
func (r *Repository) List(ctx context.Context, query AnnouncementListQuery) (*PaginatedResult, error) {
	var total int64
	tx := r.db.WithContext(ctx).Model(&model.Announcement{}).Where("status = ?", "published")

	if len(query.AllowedSiteIDs) > 0 {
		tx = tx.Where("distribution_site_id IN ?", query.AllowedSiteIDs)
	}

	if query.Category != "" {
		tx = tx.Where("category = ?", query.Category)
	}

	if err := tx.Count(&total).Error; err != nil {
		return nil, err
	}

	offset := (query.Page - 1) * query.PageSize
	var rows []model.Announcement
	if err := tx.Order("is_pinned DESC, priority DESC, published_at DESC").
		Offset(offset).
		Limit(query.PageSize).
		Find(&rows).Error; err != nil {
		return nil, err
	}

	items := make([]AnnouncementDTO, 0, len(rows))
	for _, row := range rows {
		items = append(items, toAnnouncementDTO(row))
	}

	return &PaginatedResult{
		Items:    items,
		Total:    total,
		Page:     query.Page,
		PageSize: query.PageSize,
	}, nil
}

// PublicPopup 取当前站点范围内优先级最高的弹窗公告；没有可弹公告时返回 nil, nil。
//
// 只取 published 且 is_popup = 1 的公告，按 priority DESC（其次发布时间/ID）排序取第一条，
// 因此「多条同时生效只弹优先级最高的一条」由这里保证，前台无需再筛选。
func (r *Repository) PublicPopup(ctx context.Context, allowedSiteIDs []uint64) (*AnnouncementDTO, error) {
	query := r.db.WithContext(ctx).
		Where("status = ? AND is_popup = ?", "published", true)
	if len(allowedSiteIDs) > 0 {
		query = query.Where("distribution_site_id IN ?", allowedSiteIDs)
	}

	var announcement model.Announcement
	if err := query.
		Order("priority DESC, published_at DESC, id DESC").
		First(&announcement).Error; err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, nil
		}
		return nil, err
	}

	dto := toAnnouncementDTO(announcement)
	return &dto, nil
}

// GetByID 获取公告详情（限前台可见的站点范围，避免跨站按 ID 读取）
func (r *Repository) GetByID(ctx context.Context, id uint64, allowedSiteIDs []uint64) (*AnnouncementDTO, error) {
	var announcement model.Announcement
	db := r.db.WithContext(ctx)
	query := db.Where("id = ? AND status = ?", id, "published")
	if len(allowedSiteIDs) > 0 {
		query = query.Where("distribution_site_id IN ?", allowedSiteIDs)
	}
	if err := query.First(&announcement).Error; err != nil {
		return nil, err
	}

	// 增加查看次数
	db.Model(&model.Announcement{}).Where("id = ?", id).UpdateColumn("view_count", gorm.Expr("view_count + ?", 1))

	dto := toAnnouncementDTO(announcement)
	return &dto, nil
}

// AdminList 管理员获取公告列表（可按站点筛选，含草稿/归档）
func (r *Repository) AdminList(ctx context.Context, query AnnouncementListQuery) (*PaginatedResult, error) {
	base := r.adminListBase(ctx, query)

	var total int64
	if err := base.Session(&gorm.Session{}).Count(&total).Error; err != nil {
		return nil, err
	}

	offset := (query.Page - 1) * query.PageSize
	var items []AnnouncementDTO
	if err := base.Session(&gorm.Session{}).
		Order("a.is_pinned DESC, a.priority DESC, a.id DESC").
		Offset(offset).
		Limit(query.PageSize).
		Scan(&items).Error; err != nil {
		return nil, err
	}
	if items == nil {
		items = []AnnouncementDTO{}
	}

	return &PaginatedResult{
		Items:    items,
		Total:    total,
		Page:     query.Page,
		PageSize: query.PageSize,
	}, nil
}

// adminListBase 管理端公告列表基础查询：带站点名，支持状态/分类/站点筛选。
func (r *Repository) adminListBase(ctx context.Context, query AnnouncementListQuery) *gorm.DB {
	base := r.db.WithContext(ctx).Table("announcements AS a").
		Select("a.id, a.distribution_site_id, COALESCE(s.site_name, '') AS distribution_site_name, a.title, a.content, a.category, a.priority, a.is_pinned, a.is_important, a.is_popup, a.view_count, a.status, a.published_at, a.created_at, a.updated_at").
		Joins("LEFT JOIN distribution_sites AS s ON s.id = a.distribution_site_id")

	if query.Status != "" {
		base = base.Where("a.status = ?", query.Status)
	}
	if query.Category != "" {
		base = base.Where("a.category = ?", query.Category)
	}
	if query.AdminSiteID != nil {
		base = base.Where("a.distribution_site_id = ?", *query.AdminSiteID)
	}
	return base
}

