package config

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

// Config centralizes runtime configuration loaded from the environment.
type Config struct {
	AppName      string
	Port         string
	DatabaseURL  string
	MaxOpenConns int
	MaxIdleConns int
	ConnMaxIdle  time.Duration
}

// Load reads configuration from environment variables and applies sane defaults
// for local development.
func Load() Config {
	cfg := Config{
		AppName:      getEnv("APP_NAME", "saveinmed-performance-core"),
		Port:         getEnv("PORT", "8080"),
		DatabaseURL:  getEnv("DATABASE_URL", "postgres://postgres:postgres@localhost:5432/saveinmed?sslmode=disable"),
		MaxOpenConns: getEnvInt("DB_MAX_OPEN_CONNS", 15),
		MaxIdleConns: getEnvInt("DB_MAX_IDLE_CONNS", 5),
		ConnMaxIdle:  getEnvDuration("DB_CONN_MAX_IDLE", 5*time.Minute),
	}

	return cfg
}

// Addr returns the address binding for the HTTP server.
func (c Config) Addr() string {
	return fmt.Sprintf(":%s", c.Port)
}

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

func getEnvInt(key string, fallback int) int {
	if value := os.Getenv(key); value != "" {
		if parsed, err := strconv.Atoi(value); err == nil {
			return parsed
		}
	}
	return fallback
}

func getEnvDuration(key string, fallback time.Duration) time.Duration {
	if value := os.Getenv(key); value != "" {
		if parsed, err := time.ParseDuration(value); err == nil {
			return parsed
		}
	}
	return fallback
}