package main

import (
	"bytes"
	"errors"
	"fmt"
	"net/mail"
	"os"
	"os/exec"
	"regexp"
	"strings"

	"git.tilde.town/tildetown/town/invites"
	"git.tilde.town/tildetown/town/sshkey"
	"git.tilde.town/tildetown/town/stats"
	"github.com/AlecAivazis/survey/v2"
	"github.com/charmbracelet/lipgloss"

	_ "embed"
)

//go:embed welcome.txt
var welcomeArt string

// TODO move magic key machine to static page

type newUserData struct {
	Username    string
	DisplayName string
	Email       string
	PubKey      string
}

func surveyIconSet(icons *survey.IconSet) {
	icons.Question.Text = "~"
	icons.Question.Format = "magenta:b"
}

func promptCode() (code string, err error) {
	err = survey.AskOne(&survey.Input{
		Message: "invite code?",
	}, &code,
		survey.WithValidator(survey.Required),
		survey.WithIcons(surveyIconSet))
	code = strings.TrimSpace(code)
	return
}

func confirmContinue() (conf bool, err error) {
	err = survey.AskOne(
		&survey.Confirm{
			Message: "Does the above look ok?",
		}, &conf,
		survey.WithValidator(survey.Required),
		survey.WithIcons(surveyIconSet))
	return
}

type asker struct {
	UserData *newUserData
	Style    lipgloss.Style
	Invite   invites.Invite
	TownData stats.TildeData
}

func (a *asker) Ask() (err error) {
	// TODO somehow un and email getting set to "" but pubkey works fine?

	if err = a.promptUsername(); err != nil {
		return err
	}

	if err = a.promptEmail(); err != nil {
		return err
	}

	if err = a.promptKey(); err != nil {
		return err
	}

	s := a.Style.SetString(
		fmt.Sprintf(`ok! your account is about to be created with the following details:

username: %s
email: %s
pubkey: %s`, a.UserData.Username, a.UserData.Email, a.UserData.PubKey)).Bold(true).MaxWidth(80)

	fmt.Println(s)

	return nil
}

func (a *asker) promptUsername() (err error) {
	// copied from /etc/adduser.conf
	usernameRE := regexp.MustCompile(`^[a-z][-a-z0-9_]*$`)
	err = survey.AskOne(
		&survey.Input{
			Message: "desired username?",
			Default: a.UserData.Username,
		}, &a.UserData.Username,
		survey.WithValidator(survey.Required),
		survey.WithIcons(surveyIconSet),
		survey.WithValidator(func(val interface{}) error {
			un := val.(string)
			if len(un) > 32 {
				return fmt.Errorf("username '%s' is too long", un)
			}
			return nil
		}),
		survey.WithValidator(func(val interface{}) error {
			un := val.(string)
			if !usernameRE.MatchString(un) {
				return errors.New("usernames must start with a letter and only contain letters, nubers, - or _")
			}
			return nil
		}),
		survey.WithValidator(func(val interface{}) error {
			un := val.(string)
			for _, v := range a.TownData.Users {
				if v.Username == un {
					return fmt.Errorf("username '%s' is already in use", un)
				}
			}
			return nil
		}))

	return
}

func (a *asker) promptEmail() (err error) {
	err = survey.AskOne(
		&survey.Input{
			Message: "e-mail (for account recovery only)?",
			Default: a.UserData.Email,
		}, &a.UserData.Email,
		survey.WithValidator(survey.Required),
		survey.WithIcons(surveyIconSet),
		survey.WithValidator(func(val interface{}) error {
			email := val.(string)
			_, err := mail.ParseAddress(email)
			if err != nil {
				return fmt.Errorf("'%s' doesn't look like an email: %w", email, err)
			}

			if !strings.Contains(email, ".") {
				return fmt.Errorf("'%s' doesn't look like an email: domain not fully qualified", email)
			}

			return nil
		}))

