extract: add provider mapping cache

internal/episodes/service/provider_mapping.go

@@ -0,0 +1,120 @@
+package service
+
+import (
+	"context"
+	"database/sql"
+	"errors"
+	"fmt"
+	"strings"
+	"time"
+
+	"mal/internal/db"
+	"mal/internal/domain"
+	"mal/internal/observability"
+)
+
+func (s *EpisodeService) providerID(ctx context.Context, anime domain.Anime, provider domain.EpisodeAvailabilityProvider, titles []string) (string, error) {
+	providerID, found, err := s.cachedProviderID(ctx, anime, provider)
+	if found || err != nil {
+		return providerID, err
+	}
+
+	providerID, err = provider.ResolveEpisodeProviderID(ctx, anime.MalID, titles)
+	if err != nil {
+		s.cacheProviderIDFailure(ctx, anime, provider, err)
+		return "", err
+	}
+
+	s.cacheProviderIDSuccess(ctx, anime, provider, providerID)
+	observability.Info(
+		"episodes_provider_id_resolved",
+		"episodes",
+		"",
+		map[string]any{
+			"anime_id":    anime.MalID,
+			"provider":    provider.Name(),
+			"provider_id": providerID,
+		},
+	)
+	return providerID, nil
+}
+
+func (s *EpisodeService) cachedProviderID(ctx context.Context, anime domain.Anime, provider domain.EpisodeAvailabilityProvider) (string, bool, error) {
+	row, err := s.queries.GetEpisodeProviderMapping(ctx, db.GetEpisodeProviderMappingParams{
+		AnimeID:  int64(anime.MalID),
+		Provider: provider.Name(),
+	})
+	if err != nil {
+		s.metrics.ObserveCache("episode_provider_mapping", "miss")
+		if errors.Is(err, sql.ErrNoRows) {
+			return "", false, nil
+		}
+		observability.Warn(
+			"episodes_provider_id_cache_read_failed",
+			"episodes",
+			"",
+			map[string]any{
+				"anime_id": anime.MalID,
+				"provider": provider.Name(),
+			},
+			err,
+		)
+		return "", false, nil
+	}
+
+	if row.FailedUntil.Valid && row.FailedUntil.Time.After(s.clock.Now()) {
+		s.metrics.ObserveCache("episode_provider_mapping", "hit")
+		return "", true, fmt.Errorf("cached provider mapping failure active until %s: %s", row.FailedUntil.Time.Format(time.RFC3339), row.LastError)
+	}
+	if strings.TrimSpace(row.ProviderShowID) == "" {
+		s.metrics.ObserveCache("episode_provider_mapping", "miss")
+		return "", false, nil
+	}
+
+	s.metrics.ObserveCache("episode_provider_mapping", "hit")
+	observability.Info(
+		"episodes_provider_id_cache_hit",
+		"episodes",
+		"",
+		map[string]any{
+			"anime_id":    anime.MalID,
+			"provider":    provider.Name(),
+			"provider_id": row.ProviderShowID,
+		},
+	)
+	return row.ProviderShowID, true, nil
+}
+
+func (s *EpisodeService) cacheProviderIDFailure(ctx context.Context, anime domain.Anime, provider domain.EpisodeAvailabilityProvider, resolveErr error) {
+	_ = s.queries.UpsertEpisodeProviderMapping(ctx, db.UpsertEpisodeProviderMappingParams{
+		AnimeID:        int64(anime.MalID),
+		Provider:       provider.Name(),
+		ProviderShowID: "",
+		FailedUntil:    sql.NullTime{Time: s.clock.Now().Add(time.Hour), Valid: true},
+		LastError:      truncate(resolveErr.Error(), 400),
+	})
+}
+
+func (s *EpisodeService) cacheProviderIDSuccess(ctx context.Context, anime domain.Anime, provider domain.EpisodeAvailabilityProvider, providerID string) {
+	err := s.queries.UpsertEpisodeProviderMapping(ctx, db.UpsertEpisodeProviderMappingParams{
+		AnimeID:        int64(anime.MalID),
+		Provider:       provider.Name(),
+		ProviderShowID: providerID,
+		FailedUntil:    sql.NullTime{},
+		LastError:      "",
+	})
+	if err == nil {
+		return
+	}
+
+	observability.Warn(
+		"episodes_provider_id_cache_write_failed",
+		"episodes",
+		"",
+		map[string]any{
+			"anime_id": anime.MalID,
+			"provider": provider.Name(),
+		},
+		err,
+	)
+}