use std::collections::BTreeSet;

use super::About;
use crate::Demo;
use crate::View as _;
use crate::is_mobile;
use egui::containers::menu;
use egui::style::StyleModifier;
use egui::{Modifiers, ScrollArea, Ui};
// ----------------------------------------------------------------------------

struct DemoGroup {
    demos: Vec<Box<dyn Demo>>,
}

impl std::ops::Add for DemoGroup {
    type Output = Self;

    fn add(self, other: Self) -> Self {
        let mut demos = self.demos;
        demos.extend(other.demos);
        Self { demos }
    }
}

impl DemoGroup {
    pub fn new(demos: Vec<Box<dyn Demo>>) -> Self {
        Self { demos }
    }

    pub fn checkboxes(&mut self, ui: &mut Ui, open: &mut BTreeSet<String>) {
        let Self { demos } = self;
        for demo in demos {
            if demo.is_enabled(ui.ctx()) {
                let mut is_open = open.contains(demo.name());
                ui.toggle_value(&mut is_open, demo.name());
                set_open(open, demo.name(), is_open);
            }
        }
    }

    pub fn windows(&mut self, ui: &mut Ui, open: &mut BTreeSet<String>) {
        let Self { demos } = self;
        for demo in demos {
            let mut is_open = open.contains(demo.name());
            demo.show(ui, &mut is_open);
            set_open(open, demo.name(), is_open);
        }
    }

    pub fn logic(&mut self, ctx: &egui::Context) {
        for demo in &mut self.demos {
            demo.logic(ctx);
        }
    }
}

fn set_open(open: &mut BTreeSet<String>, key: &'static str, is_open: bool) {
    if is_open {
        if !open.contains(key) {
            open.insert(key.to_owned());
        }
    } else {
        open.remove(key);
    }
}

// ----------------------------------------------------------------------------

pub struct DemoGroups {
    about: About,
    demos: DemoGroup,
    tests: DemoGroup,
}

impl Default for DemoGroups {
    fn default() -> Self {
        Self {
            about: About::default(),
            demos: DemoGroup::new(vec![
                Box::<super::paint_bezier::PaintBezier>::default(),
                Box::<super::code_editor::CodeEditor>::default(),
                Box::<super::code_example::CodeExample>::default(),
                Box::<super::dancing_strings::DancingStrings>::default(),
                Box::<super::drag_and_drop::DragAndDropDemo>::default(),
                Box::<super::extra_viewport::ExtraViewport>::default(),
                Box::<super::font_book::FontBook>::default(),
                Box::<super::frame_demo::FrameDemo>::default(),
                Box::<super::highlighting::Highlighting>::default(),
                Box::<super::interactive_container::InteractiveContainerDemo>::default(),
                Box::<super::MiscDemoWindow>::default(),
                Box::<super::modals::Modals>::default(),
                Box::<super::multi_touch::MultiTouch>::default(),
                Box::<super::painting::Painting>::default(),
                Box::<super::panels::Panels>::default(),
                Box::<super::popups::PopupsDemo>::default(),
                Box::<super::scene::SceneDemo>::default(),
                Box::<super::screenshot::Screenshot>::default(),
                Box::<super::scrolling::Scrolling>::default(),
                Box::<super::sliders::Sliders>::default(),
                Box::<super::strip_demo::StripDemo>::default(),
                Box::<super::table_demo::TableDemo>::default(),
                Box::<super::text_edit::TextEditDemo>::default(),
                Box::<super::text_layout::TextLayoutDemo>::default(),
                Box::<super::tooltips::Tooltips>::default(),
                Box::<super::undo_redo::UndoRedoDemo>::default(),
                Box::<super::widget_gallery::WidgetGallery>::default(),
                Box::<super::window_options::WindowOptions>::default(),
            ]),
            tests: DemoGroup::new(vec![
                Box::<super::tests::ClipboardTest>::default(),
                Box::<super::tests::CursorTest>::default(),
                Box::<super::tests::GridTest>::default(),
                Box::<super::tests::IdTest>::default(),
                Box::<super::tests::InputEventHistory>::default(),
                Box::<super::tests::InputTest>::default(),
                Box::<super::tests::LayoutTest>::default(),
                Box::<super::tests::ManualLayoutTest>::default(),
                Box::<super::tests::SvgTest>::default(),
                Box::<super::tests::TessellationTest>::default(),
                Box::<super::tests::WindowResizeTest>::default(),
            ]),
        }
    }
}

impl DemoGroups {
    pub fn about_egui_checkbox(&mut self, ui: &mut Ui, open: &mut BTreeSet<String>) {
        let Self { about, .. } = self;
        let mut is_open = open.contains(about.name());
        ui.toggle_value(&mut is_open, about.name());
        set_open(open, about.name(), is_open);
    }

