package service

import (
	"context"
	"fmt"
	"net/url"
	"regexp"
	"strconv"
	"strings"

	"go.uber.org/zap"

	"github.com/ShukeBta/MediaStationGo/internal/model"
)

func (s *SubscriptionService) updateSubscriptionTotalEpisodes(ctx context.Context, sub *model.Subscription, total int) {
	if s == nil || s.repo == nil || s.repo.DB == nil || sub == nil || total <= sub.TotalEpisodes {
		return
	}
	sub.TotalEpisodes = total
	_ = s.repo.DB.WithContext(ctx).Model(sub).Update("total_episodes", total).Error
}

func inferRSSTotalEpisodes(items []rssItem, sub *model.Subscription, filter *regexp.Regexp) int {
	if !subscriptionShouldInferTotal(sub) {
		return 0
	}
	maxEpisode := 0
	for _, item := range items {
		title := strings.TrimSpace(item.Title)
		if title == "" {
			continue
		}
		if filter != nil && !filter.MatchString(title) {
			continue
		}
		if !subscriptionTitleMatchesQuery(sub, title) {
			continue
		}
		if !matchesSubscriptionRules(sub, title) {
			continue
		}
		_, episode := ParseEpisode(title)
		if episode > maxEpisode {
			maxEpisode = episode
		}
	}
	return maxEpisode
}

func inferSearchTotalEpisodes(results []SearchResult, sub *model.Subscription) int {
	if !subscriptionShouldInferTotal(sub) {
		return 0
	}
	maxEpisode := 0
	for _, item := range results {
		matchText := subscriptionSearchResultText(item)
		if !subscriptionSearchResultMatchesQuery(sub, item) {
			continue
		}
		if !matchesSubscriptionRules(sub, matchText) {
			continue
		}
		_, episode := ParseEpisode(matchText)
		if episode > maxEpisode {
			maxEpisode = episode
		}
	}
	return maxEpisode
}

func subscriptionShouldInferTotal(sub *model.Subscription) bool {
	if sub == nil {
		return false
	}
	mediaType := normalizeMediaType(sub.MediaType, sub.Name+" "+sub.Filter, "")
	return isSubscriptionSeriesType(mediaType)
}

func (s *SubscriptionService) resolveSubscriptionTotalEpisodes(ctx context.Context, sub *model.Subscription, fallback int) int {
	if !subscriptionShouldInferTotal(sub) {
		return 0
	}
	if sub.TotalEpisodes > 0 {
		return sub.TotalEpisodes
	}
	if total := s.resolveSubscriptionMetadataTotalEpisodes(ctx, sub); total > 0 {
		return total
	}
	return fallback
}

func (s *SubscriptionService) resolveSubscriptionMetadataTotalEpisodes(ctx context.Context, sub *model.Subscription) int {
	if s == nil || s.scraper == nil || sub == nil {
		return 0
	}
	queries := subscriptionEpisodeMetadataQueries(sub)

	// Priority: TMDb -> Douban -> Bangumi -> TheTVDB -> Fanart -> title fallback.
	// Fanart.tv is artwork-only in MediaStationGo, so it intentionally does not
	// claim episode counts and lets the title fallback handle the final layer.
	if s.scraper.tmdb != nil {
		if id := subscriptionExplicitTMDbID(sub); id > 0 {
			if total, err := s.scraper.tmdb.GetTVEpisodeCount(ctx, id); err == nil && total > 0 {
				return total
			} else if err != nil && s.log != nil {
				s.log.Debug("subscription tmdb episode count failed", zap.Int("tmdb_id", id), zap.Error(err))
			}
		}
		for _, query := range queries {
			match, err := s.scraper.tmdb.SearchTV(ctx, query, 0)
			if err != nil {
				if s.log != nil {
					s.log.Debug("subscription tmdb search failed", zap.String("query", query), zap.Error(err))
				}
				continue
			}
			if match == nil || match.TMDbID <= 0 {
				continue
			}
			total, err := s.scraper.tmdb.GetTVEpisodeCount(ctx, match.TMDbID)
			if err != nil {
				if s.log != nil {
					s.log.Debug("subscription tmdb episode count failed", zap.Int("tmdb_id", match.TMDbID), zap.Error(err))
				}
				continue
			}
			if total > 0 {
				return total
			}
		}
	}

	if s.scraper.douban != nil {
		for _, query := range queries {
			total, err := s.scraper.douban.GetEpisodeCount(ctx, query)
			if err != nil {
				if s.log != nil {
					s.log.Debug("subscription douban episode count failed", zap.String("query", query), zap.Error(err))
				}
				continue
			}
			if total > 0 {
				return total
			}
		}
	}

	if s.scraper.bangumi != nil {
		for _, query := range queries {
			match, err := s.scraper.bangumi.Search(ctx, query)
			if err != nil {
				if s.log != nil {
					s.log.Debug("subscription bangumi search failed", zap.String("query", query), zap.Error(err))
				}
				continue
			}
			if match == nil || match.BangumiID <= 0 {
				continue
			}
			total, err := s.scraper.bangumi.GetEpisodeCount(ctx, match.BangumiID)
			if err != nil {
				if s.log != nil {
					s.log.Debug("subscription bangumi episode count failed", zap.Int("bangumi_id", match.BangumiID), zap.Error(err))
				}
				continue
			}
			if total > 0 {
				return total
			}
		}
	}

