package indentalUserDB

import (
  "time"
  "nilfm.cc/git/quartzgun/cookie"
  "nilfm.cc/git/quartzgun/auth"
  "golang.org/x/crypto/bcrypt"
  "os"
  "strings"
  "fmt"
  "errors"
)

type IndentalUserDB struct {
  Users map[string]*auth.User
  Basis string
}

func CreateIndentalUserDB(filePath string) *IndentalUserDB {
  u, err := readDB(filePath)
  if err == nil {
    uMap := map[string]*auth.User{}
    for _, usr := range u {
      uMap[usr.Name] = usr
    }
    return &IndentalUserDB{
      Users: uMap,
      Basis: filePath,
    }
  } else {
    return &IndentalUserDB{
      Users: map[string]*auth.User{},
      Basis: filePath,
    }
  }
}

func (self *IndentalUserDB) InitiateSession(user string, password string) (string, error) {
  if _, exists := self.Users[user]; !exists {
    return "", errors.New("User not in DB")
  }
  if bcrypt.CompareHashAndPassword([]byte(self.Users[user].Pass), []byte(password)) != nil {
    return "", errors.New("Incorrect password")
  }
  sessionId := cookie.GenToken(64)
  self.Users[user].Session = sessionId
  writeDB(self.Basis, self.Users)
  return sessionId, nil
}

func (self *IndentalUserDB) ValidateUser(user string, sessionId string) (bool, error) {
  if _, exists := self.Users[user]; !exists {
    return false, errors.New("User not in DB")
  }

  validated := self.Users[user].Session == sessionId
  if validated {
    self.Users[user].LastSeen = time.Now()
    writeDB(self.Basis, self.Users)
  }

  return validated, nil
}

func (self *IndentalUserDB) EndSession(user string) error {
  if _, exists := self.Users[user]; !exists {
    return errors.New("User not in DB")
  }

  self.Users[user].Session = ""
  self.Users[user].LastSeen = time.Now()
  writeDB(self.Basis, self.Users)
  return nil
}

func (self *IndentalUserDB) DeleteUser(user string) error {
  if _, exists := self.Users[user]; !exists {
    return errors.New("User not in DB")
  }

  delete(self.Users, user)
  writeDB(self.Basis, self.Users)
  return nil
}

func (self *IndentalUserDB) ChangePassword(user string, password string, oldPassword string) error {
  if _, exists := self.Users[user]; !exists {
    return errors.New("User not in DB")
  }
  if bcrypt.CompareHashAndPassword([]byte(self.Users[user].Pass), []byte(oldPassword)) != nil {
    return errors.New("Incorrect password")
  }

  hash, _ := bcrypt.GenerateFromPassword([]byte(password), 10)
  self.Users[user].Pass = string(hash[:])
  writeDB(self.Basis, self.Users)
  return nil
}

func (self *IndentalUserDB) AddUser(user string, password string) error{
  if _, exists := self.Users[user]; exists {
    return errors.New("User already in DB")
  }

  hash, _ := bcrypt.GenerateFromPassword([]byte(password), 10)

  self.Users[user] = &auth.User{
    Name: user,
    Pass: string(hash[:]),
    LastSeen: time.UnixMicro(0),
    LoginTime: time.UnixMicro(0),
    Session: "",
  }
  writeDB(self.Basis, self.Users)
  return nil;
}

const timeFmt = "2006-01-02T15:04Z"

func readDB(filePath string) (map[string]*auth.User, error) {
  f, err := os.ReadFile(filePath)
  if err != nil {
    return nil, err
  }

  data := string(f[:])
  users := map[string]*auth.User{}

  lines := strings.Split(data, "\n")
  var name string
  var pass string
  var session string
  var loginTime time.Time
  var lastSeen time.Time
  procFields := 0
  for _, l := range lines {
    if !strings.HasPrefix(l, "  ") {
      name = l
      procFields++
    } else {
      kvp := strings.Split(l, ":")
      k := strings.TrimSpace(kvp[0])
      v := strings.TrimSpace(kvp[1])
      switch k {
        case "pass":
          pass = v
        case "session":
          session = v
        case "loginTime":
          loginTime, _ = time.Parse(timeFmt, v)
        case "lastSeen":
          lastSeen, _ = time.Parse(timeFmt, v)
      }
      procFields++
      if procFields == 5 {
        users[name] = &auth.User{
          Name: name,
          Pass: pass,
          Session: session,
          LoginTime: loginTime,
          LastSeen: lastSeen,
        }
        procFields = 0
      }
    }
  }
  return users, nil
}

func writeDB(filePath string, users map[string]*auth.User) error {
  f, err := os.Create(filePath)
  if err != nil {
    return err
  }

  defer f.Close()

  for _, user := range users {
    f.WriteString(fmt.Sprintf("%s:\n  pass: %s\n  session: %s\n  loginTime: %s\n  lastSeen: %s\n",
      user.Name,
      user.Pass,
      user.Session,
      user.LoginTime,
      user.LastSeen));
  }
  f.Sync()
  return nil
}