package tind

// TinD: Because a UUID is too big for a lot of people
// a TinD is a defaults to a 4 byte ID made up of ONLY Alphabetical characters.
// To ensure more randomness, lower case and upper case letters are used
// providing up to 52 differenct characters for use in each single position.
// Arbitrary TinD sizes can also be used, by calling
// `id := NewTinDOfLength(<number of bytes>)`
//
// TinD is at it's core a byte slice. It's default alphabet can be replaced with
// whatever unicode characters you want, as the alphabet it uses is just a slice
// of runes
import (
	"crypto/rand"
	"errors"
	"log"
)

// defaults are just a call to NewConfig()
var defaults = NewTinDConfig()

// TinD represents a very simple `size` byte unique ID that is generated
// at random. TinD stands for Tiny iDentifier, and is pronouced "tind"
// Each byte can be the value 0 -> len(alphabet) that is used, to ensure
// values can be encoded and decoded reliably. The longer the alphabet
// used, the more randomness can be done.
type TinD struct{
	bytes []byte
	str string
	config *Config
}

// Gen generates a new TinD id using default values
func Gen() TinD {
	return defaults.Gen()
}

// String returns the Human Readable form of the TinD
func (t TinD) String() string {
	if len(t.str) == t.config.size {
		return t.str
	}
	t.str = makeString(t.bytes, t.config.size, t.config.runset)
	return t.str
}

// Bytes returns the raw bytes of the TinD
func (t TinD) Bytes() []byte {
	return t.bytes
}

func makeString(bytes []byte, size int, runeset []rune) string {
	r := make([]rune, size)
	for i := 0; i < size; i++ {
		r[i] = runeset[bytes[i]]
	}
	return string(r)
}