package distribution

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

	"hfb_sys/backend/internal/model"

	"gorm.io/gorm"
)

// 分站公告中心：站长在分销后台自助维护本站公告。
//
// 站点隔离口径：所有写操作与列表查询都强制 distribution_site_id = siteID，
// 且先通过 ensureSiteAccess 校验当前管理员对该站点的访问权，避免跨站读写。
// 前台展示范围由站点 announcement_mode 决定（见 announcement 模块 ResolvePublicSiteScope）。

// normalizeAnnouncementMode 校验公告中心来源模式，空值按默认 inherit 处理。
func normalizeAnnouncementMode(value string) (string, error) {
	switch strings.TrimSpace(value) {
	case "", model.AnnouncementModeInherit:
		return model.AnnouncementModeInherit, nil
	case model.AnnouncementModeOwnOnly:
		return model.AnnouncementModeOwnOnly, nil
	default:
		return "", ErrInvalidAnnouncementMode
	}
}

// ListSiteAnnouncements 分页查询本站公告（含草稿/归档，供站长管理）。
func (r *Repository) ListSiteAnnouncements(ctx context.Context, adminID, siteID uint64, status string, page, pageSize int) (*SiteAnnouncementPage, error) {
	if siteID == 0 {
		return nil, ErrSiteNotFound
	}
	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
		return nil, err
	}
	if page < 1 {
		page = 1
	}
	if pageSize < 1 {
		pageSize = 20
	}
	if pageSize > 100 {
		pageSize = 100
	}

	base := r.db.WithContext(ctx).Model(&model.Announcement{}).Where("distribution_site_id = ?", siteID)
	if s := strings.TrimSpace(status); s != "" {
		base = base.Where("status = ?", s)
	}

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

	var rows []model.Announcement
	if err := base.Session(&gorm.Session{}).
		Order("is_pinned DESC, priority DESC, id DESC").
		Offset((page - 1) * pageSize).
		Limit(pageSize).
		Find(&rows).Error; err != nil {
		return nil, err
	}

	items := make([]SiteAnnouncementDTO, 0, len(rows))
	for _, row := range rows {
		items = append(items, toSiteAnnouncementDTO(row))
	}
	return &SiteAnnouncementPage{Items: items, Total: total, Page: page, PageSize: pageSize}, nil
}

// CreateSiteAnnouncement 在指定站点下新建公告（草稿）。
func (r *Repository) CreateSiteAnnouncement(ctx context.Context, adminID, siteID uint64, req CreateSiteAnnouncementRequest) (*SiteAnnouncementDTO, error) {
	if siteID == 0 {
		return nil, ErrSiteNotFound
	}
	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
		return nil, err
	}
	createdBy := adminID
	row := model.Announcement{
		DistributionSiteID: siteID,
		Title:              strings.TrimSpace(req.Title),
		Content:            req.Content,
		Category:           strings.TrimSpace(req.Category),
		Priority:           req.Priority,
		IsPinned:           req.IsPinned,
		IsImportant:        req.IsImportant,
		IsPopup:            req.IsPopup,
		Status:             "draft",
		CreatedBy:          &createdBy,
	}
	if row.Category == "" {
		row.Category = "notice"
	}
	if err := r.db.WithContext(ctx).Create(&row).Error; err != nil {
		return nil, err
	}
	dto := toSiteAnnouncementDTO(row)
	return &dto, nil
}

// UpdateSiteAnnouncement 更新本站公告内容。
func (r *Repository) UpdateSiteAnnouncement(ctx context.Context, adminID, siteID, id uint64, req UpdateSiteAnnouncementRequest) (*SiteAnnouncementDTO, error) {
	if siteID == 0 {
		return nil, ErrSiteNotFound
	}
	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
		return nil, err
	}
	row, err := r.findSiteAnnouncement(ctx, siteID, id)
	if err != nil {
		return nil, err
	}

	updates := map[string]any{
		"priority":     req.Priority,
		"is_pinned":    req.IsPinned,
		"is_important": req.IsImportant,
		"is_popup":     req.IsPopup,
	}
	if title := strings.TrimSpace(req.Title); title != "" {
		updates["title"] = title
	}
	if req.Content != "" {
		updates["content"] = req.Content
	}
	if category := strings.TrimSpace(req.Category); category != "" {
		updates["category"] = category
	}
	if err := r.db.WithContext(ctx).Model(&model.Announcement{}).Where("id = ?", row.ID).Updates(updates).Error; err != nil {
		return nil, err
	}
	updated, err := r.findSiteAnnouncement(ctx, siteID, id)
	if err != nil {
		return nil, err
	}
	dto := toSiteAnnouncementDTO(*updated)
	return &dto, nil
}

// UpdateSiteAnnouncementStatus 站点公告上下架：publish=发布，archive=归档，unarchive=取消归档。
func (r *Repository) UpdateSiteAnnouncementStatus(ctx context.Context, adminID, siteID, id uint64, action string) (*SiteAnnouncementDTO, error) {
	if siteID == 0 {
		return nil, ErrSiteNotFound
	}
	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
		return nil, err
	}
	row, err := r.findSiteAnnouncement(ctx, siteID, id)
	if err != nil {
		return nil, err
	}

	now := time.Now()
	updates := map[string]any{}
	switch strings.TrimSpace(action) {
	case "publish":
		updates["status"] = "published"
		updates["published_at"] = now
	case "archive":
		updates["status"] = "archived"
	case "unarchive":
		updates["status"] = "published"
		updates["published_at"] = gorm.Expr("COALESCE(published_at, ?)", now)
	default:
		return nil, ErrInvalidListingStatus
	}
	if err := r.db.WithContext(ctx).Model(&model.Announcement{}).Where("id = ?", row.ID).Updates(updates).Error; err != nil {
		return nil, err
	}
	updated, err := r.findSiteAnnouncement(ctx, siteID, id)
	if err != nil {
		return nil, err
	}
	dto := toSiteAnnouncementDTO(*updated)
	return &dto, nil
}

// DeleteSiteAnnouncement 删除本站公告。
func (r *Repository) DeleteSiteAnnouncement(ctx context.Context, adminID, siteID, id uint64) error {
	if siteID == 0 {
		return ErrSiteNotFound
	}
	if err := r.ensureSiteAccess(ctx, adminID, siteID); err != nil {
		return err
	}
	row, err := r.findSiteAnnouncement(ctx, siteID, id)
	if err != nil {
		return err
	}
	return r.db.WithContext(ctx).Where("id = ?", row.ID).Delete(&model.Announcement{}).Error
}

// findSiteAnnouncement 按站点归属读取公告，跨站 ID 一律视为不存在。
func (r *Repository) findSiteAnnouncement(ctx context.Context, siteID, id uint64) (*model.Announcement, error) {
	var row model.Announcement
	err := r.db.WithContext(ctx).Where("id = ? AND distribution_site_id = ?", id, siteID).First(&row).Error
	if err != nil {
		if errors.Is(err, gorm.ErrRecordNotFound) {
			return nil, ErrAnnouncementNotFound
		}
		return nil, err
	}
	return &row, nil
}

func toSiteAnnouncementDTO(a model.Announcement) SiteAnnouncementDTO {
	return SiteAnnouncementDTO{
		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,
	}
}

// normalizeAnnouncementModeOrInherit 读侧容错：非法/历史空值一律按默认继承口径返回。
func normalizeAnnouncementModeOrInherit(value string) string {
	mode, err := normalizeAnnouncementMode(value)
	if err != nil {
		return model.AnnouncementModeInherit
	}
	return mode
}