package saccharine

import "fmt"

// A TokenType is an identifier for any token in the Saccharine language.
type TokenType int

// All official tokens of the Saccharine language.
const (
	// TokenOpenParen denotes the '(' token.
	TokenOpenParen TokenType = iota
	// TokenCloseParen denotes the ')' token.
	TokenCloseParen
	// TokenOpenBrace denotes the '{' token.
	TokenOpenBrace
	// TokenCloseBrace denotes the '}' token.
	TokenCloseBrace
	// TokenHardBreak denotes the ';' token.
	TokenHardBreak
	// TokenAssign denotes the ':=' token.
	TokenAssign
	// TokenAtom denotes an alpha-numeric variable.
	TokenAtom
	// TokenSlash denotes the '/' token.
	TokenSlash
	// TokenDot denotes the '.' token.
	TokenDot
	// TokenSoftBreak denotes a new-line.
	TokenSoftBreak
)

// A Token in the Saccharine language.
type Token struct {
	Column int       // Where the token begins in the source text.
	Type   TokenType // What type the token is.
	Value  string    // The value of the token.
}

// NewToken creates a [Token] of the given type at the given column.
// The token's value is derived from its [TokenType].
func NewToken(typ TokenType, column int) *Token {
	return &Token{Type: typ, Column: column, Value: typ.Name()}
}

// NewTokenAtom creates a [TokenAtom] with the given name at the given column.
func NewTokenAtom(name string, column int) *Token {
	return &Token{Type: TokenAtom, Column: column, Value: name}
}

// Name returns the type of the TokenType, as a string.
func (t TokenType) Name() string {
	switch t {
	case TokenOpenParen:
		return "("
	case TokenCloseParen:
		return ")"
	case TokenOpenBrace:
		return "{"
	case TokenCloseBrace:
		return "}"
	case TokenHardBreak:
		return ";"
	case TokenAssign:
		return ":="
	case TokenAtom:
		return "ATOM"
	case TokenSlash:
		return "\\"
	case TokenDot:
		return "."
	case TokenSoftBreak:
		return "\\n"
	default:
		panic(fmt.Errorf("unknown token type %v", t))
	}
}

// Name returns the type of the Token, as a string.
func (t Token) Name() string {
	return t.Type.Name()
}