package main

import (
	"fmt"
	"strings"
)

func print(expr Expr) string {
	switch e := expr.(type) {
	case Binary:
		return parenthesize(e.operator.Lexeme,
			e.left,
			e.right)
	case Grouping:
		return parenthesize("group", e.expression)
	case Literal:
		if e.value == nil {
			return "nil"
		}
		return fmt.Sprintf("%v", e.value)
	case Unary:
		return parenthesize(e.operator.Lexeme, e.right)
	}
	return "ERROR: reached impossible branch in print function"
}

func parenthesize(name string, exprs ...Expr) string {
	var sb strings.Builder

	sb.WriteString("(" + name)

	for _, expr := range exprs {
		sb.WriteString(" ")
		sb.WriteString(print(expr))
	}
	sb.WriteString(")")

	return sb.String()
}

// This was briefly a testing function for the AST class at the end of ch. 5
/*
func main() {
	var expression Expr = Binary{
		Unary{
			lexer.NewToken(lexer.MINUS, "-", nil, 1),
			Literal{123},
		},
		lexer.NewToken(lexer.STAR, "*", nil, 1),
		Grouping{
			Literal{45.67},
		},
	}
	fmt.Println(print(expression))
}
*/