use crate::expr::{Binary, Expr, ExprVisitor, Grouping, Literal, Unary};
use crate::stmt::{ExpressionStatement, PrintStatement, StatementVisitor};

pub struct ASTPrinter {
    pub(crate) depth: u32
}

impl ASTPrinter {
    fn ast_tab(&self) -> String {
        (0..self.depth).map(|_| " ").collect::<String>()
    }
}

impl ExprVisitor<()> for ASTPrinter {
    fn visit_binary(&mut self, b: &Binary) {
        println!("{}BINARY",self.ast_tab());
        println!("{}op='{}'", self.ast_tab(), b.operator.lexeme);
        println!("{}left=(", self.ast_tab());
        self.depth+=1;
        self.visit_expr(&*b.left);
        self.depth-=1;
        println!("{})", self.ast_tab());
        println!("{}right=(", self.ast_tab());
        self.depth+=1;
        self.visit_expr(&*b.right);
        self.depth-=1;
        println!("{})", self.ast_tab());
    }

    fn visit_grouping(&mut self, g: &Grouping) {
        println!("{}GROUPING(", self.ast_tab());
        self.depth+=1;
        self.visit_expr(&*g.expression);
        self.depth-=1;
        print!(") ");
    }

    fn visit_literal(&mut self, l: &Literal) {
        match l {
            Literal::LiteralNumber(i) => print!("{}NUMBER={}", self.ast_tab(), i),
            Literal::LiteralString(s) => print!("{}STRING='{}'", self.ast_tab(), s),
            Literal::LiteralBool(b) => print!("{}BOOL={}", self.ast_tab(), b),
            Literal::LiteralNil => print!("{}NIL", self.ast_tab()),
        }
    }

    fn visit_unary(&mut self, u: &Unary) {
        println!("{}UNARY(op='{}'", self.ast_tab(), u.operator.lexeme);
        self.depth+=1;
        self.visit_expr(&*u.right);
        self.depth-=1;
        print!(") ");
    }

    fn visit_expr(&mut self, e: &Expr) {
        match e {
            Expr::BinaryExpr(b) => { self.visit_binary(b); }
            Expr::GroupingExpr(g) => { self.visit_grouping(g); }
            Expr::LiteralExpr(l) => { self.visit_literal(l); }
            Expr::UnaryExpr(u) => { self.visit_unary(u); }
        }
    }
}

impl StatementVisitor<()> for ASTPrinter {
    fn visit_expr_stmt(&mut self, e: &ExpressionStatement) -> () {
        println!("{} EXPR_STMT(", self.ast_tab());
        self.depth+=1;
        self.visit_expr(&e.expr);
        self.depth-=1;
        print!(") ");
    }

    fn visit_print(&mut self, p: &PrintStatement) -> () {
        println!("{} EXPR_STMT(", self.ast_tab());
        self.depth+=1;
        self.visit_expr(&p.expr);
        self.depth-=1;
        print!(") ");
    }
}