server

package main

import (
	"encoding/json"
	"os"
)

// Config is used to configure your email server.
// Port is used to specify which port the server should listen
// to connections, a typicall value is 2525.
// Domain is what the server should respond in a HELO or EHLO request.
// VaultFile is the path to a json file containing the list of users
// that can send email.
// In order to use TLS connections Certficate and PrivateKey fields
// must have valid path to pem encoded keys.
type Config struct {
	Port              string
	Domain            string
	Certificate       string
	PrivateKey        string
	VaultFile         string
	ReadTimeout       int
	WriteTimeout      int
	MaxMessageBytes   int64
	MaxRecipients     int
	AllowInsecureAuth bool
}

// Vault interface gives validation and user fetching.
type Vault interface {
	Validate(n, p string) bool
	GetUser(n string) User
}

// User represents a user that should be able to send emails. This struct is
// found in the users json file, that is on the path pointed by VaultFile field
// in [Config].
type User struct {
	Name       string
	Email      string
	Password   string
}

type store struct {
	users []User
}

func NewStore(path string) (Vault, error) {
	f, err := os.Open(path)
	if err != nil {
		return nil, err
	}

	s := store{users: []User{}}
	json.NewDecoder(f).Decode(&s.users)
	return s, err
}

func (s store) Validate(n, p string) bool {
	u := s.GetUser(n)
	return u.Password == p
}

func (s store) GetUser(n string) User {
	for _, u := range s.users {
		if u.Name == n {
			return u
		}
	}
	return User{}
}