package services

import (
	"context"
	"fmt"
	"strings"

	"git.pengzhan.dev/haopengzhan/rsspipe/internal/crawler"
	"git.pengzhan.dev/haopengzhan/rsspipe/internal/db"
	"git.pengzhan.dev/haopengzhan/rsspipe/internal/logger"
	"git.pengzhan.dev/haopengzhan/rsspipe/internal/models"
	"git.pengzhan.dev/haopengzhan/rsspipe/internal/opml"
	"git.pengzhan.dev/haopengzhan/rsspipe/internal/parser"
	"go.uber.org/zap"
)

type FeedService struct {
	db           *db.DB
	entryService *EntryService
	parser       *parser.Parser
	crawler      *crawler.Crawler
	log          *zap.Logger
}

func NewFeedService(database *db.DB, entrySvc *EntryService, cr *crawler.Crawler) *FeedService {
	return &FeedService{
		db:           database,
		entryService: entrySvc,
		parser:       parser.NewParser(),
		crawler:      cr,
		log:          logger.Named("feed-service"),
	}
}

func (s *FeedService) ListFeeds(ctx context.Context) ([]models.Feed, error) {
	return s.db.ListFeeds()
}

func (s *FeedService) GetFeed(ctx context.Context, id string) (*models.Feed, error) {
	return s.db.GetFeed(id)
}

func (s *FeedService) CreateFeed(ctx context.Context, req models.CreateFeedRequest) (*models.Feed, error) {
	feedURL := strings.TrimSpace(req.FeedURL)
	if feedURL == "" {
		return nil, fmt.Errorf("feed_url is required")
	}

	if existing, _ := s.db.GetFeedByURL(feedURL); existing != nil {
		return nil, fmt.Errorf("feed is already subscribed")
	}

	res, err := s.parser.FetchFeed(ctx, feedURL, "", "")
	if err != nil {
		return nil, fmt.Errorf("failed to fetch feed: %w", err)
	}

	title := res.Title
	if req.Title != nil && strings.TrimSpace(*req.Title) != "" {
		title = strings.TrimSpace(*req.Title)
	}
	iconURL := ""
	if req.IconURL != nil && strings.TrimSpace(*req.IconURL) != "" {
		iconURL = strings.TrimSpace(*req.IconURL)
	}

	feed, err := s.db.CreateFeed(title, feedURL, res.SiteURL, iconURL, req.CategoryID)
	if err != nil {
		return nil, err
	}

	if len(res.Entries) > 0 {
		_, _ = s.entryService.IngestEntries(ctx, feed.ID, res.Entries, feed.Title, feed.SiteURL)
		_ = s.db.UpdateFeedFetchStatus(feed.ID, res.ETag, res.LastModified, "")
	}

	return s.db.GetFeed(feed.ID)
}

func (s *FeedService) UpdateFeed(ctx context.Context, id string, req models.UpdateFeedRequest) (*models.Feed, error) {
	if err := s.db.UpdateFeed(id, req); err != nil {
		return nil, err
	}
	return s.db.GetFeed(id)
}

func (s *FeedService) DeleteFeed(ctx context.Context, id string) error {
	return s.db.DeleteFeed(id)
}

func (s *FeedService) RefreshFeed(ctx context.Context, id string) (*models.Feed, error) {
	if s.crawler != nil {
		if err := s.crawler.RefreshSingle(ctx, id); err != nil {
			return nil, err
		}
	}
	return s.db.GetFeed(id)
}

func (s *FeedService) RefreshAllFeeds(ctx context.Context) {
	if s.crawler != nil {
		go s.crawler.RefreshAll(context.Background())
	}
}

// Category methods
func (s *FeedService) ListCategories(ctx context.Context) ([]models.Category, error) {
	return s.db.ListCategories()
}

func (s *FeedService) CreateCategory(ctx context.Context, title string, parentID *string) (*models.Category, error) {
	return s.db.CreateCategory(strings.TrimSpace(title), parentID)
}

func (s *FeedService) DeleteCategory(ctx context.Context, id string) error {
	return s.db.DeleteCategory(id)
}

func (s *FeedService) GetStats(ctx context.Context) (*models.Stats, error) {
	return s.db.GetStats()
}

// OPML methods
func (s *FeedService) ImportOPML(ctx context.Context, data []byte) (int, int, error) {
	importedFeeds, err := opml.ParseOPML(data)
	if err != nil {
		return 0, 0, fmt.Errorf("invalid OPML XML: %w", err)
	}

	categoryCache := make(map[string]string)
	cats, _ := s.db.ListCategories()
	for _, c := range cats {
		categoryCache[c.Title] = c.ID
	}

	createdCount := 0
	for _, item := range importedFeeds {
		if item.FeedURL == "" {
			continue
		}
		if existing, _ := s.db.GetFeedByURL(item.FeedURL); existing != nil {
			continue
		}

		var catID *string
		if item.CategoryTitle != "" {
			if cid, ok := categoryCache[item.CategoryTitle]; ok {
				catID = &cid
			} else {
				newCat, err := s.db.CreateCategory(item.CategoryTitle, nil)
				if err == nil {
					categoryCache[item.CategoryTitle] = newCat.ID
					catID = &newCat.ID
				}
			}
		}

		title := item.Title
		if title == "" {
			title = item.FeedURL
		}

		_, err := s.db.CreateFeed(title, item.FeedURL, item.SiteURL, "", catID)
		if err == nil {
			createdCount++
		}
	}

	if s.crawler != nil {
		go s.crawler.RefreshAll(context.Background())
	}

	return createdCount, len(importedFeeds), nil
}

func (s *FeedService) ExportOPML(ctx context.Context) ([]byte, error) {
	feeds, err := s.db.ListFeeds()
	if err != nil {
		return nil, err
	}
	cats, err := s.db.ListCategories()
	if err != nil {
		return nil, err
	}
	return opml.GenerateOPML(feeds, cats)
}