package services

import (
	"crypto/rand"
	"math/big"
)

type SensorsService struct {
	ctx *Context
}

type SensorItem struct {
	Id      int64  `json:"id"`
	Name    string `json:"name"`
	AuthKey string `json:"authKey"`
}

func (s *SensorsService) GetList() ([]SensorItem, error) {
	sensors := make([]SensorItem, 0)

	rows, err := s.ctx.DB.Query("SELECT id, name, auth_key FROM sensors")

	if err != nil {
		return nil, err
	}

	defer rows.Close()

	for rows.Next() {
		item := SensorItem{}

		err := rows.Scan(&item.Id, &item.Name, &item.AuthKey)
		if err != nil {
			return nil, err
		}

		sensors = append(sensors, item)
	}

	err = rows.Err()
	if err != nil {
		return nil, err
	}

	return sensors, nil
}

func (s *SensorsService) Create(name string) (*SensorItem, error) {
	authKey, err := generateRandomString(32)

	if err != nil {
		return nil, err
	}

	item := SensorItem{
		Name:    name,
		AuthKey: authKey,
	}

	res, err := s.ctx.DB.Exec("INSERT INTO sensors (name, auth_key) VALUES (?, ?)", item.Name, item.AuthKey)

	if err != nil {
		return nil, err
	}

	item.Id, err = res.LastInsertId()

	if err != nil {
		return nil, err
	}

	return &item, nil
}

func (s *SensorsService) GetById(id int64) (*SensorItem, error) {
	item := SensorItem{}

	row := s.ctx.DB.QueryRow("SELECT id, name, auth_key FROM sensors WHERE id = ?", id)

	err := row.Scan(&item.Id, &item.Name, &item.AuthKey)
	if err != nil {
		return nil, err
	}

	return &item, nil
}

func (s *SensorsService) Update(id int64, name string) (*SensorItem, error) {
	item, err := s.GetById(id)

	if err != nil {
		return nil, err
	}

	item.Name = name

	_, err = s.ctx.DB.Exec("UPDATE sensors SET name = ? WHERE id = ?", item.Name, item.Id)

	if err != nil {
		return nil, err
	}

	return item, nil
}

var randomKeySource = []byte("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789")

func generateRandomString(length int) (string, error) {
	key := make([]byte, length)

	for i := range key {
		value, err := rand.Int(rand.Reader, big.NewInt(int64(len(randomKeySource))))

		if err != nil {
			return "", err
		}

		key[i] = randomKeySource[value.Int64()]
	}

	return string(key), nil
}