feat: add season navigation helpers

internal/anime/simulcast.go

@@ -0,0 +1,148 @@
+package anime
+
+import (
+	"context"
+	"mal/integrations/jikan"
+	"mal/internal/domain"
+	"strconv"
+	"strings"
+)
+
+type animeSeason struct {
+	Season string
+	Year   int
+}
+
+type seasonOption struct {
+	Season string
+	Year   int
+	Label  string
+}
+
+var seasons = []string{"winter", "spring", "summer", "fall"}
+
+func seasonOptions(firstYear int, latest animeSeason) []seasonOption {
+	options := make([]seasonOption, 0, (latest.Year-firstYear+1)*len(seasons))
+	for year := latest.Year; year >= firstYear; year-- {
+		start := len(seasons) - 1
+		if year == latest.Year {
+			start = seasonIndex(latest.Season)
+		}
+		for i := start; i >= 0; i-- {
+			season := seasons[i]
+			options = append(options, seasonOption{
+				Season: season,
+				Year:   year,
+				Label:  strings.ToUpper(season[:1]) + season[1:] + " " + strconv.Itoa(year),
+			})
+		}
+	}
+	return options
+}
+
+func seasonIndex(season string) int {
+	for i, candidate := range seasons {
+		if strings.EqualFold(candidate, season) {
+			return i
+		}
+	}
+	return 0
+}
+
+func calendarSeason(year, month int) animeSeason {
+	index := (month - 1) / 3
+	if index < 0 || index >= len(seasons) {
+		index = 0
+	}
+	return animeSeason{Season: seasons[index], Year: year}
+}
+
+func adjacentSeason(season string, year, direction int) animeSeason {
+	index := 0
+	for i, candidate := range seasons {
+		if strings.EqualFold(candidate, season) {
+			index = i
+			break
+		}
+	}
+	index += direction
+	if index < 0 {
+		index = len(seasons) - 1
+		year--
+	} else if index >= len(seasons) {
+		index = 0
+		year++
+	}
+	return animeSeason{Season: seasons[index], Year: year}
+}
+
+func seasonNavigation(selected animeSeason, firstYear int, latest animeSeason) (*animeSeason, *animeSeason) {
+	var previous *animeSeason
+	var next *animeSeason
+	if selected.Year > firstYear || selected.Season != "winter" {
+		value := adjacentSeason(selected.Season, selected.Year, -1)
+		previous = &value
+	}
+	value := adjacentSeason(selected.Season, selected.Year, 1)
+	if value.Year < latest.Year || value.Year == latest.Year && seasonIndex(value.Season) <= seasonIndex(latest.Season) {
+		next = &value
+	}
+	return previous, next
+}
+
+func seasonSelection(rawSeason, rawYear string, current, latest animeSeason) animeSeason {
+	season := strings.ToLower(strings.TrimSpace(rawSeason))
+	validSeason := false
+	for _, candidate := range seasons {
+		if season == candidate {
+			validSeason = true
+			break
+		}
+	}
+	year, err := strconv.Atoi(rawYear)
+	if !validSeason || err != nil || year < 2000 || year > latest.Year || year == latest.Year && seasonIndex(season) > seasonIndex(latest.Season) {
+		return current
+	}
+	return animeSeason{Season: season, Year: year}
+}
+
+func (s *SeasonDiscoveryService) LatestAvailableSeason(ctx context.Context, current animeSeason) animeSeason {
+	next := adjacentSeason(current.Season, current.Year, 1)
+	shows, err := s.provider.SeasonalShows(ctx, next.Season, next.Year)
+	if err == nil && len(shows) > 0 {
+		return next
+	}
+	return current
+}
+
+type SimulcastData struct {
+	Animes []domain.Anime
+	Season string
+	Year   int
+}
+
+func (s *SeasonDiscoveryService) GetSimulcast(ctx context.Context, selected animeSeason) (SimulcastData, error) {
+	shows, err := s.provider.SeasonalShows(ctx, selected.Season, selected.Year)
+	if err != nil {
+		return SimulcastData{}, err
+	}
+	animes := make([]domain.Anime, 0, len(shows))
+	for _, show := range shows {
+		anime := jikan.Anime{
+			MalID:        show.MalID,
+			Title:        show.Name,
+			TitleEnglish: show.EnglishName,
+			Status:       show.Status,
+			Type:         show.Type,
+			Year:         show.Year,
+			Episodes:     show.EpisodeCount,
+		}
+		anime.Images.Webp.LargeImageURL = show.Thumbnail
+		animes = append(animes, domain.Anime{Anime: anime})
+	}
+	return SimulcastData{
+		Animes: animes,
+		Season: selected.Season,
+		Year:   selected.Year,
+	}, nil
+}