	if s.scraper.thetvdb != nil {
		for _, query := range queries {
			match, err := s.scraper.thetvdb.SearchSeries(ctx, query)
			if err != nil {
				if s.log != nil {
					s.log.Debug("subscription thetvdb search failed", zap.String("query", query), zap.Error(err))
				}
				continue
			}
			if match == nil || strings.TrimSpace(match.TheTVDBID) == "" {
				continue
			}
			total, err := s.scraper.thetvdb.GetSeriesEpisodeCount(ctx, match.TheTVDBID)
			if err != nil {
				if s.log != nil {
					s.log.Debug("subscription thetvdb episode count failed", zap.String("thetvdb_id", match.TheTVDBID), zap.Error(err))
				}
				continue
			}
			if total > 0 {
				return total
			}
		}
	}

	return 0
}

func subscriptionTitleMatchesQuery(sub *model.Subscription, title string) bool {
	if strings.TrimSpace(title) == "" {
		return false
	}
	for _, query := range subscriptionTitleMatchQueries(sub) {
		if strings.Contains(normalizeAvailabilityComparable(title), normalizeAvailabilityComparable(query)) {
			return true
		}
	}
	return len(subscriptionTitleMatchQueries(sub)) == 0
}

func subscriptionSearchResultMatchesQuery(sub *model.Subscription, item SearchResult) bool {
	matchText := subscriptionSearchResultText(item)
	if subscriptionTitleMatchesQuery(sub, matchText) {
		return true
	}
	if !subscriptionSearchResultYearCompatible(sub, matchText) {
		return false
	}
	return subscriptionKeywordMatchesQuery(sub, item.SearchKeyword)
}

func subscriptionSearchResultYearCompatible(sub *model.Subscription, title string) bool {
	expected := subscriptionExpectedYear(sub)
	if expected <= 0 {
		return true
	}
	years := titleYears(title)
	if len(years) == 0 {
		return true
	}
	for _, year := range years {
		if year == expected {
			return true
		}
	}
	return false
}

func subscriptionExpectedYear(sub *model.Subscription) int {
	if sub == nil {
		return 0
	}
	if sub.Year > 0 {
		return sub.Year
	}
	for _, value := range []string{sub.Filter, sub.Name, sub.FeedURL} {
		for _, year := range titleYears(value) {
			return year
		}
	}
	return 0
}

func titleYears(value string) []int {
	matches := regexp.MustCompile(`\b(19\d{2}|20\d{2})\b`).FindAllString(value, -1)
	if len(matches) == 0 {
		return nil
	}
	out := make([]int, 0, len(matches))
	seen := map[int]struct{}{}
	for _, match := range matches {
		year, err := strconv.Atoi(match)
		if err != nil {
			continue
		}
		if _, ok := seen[year]; ok {
			continue
		}
		seen[year] = struct{}{}
		out = append(out, year)
	}
	return out
}

func subscriptionKeywordMatchesQuery(sub *model.Subscription, keyword string) bool {
	keyword = strings.TrimSpace(keyword)
	if keyword == "" {
		return false
	}
	normalizedKeyword := normalizeAvailabilityComparable(keyword)
	if normalizedKeyword == "" {
		return false
	}
	for _, query := range subscriptionTitleMatchQueries(sub) {
		normalizedQuery := normalizeAvailabilityComparable(query)
		if normalizedQuery == "" {
			continue
		}
		if strings.Contains(normalizedKeyword, normalizedQuery) || strings.Contains(normalizedQuery, normalizedKeyword) {
			return true
		}
	}
	return len(subscriptionTitleMatchQueries(sub)) == 0
}

func subscriptionTitleMatchQueries(sub *model.Subscription) []string {
	if sub == nil {
		return nil
	}
	values := []string{
		availabilityQuery(subscriptionName(sub), subscriptionFilter(sub)),
		cleanAvailabilityTitle(subscriptionFilter(sub)),
		cleanAvailabilityTitle(subscriptionName(sub)),
	}
	for _, alias := range subscriptionFeedAliases(sub) {
		values = append(values, alias, cleanAvailabilityTitle(alias))
	}
	for _, alias := range subscriptionMetadataAliases(sub) {
		values = append(values, alias, cleanAvailabilityTitle(alias))
	}
	return compactUniqueStrings(values...)
}

func subscriptionEpisodeMetadataQueries(sub *model.Subscription) []string {
	if sub == nil {
		return nil
	}
	raw := []string{
		siteSearchKeyword(sub),
		sub.Filter,
		sub.Name,
		availabilityQuery(subscriptionName(sub), subscriptionFilter(sub)),
	}
	out := make([]string, 0, len(raw)*2)
	for _, value := range raw {
		value = cleanAvailabilityTitle(value)
		if value == "" {
			continue
		}
		if cleaned, _ := CleanQuery(value); cleaned != "" {
			out = append(out, cleaned)
		}
		out = append(out, value)
	}
	return compactUniqueStrings(out...)
}

func subscriptionExplicitTMDbID(sub *model.Subscription) int {
	if sub == nil {
		return 0
	}
	values := []string{sub.Name, sub.Filter, sub.FeedURL}
	for _, raw := range values {
		for _, pattern := range []string{`(?i)\btmdb[_:\-\s=]+(\d{2,})`, `(?i)\btmdbid[_:\-\s=]+(\d{2,})`} {
			if m := regexp.MustCompile(pattern).FindStringSubmatch(raw); len(m) >= 2 {
				var id int
				if _, err := fmt.Sscanf(m[1], "%d", &id); err == nil && id > 0 {
					return id
				}
			}
		}
		if u, err := url.Parse(raw); err == nil {
			for _, key := range []string{"tmdb_id", "tmdb", "tmdbid"} {
				var id int
				if _, err := fmt.Sscanf(u.Query().Get(key), "%d", &id); err == nil && id > 0 {
					return id
				}
			}
		}
	}
	return 0
}