sentio/order_intent.go

package sentio

import (
	"bytes"
	"fmt"
	"strconv"
	"strings"
	"unicode/utf8"
)

type OrderIntent int8

const (
	BuyToOpen OrderIntent = iota
	BuyToClose
	SellToOpen
	SellToClose
)

var intents = map[OrderIntent]string{
	BuyToOpen:   "buy_to_open",
	BuyToClose:  "buy_to_close",
	SellToOpen:  "sell_to_open",
	SellToClose: "sell_to_close",
}

func (s OrderIntent) String() string {
	if intent, ok := intents[s]; ok {
		return intent
	}

	return "undefined"
}

func (s OrderIntent) MarshalJSON() ([]byte, error) {
	intent := s.String()
	return []byte(`"` + intent + `"`), nil
}

func (s *OrderIntent) UnmarshalJSON(data []byte) error {
	var (
		intent OrderIntent
		runes  = bytes.Runes(data)
		err    error
	)

	if l := utf8.RuneCount(data); runes != nil && runes[0] == 34 && runes[l-1] == 34 {
		data = data[1 : l-1]
		intent, err = ParseOrderIntent(string(data))
	} else {
		n, err := strconv.Atoi(string(data))
		if err == nil {
			intent = OrderIntent(n)
		}
	}

	if err != nil {
		return err
	}

	if _, ok := intents[intent]; !ok {
		return fmt.Errorf("unknown `OrderIntent`: %s", data)
	}

	*s = intent
	return nil
}

func ParseOrderIntent(s string) (OrderIntent, error) {
	s = strings.TrimSpace(s)
	s = strings.ToLower(s)

	for intent, s2 := range intents {
		if s == s2 {
			return intent, nil
		}
	}

	return -1, fmt.Errorf("`sentio.ParseOrderIntent`: undefined OrderIntent `%s`", s)
}