/*
Copyright 2023, Savanni D'Gerinel <savanni@luminescent-dreams.com>

This file is part of FitnessTrax.

FitnessTrax is free software: you can redistribute it and/or modify it under the terms of the GNU
General Public License as published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.

FitnessTrax 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
General Public License for more details.

You should have received a copy of the GNU General Public License along with FitnessTrax. If not, see <https://www.gnu.org/licenses/>.
*/

mod ui;

use adw::prelude::*;
use async_channel::{Receiver, Sender};
use emseries::{EmseriesReadError, Series};
use ft_core::TraxRecord;
use gio::resources_lookup_data;
use glib::Object;
use gtk::{subclass::prelude::*, STYLE_PROVIDER_PRIORITY_USER};
use std::{
    cell::RefCell,
    env,
    path::{Path, PathBuf},
    rc::Rc,
    sync::{Arc, RwLock},
};
use ui::FileChooserRow;

const APP_ID_DEV: &str = "com.luminescent-dreams.fitnesstrax.dev";
const APP_ID_PROD: &str = "com.luminescent-dreams.fitnesstrax";

const RESOURCE_BASE_PATH: &str = "/com/luminescent-dreams/fitnesstrax/";

#[derive(Debug)]
enum AppInvocation {
    OpenDatabase(PathBuf),
    RequestRecords,
}

#[derive(Debug)]
enum AppResponse {
    NoDatabase,
    Records,
    DatabaseChanged(PathBuf),
}

// Note that I have not yet figured out the communication channel or how the central dispatcher
// should work. There's a dance between the App and the AppWindow that I haven't figured out yet.

/// The real, headless application. This is where all of the logic will reside.
#[derive(Clone)]
struct App {
    database: Arc<RwLock<Option<Series<TraxRecord>>>>,
}

impl App {
    pub fn new(db_path: Option<PathBuf>) -> Self {
        let database = db_path.map(|path| Series::open(path).unwrap());
        let s = Self {
            database: Arc::new(RwLock::new(database)),
        };

        s
    }

    pub async fn process_invocation(&self, invocation: AppInvocation) -> AppResponse {
        match invocation {
            AppInvocation::OpenDatabase(db_path) => {
                self.open_db(&db_path);
                AppResponse::DatabaseChanged(db_path)
            }
            AppInvocation::RequestRecords => {
                if self.database.read().unwrap().is_none() {
                    AppResponse::NoDatabase
                } else {
                    AppResponse::Records
                }
            }
        }
    }

    pub fn open_db(&self, path: &Path) {
        let db = Series::open(path).unwrap();
        *self.database.write().unwrap() = Some(db);
    }
}

pub struct PlaceholderViewPrivate {}

#[glib::object_subclass]
impl ObjectSubclass for PlaceholderViewPrivate {
    const NAME: &'static str = "PlaceholderView";
    type Type = PlaceholderView;
    type ParentType = gtk::Box;

    fn new() -> Self {
        Self {}
    }
}

impl ObjectImpl for PlaceholderViewPrivate {}
impl WidgetImpl for PlaceholderViewPrivate {}
impl BoxImpl for PlaceholderViewPrivate {}

glib::wrapper! {
    pub struct PlaceholderView(ObjectSubclass<PlaceholderViewPrivate>) @extends gtk::Box, gtk::Widget;
}

impl PlaceholderView {
    pub fn new() -> Self {
        let s: Self = Object::builder().build();
        s
    }
}

/// This is the view to show if the application has not yet been configured. It will walk the user
/// through the most critical setup steps so that we can move on to the other views in the app.
pub struct WelcomeViewPrivate {}

#[glib::object_subclass]
impl ObjectSubclass for WelcomeViewPrivate {
    const NAME: &'static str = "WelcomeView";
    type Type = WelcomeView;
    type ParentType = gtk::Box;

    fn new() -> Self {
        Self {}
    }
}

impl ObjectImpl for WelcomeViewPrivate {}
impl WidgetImpl for WelcomeViewPrivate {}
impl BoxImpl for WelcomeViewPrivate {}

glib::wrapper! {
    pub struct WelcomeView(ObjectSubclass<WelcomeViewPrivate>) @extends gtk::Box, gtk::Widget, @implements gtk::Orientable;
}

impl WelcomeView {
    pub fn new<F>(on_save: Box<F>) -> Self
    where
        F: Fn(PathBuf) + 'static,
    {
        let s: Self = Object::builder().build();
        s.set_orientation(gtk::Orientation::Vertical);
        s.set_css_classes(&["welcome"]);

