// Package config reads the gateway credentials from the environment.
//
// The credentials are never logged, never printed and never written to disk by
// this package.
package config

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

// Environment variable names.
const (
	EnvUser     = "SCHLUNDTECH_USER"
	EnvPassword = "SCHLUNDTECH_PASSWORD"
	EnvContext  = "SCHLUNDTECH_CONTEXT"
	EnvToken    = "SCHLUNDTECH_TOKEN"
	EnvEndpoint = "SCHLUNDTECH_ENDPOINT"
)

// Credentials are the values needed to talk to the gateway.
type Credentials struct {
	User     string
	Password string
	Context  string
	Token    string
	Endpoint string
}

// FromEnv reads the credentials. It reports every missing variable at once so
// a first run does not fail one variable at a time.
func FromEnv() (Credentials, error) {
	c := Credentials{
		User:     strings.TrimSpace(os.Getenv(EnvUser)),
		Password: os.Getenv(EnvPassword),
		Context:  strings.TrimSpace(os.Getenv(EnvContext)),
		Token:    strings.TrimSpace(os.Getenv(EnvToken)),
		Endpoint: strings.TrimSpace(os.Getenv(EnvEndpoint)),
	}

	var missing []string
	if c.User == "" {
		missing = append(missing, EnvUser)
	}
	if c.Password == "" {
		missing = append(missing, EnvPassword)
	}
	if c.Context == "" {
		missing = append(missing, EnvContext)
	}
	if len(missing) > 0 {
		return c, fmt.Errorf("missing environment variable(s): %s", strings.Join(missing, ", "))
	}
	return c, nil
}