#![allow(dead_code)]

mod common;
mod vm;

use structopt::StructOpt;
use snafu::Snafu;
use std::{fs, process, path::PathBuf};

const DEFAULT_MAX_MEM: usize = 64 * 1024 * 1024;

#[derive(Snafu, Debug, Clone, PartialEq)]
enum ArgParseError<'a> {
    #[snafu(display("invalid specified size: {} (sizes may end in G, M, or K)", text))]
    InvalidSize { text: &'a str }
}

fn from_bytes_size<'a>(mut text: &'a str) -> std::result::Result<usize, ArgParseError<'a>> {
    if text.is_empty() {
        return Err(ArgParseError::InvalidSize { text })
    }
    let multiplier = match text.chars().last().unwrap() {
        'k' | 'K' => 1024,
        'm' | 'M' => 1024 * 1024,
        'g' | 'G' => 1024 * 1024 * 1024,
        _ => 1,
    };
    // trim the last character
    if multiplier != 1 {
        text = &text[0 .. text.len() - 1];
    }
    let value = text.parse::<usize>().map_err(|_| ArgParseError::InvalidSize { text })?;
    Ok(value * multiplier)
}

#[test]
fn test_bytes_size() {
    assert_eq!(from_bytes_size("64G"), Ok(64 * 1024 * 1024 * 1024));
    assert_eq!(from_bytes_size("64M"), Ok(64 * 1024 * 1024));
    assert_eq!(from_bytes_size("64K"), Ok(64 * 1024));
    assert_eq!(from_bytes_size("64g"), Ok(64 * 1024 * 1024 * 1024));
    assert_eq!(from_bytes_size("64m"), Ok(64 * 1024 * 1024));
    assert_eq!(from_bytes_size("64k"), Ok(64 * 1024));
    assert_eq!(from_bytes_size("64"), Ok(64));

    assert!(from_bytes_size("64B").is_err());
    assert!(from_bytes_size("64MB").is_err());
    assert!(from_bytes_size("64GB").is_err());
    assert!(from_bytes_size("64KB").is_err());
    assert!(from_bytes_size("64b").is_err());
    assert!(from_bytes_size("64mb").is_err());
    assert!(from_bytes_size("64gb").is_err());
    assert!(from_bytes_size("64kb").is_err());
}

#[derive(StructOpt, Debug)]
struct Options {
    // maybe some other options:
    // * debug
    #[structopt(name = "FILE", parse(from_os_str))]
    input: PathBuf,

    #[structopt(short, long, parse(try_from_str = from_bytes_size))]
    max_mem: Option<usize>,
}

type Result<T> = std::result::Result<T, Box<dyn std::error::Error>>;

fn main() -> Result<()> {
    use vm::{
        state::State,
        obj::{
            assemble::{Asm, Assemble},
            syn::{lexer, parser},
        }
    };
    let opt = Options::from_args();
    let text = fs::read_to_string(&opt.input)?;
    let lexerdef = lexer::lexerdef();
    let lexer = lexerdef.lexer(&text);
    let (res, errors) = parser::parse(&lexer);
    // print errors
    for err in errors.iter() {
        println!("{}", err.pp(&lexer, &parser::token_epp));
    }
    if !errors.is_empty() {
        process::exit(1);
    }
    let res = res.unwrap();
    let mut asm = Asm::default();
    let object = res.assemble(&mut asm)?;
    let mut state = State::new();
    state.load_object(object, opt.max_mem.unwrap_or(DEFAULT_MAX_MEM))?;
    let status = state.exec()?;
    process::exit((status & 0xffff_ffff) as i32);
}