package main

import (
	"database/sql"
	"log"
	"time"
)

// Device : holds information about a specific Device
type Device struct {
	ID           int        `json:"id"`
	Name         string     `json:"name"`
	DeviceTypeID int        `json:"deviceTypeId"`
	DeviceType   DeviceType `json:"deviceType"`
	Address      string     `json:"address"`
	CreatedAt    time.Time  `json:"createdAt"`
	UpdatedAt    time.Time  `json:"updatedAt"`
}

// Devices : a list of Device items
type Devices []Device

const deviceTableCreationQuery = `CREATE TABLE IF NOT EXISTS devices (
	id int(10) unsigned NOT NULL AUTO_INCREMENT,
	name varchar(255),
	deviceTypeId int(10) unsigned NOT NULL,
	address varchar(255),
	createdAt datetime,
	updatedAt datetime,
	PRIMARY KEY (id),
    CONSTRAINT fk_devicetype FOREIGN KEY (deviceTypeId) REFERENCES deviceTypes(id)
  );`

func ensureDeviceTableExists(db *sql.DB) {
	if _, err := db.Exec(deviceTableCreationQuery); err != nil {
		log.Fatal(err)
	}
}

func seedDeviceData(db *sql.DB) {
	sqlQuery := `INSERT INTO devices VALUES 
		(1,'Default PLC',1,'192.168.1.10','2016-10-13 15:05:32','2016-10-13 15:05:32');`
	insStmt, insErr := db.Prepare(sqlQuery)

	if insErr != nil {
		panic(insErr.Error()) // proper error handling instead of panic in your app
	}
	defer insStmt.Close() // Close the statement when we leave main() / the program terminates

	insStmt.Exec()
}

// getDevice : used during GET command
func (d *Device) getDevice(db *sql.DB) error {
	sqlQuery := `SELECT 
		devices.name,
		devices.deviceTypeId,
		deviceTypes.id,
		deviceTypes.name,
		deviceTypes.createdAt,
		deviceTypes.updatedAt,
		devices.address,
		devices.createdAt, 
		devices.updatedAt
		FROM devices 
		LEFT JOIN deviceTypes 
		ON devices.deviceTypeId = deviceTypes.id WHERE devices.id=?`
	return db.QueryRow(sqlQuery, d.ID).Scan(&d.Name, &d.DeviceTypeID, &d.DeviceType.ID, &d.DeviceType.Name, &d.DeviceType.CreatedAt, &d.DeviceType.UpdatedAt, &d.Address, &d.CreatedAt, &d.UpdatedAt)
}

// updateDevice : used during PUT command
func (d *Device) updateDevice(db *sql.DB) error {
	updStmt, updErr := db.Prepare("UPDATE devices SET name=?, deviceTypeId=?, address=?, updatedAt=? WHERE id=?")
	if updErr != nil {
		panic(updErr.Error()) // proper error handling instead of panic in your app
	}
	defer updStmt.Close() // Close the statement when we leave main() / the program terminates

	_, err := updStmt.Exec(d.Name, d.DeviceTypeID, d.Address, time.Now(), d.ID)
	return err
}

// deleteDevice : used during DELETE command
func (d *Device) deleteDevice(db *sql.DB) error {
	_, err := db.Exec("DELETE FROM devices WHERE id=?", d.ID)
	return err
}

// createDevice : used during PUSH command
func (d *Device) createDevice(db *sql.DB) error {
	stmtIns, insErr := db.Prepare("INSERT INTO devices (name, deviceTypeId, address, createdAt, updatedAt) VALUES (?, ?, ?, ?, ?);")
	if insErr != nil {
		panic(insErr.Error()) // proper error handling instead of panic in your app
	}
	defer stmtIns.Close() // Close the statement when we leave main() / the program terminates

	_, err := stmtIns.Exec(d.Name, d.DeviceTypeID, d.Address, time.Now(), time.Now())
	return err
}

// getDevices : used during GET command for all
func getDevices(db *sql.DB, start, count int) (Devices, error) {
	sqlQuery := `SELECT 
		devices.id,
		devices.name,
		devices.deviceTypeId,
		deviceTypes.id,
		deviceTypes.name,
		deviceTypes.createdAt,
		deviceTypes.updatedAt,
		devices.address,
		devices.createdAt, 
		devices.updatedAt
		FROM devices LEFT JOIN deviceTypes ON devices.deviceTypeId = deviceTypes.id LIMIT ? OFFSET ?;`

	getStmt, prepErr := db.Prepare(sqlQuery)
	if prepErr != nil {
		panic(prepErr.Error()) // proper error handling instead of panic in your app
	}
	defer getStmt.Close() // Close the statement when we leave main() / the program terminates

	rows, err := getStmt.Query(count, start)

	if err != nil {
		return nil, err
	}

	defer rows.Close()

	devices := Devices{}

	for rows.Next() {
		var d Device
		if err := rows.Scan(&d.ID, &d.Name, &d.DeviceTypeID, &d.DeviceType.ID, &d.DeviceType.Name, &d.DeviceType.CreatedAt, &d.DeviceType.UpdatedAt, &d.Address, &d.CreatedAt, &d.UpdatedAt); err != nil {
			return nil, err
		}
		devices = append(devices, d)
	}

	return devices, nil
}