// Package depenv provides deployment environment management for NTP Pool services.
//
// This package handles different deployment environments (development, test, production)
// and provides environment-specific configuration including API endpoints, management URLs,
// and monitoring domains. It supports string-based environment identification and
// automatic URL construction for various service endpoints.
//
// The package defines three main deployment environments:
//   - DeployDevel: Development environment with dev-specific endpoints
//   - DeployTest: Test/beta environment for staging
//   - DeployProd: Production environment with live endpoints
//
// Environment detection supports both short and long forms:
//   - "dev" or "devel" → DeployDevel
//   - "test" or "beta" → DeployTest
//   - "prod" → DeployProd
package depenv

import (
	"fmt"
	"os"
)

var manageServers = map[DeploymentEnvironment]string{
	DeployDevel: "https://manage.askdev.grundclock.com",
	DeployTest:  "https://manage.beta.grundclock.com",
	DeployProd:  "https://manage.ntppool.org",
}

var apiServers = map[DeploymentEnvironment]string{
	DeployDevel: "https://dev-api.ntppool.dev",
	DeployTest:  "https://beta-api.ntppool.dev",
	DeployProd:  "https://api.ntppool.dev",
}

// var validationServers = map[DeploymentEnvironment]string{
// 	DeployDevel: "https://v.ntp.dev/d/",
// 	DeployTest:  "https://v.ntp.dev/b/",
// 	DeployProd:  "https://v.ntp.dev/p/",
// }

const (
	// DeployUndefined represents an unrecognized or unset deployment environment.
	DeployUndefined DeploymentEnvironment = iota
	// DeployDevel represents the development environment.
	DeployDevel
	// DeployTest represents the test/beta environment.
	DeployTest
	// DeployProd represents the production environment.
	DeployProd
)

// DeploymentEnvironment represents a deployment environment type.
// It provides methods for environment-specific URL construction and
// supports text marshaling/unmarshaling for configuration files.
type DeploymentEnvironment uint8

// DeploymentEnvironmentFromString parses a string into a DeploymentEnvironment.
// It supports both short and long forms of environment names:
//   - "dev" or "devel" → DeployDevel
//   - "test" or "beta" → DeployTest
//   - "prod" → DeployProd
//   - any other value → DeployUndefined
func DeploymentEnvironmentFromString(s string) DeploymentEnvironment {
	switch s {
	case "devel", "dev":
		return DeployDevel
	case "test", "beta":
		return DeployTest
	case "prod":
		return DeployProd
	default:
		return DeployUndefined
	}
}

// String returns the canonical string representation of the deployment environment.
// Returns "prod", "test", "devel", or panics for invalid environments.
func (d DeploymentEnvironment) String() string {
	switch d {
	case DeployProd:
		return "prod"
	case DeployTest:
		return "test"
	case DeployDevel:
		return "devel"
	default:
		panic("invalid DeploymentEnvironment")
	}
}

// APIHost returns the API server URL for this deployment environment.
// It first checks the API_HOST environment variable for overrides,
// then falls back to the environment-specific default API endpoint.
func (d DeploymentEnvironment) APIHost() string {
	if apiHost := os.Getenv("API_HOST"); apiHost != "" {
		return apiHost
	}
	return apiServers[d]
}

// ManageURL constructs a management interface URL for this deployment environment.
// It combines the environment-specific management server base URL with the provided path.
//
// The path parameter should start with "/" for proper URL construction.
func (d DeploymentEnvironment) ManageURL(path string) string {
	return manageServers[d] + path
}

// MonitorDomain returns the monitoring domain for this deployment environment.
// The domain follows the pattern: {environment}.mon.ntppool.dev
// For example: "devel.mon.ntppool.dev" for the development environment.
func (d DeploymentEnvironment) MonitorDomain() string {
	return d.String() + ".mon.ntppool.dev"
}

// UnmarshalText implements the encoding.TextUnmarshaler interface.
// It allows DeploymentEnvironment to be unmarshaled from configuration files
// and other text-based formats. Empty strings are treated as valid (no-op).
//
// Returns an error if the text represents an invalid deployment environment.
func (d *DeploymentEnvironment) UnmarshalText(text []byte) error {
	s := string(text)
	if s == "" {
		return nil
	}
	env := DeploymentEnvironmentFromString(s)
	if env == DeployUndefined {
		return fmt.Errorf("invalid deployment environment: %s", s)
	}
	*d = env
	return nil
}