mod cartridge;
mod bus;
mod cpu;
mod mapper;
mod palette;
mod render;
mod ppu;

use crate::bus::{Bus, NesBus};
use crate::cartridge::Cartridge;
use crate::cpu::Cpu;
use crate::render::{PpmRenderer, Renderer};


fn main() {
    let args: Vec<String> = std::env::args().collect();
    match args.len() {
        1 => run_nestest(),
        3 if args[1] == "blargg" => run_blargg(&args[2]),
        2 => run_cart(&args[1]),
        _ => eprintln!("usage: rnes [<rom> | blargg <rom>]"),
    }
}

fn run_cart(path: &str) {
    let cart = Cartridge::from_file(path).unwrap();
    let mut bus = NesBus::new(cart);
    let mut cpu = Cpu::new();
    cpu.reset(&mut bus);
    let mut renderer = PpmRenderer::new();
    let frames: u32 = 60;

    for _ in 0..frames {
        while !bus.frame_done() {
            let cycles = cpu.step(&mut bus);
            bus.tick_ppu(cycles as u64);
        }
        if bus.take_nmi() { cpu.set_nmi(); }
        renderer.present(bus.framebuffer(), 256, 240);
        bus.begin_frame();
    }
}

fn run_blargg(path: &str) {
    let cart = Cartridge::from_file(path).unwrap();
    let mut bus = NesBus::new(cart);
    let mut cpu = Cpu::new();
    cpu.reset(&mut bus);                 // boots from $FFFC-$FFFD via MMC1 PRG banking

    let cycle_cap: u64 = 5_000_000;      // blargg tests complete well under this; tune if needed
    while cpu.cycles < cycle_cap {
        cpu.step(&mut bus);
    }

    let r0 = bus.read(0x6000);
    let r1 = bus.read(0x6001);
    let r2 = bus.read(0x6002);
    let r3 = bus.read(0x6003);
    println!("result: $6000={:02X} $6001={:02X} $6002={:02X} $6003={:02X}", r0, r1, r2, r3);
    if r0 == 0 { println!("PASS"); } else { println!("FAIL (error {:#04X})", r0); }
}

fn run_nestest() {
    let cart: Cartridge = Cartridge::from_file("roms/test/cpu/nestest/nestest.nes").unwrap();
    let mut bus: NesBus = NesBus::new(cart);
    let mut cpu = Cpu::new();
    cpu.set_test_start(0xC000, 7);
    loop {
        println!("{}", cpu.trace(&mut bus));
        cpu.step(&mut bus);
    }
}