use serde::{ Serialize, Deserialize };

use fltk::*;
use fltk::prelude::*;
use fltk::enums::*;
use fltk::image::PngImage;

extern crate image;
use image::io::Reader as ImageReader;
use image::{ DynamicImage };

use std::collections::{HashMap, HashSet};

use std::cell::RefCell;
use std::rc::Rc;

use std::io::{ Write, Read, Cursor };
use std::fs::File;

#[derive(Serialize, Deserialize, Debug)]
struct Node {
    pub x: f32,
    pub y: f32,

    pub name: String,
    pub edges: HashSet<usize>,
}
#[derive(Serialize, Deserialize, Debug)]
struct Board {
    nodes: HashMap<usize, Node>,
}
impl Board {
    pub fn new() -> Self {
	let nodes = HashMap::new();
	Board { nodes }
    }

    pub fn add_node(&mut self, x: f32, y: f32) {
	self.nodes.insert(self.next_id(), Node {
	    x,
	    y,
	    name: "Canada".to_string(),
	    edges: HashSet::new(),
	});   
    }

    pub fn remove_node(&mut self, id: usize) {
	self.nodes.remove(&id);
	for (_, node) in &mut self.nodes {
	    node.edges.remove(&id);
	}
    }

    pub fn nearest_node(&self, x: f32, y: f32) -> Option<usize> {
	let f = |n: &Node| dist_sq((n.x, n.y), (x, y));
	let mut iter = self.nodes.iter();
	if let Some((id, node)) = iter.next() {
	    let mut min = *id;
	    let mut min_val = f(node);
	    for (id, node) in iter {
		let val = f(node);
		if val < min_val {
		    min = *id;
		    min_val = val;
		}
	    }
	    Some(min)
	} else {
	    None
	}
    }

    fn next_id(&self) -> usize {
	for i in 0 .. {
	    if !self.nodes.contains_key(&i) {
		return i;
	    }
	}
	unreachable!();
    }
}

struct AppState {
    pub board: Board,
    pub image_raw: Option<DynamicImage>,
    pub image: Option<PngImage>,
}

impl AppState {
    fn new() -> Self {
	AppState {
	    board: Board::new(),
	    image_raw: None,
	    image: None
	}
    }
}

fn menu_cb(_m: &mut impl MenuExt) {
    todo!();
}

fn encode_png(image: &DynamicImage) -> Vec<u8> {
    let mut cursor = Cursor::new(Vec::new());
    image.write_to(&mut cursor, image::ImageOutputFormat::Png).unwrap();
    cursor.into_inner()
}

fn decode_png(buf: &[u8]) -> DynamicImage {
    let cursor = Cursor::new(buf);
    let mut reader = ImageReader::new(cursor);
    reader.set_format(image::ImageFormat::Png);
    reader.decode().unwrap()
}

fn lerp(v0: f32, v1: f32, t: f32) -> f32 {
    v0 + t * (v1 - v0)
}

fn inv_lerp(v0: f32, v1: f32, a: f32) -> f32 {
    (a - v0) / (v1 - v0)
}

fn dist_sq((x0, y0): (f32, f32), (x1, y1): (f32, f32)) -> f32 {
    (x1 - x0) * (x1 - x0) + (y1 - y0) * (y1 - y0)
}

trait CoordTransformer {
    fn to_coords(&self, x: i32, y: i32) -> (f32, f32);
    fn from_coords(&self, x: f32, y: f32) -> (i32, i32);
}

impl CoordTransformer for frame::Frame {
    fn to_coords(&self, x: i32, y: i32) -> (f32, f32) {
	(
	    inv_lerp(self.x() as f32, (self.x() + self.w()) as f32, x as f32),
	    inv_lerp(self.y() as f32, (self.y() + self.h()) as f32, y as f32),
	)
    }

    fn from_coords(&self, x: f32, y: f32) -> (i32, i32) {
	(
	    lerp(self.x() as f32, (self.x() + self.w()) as f32, x) as i32,
	    lerp(self.y() as f32, (self.y() + self.h()) as f32, y) as i32,
	)
    }
}

fn main() {
    let app = app::App::default()
	.with_scheme(app::Scheme::Gtk);
    let mut win = window::Window::default()
	.with_size(400, 300)
	.with_label("Board Builder");
    let mut flex = group::Flex::default()
	.size_of_parent();
    flex.set_type(group::FlexType::Column);

    // State
    let state = Rc::new(RefCell::new(AppState::new()));
    