    pub fn checkboxes(&mut self, ui: &mut Ui, open: &mut BTreeSet<String>) {
        let Self {
            about: _,
            demos,
            tests,
        } = self;

        ui.vertical_centered(|ui| {
            ui.strong("Demos");
        });
        demos.checkboxes(ui, open);

        ui.separator();

        ui.vertical_centered(|ui| {
            ui.strong("Tests");
        });
        tests.checkboxes(ui, open);
    }

    pub fn windows(&mut self, ui: &mut Ui, open: &mut BTreeSet<String>) {
        let Self {
            about,
            demos,
            tests,
        } = self;
        {
            let mut is_open = open.contains(about.name());
            about.show(ui, &mut is_open);
            set_open(open, about.name(), is_open);
        }
        demos.windows(ui, open);
        tests.windows(ui, open);
    }

    pub fn logic(&mut self, ctx: &egui::Context) {
        self.demos.logic(ctx);
        self.tests.logic(ctx);
    }
}

// ----------------------------------------------------------------------------

/// A menu bar in which you can select different demo windows to show.
#[cfg_attr(feature = "serde", derive(serde::Deserialize, serde::Serialize))]
#[cfg_attr(feature = "serde", serde(default))]
pub struct DemoWindows {
    #[cfg_attr(feature = "serde", serde(skip))]
    groups: DemoGroups,

    open: BTreeSet<String>,
}

impl Default for DemoWindows {
    fn default() -> Self {
        let mut open = BTreeSet::new();

        // Explains egui very well
        set_open(&mut open, About::default().name(), true);

        // Explains egui very well
        set_open(
            &mut open,
            super::code_example::CodeExample::default().name(),
            true,
        );

        // Shows off the features
        set_open(
            &mut open,
            super::widget_gallery::WidgetGallery::default().name(),
            true,
        );

        Self {
            groups: Default::default(),
            open,
        }
    }
}

impl DemoWindows {
    /// Show the app ui (menu bar and windows).
    pub fn ui(&mut self, ui: &mut egui::Ui) {
        if is_mobile(ui.ctx()) {
            self.mobile_ui(ui);
        } else {
            self.desktop_ui(ui);
        }
    }

    /// Run background logic for all demos.
    ///
    /// Called every frame, even when hidden, so demos can keep working in the background.
    pub fn logic(&mut self, ctx: &egui::Context) {
        self.groups.logic(ctx);
    }

    fn about_is_open(&self) -> bool {
        self.open.contains(About::default().name())
    }

    fn mobile_ui(&mut self, ui: &mut egui::Ui) {
        if self.about_is_open() {
            let mut close = false;

            egui::ScrollArea::vertical()
                .auto_shrink(false)
                .show(ui, |ui| {
                    self.groups.about.ui(ui);
                    ui.add_space(12.0);
                    ui.vertical_centered_justified(|ui| {
                        if ui
                            .button(egui::RichText::new("Continue to the demo!").size(20.0))
                            .clicked()
                        {
                            close = true;
                        }
                    });
                });

            if close {
                set_open(&mut self.open, About::default().name(), false);
            }
        } else {
            self.mobile_top_bar(ui);
            self.groups.windows(ui, &mut self.open);
        }
    }

    fn mobile_top_bar(&mut self, ui: &mut egui::Ui) {
        egui::Panel::top("menu_bar").show(ui, |ui| {
            menu::MenuBar::new()
                .config(menu::MenuConfig::new().style(StyleModifier::default()))
                .ui(ui, |ui| {
                    let font_size = 16.5;

                    ui.menu_button(egui::RichText::new("⏷ demos").size(font_size), |ui| {
                        self.demo_list_ui(ui);
                    });

                    ui.with_layout(egui::Layout::right_to_left(egui::Align::Center), |ui| {
                        use egui::special_emojis::GITHUB;
                        ui.hyperlink_to(
                            egui::RichText::new("🦋").size(font_size),
                            "https://bsky.app/profile/ernerfeldt.bsky.social",
                        );
                        ui.hyperlink_to(
                            egui::RichText::new(GITHUB).size(font_size),
                            "https://github.com/emilk/egui",
                        );
                    });
                });
        });
    }

    fn desktop_ui(&mut self, ui: &mut egui::Ui) {
        egui::Panel::right("egui_demo_panel")
            .resizable(false)
            .default_size(160.0)
            .min_size(160.0)
            .show(ui, |ui| {
                ui.vertical_centered_justified(|ui| {
                    ui.add_space(4.0);
                    ui.add(
                        egui::Image::new(egui::include_image!("../../data/egui-logo.svg"))
                            .max_height(32.0)
                            .tint(ui.visuals().strong_text_color()),
                    );

