// Tablet emulator, for people who don’t own one
// Copyright © 2020 Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

use gio::prelude::*;
use glib::clone;
use gtk::prelude::*;

use std::env::args;
use std::io::ErrorKind;
use std::sync::Arc;
use input_linux::Key;

mod uinput;
mod state;
use state::State;

const WIDTH: i32 = 320;
const HEIGHT: i32 = 180;

const MAX_X: i32 = 69920;
const MAX_Y: i32 = 39980;

fn build_main_menu(application: &gtk::Application) {
    let quit = gio::SimpleAction::new("quit", None);
    application.set_accels_for_action("app.quit", &["<Control>q"]);
    application.add_action(&quit);
    quit.connect_activate(clone!(@weak application => move |_, _| application.quit()));

    let about = gio::SimpleAction::new("about", None);
    application.add_action(&about);
    about.connect_activate(|_, _| {
        let about = gtk::AboutDialog::new();
        about.set_program_name("TabletEmu");
        about.set_logo_icon_name(Some("input-tablet"));
        about.set_website(Some("https://hg.linkmauve.fr/tablet-emu"));
        about.set_version(Some("0.1"));
        about.set_license_type(gtk::License::Agpl30);
        about.set_copyright(Some("© 2020 Emmanuel Gil Peyrot <linkmauve@linkmauve.fr>"));
        about.run();
        unsafe {
            about.destroy();
        }
    });

    let menu = gio::Menu::new();
    {
        let file = gio::Menu::new();
        file.append(Some("_Quit"), Some("app.quit"));
        menu.append_submenu(Some("_File"), &file);
    }
    {
        let help = gio::Menu::new();
        help.append(Some("_About"), Some("app.about"));
        menu.append_submenu(Some("_Help"), &help);
    }
    application.set_menubar(Some(&menu));
}

fn build_ui(application: &gtk::Application) {
    build_main_menu(application);

    let state = match State::new() {
        Ok(state) => state,
        Err(err) => {
            match err.kind() {
                ErrorKind::NotFound => {
                    eprintln!("Couldn’t find /dev/uinput: {}", err);
                    eprintln!("Maybe you forgot to `modprobe uinput`?");
                }
                ErrorKind::PermissionDenied => {
                    eprintln!("Couldn’t open /dev/uinput for writing: {}", err);
                    eprintln!("Maybe you aren’t allowed to create input devices?");
                }
                _ => eprintln!("Couldn’t open /dev/uinput for writing: {}", err),
            }
            std::process::exit(1);
        }
    };

    let window = gtk::ApplicationWindow::new(application);
    window.set_title("tablet-emu");
    window.set_position(gtk::WindowPosition::Center);

    let hbox = gtk::Box::new(gtk::Orientation::Horizontal, 0);
    let tools_box = gtk::Box::new(gtk::Orientation::Vertical, 0);

    macro_rules! impl_tool {
        ($tool:tt) => {
            let tool = gtk::Button::with_mnemonic($tool);
            let state_weak = Arc::downgrade(&state);
            tool.connect_clicked(move |b| {
                let state = state_weak.upgrade().unwrap();
                let mut state = state.lock().unwrap();
                let tool = match b.get_label().unwrap().as_str() {
                    "_Pen" => Key::ButtonToolPen,
                    "_Rubber" => Key::ButtonToolRubber,
                    "_Brush" => Key::ButtonToolBrush,
                    "P_encil" => Key::ButtonToolPencil,
                    "_Airbrush" => Key::ButtonToolAirbrush,
                    _ => unreachable!(),
                };
                state.select_tool(tool);
            });
            tools_box.add(&tool);
        };
    };
    impl_tool!("_Pen");
    impl_tool!("_Rubber");
    impl_tool!("_Brush");
    impl_tool!("P_encil");
    impl_tool!("_Airbrush");

    let drawing_area = gtk::DrawingArea::new();
    drawing_area.set_size_request(WIDTH, HEIGHT);
    drawing_area.set_hexpand(true);
    drawing_area.set_events(
        gdk::EventMask::BUTTON_PRESS_MASK
            | gdk::EventMask::BUTTON_RELEASE_MASK
            | gdk::EventMask::POINTER_MOTION_MASK,
    );
    let state_weak = Arc::downgrade(&state);
    drawing_area.connect_configure_event(move |_, event| {
        let state = state_weak.upgrade().unwrap();
        let mut state = state.lock().unwrap();
        state.set_size(event.get_size());
        true
    });
    let state_weak = Arc::downgrade(&state);
    drawing_area.connect_button_press_event(move |_, event| {
        if event.get_button() != 1 {
            return Inhibit(false);
        }

        let state = state_weak.upgrade().unwrap();
        let mut state = state.lock().unwrap();
        let (x, y) = event.get_position();
        state.press(x, y).unwrap();
        Inhibit(false)
    });
    let state_weak = Arc::downgrade(&state);
    drawing_area.connect_button_release_event(move |_, event| {
        if event.get_button() != 1 {
            return Inhibit(false);
        }

        let state = state_weak.upgrade().unwrap();
        let mut state = state.lock().unwrap();
        let (x, y) = event.get_position();
        state.release(x, y).unwrap();
        Inhibit(false)
    });
    drawing_area.connect_motion_notify_event(move |_, event| {
        let mut state = state.lock().unwrap();
        let (x, y) = event.get_position();
        state.motion(x, y).unwrap();
        Inhibit(false)
    });
    drawing_area.connect_draw(move |_, ctx| {
        //println!("drawing {}", drawing_area);
        ctx.set_source_rgb(1., 0., 0.);
        ctx.set_operator(cairo::Operator::Screen);
        ctx.paint();
        Inhibit(false)
    });

    hbox.add(&tools_box);
    hbox.add(&drawing_area);

    window.add(&hbox);

    window.show_all();
}

fn main() {
    let application = gtk::Application::new(
        Some("fr.linkmauve.TabletEmu"),
        gio::ApplicationFlags::empty(),
    )
    .expect("Initialisation failed…");
    application.connect_activate(build_ui);
    application.run(&args().collect::<Vec<_>>());
}