package service

import (
	"encoding/json"
	"errors"
	"fmt"
	"net/url"
	"strings"
	"time"
	"unicode/utf8"

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

const (
	SettingKeySponsorsConfig = "sponsors_config"
	SponsorDefaultTitle      = "赞助商"
	SponsorMaxItems          = 24
	SponsorMaxNameRunes      = 32
	SponsorMaxHoverRunes     = 120
)

// SponsorItem 侧栏赞助商条目
type SponsorItem struct {
	ID        string `json:"id"`
	Name      string `json:"name"`
	LogoURL   string `json:"logo_url"`
	LinkURL   string `json:"link_url"`
	HoverText string `json:"hover_text"`
	Enabled   bool   `json:"enabled"`
	SortOrder int    `json:"sort_order"`
}

// SponsorsConfig 赞助商板块配置
type SponsorsConfig struct {
	Enabled    bool          `json:"enabled"`
	PanelTitle string        `json:"panel_title"`
	Items      []SponsorItem `json:"items"`
}

func DefaultSponsorsConfig() SponsorsConfig {
	return SponsorsConfig{
		Enabled:    true,
		PanelTitle: SponsorDefaultTitle,
		Items:      []SponsorItem{},
	}
}

func (s *AdService) loadSponsorsConfig() (SponsorsConfig, error) {
	var row model.SiteSetting
	err := s.db.Where("key = ?", SettingKeySponsorsConfig).First(&row).Error
	if errors.Is(err, gorm.ErrRecordNotFound) {
		return DefaultSponsorsConfig(), nil
	}
	if err != nil {
		return SponsorsConfig{}, err
	}
	cfg := DefaultSponsorsConfig()
	if strings.TrimSpace(row.Value) == "" {
		return cfg, nil
	}
	if err := json.Unmarshal([]byte(row.Value), &cfg); err != nil {
		return DefaultSponsorsConfig(), nil
	}
	if strings.TrimSpace(cfg.PanelTitle) == "" {
		cfg.PanelTitle = SponsorDefaultTitle
	}
	return cfg, nil
}

func (s *AdService) GetSponsorsConfig() (SponsorsConfig, error) {
	return s.loadSponsorsConfig()
}

// PublicSponsors 侧栏展示用（仅启用且有 logo 的条目）
func (s *AdService) PublicSponsors() (SponsorsConfig, []SponsorItem, error) {
	cfg, err := s.loadSponsorsConfig()
	if err != nil {
		return cfg, nil, err
	}
	if !cfg.Enabled {
		return cfg, []SponsorItem{}, nil
	}
	out := make([]SponsorItem, 0, len(cfg.Items))
	for _, it := range cfg.Items {
		if !it.Enabled {
			continue
		}
		if strings.TrimSpace(it.LogoURL) == "" {
			continue
		}
		out = append(out, it)
	}
	return cfg, out, nil
}

func (s *AdService) SaveSponsorsConfig(in SponsorsConfig) (SponsorsConfig, error) {
	out, err := normalizeSponsorsConfig(in)
	if err != nil {
		return SponsorsConfig{}, err
	}
	b, err := json.Marshal(out)
	if err != nil {
		return SponsorsConfig{}, err
	}
	row := model.SiteSetting{Key: SettingKeySponsorsConfig, Value: string(b), UpdatedAt: time.Now()}
	if err := s.db.Save(&row).Error; err != nil {
		return SponsorsConfig{}, err
	}
	return out, nil
}

func normalizeSponsorsConfig(in SponsorsConfig) (SponsorsConfig, error) {
	out := DefaultSponsorsConfig()
	out.Enabled = in.Enabled
	title := strings.TrimSpace(in.PanelTitle)
	if title == "" {
		title = SponsorDefaultTitle
	}
	if utf8.RuneCountInString(title) > 16 {
		return SponsorsConfig{}, errors.New("侧栏标题最多 16 字")
	}
	out.PanelTitle = title

	if len(in.Items) > SponsorMaxItems {
		return SponsorsConfig{}, fmt.Errorf("赞助商最多 %d 个", SponsorMaxItems)
	}
	seen := map[string]struct{}{}
	items := make([]SponsorItem, 0, len(in.Items))
	for i, raw := range in.Items {
		id := strings.TrimSpace(raw.ID)
		if id == "" {
			id = fmt.Sprintf("sp_%d", i+1)
		}
		if _, ok := seen[id]; ok {
			return SponsorsConfig{}, errors.New("赞助商 id 重复")
		}
		seen[id] = struct{}{}

		name := strings.TrimSpace(raw.Name)
		if name == "" {
			return SponsorsConfig{}, errors.New("请填写赞助商名称")
		}
		if utf8.RuneCountInString(name) > SponsorMaxNameRunes {
			return SponsorsConfig{}, fmt.Errorf("赞助商名称最多 %d 字", SponsorMaxNameRunes)
		}

		logo := strings.TrimSpace(raw.LogoURL)
		if logo == "" {
			return SponsorsConfig{}, errors.New("请上传或填写赞助商 logo")
		}
		if !validSponsorLogoURL(logo) {
			return SponsorsConfig{}, errors.New("logo 须为 https 或本站 /uploads/ 图片")
		}

		link := strings.TrimSpace(raw.LinkURL)
		if link != "" {
			u, err := url.Parse(link)
			if err != nil || (u.Scheme != "https" && u.Scheme != "http") || u.Host == "" {
				return SponsorsConfig{}, errors.New("赞助商链接须为 http(s) 地址")
			}
			link = u.String()
		}

		hover := strings.TrimSpace(raw.HoverText)
		if utf8.RuneCountInString(hover) > SponsorMaxHoverRunes {
			return SponsorsConfig{}, fmt.Errorf("赞助说明最多 %d 字", SponsorMaxHoverRunes)
		}

		items = append(items, SponsorItem{
			ID:        id,
			Name:      name,
			LogoURL:   logo,
			LinkURL:   link,
			HoverText: hover,
			Enabled:   raw.Enabled,
			SortOrder: i,
		})
	}
	out.Items = items
	return out, nil
}

func validSponsorLogoURL(u string) bool {
	if adImageUploadRe.MatchString(u) {
		return true
	}
	if strings.HasPrefix(strings.ToLower(u), "https://") && adImageHTTPSRe.MatchString(u) {
		return true
	}
	// 允许常见本站 uploads 路径（赞助 logo）
	low := strings.ToLower(u)
	if strings.HasPrefix(low, "/uploads/") && len(u) <= 500 {
		return true
	}
	return false
}