use std::{collections::HashMap, fmt, time::Duration};

use iced::{
    Color, Element, Font,
    Length::{Fill, Shrink},
    Point, Renderer, Size, Subscription, Task, Theme, mouse,
    widget::{
        Canvas, button,
        canvas::{Frame, Program},
        column, container, row, text,
    },
    window::{self, Id, Settings},
};
use nes_emu::{
    NES, PPU,
    debugger::{DebuggerMessage, DebuggerState},
    header_menu::header_menu,
    hex_view::{HexEvent, HexView},
    resize_watcher::resize_watcher,
};
use tokio::runtime::Runtime;
use tracing_subscriber::EnvFilter;

// const ROM_FILE: &str = concat!(env!("ROM_DIR"), "/", "even_odd.nes");
const ROM_FILE: &str = concat!(env!("ROM_DIR"), "/", "crc_check.nes");
// const ROM_FILE: &str = "./Super Mario Bros. (World).nes";

extern crate nes_emu;

fn main() -> Result<(), iced::Error> {
    tracing_subscriber::fmt()
        .with_env_filter(EnvFilter::from_default_env())
        .init();

    iced::daemon(Emulator::new, Emulator::update, Emulator::view)
        .subscription(Emulator::subscriptions)
        .theme(Theme::Dark)
        .title(Emulator::title)
        .executor::<Runtime>()
        .run()
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum MemoryTy {
    Cpu,
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum WindowType {
    Main,
    Memory(MemoryTy, HexView),
    TileMap,
    TileViewer,
    Palette,
    Debugger,
}

#[derive(Debug, Clone, PartialEq, Eq)]
enum HeaderButton {
    // OpenMemory,
    // OpenTileMap,
    // OpenTileViewer,
    // OpenDebugger,
    Open(WindowType),
    Reset,
    PowerCycle,
}

impl fmt::Display for HeaderButton {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            Self::Open(WindowType::Memory(MemoryTy::Cpu, _)) => write!(f, "Open Memory Viewer"),
            Self::Open(WindowType::TileMap) => write!(f, "Open TileMap Viewer"),
            Self::Open(WindowType::TileViewer) => write!(f, "Open Tile Viewer"),
            Self::Open(WindowType::Debugger) => write!(f, "Open Debugger"),
            Self::Open(WindowType::Palette) => write!(f, "Open Palette"),
            Self::Open(WindowType::Main) => write!(f, "Create new Main window"),
            Self::Reset => write!(f, "Reset"),
            Self::PowerCycle => write!(f, "Power Cycle"),
        }
    }
}

struct Emulator {
    nes: NES,
    windows: HashMap<Id, WindowType>,
    debugger: DebuggerState,
    main_win_size: Size,
}

#[derive(Debug, Clone)]
enum Message {
    Tick(usize),
    Frame,
    DMA,
    CPU,
    DebugInt,
    WindowClosed(Id),
    Header(HeaderButton),
    Hex(Id, HexEvent),
    Debugger(DebuggerMessage),
    SetSize(window::Id, Size),
}

impl Emulator {
    fn new() -> (Self, Task<Message>) {
        let mut nes = nes_emu::NES::load_nes_file(ROM_FILE).expect("Failed to load nes file");
        nes.reset();
        let (win, task) = iced::window::open(Settings {
            min_size: None,
            ..Settings::default()
        });
        (
            Self {
                nes,
                windows: HashMap::from_iter([(win, WindowType::Main)]),
                debugger: DebuggerState::new(),
                main_win_size: Size::new(0., 0.),
            },
            task.discard(),
        )
    }
    fn title(&self, win: Id) -> String {
        match self.windows.get(&win) {
            Some(WindowType::Main) => "NES emu".into(),
            Some(WindowType::Memory(_, _)) => "NES MemoryView".into(),
            Some(WindowType::TileMap) => "NES TileMap".into(),
            Some(WindowType::TileViewer) => "NES Tile Viewer".into(),
            Some(WindowType::Palette) => "NES Palette Viewer".into(),
            Some(WindowType::Debugger) => "NES Debugger".into(),
            None => todo!(),
        }
    }

    fn open(&mut self, ty: WindowType) -> Task<Message> {
        let (win, task) = iced::window::open(Settings::default());
        self.windows.insert(win, ty);
        return task.discard();
    }

    fn update(&mut self, message: Message) -> Task<Message> {
        match message {
            Message::Tick(count) => {
                for _ in 0..count {
                    self.nes.run_one_clock_cycle();
                }
            }
            Message::Frame => while !self.nes.run_one_clock_cycle().ppu_frame {},
            Message::DMA => while !self.nes.run_one_clock_cycle().dma {},
            Message::CPU => while !self.nes.run_one_clock_cycle().cpu_exec {},
            Message::DebugInt => while !self.nes.run_one_clock_cycle().dbg_int {},
            Message::WindowClosed(id) => {
                if let Some(WindowType::Main) = self.windows.remove(&id) {
                    return iced::exit();
                }
            }
            Message::Header(HeaderButton::Open(w)) => {
                return self.open(w);
            }
            Message::Hex(id, val) => {
                if let Some(WindowType::Memory(_, view)) = self.windows.get_mut(&id) {
                    return view.update(val).map(move |e| Message::Hex(id, e));
                }
            }
            Message::Header(HeaderButton::Reset) => {
                self.nes.reset();
            }
            Message::Header(HeaderButton::PowerCycle) => {
                self.nes.power_cycle();
            }
            Message::Debugger(debugger_message) => {
                self.debugger.update(debugger_message, &mut self.nes)
            }
            Message::SetSize(id, size) => {
                if let Some(WindowType::Main) = self.windows.get(&id) {
                    self.main_win_size = size;
                }
                return Task::future(async {
                    tokio::time::sleep(Duration::from_millis(50)).await;
                })
                .then(move |_| iced::window::resize(id, size));
            }
        }
        // self.image.0.clone_from(self.nes.image());
        Task::none()
    }

