package main

import (
	"database/sql"
	"database/sql/driver"
	"encoding/json"
	"time"
)

// Źródło poniższych:
// https://stackoverflow.com/questions/33072172/how-can-i-work-with-sql-null-values-and-json-in-golang-in-a-good-way
type NullTime struct {
	Time  time.Time
	Valid bool // Valid is true if Time is not NULL
}

// Scan implements the Scanner interface.
func (nt *NullTime) Scan(value interface{}) error {
	nt.Time, nt.Valid = value.(time.Time)
	return nil
}

// Value implements the driver Valuer interface.
func (nt NullTime) Value() (driver.Value, error) {
	if !nt.Valid {
		return nil, nil
	}
	return nt.Time, nil
}
func (nt NullTime) MarshalJSON() ([]byte, error) {
	if nt.Valid {
		return json.Marshal(nt.Time)
	}
	return json.Marshal(nil)
}

type nullTimeInHours struct {
	NullTime
}

// Scan implements the Scanner interface.
func (nt *nullTimeInHours) Scan(value interface{}) error {
	nt.Time = value.(time.Time)
	return nil
}

// Value implements the driver Valuer interface.
func (nt nullTimeInHours) Value() (driver.Value, error) {
	if !nt.Valid {
		return nil, nil
	}
	return nt.Time, nil
}
func (nt nullTimeInHours) MarshalJSON() ([]byte, error) {
	if nt.Valid {
		t, _ := time.Parse("15:04:05", time.Time.String(nt.Time))
		return json.Marshal(t)
	}
	return json.Marshal(nil)

}

type nullString struct {
	sql.NullString
}

// Scan implements the Scanner interface.
func (nt *nullString) Scan(value interface{}) error {
	nt.String, nt.Valid = value.(string)
	return nil
}

// Value implements the driver Valuer interface.
func (nt nullString) Value() (driver.Value, error) {
	if !nt.Valid {
		return nil, nil
	}
	return nt.String, nil
}
func (nt nullString) MarshalJSON() ([]byte, error) {
	if nt.Valid {
		return json.Marshal(nt.String)
	}
	return json.Marshal("null")
}