	return
}

func (a *asker) promptKey() (err error) {
	err = survey.AskOne(
		&survey.Input{
			Message: "SSH public key?",
			Default: a.UserData.PubKey,
		}, &a.UserData.PubKey,
		survey.WithValidator(survey.Required),
		survey.WithIcons(surveyIconSet),
		survey.WithValidator(func(v interface{}) error {
			key := v.(string)
			valid, err := sshkey.ValidKey(key)
			if err != nil {
				return fmt.Errorf("failed to validate key: %w", err)
			}
			if !valid {
				return errors.New("that doesn't seem like a valid SSH key. try another public key?")
			}
			return nil
		}))

	return
}

func _main() error {
	inviteDB, err := invites.ConnectDB()
	if err != nil {
		return err
	}

	s := lipgloss.NewStyle().
		Foreground(lipgloss.AdaptiveColor{
			Light: "#7D19BD",
			Dark:  "#E0B0FF",
		})

	s = s.SetString(welcomeArt)
	fmt.Println(s)

	code, err := promptCode()
	if err != nil {
		return err
	}

	invite, err := invites.Get(inviteDB, code)
	if err != nil {
		return fmt.Errorf("could not look up invite code: %w", err)
	}

	if invite.Used {
		return errors.New("that invite code has already been used.")
	}

	s = s.SetString("thanks!! just gotta collect some information now and then your account will be ready.")

	fmt.Println(s)

	townData, err := stats.Stats()
	if err != nil {
		return err
	}
	data := &newUserData{
		Email: invite.Email,
	}

	a := &asker{
		UserData: data,
		Invite:   *invite,
		TownData: townData,
		Style:    s,
	}

	if err = a.Ask(); err != nil {
		return err
	}

	conf, err := confirmContinue()
	if err != nil {
		return err
	}

	if !conf {
		for !conf {
			if err = a.Ask(); err != nil {
				return err
			}
			if conf, err = confirmContinue(); err != nil {
				return err
			}
		}
	}

	s = s.SetString("cool, awesome, going to make your account now...")
	fmt.Println(s)

	if err = createUser(*data); err != nil {
		s = s.SetString(fmt.Sprintf(`augh, I'm sorry. the account creation failed.
Please email root@tilde.town and paste the following error:

%s

Your invite code has not been marked as used and you're welcome to try again, though if there is a system issue you might need to wait for word from an admin.`, err.Error()))
		fmt.Println(s)
		return nil
	}

	// TODO assuming account creation succeeded, mark invite as used

	return nil
}

// TODO add logging like the signup tool has

func createUser(data newUserData) (err error) {
	cmd := exec.Command("sudo", "/usr/sbin/adduser", "--quiet", "--disabled-password", data.Username)
	if err = cmd.Run(); err != nil {
		return fmt.Errorf("adduser failed: %w", err)
	}

	cmd = exec.Command("sudo", "/usr/sbin/usermod", "-a", "-G", "town", data.Username)
	if err = cmd.Run(); err != nil {
		return fmt.Errorf("usermod failed: %w", err)
	}

	cmd = exec.Command("sudo", "/town/bin/createkeyfile", data.Username)
	cmd.Stdin = bytes.NewBufferString(keyfileText(data))
	if err = cmd.Run(); err != nil {
		return fmt.Errorf("createkeyfile failed: %w", err)
	}

	cmd = exec.Command("sudo", "/town/bin/generate_welcome_present.sh", data.Username)
	if err = cmd.Run(); err != nil {
		// TODO log this. no reason to bail out.
	}

	// TODO any alerts

	return nil
}

func keyfileText(data newUserData) string {
	header := `########## GREETINGS! ##########
# Hi! This file was automatically generated by tilde.town when
# your account was created. You can edit it if you want, but we
# recommend adding stuff to ~/.ssh/authorized_keys instead.`

	return fmt.Sprintf("%s\n%s", header, data.PubKey)
}

func main() {
	// TODO friendlier error handling
	err := _main()
	if err != nil {
		fmt.Fprintln(os.Stderr, err)
		os.Exit(1)
	}
}