    fn subscriptions(&self) -> Subscription<Message> {
        Subscription::batch([
            window::close_events().map(Message::WindowClosed),
            // window::events().map(Message::Window),
            // window::resize_events().map(Message::WindowResized),
        ])
    }

    fn view(&self, win: Id) -> Element<'_, Message> {
        match self.windows.get(&win) {
            Some(WindowType::Main) => {
                let content = column![
                    self.dropdowns(),
                    Element::from(Canvas::new(self).width(256. * 2.).height(240. * 2.)),
                    // self.cpu_state(),
                    // self.controls(),
                ]
                .height(Shrink);
                resize_watcher(content)
                    .on_resize(move |s| Message::SetSize(win, s))
                    .width(Shrink)
                    .height(Shrink)
                    .into()
            }
            Some(WindowType::Memory(ty, view)) => {
                let hex = match ty {
                    MemoryTy::Cpu => view
                        .render(self.nes.cpu_mem())
                        .map(move |e| Message::Hex(win, e)),
                };
                let content = column![hex].width(Fill).height(Fill);
                container(content).width(Fill).height(Fill).into()
            }
            Some(WindowType::TileMap) => {
                container(Canvas::new(DbgImage::NameTable(self.nes.ppu())))
                    .width(Fill)
                    .height(Fill)
                    .into()
            }
            Some(WindowType::TileViewer) => {
                container(Canvas::new(DbgImage::PatternTable(self.nes.ppu())))
                    .width(Fill)
                    .height(Fill)
                    .into()
            }
            Some(WindowType::Palette) => container(Canvas::new(DbgImage::Palette(self.nes.ppu())))
                .width(Fill)
                .height(Fill)
                .into(),
            Some(WindowType::Debugger) => {
                container(self.debugger.view(&self.nes).map(Message::Debugger))
                    .width(Fill)
                    .height(Fill)
                    .into()
            }
            None => panic!("Window not found"),
            // _ => todo!(),
        }
    }

    fn dropdowns(&self) -> Element<'_, Message> {
        row![
            header_menu(
                "Console",
                [HeaderButton::Reset, HeaderButton::PowerCycle,],
                Message::Header
            ),
            header_menu(
                "Debugging",
                [
                    HeaderButton::Open(WindowType::Debugger),
                    HeaderButton::Open(WindowType::Memory(MemoryTy::Cpu, HexView {})),
                    HeaderButton::Open(WindowType::TileMap),
                    HeaderButton::Open(WindowType::TileViewer),
                    HeaderButton::Open(WindowType::Palette),
                ],
                Message::Header
            )
        ]
        .width(Fill)
        .into()
    }
}

impl Program<Message> for Emulator {
    type State = ();

    fn draw(
        &self,
        _state: &Self::State,
        renderer: &Renderer,
        _theme: &Theme,
        bounds: iced::Rectangle,
        _cursor: mouse::Cursor,
    ) -> Vec<iced::widget::canvas::Geometry<Renderer>> {
        // const SIZE: f32 = 2.;
        let mut frame = Frame::new(
            renderer,
            bounds.size(), // iced::Size {
                           //     width: 256. * 2.,
                           //     height: 240. * 2.,
                           // },
        );
        frame.scale(2.);
        for y in 0..240 {
            for x in 0..256 {
                let c = self.nes.image().read(y, x);
                frame.fill_rectangle(
                    Point::new(x as f32, y as f32),
                    Size::new(1., 1.),
                    Color::from_rgb8(c.r, c.g, c.b),
                );
            }
        }
        vec![frame.into_geometry()]
    }
}

enum DbgImage<'a> {
    NameTable(&'a PPU),
    PatternTable(&'a PPU),
    Palette(&'a PPU),
}

impl Program<Message> for DbgImage<'_> {
    type State = ();

    fn draw(
        &self,
        _state: &Self::State,
        renderer: &Renderer,
        _theme: &Theme,
        _bounds: iced::Rectangle,
        _cursor: mouse::Cursor,
    ) -> Vec<iced::widget::canvas::Geometry<Renderer>> {
        // const SIZE: f32 = 2.;
        let mut name_table_frame =
            Frame::new(renderer, Size::new(256. * 4. + 260. * 2., 256. * 4.));
        name_table_frame.scale(2.);
        match self {
            DbgImage::NameTable(ppu) => ppu.render_name_table(&mut name_table_frame),
            DbgImage::PatternTable(ppu) => ppu.render_pattern_tables(&mut name_table_frame),
            DbgImage::Palette(ppu) => ppu.render_palette(&mut name_table_frame),
        }
        vec![name_table_frame.into_geometry()]
    }
}