package config

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

const defaultShutdownTimeout = 10 * time.Second
const defaultMigrationLockTimeout = 30 * time.Second

type Config struct {
	Environment          string
	HTTPAddress          string
	DatabaseURL          string
	DatabaseIdentityURL  string
	DatabaseMigrationURL string
	DatabaseRuntimeRole  string
	DatabaseIdentityRole string
	MigrationLockTimeout time.Duration
	IOPEndpoint          string
	ShutdownTimeout      time.Duration
}

func Load() (Config, error) {
	shutdownTimeout, err := positiveDuration(
		"ARIADNE_SHUTDOWN_TIMEOUT",
		defaultShutdownTimeout,
	)
	if err != nil {
		return Config{}, err
	}
	migrationLockTimeout, err := positiveDuration(
		"ARIADNE_MIGRATION_LOCK_TIMEOUT",
		defaultMigrationLockTimeout,
	)
	if err != nil {
		return Config{}, err
	}

	config := Config{
		Environment:          valueOrDefault("ARIADNE_ENVIRONMENT", "development"),
		HTTPAddress:          valueOrDefault("ARIADNE_HTTP_ADDRESS", ":8080"),
		DatabaseURL:          strings.TrimSpace(os.Getenv("ARIADNE_DATABASE_URL")),
		DatabaseIdentityURL:  strings.TrimSpace(os.Getenv("ARIADNE_DATABASE_IDENTITY_URL")),
		DatabaseMigrationURL: strings.TrimSpace(os.Getenv("ARIADNE_DATABASE_MIGRATION_URL")),
		DatabaseRuntimeRole:  strings.TrimSpace(os.Getenv("ARIADNE_DATABASE_RUNTIME_ROLE")),
		DatabaseIdentityRole: strings.TrimSpace(os.Getenv("ARIADNE_DATABASE_IDENTITY_ROLE")),
		MigrationLockTimeout: migrationLockTimeout,
		IOPEndpoint:          strings.TrimSpace(os.Getenv("ARIADNE_IOP_ENDPOINT")),
		ShutdownTimeout:      shutdownTimeout,
	}

	return config, nil
}

func valueOrDefault(name, fallback string) string {
	if value := strings.TrimSpace(os.Getenv(name)); value != "" {
		return value
	}
	return fallback
}

func positiveDuration(name string, fallback time.Duration) (time.Duration, error) {
	value := strings.TrimSpace(os.Getenv(name))
	if value == "" {
		return fallback, nil
	}
	parsed, err := time.ParseDuration(value)
	if err != nil {
		return 0, fmt.Errorf("parse %s: %w", name, err)
	}
	if parsed <= 0 {
		return 0, fmt.Errorf("%s must be greater than zero", name)
	}
	return parsed, nil
}