package token

// All tokens in the pseudo-lambda language.
type Type int

const (
	OpenParen  Type = iota // Denotes the '(' token.
	CloseParen             // Denotes the ')' token.
	Atom                   // Denotes an alpha-numeric variable.
	Slash                  // Denotes the '/' token.
	Dot                    // Denotes the '.' token.
	Newline                // Denotes a new-line.
)

// A representation of a token in source code.
type Token struct {
	Index int    // Where the token begins in the source text.
	Type  Type   // What type the token is.
	Value string // The value of the token.
}

func NewOpenParen(index int) *Token {
	return &Token{Type: OpenParen, Index: index, Value: "("}
}

func NewCloseParen(index int) *Token {
	return &Token{Type: CloseParen, Index: index, Value: ")"}
}

func NewDot(index int) *Token {
	return &Token{Type: Dot, Index: index, Value: "."}
}

func NewSlash(index int) *Token {
	return &Token{Type: Slash, Index: index, Value: "\\"}
}

func NewAtom(name string, index int) *Token {
	return &Token{Type: Atom, Index: index, Value: name}
}

func NewNewline(index int) *Token {
	return &Token{Type: Newline, Index: index, Value: "\\n"}
}

func Name(typ Type) string {
	switch typ {
	case OpenParen:
		return "("
	case CloseParen:
		return ")"
	case Slash:
		return "\\"
	case Dot:
		return "."
	case Atom:
		return "ATOM"
	case Newline:
		return "\\n"
	default:
		return "?"
	}
}

func (t Token) Name() string {
	return Name(t.Type)
}