feat: add central config package

internal/config/config.go

@@ -0,0 +1,85 @@
+package config
+
+import (
+	"errors"
+	"fmt"
+	"os"
+	"strings"
+)
+
+type EpisodeAvailabilityMode string
+
+const (
+	EpisodeAvailabilityModeAuto   EpisodeAvailabilityMode = "auto"
+	EpisodeAvailabilityModeLegacy EpisodeAvailabilityMode = "legacy"
+	EpisodeAvailabilityModeJikan  EpisodeAvailabilityMode = "jikan"
+)
+
+type Config struct {
+	Port string
+
+	// GinMode maps to gin.SetMode. When empty, the server uses release mode by default.
+	GinMode string
+
+	DatabaseFile string
+
+	// Allow any Origin for CORS. Intended for local dev / reverse proxy setups only.
+	CORSAllowAll bool
+
+	EpisodeAvailabilityMode EpisodeAvailabilityMode
+
+	// Optional. When empty, proxy token signing is disabled.
+	PlaybackProxySecret string
+
+	// Optional debug toggle for Jikan client tracing.
+	JikanTrace bool
+}
+
+func Load() (Config, error) {
+	cfg := Config{
+		Port:                   firstNonEmpty(strings.TrimSpace(os.Getenv("PORT")), "3000"),
+		GinMode:                strings.TrimSpace(os.Getenv("GIN_MODE")),
+		DatabaseFile:           firstNonEmpty(strings.TrimSpace(os.Getenv("DATABASE_FILE")), "mal.db"),
+		CORSAllowAll:           strings.TrimSpace(os.Getenv("MAL_CORS_ALLOW_ALL")) == "1",
+		PlaybackProxySecret:    strings.TrimSpace(os.Getenv("PLAYBACK_PROXY_SECRET")),
+		JikanTrace:             truthy(strings.TrimSpace(os.Getenv("MAL_JIKAN_TRACE"))),
+		EpisodeAvailabilityMode: EpisodeAvailabilityModeAuto,
+	}
+
+	if raw := strings.ToLower(strings.TrimSpace(os.Getenv("EPISODE_AVAILABILITY_MODE"))); raw != "" {
+		switch EpisodeAvailabilityMode(raw) {
+		case EpisodeAvailabilityModeAuto, EpisodeAvailabilityModeLegacy, EpisodeAvailabilityModeJikan:
+			cfg.EpisodeAvailabilityMode = EpisodeAvailabilityMode(raw)
+		default:
+			return Config{}, fmt.Errorf("invalid EPISODE_AVAILABILITY_MODE: %q (expected auto|legacy|jikan)", raw)
+		}
+	}
+
+	if strings.TrimSpace(cfg.Port) == "" {
+		return Config{}, errors.New("PORT must not be empty")
+	}
+	if strings.TrimSpace(cfg.DatabaseFile) == "" {
+		return Config{}, errors.New("DATABASE_FILE must not be empty")
+	}
+
+	return cfg, nil
+}
+
+func firstNonEmpty(values ...string) string {
+	for _, v := range values {
+		if strings.TrimSpace(v) != "" {
+			return v
+		}
+	}
+	return ""
+}
+
+func truthy(v string) bool {
+	switch strings.ToLower(strings.TrimSpace(v)) {
+	case "1", "true", "yes", "y", "on":
+		return true
+	default:
+		return false
+	}
+}
+

internal/config/module.go

@@ -0,0 +1,8 @@
+package config
+
+import "go.uber.org/fx"
+
+var Module = fx.Options(
+	fx.Provide(Load),
+)
+