// AdminGetByID 管理员获取公告详情（带站点名）
func (r *Repository) AdminGetByID(ctx context.Context, id uint64) (*AnnouncementDTO, error) {
	var dto AnnouncementDTO
	if err := r.adminListBase(ctx, AnnouncementListQuery{}).
		Where("a.id = ?", id).
		Scan(&dto).Error; err != nil {
		return nil, err
	}
	if dto.ID == 0 {
		return nil, gorm.ErrRecordNotFound
	}
	return &dto, nil
}

// Create 创建公告
func (r *Repository) Create(ctx context.Context, req CreateAnnouncementRequest, createdBy uint64) (*AnnouncementDTO, error) {
	announcement := model.Announcement{
		DistributionSiteID: req.DistributionSiteID,
		Title:              req.Title,
		Content:            req.Content,
		Category:           req.Category,
		Priority:           req.Priority,
		IsPinned:           req.IsPinned,
		IsImportant:        req.IsImportant,
		IsPopup:            req.IsPopup,
		Status:             "draft",
		CreatedBy:          &createdBy,
	}

	if err := r.db.WithContext(ctx).Create(&announcement).Error; err != nil {
		return nil, err
	}

	dto := toAnnouncementDTO(announcement)
	return &dto, nil
}

// Update 更新公告
func (r *Repository) Update(ctx context.Context, id uint64, req UpdateAnnouncementRequest) (*AnnouncementDTO, error) {
	updates := make(map[string]interface{})

	if req.Title != "" {
		updates["title"] = req.Title
	}
	if req.Content != "" {
		updates["content"] = req.Content
	}
	if req.Category != "" {
		updates["category"] = req.Category
	}
	updates["priority"] = req.Priority
	updates["is_pinned"] = req.IsPinned
	updates["is_important"] = req.IsImportant
	updates["is_popup"] = req.IsPopup

	if err := r.db.WithContext(ctx).Model(&model.Announcement{}).Where("id = ?", id).Updates(updates).Error; err != nil {
		return nil, err
	}

	return r.AdminGetByID(ctx, id)
}

// Publish 发布公告
func (r *Repository) Publish(ctx context.Context, id uint64) error {
	now := time.Now()
	return r.db.WithContext(ctx).Model(&model.Announcement{}).
		Where("id = ?", id).
		Updates(map[string]interface{}{
			"status":       "published",
			"published_at": now,
		}).Error
}

// Archive 归档公告
func (r *Repository) Archive(ctx context.Context, id uint64) error {
	return r.db.WithContext(ctx).Model(&model.Announcement{}).
		Where("id = ?", id).
		Update("status", "archived").Error
}

// Unarchive 取消归档公告，恢复为已发布状态
func (r *Repository) Unarchive(ctx context.Context, id uint64) error {
	now := time.Now()
	return r.db.WithContext(ctx).Model(&model.Announcement{}).
		Where("id = ?", id).
		Updates(map[string]interface{}{
			"status":       "published",
			"published_at": gorm.Expr("COALESCE(published_at, ?)", now),
		}).Error
}

// Delete 删除公告
func (r *Repository) Delete(ctx context.Context, id uint64) error {
	return r.db.WithContext(ctx).Where("id = ?", id).Delete(&model.Announcement{}).Error
}

func toAnnouncementDTO(a model.Announcement) AnnouncementDTO {
	return AnnouncementDTO{
		ID:                 a.ID,
		DistributionSiteID: a.DistributionSiteID,
		Title:              a.Title,
		Content:            a.Content,
		Category:           a.Category,
		Priority:           a.Priority,
		IsPinned:           a.IsPinned,
		IsImportant:        a.IsImportant,
		IsPopup:            a.IsPopup,
		ViewCount:          a.ViewCount,
		Status:             a.Status,
		PublishedAt:        a.PublishedAt,
		CreatedAt:          a.CreatedAt,
		UpdatedAt:          a.UpdatedAt,
	}
}