    // Menu
    let mut menubar = menu::MenuBar::default();
    let state_clone = Rc::clone(&state);
    menubar.add("File/New"		, Shortcut::None, menu::MenuFlag::Normal, move |_| {
	state_clone.replace(AppState::new());
	app::redraw();
    });
    let state_clone = Rc::clone(&state);
    menubar.add("File/Open..."		, Shortcut::None, menu::MenuFlag::Normal, move |_| {
	let mut fc = dialog::NativeFileChooser::new(dialog::NativeFileChooserType::BrowseFile);
	fc.show();
	
	let file = File::open(fc.filename()).unwrap();
	let mut ar = zip::ZipArchive::new(file).unwrap();
	let mut state = AppState::new();
	
	let json_file = ar.by_name("graph.json").unwrap();
	state.board = serde_json::from_reader(json_file).unwrap();
	if let Ok(mut image_file) = ar.by_name("image.png") {
	    let mut buf = Vec::new();
	    image_file.read_to_end(&mut buf).ok();

	    let image = decode_png(&buf);
	    state.image = Some(PngImage::from_data(&buf).unwrap());
	    state.image_raw = Some(image);
	    app::redraw();
	}
	state_clone.replace(state);
    });
    let state_clone = Rc::clone(&state);
    menubar.add("File/Open Image..."	, Shortcut::None, menu::MenuFlag::Normal, move |_| {
	let mut fc = dialog::NativeFileChooser::new(dialog::NativeFileChooserType::BrowseFile);
	fc.show();
	let filename = fc.filename();

	match ImageReader::open(filename).map(|i| i.decode()) {
	    Ok(Ok(image)) => {
		let mut state = state_clone.borrow_mut();
		let data = encode_png(&image);
		state.image = Some(PngImage::from_data(&data).unwrap());
		state.image_raw = Some(image);
		app::redraw();
	    }
	    _ => dialog::alert_default("Error opening file"),
	}
    });
    let state_clone = Rc::clone(&state);
    menubar.add("File/Save As ..."	, Shortcut::None, menu::MenuFlag::Normal, move |_| {
	let mut fc = dialog::NativeFileChooser::new(dialog::NativeFileChooserType::BrowseSaveFile);
	fc.show();

	let file = File::create(fc.filename()).unwrap();
	let mut ar = zip::ZipWriter::new(file);
	let options = zip::write::FileOptions::default();
	let state = state_clone.borrow();
	
	ar.start_file("graph.json", options).ok();
	ar.write(&serde_json::to_vec(&state.board).unwrap()).ok();
	if let Some(image) = state.image_raw.as_ref() {
	    ar.start_file("image.png", options).ok();
	    let data = encode_png(image);
	    ar.write_all(&data).unwrap();
	    ar.flush().unwrap();
	}
	ar.finish().ok();
    });
    menubar.add("Edit/Edit Nodes"	, Shortcut::None, menu::MenuFlag::Normal, menu_cb);
    menubar.add("Edit/Edit Edges"	, Shortcut::None, menu::MenuFlag::Normal, menu_cb);
    flex.set_size(&menubar, 40);

    // Canvas
    let mut frame = frame::Frame::default();
    let state_clone = Rc::clone(&state);
    frame.draw(move |f| {
	use draw::*;
	let mut state = state_clone.borrow_mut();
	let image = &mut state.image;
	if let Some(image) = image.as_mut() {
	    image.scale(f.w(), f.h(), false, true);
	    image.draw(f.x(), f.y(), f.w(), f.h());
	}
	let board = &state.board;
	for (_, node) in &board.nodes {
	    let (x, y) = f.from_coords(node.x, node.y);
	    draw_text(&node.name, x, y);
	}
    });
    let state_clone = Rc::clone(&state);
    frame.handle(move |f, e| {
	match e {
	    Event::Push => {
		let mut state = state_clone.borrow_mut();
		let (pos_x, pos_y) = f.to_coords(app::event_x(), app::event_y());
		if app::event_button() == 1 {
		    state.board.add_node(pos_x, pos_y);
		} else if app::event_button() == 3 {
		    let id = state.board.nearest_node(pos_x, pos_y);
		    if let Some(id) = id {
			state.board.remove_node(id);
		    }
		}
		app::redraw();
		true
	    }
	    _ => false,
	}
    });
    
    flex.end();

    win.end();
    win.make_resizable(true);
    win.show();

    app.run().unwrap();
}