use std::{fs, io};
use crate::EX_OK;
use std::io::Write;
use crate::astprinter::ASTPrinter;
use crate::expr::ExprVisitor;
use crate::parser::Parser;

use crate::scanner::Scanner;

pub struct RLoxInterpreter;

impl RLoxInterpreter {
    pub fn new() -> Self {
        RLoxInterpreter
    }

    pub fn run_file(&self, file_path: &str ) -> i32 {
        let contents = fs::read_to_string(file_path)
            .expect(&format!("Should have been able to read the file {file_path}"));

        self.run(contents)
    }

    pub fn run_prompt(&self) -> i32 {
        let mut exit_code = EX_OK;
        loop {
            print!("> ");
            io::stdout().flush().expect("Unable to flush stdout");
            let mut line = String::new();

            io::stdin()
                .read_line(&mut line)
                .expect("Failed to read line");

            if line.trim().is_empty() {
                break;
            }

            exit_code = self.run(line);
        }
        exit_code
    }

    fn run(&self, src: String) -> i32 {
        let mut scanner = Scanner::new( src );
        scanner.scan_tokens();

        let mut parser = Parser::new( scanner.tokens );
        match parser.parse() {
            Some(expr) => {
                let mut printer = ASTPrinter { depth: 0 };
                printer.visit_expr(&expr);
                println!();
            },
            None => println!("An error occurred while parsing expression.")
        }

        EX_OK
    }
}