// Package config loads rule-engine-service settings from environment
// variables, matching the names used in the repo-root .env.example.
package config

import (
	"fmt"
	"os"
	"time"
)

type Config struct {
	PostgresDSN string

	DeviceControlGRPCTarget string

	RabbitMQURL string

	RuleCacheRefreshInterval time.Duration
}

func Load() (Config, error) {
	cfg := Config{
		PostgresDSN: fmt.Sprintf("postgres://%s:%s@%s:%s/%s",
			getEnv("POSTGRES_USER", "home_automation"),
			getEnv("POSTGRES_PASSWORD", ""),
			getEnv("POSTGRES_HOST", "localhost"),
			getEnv("POSTGRES_PORT", "5432"),
			getEnv("POSTGRES_DB", "home_automation"),
		),

		DeviceControlGRPCTarget: fmt.Sprintf("%s:%s",
			getEnv("DEVICE_CONTROL_HOST", "localhost"),
			getEnv("DEVICE_CONTROL_GRPC_PORT", "50051"),
		),

		RabbitMQURL: fmt.Sprintf("amqp://%s:%s@%s:%s/",
			getEnv("RABBITMQ_USER", "guest"),
			getEnv("RABBITMQ_PASSWORD", "guest"),
			getEnv("RABBITMQ_HOST", "localhost"),
			getEnv("RABBITMQ_PORT", "5672"),
		),
	}

	interval, err := getEnvDuration("RULE_ENGINE_CACHE_REFRESH_INTERVAL", 15*time.Second)
	if err != nil {
		return Config{}, err
	}
	cfg.RuleCacheRefreshInterval = interval

	return cfg, nil
}

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

func getEnvDuration(key string, fallback time.Duration) (time.Duration, error) {
	v := os.Getenv(key)
	if v == "" {
		return fallback, nil
	}
	d, err := time.ParseDuration(v)
	if err != nil {
		return 0, fmt.Errorf("%s: %w", key, err)
	}
	return d, nil
}