package scsusers

import (
	"bytes"
	"database/sql"
	"fmt"
	"github.com/jmoiron/sqlx"
	"golang.org/x/crypto/bcrypt"
	"html/template"
	"log"
	"crypto/rand"
	"encoding/json"
	"encoding/base32"
	"net/smtp"
	"strings"
)


type templates struct {
	Registration *template.Template
	Alert        *template.Template
	Recovery     *template.Template
}

type config struct {
	SiteName    string
	FromEmail   string
	Templates   templates
	SMTPServer string
	db          *sqlx.DB
	TablePrefix string
}

type UserData struct {
	Username string `json:"username"`
	UserPerms map[string]string `json:"perms"`
	UserSettings map[string]string `json:"settings"`
}

var c config

func Init(dbin *sqlx.DB, tp, sitename, fromaddr, smtpserver string) {
	c.db = dbin
	c.TablePrefix = tp
	c.SiteName = sitename
	c.FromEmail = fromaddr
	c.SMTPServer=smtpserver

	SetRegistrationTemplate("")
	SetAlertTemplate("")
	SetRecoveryTemplate("")
}

func UsernameAvailable(username string) bool {
	if len(username)==0 {
		return false
	}
	var u string
	q := fmt.Sprintf("select username from %s_auth where username=$1", c.TablePrefix)
	err := c.db.Get(&u, q, username)
	if err == sql.ErrNoRows {
		return true
	}
	if err != nil {
		log.Printf("UsernameAvailable returned error: " + err.Error() + " Query was " + q)
		return false
	}
	return false
}

/* Check for username availability, add to database, send email */

func Register(username, email, ip string) bool {
	if !UsernameAvailable(username) {
		return false
	}
	pass := randBytes(16)
	crypt, err := bcrypt.GenerateFromPassword(pass, 10)
	if err != nil {
		log.Printf("scsusers.Register: Bcrypt GenerateFromPassword failed? Pass is %s and error is %s\n", pass, err.Error())
		return false
	}
	q := fmt.Sprintf("insert into %s_auth (username, email, password, registration_date, registration_ip) values ($1, $2, $3, CURRENT_TIMESTAMP, $4)", c.TablePrefix)
	_, err = c.db.Exec(q, username, email, crypt, ip)
	if err != nil {
		log.Printf("scsusers.Register: insert failed: %s\n", err.Error())
		return false
	}
	if sendRegistrationEmail(email, username, string(pass)) {
		log.Printf("scsusers.Register: New user registration: %s from %s\n", username, ip)
		return true
	}
	log.Printf("scsusers.Register: Failed to send registration email, deleting user %s\n", username)
	q=fmt.Sprintf("delete from %s_auth where username=$1 AND password=$2", c.TablePrefix)
	_,err = c.db.Exec(q, username, string(crypt))
	if err != nil {
		log.Printf("scsusers.Register: Failed to delete new user %s: %s\n", username, err.Error())
	}
	return false
}

func Login(username, password string) bool {
	log.Printf("scsusers.Login: Attempting login for %s\n", username)
	q:=fmt.Sprintf("select password from %s_auth where username=$1 AND status='active'",c.TablePrefix)
	var crypt string
	err:=c.db.Get(&crypt, q, username)
	if err != nil {
		log.Printf("scsusers.Login: Failed login attempt for unknown username: %s\n", username)
		return false
	}
	if bcrypt.CompareHashAndPassword([]byte(crypt), []byte(password)) != nil {
		log.Printf("scsusers.Login: Failed password for " + username)
		return false
	}
	Bump(username)
	return true
}

func ChangePassword(username, oldpass, newpass string) bool {
	log.Println("scsusers.ChangePassword: Attempting password change for "+ username)
	q:=fmt.Sprintf("select password from %s_auth where username=$1 AND status='active'",c.TablePrefix)
	var crypt string
	err:=c.db.Get(&crypt, q, username)
	if err != nil {
		log.Println("scsusers.ChangePassword: Failed change attempt for unknown username: " + username)
		return false
	}
	if bcrypt.CompareHashAndPassword([]byte(crypt), []byte(oldpass)) != nil {
		log.Printf("scsusers.ChangePassword: Failed password for %s\n",  username)
		return false
	}
	newcrypt, err := bcrypt.GenerateFromPassword([]byte(newpass), 10)
	q=fmt.Sprintf("update %s_auth set password=$2 where username=$1", c.TablePrefix)
	_,err=c.db.Exec(q, username, newcrypt)
	if err!= nil {
		log.Printf("scsusers.ChangePassword: update failed for %s: %s\n", username, err.Error())
		return false
	}
	Bump(username)
	return true
	