        // Replace this with the welcome screen that we set up in the fitnesstrax/unconfigured-page
        // branch.
        let title = gtk::Label::builder()
            .label("Welcome to FitnessTrax")
            .css_classes(["welcome-title"])
            .build();

        let content = gtk::Box::builder()
            .css_classes(["model-content"])
            .orientation(gtk::Orientation::Vertical)
            .vexpand(true)
            .build();

        let save_button = gtk::Button::builder()
            .label("Save Settings")
            .sensitive(false)
            .build();

        // The database selection row should be a box that shows a default database path, along with a
        // button that triggers a file chooser dialog. Once the dialog returns, the box should be
        // updated to reflect the chosen path.
        let db_row = FileChooserRow::new({
            let save_button = save_button.clone();
            move |_| save_button.set_sensitive(true)
        });

        content.append(&gtk::Label::new(Some("Welcome to FitnessTrax. The application has not yet been configured, so I will walk you through that. Let's start out by selecting your database.")));
        content.append(&db_row);

        let on_save = on_save;
        save_button.connect_clicked({
            move |_| {
                if let Some(path) = db_row.path() {
                    on_save(path)
                }
            }
        });

        s.append(&title);
        s.append(&content);
        s.append(&save_button);

        s
    }
}

/// The historical view will show a window into the main database. It will show some version of
/// daily summaries, daily details, and will provide all functions the user may need for editing
/// records.
pub struct HistoricalViewPrivate {}

#[glib::object_subclass]
impl ObjectSubclass for HistoricalViewPrivate {
    const NAME: &'static str = "HistoricalView";
    type Type = HistoricalView;
    type ParentType = gtk::Box;

    fn new() -> Self {
        Self {}
    }
}

impl ObjectImpl for HistoricalViewPrivate {}
impl WidgetImpl for HistoricalViewPrivate {}
impl BoxImpl for HistoricalViewPrivate {}

glib::wrapper! {
    pub struct HistoricalView(ObjectSubclass<HistoricalViewPrivate>) @extends gtk::Box, gtk::Widget;
}

impl HistoricalView {
    pub fn new() -> Self {
        let s: Self = Object::builder().build();

        let label = gtk::Label::builder()
            .label("Database has been configured and now it is time to show data")
            .build();
        s.append(&label);
        s
    }
}

#[derive(Clone, Debug, PartialEq)]
enum ViewName {
    Placeholder,
    Welcome,
    Historical,
}

enum View {
    Placeholder(gtk::Widget),
    Welcome(gtk::Widget),
    Historical(gtk::Widget),
}

impl View {
    fn widget<'a>(&'a self) -> &'a gtk::Widget {
        match self {
            View::Placeholder(widget) => widget,
            View::Welcome(widget) => widget,
            View::Historical(widget) => widget,
        }
    }
}

/// The application window, or the main window, is the main user interface for the app. Almost
/// everything occurs here.
#[derive(Clone)]
struct AppWindow {
    app_tx: Sender<AppInvocation>,
    window: adw::ApplicationWindow,
    layout: gtk::Box,
    current_view: Rc<RefCell<View>>,
    settings: gio::Settings,
}

impl AppWindow {
    /// Construct a new App Window.
    ///
    /// adw_app is an Adwaita application. Application windows need to have access to this, but
    /// otherwise we don't use this.
    ///
    /// app is a core [App] object which encapsulates all of the basic logic.
    fn new(app_id: &str, adw_app: &adw::Application, app_tx: Sender<AppInvocation>) -> AppWindow {
        let window = adw::ApplicationWindow::builder()
            .application(adw_app)
            .width_request(800)
            .height_request(600)
            .build();

        let stylesheet = String::from_utf8(
            resources_lookup_data(
                &format!("{}style.css", RESOURCE_BASE_PATH),
                gio::ResourceLookupFlags::NONE,
            )
            .expect("stylesheet must be available in the resources")
            .to_vec(),
        )
        .expect("to parse stylesheet");

        let provider = gtk::CssProvider::new();
        provider.load_from_data(&stylesheet);

