package usermanager

import (
  "errors"
  "time"
  "math/rand"
  "strconv"
  "git.mmnx.de/Moe/databaseutils"
  "git.mmnx.de/Moe/configutils"
  "github.com/dgrijalva/jwt-go"
  "github.com/kataras/iris"
  "golang.org/x/crypto/bcrypt"
  "fmt"
)

var (
  Users *[]User // stores all currently logged in users
)

const ( // Error constants
  ERR_USER_NOT_FOUND = "ERR_USER_NOT_FOUND"
  ERR_PASSWORD_MISMATCH = "ERR_PASSWORD_MISMATCH"
  ERR_SESSION_TIMED_OUT = "ERR_SESSION_TIMED_OUT"
  ERR_INVALID_TOKEN = "ERR_INVALID_TOKEN"
  ERR_USERNAME_TAKEN = "ERR_USERNAME_TAKEN"
)

type User struct { // User
  ID string
  Username string
  Password string
  Admin string
  TokenUsed string
}

type PageParams struct{
  HasError string
  Error string
  ReqDir string
  Admin string
  }

type PageUserParams struct{
  HasError string
  Error string
  ReqDir string
  Username string
  Admin string
  Custom []string
  }

type PageUserParamsMessage struct{
  HasError string
  Error string
  ReqDir string
  Username string
  Email string
  Admin string
  Message string
  }

func (user *User) Login(username string, password string) (string, error) {
  hmacSampleSecret := []byte(configutils.Conf.CryptoKey) // crypto key for JWT encryption
  row, err := databaseutils.DBUtil.GetRow("*", "users", "username", username) // get user from db

  if err != nil {
    if err.Error() == databaseutils.ERR_EMPTY_RESULT { // empty result -> user not found
      return "", errors.New(ERR_USER_NOT_FOUND)
    } else {
      return "", errors.New("Unknown error")
    }
  }

  err = bcrypt.CompareHashAndPassword([]byte(row[2]), []byte(password))

  if err == nil { // if sent' pw hash == stored pw hash
    expire, _ := time.ParseDuration("168h") // 7 days

    token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.MapClaims{
      "username": username,
      "userid": row[0],
      "nbf": time.Now().Unix(),
      "exp": time.Now().Add(expire).Unix(),
      "token": "nigger", // TODO db based tokens
    })

    tokenString, _ := token.SignedString(hmacSampleSecret)

    user.ID = row[0]
    user.Username = row[1]
    user.Password = string(row[2])
    user.Admin = string(row[3])
    user.TokenUsed = string(row[4])

    if err != nil {
      fmt.Printf("Error: ", err.Error())
    }

    *Users = append(*Users, *user) // store user in logged-in-users list

    return tokenString, nil // return tokenString (Cookie)
  } else {
    return "", errors.New(ERR_PASSWORD_MISMATCH) // wrong password
  }
}

func (user *User) Update() error {
  colsVals := make([][]string, 2)
  colsVals[0] = []string{"username", user.Username}
  colsVals[1] = []string{"password", user.Password}

  err := databaseutils.DBUtil.UpdateRow("users", "id", string(user.ID), colsVals)

  if err != nil {
    fmt.Println("ERROOR UPDATING: " + err.Error())
  }

  return nil
}

func SearchUser(userID string) int {
    for i := range *Users {
        if (*Users)[i].ID == userID {
          return i
        }
    }
    return -1
}

func SearchUserByUsername(username string) int {
    for i := range *Users {
        if (*Users)[i].Username == username {
          return i
        }
    }
    return -1
}

func VerifyUserLoggedIn(tokenString string) (bool, string, error) { // TODO renew JWT from time to time preventing expiry
  if tokenString == "" { // if no tokenString("Cookie") exists fail
    return false, "-1", errors.New(ERR_INVALID_TOKEN)
  }

  hmacSampleSecret := []byte(configutils.Conf.CryptoKey) // crypto key for JWT encryption

  token, _ := jwt.Parse(tokenString, func(token *jwt.Token) (interface{}, error) {
    if _, ok := token.Method.(*jwt.SigningMethodHMAC); !ok {
      return nil, fmt.Errorf("Unexpected signing method: %v", token.Header["alg"])
    }
    return hmacSampleSecret, nil
  })

