use std::{
    fs,
    path::PathBuf,
    sync::{Arc, mpsc},
};

use crate::{file_editor::FileEditor, preferences::Preferences, util::GuiSender};
use egui::{
    Align, Button, Color32, FontData, FontDefinitions, PointerButton, RichText, ScrollArea, Stroke,
};

#[derive(serde::Deserialize, serde::Serialize)]
#[serde(default)]
pub struct App {
    preferences: Preferences,

    #[serde(skip)]
    actions_tx: mpsc::Sender<Action>,
    #[serde(skip)]
    actions_rx: mpsc::Receiver<Action>,

    tabs: Vec<(TabId, Tab)>,
    open_tab_index: Option<usize>,

    next_tab_id: TabId,
}

#[derive(serde::Deserialize, serde::Serialize)]
enum Tab {
    File(FileEditor),
}

impl Tab {
    pub fn title(&self) -> &str {
        match self {
            Tab::File(file_editor) => file_editor.title(),
        }
    }
}

pub type TabId = usize;

pub enum Action {
    OpenFile(FileEditor),
    MoveFile(TabId, PathBuf),
    CloseTab(TabId),
    // TODO
    //ShowError {
    //    error: RichText
    //},
}

impl Default for App {
    fn default() -> Self {
        let (actions_tx, actions_rx) = mpsc::channel();
        Self {
            preferences: Preferences::default(),
            actions_tx,
            actions_rx,
            tabs: vec![(1, Tab::File(FileEditor::new("note.md")))],
            open_tab_index: None,
            next_tab_id: 2,
        }
    }
}

impl App {
    /// Called once before the first frame.
    pub fn new(cc: &eframe::CreationContext<'_>) -> Self {
        let mut fonts = FontDefinitions::empty();
        fonts.font_data = [
            //(
            //    "IosevkaAile-Thin",
            //    include_bytes!("../fonts/IosevkaAile-Thin.ttc").as_slice(),
            //),
            //(
            //    "IosevkaAile-ExtraLight",
            //    include_bytes!("../fonts/IosevkaAile-ExtraLight.ttc").as_slice(),
            //),
            //(
            //    "IosevkaAile-Light",
            //    include_bytes!("../fonts/IosevkaAile-Light.ttc").as_slice(),
            //),
            (
                "IosevkaAile-Regular",
                include_bytes!("../fonts/IosevkaAile-Regular.ttc").as_slice(),
            ),
            //(
            //    "IosevkaAile-Medium",
            //    include_bytes!("../fonts/IosevkaAile-Medium.ttc").as_slice(),
            //),
            //(
            //    "IosevkaAile-Bold",
            //    include_bytes!("../fonts/IosevkaAile-Bold.ttc").as_slice(),
            //),
            (
                "Iosevka-Thin",
                include_bytes!("../fonts/Iosevka-Thin.ttc").as_slice(),
            ),
            //(
            //    "Iosevka-ExtraLight",
            //    include_bytes!("../fonts/Iosevka-ExtraLight.ttc").as_slice(),
            //),
            //(
            //    "Iosevka-Light",
            //    include_bytes!("../fonts/Iosevka-Light.ttc").as_slice(),
            //),
            //(
            //    "Iosevka-Medium",
            //    include_bytes!("../fonts/Iosevka-Medium.ttc").as_slice(),
            //),
            //(
            //    "Iosevka-Regular",
            //    include_bytes!("../fonts/Iosevka-Regular.ttc").as_slice(),
            //),
            //(
            //    "Iosevka-Heavy",
            //    include_bytes!("../fonts/Iosevka-Heavy.ttc").as_slice(),
            //),
        ]
        .into_iter()
        .map(|(name, data)| (name.to_string(), Arc::new(FontData::from_static(data))))
        .collect();

        fonts.families.insert(
            egui::FontFamily::Proportional,
            vec!["IosevkaAile-Regular".into()],
        );

        fonts
            .families
            .insert(egui::FontFamily::Monospace, vec!["Iosevka-Thin".into()]);

        cc.egui_ctx.set_fonts(fonts);

        cc.egui_ctx.style_mut(|style| {
            // TODO: change color of text in TextEdit
            style.visuals.widgets.noninteractive.fg_stroke =
                Stroke::new(1.0, Color32::from_rgb(200, 200, 200));
        });

        if let Some(storage) = cc.storage {
            return eframe::get_value(storage, eframe::APP_KEY).unwrap_or_default();
        }

        Default::default()
    }

    fn actions_tx(&self, ctx: &egui::Context) -> GuiSender<Action> {
        GuiSender::new(self.actions_tx.clone(), ctx)
    }

    fn handle_action(&mut self, action: Action) {
        match action {
            Action::OpenFile(file_editor) => {
                self.open_tab(Tab::File(file_editor));
            }
            Action::MoveFile(tab_id, new_path) => {
                let tab = self.tabs.iter_mut().find(|(id, _)| &tab_id == id);
                let Some((_, tab)) = tab else { return };
                let Tab::File(editor) = tab; // else { return };

                editor.set_path(new_path);
            }
            Action::CloseTab(id) => {
                // TODO: check if the file is dirty and ask to save it first?
                self.tabs.retain(|(tab_id, _)| &id != tab_id);
            }
        }
    }
}

impl eframe::App for App {
    fn save(&mut self, storage: &mut dyn eframe::Storage) {
        eframe::set_value(storage, eframe::APP_KEY, self);
    }

    fn update(&mut self, ctx: &egui::Context, _frame: &mut eframe::Frame) {
        self.preferences.apply(ctx);

        while let Ok(action) = self.actions_rx.try_recv() {
            self.handle_action(action);
        }

        if self.open_tab_index >= Some(self.tabs.len()) {
            self.open_tab_index = Some(self.tabs.len().saturating_sub(1));
        }

