feat: add season-aware episode title selection to tvmaze client

integrations/tvmaze/client.go

@@ -8,10 +8,19 @@ import (
 	"io"
 	"net/http"
 	"net/url"
+	"regexp"
 	"strconv"
 	"strings"
 	"time"
 	"unicode"
+
+	"mal/internal/domain"
+)
+
+var (
+	seasonNumberPattern = regexp.MustCompile(`(?i)(?:\bseason\s+(\d+)|\b(\d+)(?:st|nd|rd|th)\s+season)\b`)
+	seasonSuffixPattern = regexp.MustCompile(`(?i)\s+(?:(?:season\s+\d+)|(?:\d+(?:st|nd|rd|th)\s+season))(?:\s+part\s+\d+)?\s*$`)
+	partNumberPattern   = regexp.MustCompile(`(?i)\bpart\s+(\d+)\b`)
 )
 
 const baseURL = "https://api.tvmaze.com"
@@ -50,7 +59,7 @@ func (c *Client) Name() string {
 
 func (c *Client) ResolveEpisodeProviderID(ctx context.Context, _ int, titleCandidates []string) (string, error) {
 	matches := map[int]struct{}{}
-	for _, candidate := range uniqueTitleCandidates(titleCandidates, 4) {
+	for _, candidate := range titleSearchCandidates(titleCandidates, 6) {
 		results, err := c.search(ctx, candidate)
 		if err != nil {
 			return "", err
@@ -101,11 +110,15 @@ func addExactMatches(matches map[int]struct{}, results []searchResult, normalize
 	}
 }
 
-func (c *Client) GetEpisodeTitlesByProviderID(ctx context.Context, providerID string) (map[int]string, error) {
+func (c *Client) GetEpisodeTitlesByProviderID(ctx context.Context, providerID string, anime domain.Anime, episodeCount int) (map[int]string, error) {
 	var episodes []episode
 	if err := c.getJSON(ctx, "/shows/"+url.PathEscape(providerID)+"/episodes", &episodes); err != nil {
 		return nil, err
 	}
+	episodes, err := episodesForAnimeSeason(episodes, anime, episodeCount)
+	if err != nil {
+		return nil, err
+	}
 
 	titles := make(map[int]string, len(episodes))
 	for i, item := range episodes {
@@ -120,6 +133,99 @@ func (c *Client) GetEpisodeTitlesByProviderID(ctx context.Context, providerID st
 	return titles, nil
 }
 
+func titleSearchCandidates(candidates []string, limit int) []string {
+	expanded := make([]string, 0, len(candidates)*2)
+	for _, candidate := range candidates {
+		parent := strings.TrimSpace(seasonSuffixPattern.ReplaceAllString(candidate, ""))
+		if parent != "" && parent != strings.TrimSpace(candidate) {
+			expanded = append(expanded, parent)
+		}
+		expanded = append(expanded, candidate)
+	}
+	return uniqueTitleCandidates(expanded, limit)
+}
+
+func episodesForAnimeSeason(episodes []episode, anime domain.Anime, episodeCount int) ([]episode, error) {
+	seasons := groupEpisodesBySeason(episodes)
+	season := animeSeasonNumber(anime)
+	if season == 0 {
+		season = seasonForYear(seasons, anime.Year)
+	}
+	if season == 0 {
+		season = 1
+	}
+
+	selected := seasons[season]
+	if len(selected) == 0 {
+		return nil, fmt.Errorf("tvmaze: season %d has no episodes", season)
+	}
+	if episodeCount <= 0 || episodeCount >= len(selected) {
+		return selected, nil
+	}
+	if animePartNumber(anime) > 1 {
+		return selected[len(selected)-episodeCount:], nil
+	}
+	return selected[:episodeCount], nil
+}
+
+func groupEpisodesBySeason(episodes []episode) map[int][]episode {
+	seasons := map[int][]episode{}
+	for _, item := range episodes {
+		if item.Season > 0 {
+			seasons[item.Season] = append(seasons[item.Season], item)
+		}
+	}
+	return seasons
+}
+
+func animeSeasonNumber(anime domain.Anime) int {
+	return titleNumber(animeTitles(anime), seasonNumberPattern)
+}
+
+func animePartNumber(anime domain.Anime) int {
+	return titleNumber(animeTitles(anime), partNumberPattern)
+}
+
+func titleNumber(titles []string, pattern *regexp.Regexp) int {
+	for _, title := range titles {
+		match := pattern.FindStringSubmatch(title)
+		if len(match) <= 1 {
+			continue
+		}
+		for _, value := range match[1:] {
+			number, err := strconv.Atoi(value)
+			if err == nil && number > 0 {
+				return number
+			}
+		}
+	}
+	return 0
+}
+
+func animeTitles(anime domain.Anime) []string {
+	titles := make([]string, 0, 3+len(anime.TitleSynonyms))
+	titles = append(titles, anime.Title, anime.TitleEnglish, anime.TitleJapanese)
+	titles = append(titles, anime.TitleSynonyms...)
+	return titles
+}
+
+func seasonForYear(seasons map[int][]episode, year int) int {
+	if year <= 0 {
+		return 0
+	}
+	matchedSeason := 0
+	for season, episodes := range seasons {
+		if len(episodes) == 0 || !strings.HasPrefix(episodes[0].Airdate, strconv.Itoa(year)+"-") {
+			continue
+		}
+		if matchedSeason != 0 {
+			return 0
+		}
+		matchedSeason = season
+	}
+	return matchedSeason
+}
+
 func (c *Client) search(ctx context.Context, title string) ([]searchResult, error) {
 	var results []searchResult
 	err := c.getJSON(ctx, "/search/shows?q="+url.QueryEscape(title), &results)