        let context = window.style_context();
        context.add_provider(&provider, STYLE_PROVIDER_PRIORITY_USER);

        let header = adw::HeaderBar::builder()
            .title_widget(&gtk::Label::new(Some("FitnessTrax")))
            .build();

        let layout = gtk::Box::builder()
            .orientation(gtk::Orientation::Vertical)
            .build();

        let initial_view = View::Placeholder(PlaceholderView::new().upcast());

        layout.append(&header);
        layout.append(initial_view.widget());

        window.set_content(Some(&layout));
        window.present();

        let s = Self {
            app_tx,
            window,
            layout,
            current_view: Rc::new(RefCell::new(initial_view)),
            settings: gio::Settings::new(app_id),
        };

        s
    }

    pub fn change_view(&self, view: ViewName) {
        self.swap_main(self.construct_view(view));
    }

    pub fn process_response(&self, response: AppResponse) {
        match response {
            AppResponse::DatabaseChanged(db_path) => {
                self.settings
                    .set_string("series-path", db_path.to_str().unwrap())
                    .unwrap();
                self.change_view(ViewName::Historical);
            }
            AppResponse::NoDatabase => {
                self.change_view(ViewName::Welcome);
            }
            AppResponse::Records => {
                self.change_view(ViewName::Historical);
            }
        }
    }

    // Switch views.
    //
    // This function only replaces the old view with the one which matches the current view state.
    // It is responsible for ensuring that the new view goes into the layout in the correct
    // position.
    fn swap_main(&self, view: View) {
        let mut current_widget = self.current_view.borrow_mut();
        self.layout.remove(&*current_widget.widget());
        *current_widget = view;
        self.layout.append(&*current_widget.widget());
    }

    fn construct_view(&self, view: ViewName) -> View {
        match view {
            ViewName::Placeholder => View::Placeholder(PlaceholderView::new().upcast()),
            ViewName::Welcome => View::Welcome(
                WelcomeView::new({
                    let s = self.clone();
                    Box::new(move |path: PathBuf| {
                        s.app_tx
                            .send_blocking(AppInvocation::OpenDatabase(path))
                            .unwrap();
                    })
                })
                .upcast(),
            ),
            ViewName::Historical => View::Historical(HistoricalView::new().upcast()),
        }
    }
}

fn main() {
    // I still don't fully understand gio resources. resources_register_include! is convenient
    // because I don't have to deal with filesystem locations at runtime. However, I think other
    // GTK applications do that rather than compiling the resources directly into the app. So, I'm
    // unclear as to how I want to handle this.
    gio::resources_register_include!("com.luminescent-dreams.fitnesstrax.gresource")
        .expect("to register resources");

    let app_id = if std::env::var_os("ENV") == Some("dev".into()) {
        APP_ID_DEV
    } else {
        APP_ID_PROD
    };

    let settings = gio::Settings::new(app_id);
    let app = App::new({
        let path = settings.string("series-path");
        if path.is_empty() {
            None
        } else {
            Some(PathBuf::from(path))
        }
    });

    let adw_app = adw::Application::builder()
        .application_id(app_id)
        .resource_base_path(RESOURCE_BASE_PATH)
        .build();

    let runtime = tokio::runtime::Builder::new_multi_thread()
        .enable_all()
        .build()
        .unwrap();

    adw_app.connect_activate(move |adw_app| {
        let (gtk_tx, gtk_rx) = async_channel::unbounded::<AppResponse>();
        let (app_tx, app_rx) = async_channel::unbounded::<AppInvocation>();

        let window = AppWindow::new(app_id, adw_app, app_tx.clone());

        glib::spawn_future_local(async move {
            // The app requests data to start with. This kicks everything off. The response from
            // the app will cause the window to be updated shortly.
            let _ = app_tx.send(AppInvocation::RequestRecords).await;

            while let Ok(response) = gtk_rx.recv().await {
                println!("response received: {:?}", response);
                window.process_response(response);
            }
        });

        runtime.spawn({
            let app = app.clone();
            async move {
                while let Ok(invocation) = app_rx.recv().await {
                    let response = app.process_invocation(invocation).await;
                    let _ = gtk_tx.send(response).await;
                }
            }
        });
    });

    let args: Vec<String> = env::args().collect();
    ApplicationExtManual::run_with_args(&adw_app, &args);
}