use crate::{
    h_flex, prelude::*, utils::WithRemSize, v_flex, Icon, IconName, IconSize, KeyBinding, Label,
    List, ListItem, ListSeparator, ListSubHeader,
};
use gpui::{
    px, Action, AnyElement, App, AppContext as _, DismissEvent, Entity, EventEmitter, FocusHandle,
    Focusable, IntoElement, Render, Subscription,
};
use menu::{SelectFirst, SelectLast, SelectNext, SelectPrevious};
use settings::Settings;
use std::{rc::Rc, time::Duration};
use theme::ThemeSettings;

pub enum ContextMenuItem {
    Separator,
    Header(SharedString),
    Label(SharedString),
    Entry(ContextMenuEntry),
    CustomEntry {
        entry_render: Box<dyn Fn(&mut Window, &mut App) -> AnyElement>,
        handler: Rc<dyn Fn(Option<&FocusHandle>, &mut Window, &mut App)>,
        selectable: bool,
    },
}

impl ContextMenuItem {
    pub fn custom_entry(
        entry_render: impl Fn(&mut Window, &mut App) -> AnyElement + 'static,
        handler: impl Fn(&mut Window, &mut App) + 'static,
    ) -> Self {
        Self::CustomEntry {
            entry_render: Box::new(entry_render),
            handler: Rc::new(move |_, window, cx| handler(window, cx)),
            selectable: true,
        }
    }
}

pub struct ContextMenuEntry {
    toggle: Option<(IconPosition, bool)>,
    label: SharedString,
    icon: Option<IconName>,
    icon_position: IconPosition,
    icon_size: IconSize,
    icon_color: Option<Color>,
    handler: Rc<dyn Fn(Option<&FocusHandle>, &mut Window, &mut App)>,
    action: Option<Box<dyn Action>>,
    disabled: bool,
    documentation_aside: Option<Rc<dyn Fn(&mut App) -> AnyElement>>,
}

impl ContextMenuEntry {
    pub fn new(label: impl Into<SharedString>) -> Self {
        ContextMenuEntry {
            toggle: None,
            label: label.into(),
            icon: None,
            icon_position: IconPosition::Start,
            icon_size: IconSize::Small,
            icon_color: None,
            handler: Rc::new(|_, _, _| {}),
            action: None,
            disabled: false,
            documentation_aside: None,
        }
    }

    pub fn toggleable(mut self, toggle_position: IconPosition, toggled: bool) -> Self {
        self.toggle = Some((toggle_position, toggled));
        self
    }

    pub fn icon(mut self, icon: IconName) -> Self {
        self.icon = Some(icon);
        self
    }

    pub fn icon_position(mut self, position: IconPosition) -> Self {
        self.icon_position = position;
        self
    }

    pub fn icon_size(mut self, icon_size: IconSize) -> Self {
        self.icon_size = icon_size;
        self
    }

    pub fn icon_color(mut self, icon_color: Color) -> Self {
        self.icon_color = Some(icon_color);
        self
    }

    pub fn toggle(mut self, toggle_position: IconPosition, toggled: bool) -> Self {
        self.toggle = Some((toggle_position, toggled));
        self
    }

    pub fn action(mut self, action: Box<dyn Action>) -> Self {
        self.action = Some(action);
        self
    }

    pub fn handler(mut self, handler: impl Fn(&mut Window, &mut App) + 'static) -> Self {
        self.handler = Rc::new(move |_, window, cx| handler(window, cx));
        self
    }

    pub fn disabled(mut self, disabled: bool) -> Self {
        self.disabled = disabled;
        self
    }

    pub fn documentation_aside(
        mut self,
        element: impl Fn(&mut App) -> AnyElement + 'static,
    ) -> Self {
        self.documentation_aside = Some(Rc::new(element));
        self
    }
}

impl From<ContextMenuEntry> for ContextMenuItem {
    fn from(entry: ContextMenuEntry) -> Self {
        ContextMenuItem::Entry(entry)
    }
}

pub struct ContextMenu {
    items: Vec<ContextMenuItem>,
    focus_handle: FocusHandle,
    action_context: Option<FocusHandle>,
    selected_index: Option<usize>,
    delayed: bool,
    clicked: bool,
    _on_blur_subscription: Subscription,
    keep_open_on_confirm: bool,
    documentation_aside: Option<(usize, Rc<dyn Fn(&mut App) -> AnyElement>)>,
}