}
func LoadUser(username string) (UserData, error) {
	var u UserData
	q:=fmt.Sprintf("select data from %s_userdata where username=$1", c.TablePrefix)
	var d string
	err:=c.db.Get(d, q, username)
	if err != nil {
		log.Printf("scsusers.LoadUser: Error loading user: %s : %s\n", username, err.Error())
		return u, err
	}
	err=json.Unmarshal([]byte(d), &u)
	if err != nil {
		log.Printf("scsusers.LoadUser: Error decoding json on user %s. Unmarshal returned %s\n", username, err.Error())
	}
	return u,err
}

func SaveUser(username string, d UserData) bool {
	q:=fmt.Sprintf("update %s_userdata set data=$1 where username=$2")
	j, err:=json.Marshal(d)
	if err != nil {
		log.Printf("scsusers.SaveUser: json.Marshal failed for username %s : %s\n", username, err.Error())
		return false
	}
	_, err=c.db.Exec(q, username, j)
	if err != nil {
		log.Printf("scsusers.SaveUser: db.Exec failed for username %s : %s\n", username, err.Error())
		return false
	}
	return true
	
}

func Bump(username string) {
	q:=fmt.Sprintf("update %s_auth set lastseen=CURRENT_TIMESTAMP where username=$1", c.TablePrefix)
	_, err :=c.db.Exec(q, username)
	if err != nil {
		log.Printf("scsusers.Bump: Error on user bump: %s : %s\n", username,  err.Error())
	}
}
func RecoverByUsername(u string) {
	var username, email string
	q:=fmt.Sprintf("select username, email from %s_auth where username=$1", c.TablePrefix)
	row:=c.db.QueryRow(q, u)
	err:=row.Scan(&username, &email)
	if err!=sql.ErrNoRows {
		recoverycode:=randBytes(16)
		qq:=fmt.Sprintf("update %s_auth set recoverycode=$1, recoverytime=NOW() where username=$2", c.TablePrefix)
		_,err:=c.db.Exec(qq, recoverycode, username)
		if err==nil {
			sendRecoveryEmail(email, username, string(recoverycode))
		}
	}
}

func RecoverByEmail(e string) {
	var username, email string
	q:=fmt.Sprintf("select username, email from %s_auth where email=$1", c.TablePrefix)
	row:=c.db.QueryRow(q, e)
	err:=row.Scan(&username, &email)
	if err!=sql.ErrNoRows {
		recoverycode:=randBytes(16)
		qq:=fmt.Sprintf("update %s_auth set recoverycode=$1, recoverytime=NOW() where username=$2", c.TablePrefix)
		_,err:=c.db.Exec(qq, recoverycode, username)
		if err==nil {
			sendRecoveryEmail(email, username, string(recoverycode))
		}
	}
}


func randBytes(n int) []byte {
   randomBytes := make([]byte, 32)
    _, err := rand.Read(randomBytes)
    if err != nil {
        panic(err)
    }
    return []byte(base32.StdEncoding.EncodeToString(randomBytes)[:n])
}

func sendRegistrationEmail(recipient, username, password string) bool {
	data := struct {
		SiteName  string
		FromEmail string
		UserName  string
		Pass      string
	}{
		SiteName:  c.SiteName,
		FromEmail: c.FromEmail,
		UserName:  username,
		Pass:      password,
	}
	var body bytes.Buffer
	err := c.Templates.Registration.Execute(&body, data)
	if err != nil {
		log.Printf("scsusers.sendRegistrationEmail: Registration template failed to execute: %v returned %s\n", data, err.Error())
		return false
	}
	subject := fmt.Sprintf("Welcome to %s", c.SiteName)
	err = SendMail(c.SMTPServer, c.FromEmail, subject, body.String(), recipient)
	if err != nil {
		log.Printf("scsusers.SendRegistrationEmail: Error sending mail to %s: %s\n", recipient, err.Error())
		return false
	}
	return true
}


func sendAlertEmail(username, recipient, message string) bool {
	data := struct {
		SiteName  string
		FromEmail string
		UserName  string
		Activity      string
	}{
		SiteName:  c.SiteName,
		FromEmail: c.FromEmail,
		UserName:  username,
		Activity:  message,
	}
	var body bytes.Buffer
	err := c.Templates.Registration.Execute(&body, data)
	if err != nil {
		log.Printf("scsusers.sendAlertEmail: Alert template failed to execute: %v returned %s\n", data, err.Error())
		return false
	}
	