                    ui.add_space(4.0);

                    self.groups.about_egui_checkbox(ui, &mut self.open);
                });

                ui.add_space(4.0);

                ui.separator();

                self.demo_list_ui(ui);
            });

        egui::Panel::top("menu_bar").show(ui, |ui| {
            menu::MenuBar::new().ui(ui, |ui| {
                file_menu_button(ui);
            });
        });

        self.groups.windows(ui, &mut self.open);
    }

    fn demo_list_ui(&mut self, ui: &mut egui::Ui) {
        ScrollArea::vertical().show(ui, |ui| {
            ui.with_layout(egui::Layout::top_down_justified(egui::Align::LEFT), |ui| {
                self.groups.checkboxes(ui, &mut self.open);
                ui.separator();
                if ui.button("Organize windows").clicked() {
                    ui.memory_mut(|mem| mem.reset_areas());
                }
            });
        });
    }
}

// ----------------------------------------------------------------------------

fn file_menu_button(ui: &mut Ui) {
    let organize_shortcut =
        egui::KeyboardShortcut::new(Modifiers::CTRL | Modifiers::SHIFT, egui::Key::O);
    let reset_shortcut =
        egui::KeyboardShortcut::new(Modifiers::CTRL | Modifiers::SHIFT, egui::Key::R);

    // NOTE: we must check the shortcuts OUTSIDE of the actual "File" menu,
    // or else they would only be checked if the "File" menu was actually open!

    if ui.input_mut(|i| i.consume_shortcut(&organize_shortcut)) {
        ui.memory_mut(|mem| mem.reset_areas());
    }

    if ui.input_mut(|i| i.consume_shortcut(&reset_shortcut)) {
        ui.memory_mut(|mem| *mem = Default::default());
    }

    ui.menu_button("File", |ui| {
        ui.style_mut().wrap_mode = Some(egui::TextWrapMode::Extend);

        // On the web the browser controls the zoom
        #[cfg(not(target_arch = "wasm32"))]
        {
            egui::gui_zoom::zoom_menu_buttons(ui);
            ui.weak(format!(
                "Current zoom: {:.0}%",
                100.0 * ui.ctx().zoom_factor()
            ))
            .on_hover_text("The UI zoom level, on top of the operating system's default value");
            ui.separator();
        }

        if ui
            .add(
                egui::Button::new("Organize Windows")
                    .shortcut_text(ui.ctx().format_shortcut(&organize_shortcut)),
            )
            .clicked()
        {
            ui.memory_mut(|mem| mem.reset_areas());
        }

        if ui
            .add(
                egui::Button::new("Reset egui memory")
                    .shortcut_text(ui.ctx().format_shortcut(&reset_shortcut)),
            )
            .on_hover_text("Forget scroll, positions, sizes etc")
            .clicked()
        {
            ui.memory_mut(|mem| *mem = Default::default());
        }
    });
}

#[cfg(test)]
mod tests {
    use crate::{Demo as _, demo::demo_app_windows::DemoGroups};

    use egui::Vec2;
    use egui_kittest::{HarnessBuilder, OsThreshold, SnapshotOptions, SnapshotResults};

    #[test]
    fn demos_should_match_snapshot() {
        let DemoGroups {
            demos,
            tests,
            about: _,
        } = DemoGroups::default();
        let demos = demos + tests;

        let mut results = SnapshotResults::new();

        for mut demo in demos.demos {
            // Widget Gallery needs to be customized (to set a specific date) and has its own test
            if demo.name() == crate::WidgetGallery::default().name() {
                continue;
            }

            let name = remove_leading_emoji(demo.name());

            let mut harness = HarnessBuilder::default()
                .with_size(Vec2::splat(2048.0))
                .build_ui(|ui| {
                    egui_extras::install_image_loaders(ui);
                    demo.show(ui, &mut true);
                });

            // Resize to fit every window, plus some margin:
            harness.set_size(harness.ctx.globally_used_rect().max.to_vec2() + Vec2::splat(16.0));

            // Run the app for some more frames...
            harness.run_ok();

            let mut options = SnapshotOptions::default();

            if name == "Bézier Curve" {
                // The Bézier Curve demo needs a threshold of 2.1 to pass on linux:
                options = options.threshold(OsThreshold::new(0.0_f32).linux(2.1));
            }

            results.add(harness.try_snapshot_options(format!("demos/{name}"), &options));
        }
    }

    fn remove_leading_emoji(full_name: &str) -> &str {
        if let Some((start, name)) = full_name.split_once(' ')
            && start.len() <= 4
            && start.bytes().next().is_some_and(|byte| byte >= 128)
        {
            return name;
        }
        full_name
    }
}