impl Focusable for ContextMenu {
    fn focus_handle(&self, _cx: &App) -> FocusHandle {
        self.focus_handle.clone()
    }
}

impl EventEmitter<DismissEvent> for ContextMenu {}

impl FluentBuilder for ContextMenu {}

impl ContextMenu {
    pub fn build(
        window: &mut Window,
        cx: &mut App,
        f: impl FnOnce(Self, &mut Window, &mut Context<Self>) -> Self,
    ) -> Entity<Self> {
        cx.new(|cx| {
            let focus_handle = cx.focus_handle();
            let _on_blur_subscription = cx.on_blur(
                &focus_handle,
                window,
                |this: &mut ContextMenu, window, cx| this.cancel(&menu::Cancel, window, cx),
            );
            window.refresh();
            f(
                Self {
                    items: Default::default(),
                    focus_handle,
                    action_context: None,
                    selected_index: None,
                    delayed: false,
                    clicked: false,
                    _on_blur_subscription,
                    keep_open_on_confirm: false,
                    documentation_aside: None,
                },
                window,
                cx,
            )
        })
    }

    pub fn context(mut self, focus: FocusHandle) -> Self {
        self.action_context = Some(focus);
        self
    }

    pub fn header(mut self, title: impl Into<SharedString>) -> Self {
        self.items.push(ContextMenuItem::Header(title.into()));
        self
    }

    pub fn separator(mut self) -> Self {
        self.items.push(ContextMenuItem::Separator);
        self
    }

    pub fn extend<I: Into<ContextMenuItem>>(mut self, items: impl IntoIterator<Item = I>) -> Self {
        self.items.extend(items.into_iter().map(Into::into));
        self
    }

    pub fn item(mut self, item: impl Into<ContextMenuItem>) -> Self {
        self.items.push(item.into());
        self
    }

    pub fn entry(
        mut self,
        label: impl Into<SharedString>,
        action: Option<Box<dyn Action>>,
        handler: impl Fn(&mut Window, &mut App) + 'static,
    ) -> Self {
        self.items.push(ContextMenuItem::Entry(ContextMenuEntry {
            toggle: None,
            label: label.into(),
            handler: Rc::new(move |_, window, cx| handler(window, cx)),
            icon: None,
            icon_position: IconPosition::End,
            icon_size: IconSize::Small,
            icon_color: None,
            action,
            disabled: false,
            documentation_aside: None,
        }));
        self
    }

    pub fn toggleable_entry(
        mut self,
        label: impl Into<SharedString>,
        toggled: bool,
        position: IconPosition,
        action: Option<Box<dyn Action>>,
        handler: impl Fn(&mut Window, &mut App) + 'static,
    ) -> Self {
        self.items.push(ContextMenuItem::Entry(ContextMenuEntry {
            toggle: Some((position, toggled)),
            label: label.into(),
            handler: Rc::new(move |_, window, cx| handler(window, cx)),
            icon: None,
            icon_position: position,
            icon_size: IconSize::Small,
            icon_color: None,
            action,
            disabled: false,
            documentation_aside: None,
        }));
        self
    }

    pub fn custom_row(
        mut self,
        entry_render: impl Fn(&mut Window, &mut App) -> AnyElement + 'static,
    ) -> Self {
        self.items.push(ContextMenuItem::CustomEntry {
            entry_render: Box::new(entry_render),
            handler: Rc::new(|_, _, _| {}),
            selectable: false,
        });
        self
    }

    pub fn custom_entry(
        mut self,
        entry_render: impl Fn(&mut Window, &mut App) -> AnyElement + 'static,
        handler: impl Fn(&mut Window, &mut App) + 'static,
    ) -> Self {
        self.items.push(ContextMenuItem::CustomEntry {
            entry_render: Box::new(entry_render),
            handler: Rc::new(move |_, window, cx| handler(window, cx)),
            selectable: true,
        });
        self
    }

    pub fn label(mut self, label: impl Into<SharedString>) -> Self {
        self.items.push(ContextMenuItem::Label(label.into()));
        self
    }

