package ast

import (
	"fmt"
)

type Printer struct {
}

func NewPrinter() *Printer {
	return &Printer{}
}

func (ap *Printer) PrintStmts(stmts []Stmt) string {
	str := ""

	for _, stmt := range stmts {
		str += stmt.Accept(ap).(string) + "\n"
	}

	return str
}

func (ap *Printer) PrintExpr(expr Expr) string {
	return expr.Accept(ap).(string)
}

func (ap *Printer) VisitErrorStmt(stmt *ErrorStmt) any {
	return stmt.Value
}

func (ap *Printer) VisitExpressionStmt(stmt *ExpressionStmt) any {
	return stmt.Expression.Accept(ap)
}

func (ap *Printer) VisitPrintStmt(stmt *PrintStmt) any {
	return ap.parenthesize("print", stmt.Expression)
}

func (ap *Printer) VisitVarStmt(stmt *VarStmt) any {
	return ap.parenthesize("var", &LiteralExpr{stmt.Name}, stmt.Initializer)
}

func (ap *Printer) VisitVariableExpr(expr *VariableExpr) any {
	return expr.Name.Lexeme
}

func (ap *Printer) VisitBinaryExpr(expr *BinaryExpr) any {
	return ap.parenthesize(expr.Operator.Lexeme, expr.Left, expr.Right)
}

func (ap *Printer) VisitGroupingExpr(expr *GroupingExpr) any {
	return ap.parenthesize("group", expr.Expression)
}

func (ap *Printer) VisitLiteralExpr(expr *LiteralExpr) any {
	if expr.Value == nil {
		return "nil"
	}
	return fmt.Sprint(expr.Value)
}

func (ap *Printer) VisitUnaryExpr(expr *UnaryExpr) any {
	return ap.parenthesize(expr.Operator.Lexeme, expr.Right)
}

func (ap *Printer) VisitErrorExpr(expr *ErrorExpr) any {
	return expr.Value
}

func (ap *Printer) VisitAssignExpr(expr *AssignExpr) any {
	return ap.parenthesize("=", &VariableExpr{expr.Name}, expr.Value)
}

func (ap *Printer) parenthesize(name string, exprs ...Expr) string {
	str := "(" + name

	for _, expr := range exprs {
		if expr == nil {
			continue
		}
		str += " " + expr.Accept(ap).(string)
	}

	return str + ")"
}