package config

import (
	"errors"
	"fmt"
	"os"
	"strconv"
	"strings"
)

type Config struct {
	ServiceName string
	Environment string
	HTTP        HTTPConfig
	Database    DatabaseConfig
	Auth        AuthConfig
}

type HTTPConfig struct {
	Address string
}

type DatabaseConfig struct {
	DSN string
}

type AuthConfig struct {
	JWKSURL        string
	Audience       string
	Issuer         string
	FallbackSecret string
	ClockSkew      int
}

func Load() (Config, error) {
	cfg := Config{
		ServiceName: getenvDefault("SERVICE_NAME", "platform-projects-core"),
		Environment: getenvDefault("ENVIRONMENT", "development"),
		HTTP: HTTPConfig{
			Address: getenvDefault("HTTP_ADDRESS", ":8080"),
		},
		Database: DatabaseConfig{
			DSN: os.Getenv("DATABASE_DSN"),
		},
		Auth: AuthConfig{
			JWKSURL:        os.Getenv("AUTH_JWKS_URL"),
			Audience:       os.Getenv("AUTH_AUDIENCE"),
			Issuer:         os.Getenv("AUTH_ISSUER"),
			FallbackSecret: os.Getenv("AUTH_FALLBACK_SECRET"),
			ClockSkew:      parseIntDefault("AUTH_CLOCK_SKEW_SECONDS", 60),
		},
	}

	if cfg.Database.DSN == "" {
		return Config{}, errors.New("DATABASE_DSN is required")
	}
	if cfg.Auth.JWKSURL == "" && cfg.Auth.FallbackSecret == "" {
		return Config{}, errors.New("AUTH_JWKS_URL or AUTH_FALLBACK_SECRET must be provided")
	}
	if cfg.Auth.Audience == "" {
		return Config{}, errors.New("AUTH_AUDIENCE is required")
	}
	if cfg.Auth.Issuer == "" {
		return Config{}, errors.New("AUTH_ISSUER is required")
	}
	if err := cfg.Validate(); err != nil {
		return Config{}, err
	}

	return cfg, nil
}

func getenvDefault(key, fallback string) string {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback
	}
	return value
}

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

func (c Config) Validate() error {
	if c.ServiceName == "" {
		return fmt.Errorf("service name must not be empty")
	}
	if c.HTTP.Address == "" {
		return fmt.Errorf("http address must not be empty")
	}
	return nil
}