package config

import (
	"os"
	"strings"

	"github.com/joho/godotenv"
)

// Config holds all runtime settings, loaded from environment (.env optional).
type Config struct {
	// Slack
	SlackBotToken       string
	DefaultSlackChannel string // 모든 이벤트 브로드캐스트 채널
	MonitorChannel      string // 에러(slog.Error) 발생 시 알림을 보낼 채널 (예: monitor-dev)

	// Gitea
	GiteaWebhookSecret string

	// Notion
	NotionVerificationToken string
	NotionAPIToken          string
	NotionAssigneeProperty  string

	// App
	MappingFile string
	Addr        string

	// Logging
	Env       string // development | production
	LogLevel  string // debug | info | warn | error
	LogFormat string // text | json
	LogFile   string // optional file path; empty = stdout only
}

// Load reads configuration for the given environment and loads its .env files.
//
// The environment is decided by the run command (the -env flag passed as
// envOverride). If empty, it falls back to the APP_ENV variable, then
// "development". This keeps env selection command-driven, not ambient.
//
// Precedence: an earlier-loaded file wins (godotenv.Load never overrides an
// already-set variable), and missing files are ignored:
//
//	.env.{env}.local  # 개인 비밀값 (git 제외, 선택)
//	.env.{env}        # 환경별 설정 (.env.dev / .env.prod)
//	.env              # 공통 기본값 (fallback)
func Load(envOverride string) Config {
	env := envOverride
	if env == "" {
		env = getenv("APP_ENV", "dev")
	}
	env = normalizeEnv(env)

	_ = godotenv.Load(".env." + env + ".local")
	_ = godotenv.Load(".env." + env)
	_ = godotenv.Load(".env")

	return Config{
		SlackBotToken:           os.Getenv("SLACK_BOT_TOKEN"),
		DefaultSlackChannel:     os.Getenv("DEFAULT_SLACK_CHANNEL"),
		MonitorChannel:          os.Getenv("MONITOR_SLACK_CHANNEL"),
		GiteaWebhookSecret:      os.Getenv("GITEA_WEBHOOK_SECRET"),
		NotionVerificationToken: os.Getenv("NOTION_VERIFICATION_TOKEN"),
		NotionAPIToken:          os.Getenv("NOTION_API_TOKEN"),
		NotionAssigneeProperty:  getenv("NOTION_ASSIGNEE_PROPERTY", "담당자"),
		MappingFile:             getenv("MAPPING_FILE", "data/mappings.json"),
		Addr:                    getenv("ADDR", ":8000"),

		Env:       env,
		LogLevel:  getenv("LOG_LEVEL", defaultLogLevel(env)),
		LogFormat: getenv("LOG_FORMAT", defaultLogFormat(env)),
		LogFile:   getenv("LOG_FILE", defaultLogFile(env)),
	}
}

// normalizeEnv canonicalizes the env name to the short form "dev" or "prod".
// Long forms (development/production) and unknown values map sensibly.
func normalizeEnv(s string) string {
	switch strings.ToLower(strings.TrimSpace(s)) {
	case "prod", "production":
		return "prod"
	default:
		return "dev"
	}
}

// IsProduction reports whether the app runs in the production environment.
func (c Config) IsProduction() bool { return c.Env == "prod" }

func defaultLogLevel(env string) string {
	if env == "prod" {
		return "info"
	}
	return "debug"
}

func defaultLogFormat(env string) string {
	if env == "prod" {
		return "json"
	}
	return "text"
}

// defaultLogFile decides where logs are written when LOG_FILE is unset:
//   - dev  → "" (콘솔/IDE 출력만)
//   - prod → 파일로 추출 (logs/app.log)
func defaultLogFile(env string) string {
	if env == "prod" {
		return "logs/app.log"
	}
	return ""
}

func getenv(key, fallback string) string {
	if v := os.Getenv(key); v != "" {
		return v
	}
	return fallback
}