package mailfull

import (
	"bufio"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"sort"
	"strings"
)

// Errors for parameter.
var (
	ErrNotEnoughAliasUserTargets = errors.New("AliasUser: targets not enough")
)

// AliasUser represents a AliasUser.
type AliasUser struct {
	name    string
	targets []string
}

// NewAliasUser creates a new AliasUser instance.
func NewAliasUser(name string, targets []string) (*AliasUser, error) {
	au := &AliasUser{}

	if err := au.setName(name); err != nil {
		return nil, err
	}

	if err := au.SetTargets(targets); err != nil {
		return nil, err
	}

	return au, nil
}

// setName sets the name.
func (au *AliasUser) setName(name string) error {
	if !validAliasUserName(name) {
		return ErrInvalidAliasUserName
	}

	au.name = name

	return nil
}

// Name returns name.
func (au *AliasUser) Name() string {
	return au.name
}

// SetTargets sets targets.
func (au *AliasUser) SetTargets(targets []string) error {
	if len(targets) < 1 {
		return ErrNotEnoughAliasUserTargets
	}

	for _, target := range targets {
		if !validAliasUserTarget(target) {
			return ErrInvalidAliasUserTarget
		}
	}

	au.targets = targets

	return nil
}

// Targets returns targets.
func (au *AliasUser) Targets() []string {
	return au.targets
}

// AliasUsers returns a AliasUser slice.
func (r *Repository) AliasUsers(domainName string) ([]*AliasUser, error) {
	domain, err := r.Domain(domainName)
	if err != nil {
		return nil, err
	}
	if domain == nil {
		return nil, ErrDomainNotExist
	}

	file, err := os.Open(filepath.Join(r.DirMailDataPath, domainName, FileNameAliasUsers))
	if err != nil {
		return nil, err
	}
	defer file.Close()

	aliasUsers := make([]*AliasUser, 0, 50)

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		words := strings.Split(scanner.Text(), ":")
		if len(words) != 2 {
			return nil, ErrInvalidFormatAliasUsers
		}

		name := words[0]
		targets := strings.Split(words[1], ",")

		aliasUser, err := NewAliasUser(name, targets)
		if err != nil {
			return nil, err
		}

		aliasUsers = append(aliasUsers, aliasUser)
	}

	if err := scanner.Err(); err != nil {
		return nil, err
	}

	return aliasUsers, nil
}

// AliasUser returns a AliasUser of the input name.
func (r *Repository) AliasUser(domainName, aliasUserName string) (*AliasUser, error) {
	aliasUsers, err := r.AliasUsers(domainName)
	if err != nil {
		return nil, err
	}

	for _, aliasUser := range aliasUsers {
		if aliasUser.Name() == aliasUserName {
			return aliasUser, nil
		}
	}

	return nil, nil
}

// AliasUserCreate creates the input AliasUser.
func (r *Repository) AliasUserCreate(domainName string, aliasUser *AliasUser) error {
	aliasUsers, err := r.AliasUsers(domainName)
	if err != nil {
		return err
	}

	for _, au := range aliasUsers {
		if au.Name() == aliasUser.Name() {
			return ErrAliasUserAlreadyExist
		}
	}
	existUser, err := r.User(domainName, aliasUser.Name())
	if err != nil {
		return err
	}
	if existUser != nil {
		return ErrUserAlreadyExist
	}

	aliasUsers = append(aliasUsers, aliasUser)

	if err := r.writeAliasUsersFile(domainName, aliasUsers); err != nil {
		return err
	}

	return nil
}

// AliasUserUpdate updates the input AliasUser.
func (r *Repository) AliasUserUpdate(domainName string, aliasUser *AliasUser) error {
	aliasUsers, err := r.AliasUsers(domainName)
	if err != nil {
		return err
	}

	idx := -1
	for i, au := range aliasUsers {
		if au.Name() == aliasUser.Name() {
			idx = i
		}
	}
	if idx < 0 {
		return ErrAliasUserNotExist
	}

	aliasUsers[idx] = aliasUser

	if err := r.writeAliasUsersFile(domainName, aliasUsers); err != nil {
		return err
	}

	return nil
}

// AliasUserRemove removes a AliasUser of the input name.
func (r *Repository) AliasUserRemove(domainName string, aliasUserName string) error {
	aliasUsers, err := r.AliasUsers(domainName)
	if err != nil {
		return err
	}

	idx := -1
	for i, aliasUser := range aliasUsers {
		if aliasUser.Name() == aliasUserName {
			idx = i
		}
	}
	if idx < 0 {
		return ErrAliasUserNotExist
	}

	aliasUsers = append(aliasUsers[:idx], aliasUsers[idx+1:]...)

	if err := r.writeAliasUsersFile(domainName, aliasUsers); err != nil {
		return err
	}

	return nil
}

// writeAliasUsersFile writes a AliasUser slice to the file.
func (r *Repository) writeAliasUsersFile(domainName string, aliasUsers []*AliasUser) error {
	if !validDomainName(domainName) {
		return ErrInvalidDomainName
	}

	file, err := os.OpenFile(filepath.Join(r.DirMailDataPath, domainName, FileNameAliasUsers), os.O_RDWR|os.O_TRUNC, 0600)
	if err != nil {
		return err
	}
	defer file.Close()

	sort.Slice(aliasUsers, func(i, j int) bool { return aliasUsers[i].Name() < aliasUsers[j].Name() })

	for _, aliasUser := range aliasUsers {
		if _, err := fmt.Fprintf(file, "%s:%s\n", aliasUser.Name(), strings.Join(aliasUser.Targets(), ",")); err != nil {
			return err
		}
	}

	return nil
}