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

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


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]),
        3 if args[1] == "dbg" => run_dbg(&args[2]),
        3 if args[1] == "gui" => run_gui(&args[2]),
        2 => run_cart(&args[1]),
        _ => eprintln!("usage: rnes [<rom> | blargg <rom> | dbg <rom> | gui <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 = 180;

    for _ in 0..frames {
        run_one_frame(&mut bus, &mut cpu);
        renderer.present(bus.framebuffer(), 256, 240);
    }
}

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);
    }
}

fn run_dbg(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 dumper = dump::Dumper::new();
    let mut renderer = PpmRenderer::new();          // <-- add this
    let frames: u32 = 1800;

    for f 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);   // <-- and this
        dumper.snapshot(f, &bus, &cpu);
        bus.begin_frame();
    }
    println!("wrote debug_out/ + renders/, {frames} frames");
}

fn run_one_frame(bus: &mut NesBus, cpu: &mut Cpu) {
    while !bus.frame_done() {
        let cycles = cpu.step(bus);
        bus.tick_ppu(cycles as u64);
        if bus.take_nmi() { cpu.set_nmi(); }
    }
    bus.begin_frame();
}

struct GuiApp {
    bus: NesBus,
    cpu: Cpu,
    renderer: WindowRenderer,
}

impl GuiApp {
    fn new(cc: &eframe::CreationContext<'_>, cart: Cartridge) -> Self {
        let mut bus = NesBus::new(cart);
        let mut cpu = Cpu::new();
        cpu.reset(&mut bus);
        let renderer = WindowRenderer::new(cc, 256, 240);
        Self { bus, cpu, renderer }
    }
}

impl eframe::App for GuiApp {
    // Non-UI work: emulation runs here, before painting.
    fn logic(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        self.renderer.poll_input(self.bus.controller_mut());  // keyboard -> $4016/$4017
        run_one_frame(&mut self.bus, &mut self.cpu);          // one emulated frame
        self.renderer.present(self.bus.framebuffer(), 256, 240);
        ctx.request_repaint();                                // keep it running at 60fps
    }

    // Painting: draw the framebuffer texture.
    fn ui(&mut self, ui: &mut egui::Ui, _frame: &mut eframe::Frame) {
        self.renderer.draw(ui);
    }
}

fn run_gui(path: &str) {
    let cart = Cartridge::from_file(path).unwrap();
    let options = eframe::NativeOptions {
        viewport: egui::ViewportBuilder::default()
            .with_inner_size([1024.0, 960.0])
            .with_title("rnes"),
        ..Default::default()
    };
    eframe::run_native(
        "rnes",
        options,
        Box::new(move |cc| Ok(Box::new(GuiApp::new(cc, cart)))),
    ).expect("failed to run GUI");
}