package token

import "fmt"

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

const (
	OpenParen  Type = iota // Denotes the '(' token.
	CloseParen             // Denotes the ')' token.
	OpenBrace              // Denotes the '{' token.
	CloseBrace             // Denotes the '}' token.
	HardBreak              // Denotes the ';' token.
	Assign                 // Denotes the ':=' token.
	Atom                   // Denotes an alpha-numeric variable.
	Slash                  // Denotes the '/' token.
	Dot                    // Denotes the '.' token.
	SoftBreak              // Denotes a new-line.
)

// A representation of a token in source code.
type Token struct {
	Column 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(column int) *Token {
	return &Token{Type: OpenParen, Column: column, Value: "("}
}

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

func NewOpenBrace(column int) *Token {
	return &Token{Type: OpenBrace, Column: column, Value: "{"}
}

func NewCloseBrace(column int) *Token {
	return &Token{Type: CloseBrace, Column: column, Value: "}"}
}

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

func NewHardBreak(column int) *Token {
	return &Token{Type: HardBreak, Column: column, Value: ";"}
}

func NewAssign(column int) *Token {
	return &Token{Type: Assign, Column: column, Value: ":="}
}

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

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

func NewSoftBreak(column int) *Token {
	return &Token{Type: SoftBreak, Column: column, 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 SoftBreak:
		return "\\n"
	case HardBreak:
		return ";"
	default:
		panic(fmt.Errorf("unknown token type %v", typ))
	}
}

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