config.go

package main

import (
	"encoding/json"
	"errors"
	"io"
	"os"
	"path/filepath"
)

type config struct {
	BotName               string `json:"bot_name"`                // the name of the bot
	MailAddress           string `json:"mail_address"`            // the address to listen to incoming mail
	MaxSize               int    `json:"max_size"`                // the maximum email size in bytes
	MaxTextChunkSize      int    `json:"max_text_chunk_size"`     // the maximum text chunk size
	ListenPath            string `json:"listen_path"`             // the path excluding domain to listen to, the good choice is "/your-telegram-bot-token"
	ListenAddress         string `json:"listen_address"`          // the address to listen to incoming telegram messages
	Host                  string `json:"host"`                    // the host name for the email addresses and the webhook
	BotToken              string `json:"bot_token"`               // your telegram bot token
	FreeEmails            int    `json:"free_emails"`             // number of free emails on first start
	ReferralBonus         int    `json:"referral_bonus"`          // number of emails for a referrer
	FollowerBonus         int    `json:"follower_bonus"`          // number of emails for a new user registered by a referral link
	TimeoutSeconds        int    `json:"timeout_seconds"`         // HTTP timeout
	AdminID               int64  `json:"admin_id"`                // admin telegram ID
	DBPath                string `json:"db_path"`                 // path to the database
	Debug                 bool   `json:"debug"`                   // debug mode
	StatPassword          string `json:"stat_password"`           // password for statistics
	Certificate           string `json:"certificate"`             // certificate path for STARTTLS
	CertificateKey        string `json:"certificate_key"`         // certificate key path for STARTTLS
	LimitIntervalSeconds  int    `json:"limit_interval_seconds"`  // the limit interval
	LimitWindowSeconds    int    `json:"limit_window_seconds"`    // the limit window
	BlockedBackoffSeconds int    `json:"blocked_backoff_seconds"` // a backoff if user blocked the bot
}

func readConfig(path string) *config {
	file, err := os.Open(filepath.Clean(path))
	checkErr(err)
	defer func() { checkErr(file.Close()) }()
	return parseConfig(file)
}

func parseConfig(r io.Reader) *config {
	decoder := json.NewDecoder(r)
	decoder.DisallowUnknownFields()
	cfg := &config{}
	err := decoder.Decode(cfg)
	checkErr(err)
	checkErr(checkConfig(cfg))
	return cfg
}

func checkConfig(cfg *config) error {
	if cfg.BotName == "" {
		return errors.New("configure bot_name")
	}
	if cfg.MailAddress == "" {
		return errors.New("configure mail_address")
	}
	if cfg.MaxSize == 0 {
		return errors.New("configure max_size")
	}
	if cfg.MaxTextChunkSize == 0 {
		return errors.New("configure max_text_chunk_size")
	}
	if cfg.ListenAddress == "" {
		return errors.New("configure listen_address")
	}
	if cfg.ListenPath == "" {
		return errors.New("configure listen_path")
	}
	if cfg.BotToken == "" {
		return errors.New("configure bot_token")
	}
	if cfg.TimeoutSeconds == 0 {
		return errors.New("configure timeout_seconds")
	}
	if cfg.AdminID == 0 {
		return errors.New("configure admin_id")
	}
	if cfg.DBPath == "" {
		return errors.New("configure db_path")
	}
	if cfg.StatPassword == "" {
		return errors.New("configure stat_password")
	}
	if cfg.FreeEmails == 0 {
		return errors.New("configure free_emails")
	}
	if cfg.ReferralBonus == 0 {
		return errors.New("configure referral_bonus")
	}
	if cfg.FollowerBonus == 0 {
		return errors.New("configure follower_bonus")
	}
	if cfg.Certificate == "" {
		return errors.New("configure certificate")
	}
	if cfg.CertificateKey == "" {
		return errors.New("configure certificate_key")
	}
	if cfg.LimitIntervalSeconds == 0 {
		return errors.New("configure limit_interval_seconds")
	}
	if cfg.LimitWindowSeconds == 0 {
		return errors.New("configure limit_window_seconds")
	}
	if cfg.BlockedBackoffSeconds == 0 {
		return errors.New("configure blocked_backoff_seconds")
	}
	return nil
}