  if claims, ok := token.Claims.(jwt.MapClaims); ok && token.Valid { // if token is valid
    if userID, ok := claims["userid"].(string); ok { // extract userID
      sliceID := SearchUser(userID) // verify that user has a session on the server
      if sliceID != -1 { // searchUser returns -1 if there's no such user
        return true, userID, nil // logged in, TODO: "0" template comparision dynamic
      } else {
        return false, "-1", errors.New(ERR_SESSION_TIMED_OUT) // Session probably expired - may also be faked? TODO more checks?
      }
    } else {
        return false, "-1", errors.New("Unknown error") // This should never happen, prolly can't convert something in claims then..
    }
  } else {
    return false, "-1", errors.New(ERR_INVALID_TOKEN) // Token is invalid, expired or whatever, TODO switch with ERR_SESSION_TIMED_OUT when database based session system
  }
}

func AuthHandler(ctx *iris.Context) {
  tokenString := ctx.GetCookie("token")
  isAuthed, userID, err := VerifyUserLoggedIn(tokenString)

  ctx.Set("userID", userID) // save userID for in-context use

  if err != nil {
    fmt.Println("Auth error: ", err.Error())
  }

  if isAuthed {
    ctx.Next() // successfully authed, next handler
  } else {
    if err := ctx.Render("login_box.html", PageParams{"1", err.Error(), "login", "0"}); err != nil {
      println(err.Error())
    } // failed to auth

  }
}

func AdminHandler(ctx *iris.Context) {
  userID := ctx.GetString("userID")
  user, err := GetUser(userID)

  if user.Admin != "1" { // check if user is admin
      err = errors.New("User no Admin: " + userID)
      fmt.Println(err.Error())
      ctx.Redirect("/")
      return
    } else {
      ctx.Next()
    }
}

func GenerateTokens(numTokens int) []string {
  const letterBytes = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
    tokens := make([]string, 0)
    dbTokens := make([][]string, 0)

    for i := 0; i < numTokens; i++ {
      b := make([]byte, 16)
      for i := range b {
          b[i] = letterBytes[rand.Intn(len(letterBytes))]
      }
      tokens = append(tokens, string(b))
      dbTokens = [][]string{[]string{"value", string(b)}, []string{"used", "0"}}
      err := databaseutils.DBUtil.InsertRow("tokens", dbTokens)
      if err != nil {
        fmt.Println(err.Error())
        return []string{""}
      }
    }

    return tokens
}

func GetTokens(used bool) []string {
  dbTokens, err := databaseutils.DBUtil.GetRows("*", "tokens", "used", "0") // get unused tokens
  if used {
    dbTokens, err = databaseutils.DBUtil.GetRows("*", "tokens", "used", "1") // get used tokens
  }

  if err != nil {
    fmt.Println(err.Error()) // TODO: nicer / outsource
  }

  tokens := make([]string, 0)

  for i, _ := range dbTokens {
    tokens = append(tokens, dbTokens[i][1])
  }

  return tokens
}

func GetUser(userID string) (User, error) {
  usersArrayID := SearchUser(userID)

  if usersArrayID == -1 { // TODO check if unneccessary (AuthHandler) (Ddepends on where used: TODO CHECK)
    return User{}, errors.New("User not logged in")
  }

  user := (*Users)[usersArrayID] // user must be logged in to do this -> get from users list
  return user, nil
}

func SearchUserByUsernameInDB(username string) int {
  user, err := databaseutils.DBUtil.GetRow("*", "users", "username", username)
  if err != nil {
    if err.Error() != "ERR_EMPTY_RESULT" {
      fmt.Println(err.Error())
    }
    return -1
  }

  userID, err := strconv.Atoi(user[0])
  if err != nil {
    fmt.Println(err.Error())
  }

  return userID
}

func RegisterUserWithToken(username string, password string, token string) error {
  tokenID := databaseutils.DBUtil.GetString("id", "tokens", "value", token)

  user := [][]string{[]string{"username", username}, []string{"password", password}, []string{"admin", "0"}, []string{"token-id", tokenID}}
  err := databaseutils.DBUtil.InsertRow("users", user)
  if err != nil {
    fmt.Println(err.Error())
    return err
  }

  err = databaseutils.DBUtil.UpdateRow("tokens", "value", token, [][]string{[]string{"used", "1"}})
  if err != nil {
    fmt.Println(err.Error())
    return err
  }

  return nil
}