papero/config/config.go

package config

import (
	"bufio"
	"errors"
	"fmt"
	"log"
	"os"
	"path"
	"strings"

	"git.sr.ht/~blallo/papero/worker"
	"github.com/mitchellh/go-homedir"
)

var ErrPortOutOfRange = errors.New("port out of range")
var ErrMissingPassword = errors.New("password has not been set")
var ErrMissingDefaultAccount = errors.New("default_account is missing from config")

// CastingErrors is a simple wrapper around map[string]error. It's endowed with a utility
// function to check if there are any errors.
type CastingErrors struct {
	GeneralErrors []error
	AccountErrors map[string]error
}

func initCastingErrors() *CastingErrors {
	c := CastingErrors{}
	c.AccountErrors = make(map[string]error)
	return &c
}

func (c *CastingErrors) appendGeneralError(e error) {
	c.GeneralErrors = append(c.GeneralErrors, e)
}

func (c *CastingErrors) String() string {
	out := "CastingErrors{"
	out += fmt.Sprintf("GeneralErrors: %s, ", c.GeneralErrors)
	out += fmt.Sprintf("AccountErrors: %s", c.AccountErrors)
	out += "}"
	return out
}

// Check if there are any errors, i.e. if any value of the map is not nil.
func (c CastingErrors) Check() bool {
	if len(c.GeneralErrors) != 0 {
		return false
	}
	for _, err := range c.GeneralErrors {
		if err != nil {
			return false
		}
	}
	return true
}

// MemConfig is the data structure that will be used program-wise. It holds all the
// necessary information to authenticate and manage each provided account.
type MemConfig struct {
	Default  string
	Accounts map[string]*AccountData
	Workers  map[string]*worker.Worker
}

func initMemConfig() MemConfig {
	m := MemConfig{}
	m.Accounts = make(map[string]*AccountData)
	m.Workers = make(map[string]*worker.Worker)
	return m
}

// AccountData holds the data for the single account.
type AccountData struct {
	Host            string
	Port            int
	Username        string
	Password        string
	ExcludedFolders []string
	MailboxPath     string
	Messages        int
}

func (a *AccountData) String() string {
	var res string
	res = "{"
	res += fmt.Sprintf("Host: %s, ", a.Host)
	res += fmt.Sprintf("Port: %d, ", a.Port)
	res += fmt.Sprintf("Username: %s, ", a.Username)
	res += fmt.Sprintf("Password: ********, ")
	res += fmt.Sprintf("ExcludedFolders: %s, ", a.ExcludedFolders)
	res += fmt.Sprintf("MailboxPath: %s}", a.MailboxPath)
	res += fmt.Sprintf("Messages: %d}", a.Messages)
	return res
}

// parseConfig translates a *fileConfig, as obtained from a file read, into a usable
// *MemConfig that could be used in computation, together with a custom *CastingErrors
// type, that holds the translation errors for each account.
func parseConfig(fileConfig *fileConfig) (*MemConfig, *CastingErrors) {
	errors := initCastingErrors()
	outConfig := initMemConfig()
	defaultAccount := fileConfig.Default
	if defaultAccount == "" {
		errors.appendGeneralError(ErrMissingDefaultAccount)
	}
	outConfig.Default = defaultAccount
	basePath, err := getOrDefaultMailbox(fileConfig.MailboxPath)
	defaultMessages := getOrDefaultMessages(fileConfig.DefaultMessages)
	if err != nil {
		log.Fatal("Could not determine base path")
	}
	for _, account := range fileConfig.Accounts {
		outConfig.Accounts[account.Name], errors.AccountErrors[account.Name] = parseData(&account, basePath, defaultMessages)
		outConfig.Workers[account.Name] = &worker.Worker{}
	}
	return &outConfig, errors
}

func getOrDefaultMailbox(mailboxPath string) (string, error) {
	if mailboxPath == "" {
		if homePath, err := homedir.Dir(); err != nil {
			return "", err
		} else {
			return path.Join(homePath, ".papero"), nil
		}
	}
	return mailboxPath, nil
}

func getOrDefaultMessages(messages maybeInt) int {
	if messages.empty() {
		return 50
	}
	return messages.value()
}

func valueOrEmptySlice(value []string) []string {
	if value == nil {
		return []string{}
	}
	return value
}

func valueOrDefaultInt(value maybeInt, defaultVal int) int {
	if value.empty() {
		return defaultVal
	}
	return value.value()
}

func parseData(a *account, basePath string, defaultMessages int) (*AccountData, error) {
	port, err := validatePort(a.ConnectionInfo.Port)
	if err != nil {
		return nil, err
	}
	password, err := getPassword(a.ConnectionInfo)
	if err != nil {
		return nil, err
	}
	accountData := AccountData{
		Host:            a.ConnectionInfo.Host,
		Port:            port,
		Username:        a.ConnectionInfo.Username,
		Password:        password,
		ExcludedFolders: valueOrEmptySlice(a.ExcludedFolders),
		MailboxPath:     getMailboxPath(a.Name, a.MailboxPath, basePath),
		Messages:        valueOrDefaultInt(a.Messages, defaultMessages),
	}
	return &accountData, nil
}

func validatePort(port int) (int, error) {
	if port > 0 && port < 2<<15 {
		return port, nil
	}
	return 0, ErrPortOutOfRange
}

func getPassword(connection *connectionInfo) (string, error) {
	if connection.PasswordExec.Present() {
		pass, err := connection.PasswordExec.Run()
		if err != nil {
			return "", err
		}
		return strings.TrimRight(pass, "\n"), nil
	}
	if connection.PasswordFile != "" {
		file, err := os.Open(connection.PasswordFile)
		if err != nil {
			return "", err
		}
		reader := bufio.NewReader(file)
		line, _, err := reader.ReadLine()
		return string(line), err
	}
	if connection.Password == "" {
		return "", ErrMissingPassword
	}
	return connection.Password, nil
}

func getMailboxPath(name, configPath, basePath string) string {
	if configPath != "" {
		if info, err := os.Stat(configPath); err == nil || err != os.ErrNotExist && info != nil {
			if info.IsDir() {
				return configPath
			}
		}
	}
	return path.Join(basePath, name)
}