	subject := fmt.Sprintf("New activity on %s", c.SiteName)
	err = SendMail(c.SMTPServer,  c.FromEmail, subject, body.String(), recipient)
	if err != nil {
		log.Printf("scsusers.sendAlertEmail: Error sending mail to %s: %s\n", recipient, err.Error())
		return false
	}
	return true
}

func sendRecoveryEmail(recipient, username, code string) bool {
	data := struct {
		SiteName  string
		FromEmail string
		UserName  string
		RecoveryCode      string
	}{
		SiteName:  c.SiteName,
		FromEmail: c.FromEmail,
		UserName:  username,
		RecoveryCode:      code,
	}
	var body bytes.Buffer
	err := c.Templates.Registration.Execute(&body, data)
	if err != nil {
		log.Printf("scsusers.sendRecoveryEmail: Recovery template failed to execute: %v returned %s\n", data, err.Error())
		return false
	}
	subject := fmt.Sprintf("Account recovery at %s", c.SiteName)
	err = SendMail(c.SMTPServer, c.FromEmail, subject, body.String(), recipient)
	if err != nil {
		log.Printf("scsusers.sendRecoveryEmail: Error sending mail to %s: %s\n", recipient, err.Error())
		return false
	}
	return true
}


func SetRegistrationTemplate(t string) bool {
	if len(t) != 0 {
		r, err := template.New("reg").Parse(t)
		if err != nil {
			c.Templates.Registration = r
			return true
		}
	}
	df := `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html></head><body><p>Hello {{.UserName}}! Welcome to {{.SiteName}}! We've created your account with the username you selected and the following password: {{.Pass}}<br>You can change your password to whatever you want once you log in.</p></body></html>`

	r, err := template.New("reg").Parse(df)
	if err != nil {
		log.Fatal("scsusers.SetRegistrationTemplate: Default registration template MUST compile. Error: " + err.Error())
	}
	c.Templates.Registration = r

	return false
}

func SetAlertTemplate(t string) bool {
	if len(t) != 0 {
		r, err := template.New("alert").Parse(t)
		if err != nil {
			c.Templates.Alert = r
			return true
		}
	}
	df := `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html></head><body><p>    Hey {{.UserName}}! Just letting you know that {{.Activity}}.<br>    You can disable future notifications in your user settings.</p></body></html>`
	r, err := template.New("alert").Parse(df)
	if err != nil {
		log.Fatal("scsusers.SetAlertTemplate: Default alert template MUST compile. Error: " + err.Error())
	}
	c.Templates.Alert = r
	return false
}

func SetRecoveryTemplate(t string) bool {
	if len(t) != 0 {
		r, err := template.New("recovery").Parse(t)
		if err != nil {
			c.Templates.Recovery = r
			return true
		}
	}
	df := `<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html></head><body><p>Hello {{.UserName}}! Someone (hopefully you) has attempted an account recovery agt {{.SiteName}}. If this was you, enter the following code to regain access: {{.RecoveryCode}}<br>    If this was not you, you can ignore this email.</p></body></html>`
	r, err := template.New("recovery").Parse(df)
	if err != nil {
		log.Fatal("scsusers.SetRecoveryTemplate: Default recovery template MUST compile. Error: " + err.Error())
	}
	c.Templates.Recovery = r

	return false
}

func SendMail(addr, from, subject, body string, to string) error {
	r := strings.NewReplacer("\r\n", "", "\r", "", "\n", "", "%0a", "", "%0d", "")

	c, err := smtp.Dial(addr)
	if err != nil {
		return err
	}
	defer c.Close()
	if err = c.Mail(r.Replace(from)); err != nil {
		return err
	}
	to = r.Replace(to)
	if err = c.Rcpt(to); err != nil {
		return err
	}

	w, err := c.Data()
	if err != nil {
		return err
	}

	msg := "To: " + to + "\r\n" +
		"From: " + from + "\r\n" +
		"Subject: " + subject + "\r\n" +
		"Content-Type: text/html; charset=\"UTF-8\"\r\n" +
		"\r\n" + body

	_, err = w.Write([]byte(msg))
	if err != nil {
		return err
	}
	err = w.Close()
	if err != nil {
		return err
	}
	return c.Quit()
}