        //ctx.input_mut(|input| {
        //    if input.consume_key(Modifiers::CTRL, Key::H) {
        //        self.buffer.push(BufferItem::Painting(Default::default()));
        //    }
        //});

        egui::TopBottomPanel::top("top_panel").show(ctx, |ui| {
            egui::containers::menu::Bar::new().ui(ui, |ui| {
                // NOTE: no File->Quit on web pages!
                ui.menu_button("Menu ⚙", |ui| {
                    ui.label(RichText::new("Action").weak());

                    if ui.button("New File").clicked() {
                        let file = FileEditor::new("note.md");
                        self.open_tab(Tab::File(file));
                    }

                    #[cfg(not(target_arch = "wasm32"))]
                    if ui.button("Open File").clicked() {
                        let actions_tx = self.actions_tx(ui.ctx());
                        std::thread::spawn(move || {
                            let file = rfd::FileDialog::new().pick_file();

                            let Some(file_path) = file else { return };

                            let text = match fs::read_to_string(&file_path) {
                                Ok(text) => text,
                                Err(e) => {
                                    log::error!("Failed to read {file_path:?}: {e}");
                                    return;
                                }
                            };

                            let editor = FileEditor::from_file(file_path, &text);
                            let _ = actions_tx.send(Action::OpenFile(editor));
                        });
                    }

                    if ui.button("Open Folder").clicked() {
                        log::error!("Open Folder not implemented");
                    }

                    if ui
                        .add_enabled(self.open_tab_index.is_some(), Button::new("Close File"))
                        .clicked()
                    {
                        if let Some(i) = self.open_tab_index.take() {
                            self.tabs.remove(i);
                        }
                    }

                    let open_file =
                        self.open_tab_index
                            .and_then(|i| self.tabs.get(i))
                            .and_then(|(id, tab)| match tab {
                                Tab::File(file_editor) => Some((*id, file_editor)),
                            });

                    let open_file_with_path = open_file
                        .clone()
                        .and_then(|(_, file_editor)| file_editor.path().zip(Some(file_editor)));

                    if ui
                        .add_enabled(open_file_with_path.is_some(), Button::new("Save"))
                        .clicked()
                    {
                        if let Some((file_path, file_editor)) = open_file_with_path {
                            let text = file_editor.to_string();
                            let file_path = file_path.to_owned();
                            std::thread::spawn(move || {
                                if let Err(e) = fs::write(file_path, text.as_bytes()) {
                                    log::error!("{e}");
                                };
                            });
                        }
                    }

                    #[cfg(not(target_arch = "wasm32"))]
                    if ui
                        .add_enabled(open_file.is_some(), Button::new("Save As"))
                        .clicked()
                    {
                        let actions_tx = self.actions_tx(ui.ctx());
                        let (tab_id, editor) =
                            open_file.expect("We checked that open_file is_some");
                        let text = editor.to_string();
                        std::thread::spawn(move || {
                            let Some(file_path) = rfd::FileDialog::new().save_file() else {
                                return;
                            };

                            if let Err(e) = fs::write(&file_path, text.as_bytes()) {
                                log::error!("{e}");
                                return;
                            };

                            let _ = actions_tx.send(Action::MoveFile(tab_id, file_path));
                        });
                    }

                    ui.add_space(8.0);

                    self.preferences.show(ui);

                    ui.add_space(8.0);

                    if cfg!(not(target_arch = "wasm32")) && ui.button("Quit").clicked() {
                        ctx.send_viewport_cmd(egui::ViewportCommand::Close);
                    }
                });

                ui.add_space(16.0);

                ui.add_space(16.0);

                ScrollArea::horizontal().show(ui, |ui| {
                    for (i, (tab_id, tab)) in self.tabs.iter().enumerate() {
                        let selected = self.open_tab_index == Some(i);
                        let mut button = Button::new(tab.title()).selected(selected);

                        let dirty = i == 0; // TODO: mark as dirty when contents hasn't been saved
                        if dirty {
                            button = button.right_text(RichText::new("*").strong())
                        }

                        let response = ui.add(button);

                        if response.clicked() {
                            self.open_tab_index = Some(i);
                        } else if response.clicked_by(PointerButton::Secondary) {
                            let _ = self.actions_tx(ui.ctx()).send(Action::CloseTab(*tab_id));
                        }
                    }
                });
            });
        });

        egui::CentralPanel::default().show(ctx, |ui| {
            if let Some(Tab::File(file_editor)) = self
                .open_tab_index
                .and_then(|i| self.tabs.get_mut(i))
                .map(|(_tab_id, tab)| tab)
            {
                file_editor.show(ui, &self.preferences);
            }

            ui.with_layout(egui::Layout::bottom_up(Align::LEFT), |ui| {
                egui::warn_if_debug_build(ui);
            });
        });
    }
}

impl App {
    /// Figure out where we should insert the next tab.
    fn insert_tab_at(&self) -> usize {
        match self.open_tab_index {
            None => 0,
            Some(i) => (i + 1).min(self.tabs.len()),
        }
    }

    /// Open a [Tab].
    fn open_tab(&mut self, tab: Tab) {
        let i = self.insert_tab_at();
        let id = self.next_tab_id;
        self.next_tab_id += 1;
        self.tabs.insert(i, (id, tab));
    }
}