package post

import "errors"

// ErrFormatStringMalformed indicates that a string could not be converted to a
// Format.
var ErrFormatStringMalformed = errors.New("format string malformed")

// Format describes the format of the body of a Post.
type Format string

// Enumeration of possible formats.
const (
	FormatMarkdown Format = "md"
	FormatGemtext  Format = "gmi"
)

// Formats slice of all possible Formats.
var Formats = []Format{
	FormatMarkdown,
	FormatGemtext,
}

var strsToFormats = func() map[string]Format {

	m := map[string]Format{}

	for _, f := range Formats {
		m[string(f)] = f
	}

	return m
}()

// FormatFromString parses a string into a Format, or returns
// ErrFormatStringMalformed.
func FormatFromString(str string) (Format, error) {

	if f, ok := strsToFormats[str]; ok {
		return f, nil
	}

	return "", ErrFormatStringMalformed
}