    pub fn action(mut self, label: impl Into<SharedString>, action: Box<dyn Action>) -> Self {
        self.items.push(ContextMenuItem::Entry(ContextMenuEntry {
            toggle: None,
            label: label.into(),
            action: Some(action.boxed_clone()),
            handler: Rc::new(move |context, window, cx| {
                if let Some(context) = &context {
                    window.focus(context);
                }
                window.dispatch_action(action.boxed_clone(), cx);
            }),
            icon: None,
            icon_position: IconPosition::End,
            icon_size: IconSize::Small,
            icon_color: None,
            disabled: false,
            documentation_aside: None,
        }));
        self
    }

    pub fn disabled_action(
        mut self,
        label: impl Into<SharedString>,
        action: Box<dyn Action>,
    ) -> Self {
        self.items.push(ContextMenuItem::Entry(ContextMenuEntry {
            toggle: None,
            label: label.into(),
            action: Some(action.boxed_clone()),
            handler: Rc::new(move |context, window, cx| {
                if let Some(context) = &context {
                    window.focus(context);
                }
                window.dispatch_action(action.boxed_clone(), cx);
            }),
            icon: None,
            icon_size: IconSize::Small,
            icon_position: IconPosition::End,
            icon_color: None,
            disabled: true,
            documentation_aside: None,
        }));
        self
    }

    pub fn link(mut self, label: impl Into<SharedString>, action: Box<dyn Action>) -> Self {
        self.items.push(ContextMenuItem::Entry(ContextMenuEntry {
            toggle: None,
            label: label.into(),
            action: Some(action.boxed_clone()),
            handler: Rc::new(move |_, window, cx| window.dispatch_action(action.boxed_clone(), cx)),
            icon: Some(IconName::ArrowUpRight),
            icon_size: IconSize::XSmall,
            icon_position: IconPosition::End,
            icon_color: None,
            disabled: false,
            documentation_aside: None,
        }));
        self
    }

    pub fn keep_open_on_confirm(mut self) -> Self {
        self.keep_open_on_confirm = true;
        self
    }

    pub fn confirm(&mut self, _: &menu::Confirm, window: &mut Window, cx: &mut Context<Self>) {
        let context = self.action_context.as_ref();
        if let Some(
            ContextMenuItem::Entry(ContextMenuEntry {
                handler,
                disabled: false,
                ..
            })
            | ContextMenuItem::CustomEntry { handler, .. },
        ) = self.selected_index.and_then(|ix| self.items.get(ix))
        {
            (handler)(context, window, cx)
        }

        if !self.keep_open_on_confirm {
            cx.emit(DismissEvent);
        }
    }

    pub fn cancel(&mut self, _: &menu::Cancel, _: &mut Window, cx: &mut Context<Self>) {
        cx.emit(DismissEvent);
        cx.emit(DismissEvent);
    }

    fn select_first(&mut self, _: &SelectFirst, _: &mut Window, cx: &mut Context<Self>) {
        if let Some(ix) = self.items.iter().position(|item| item.is_selectable()) {
            self.select_index(ix);
        }
        cx.notify();
    }

    pub fn select_last(&mut self) -> Option<usize> {
        for (ix, item) in self.items.iter().enumerate().rev() {
            if item.is_selectable() {
                return self.select_index(ix);
            }
        }
        None
    }

    fn handle_select_last(&mut self, _: &SelectLast, _: &mut Window, cx: &mut Context<Self>) {
        if self.select_last().is_some() {
            cx.notify();
        }
    }

    fn select_next(&mut self, _: &SelectNext, window: &mut Window, cx: &mut Context<Self>) {
        if let Some(ix) = self.selected_index {
            let next_index = ix + 1;
            if self.items.len() <= next_index {
                self.select_first(&SelectFirst, window, cx);
            } else {
                for (ix, item) in self.items.iter().enumerate().skip(next_index) {
                    if item.is_selectable() {
                        self.select_index(ix);
                        cx.notify();
                        break;
                    }
                }
            }
        } else {
            self.select_first(&SelectFirst, window, cx);
        }
    }

    pub fn select_previous(
        &mut self,
        _: &SelectPrevious,
        window: &mut Window,
        cx: &mut Context<Self>,
    ) {
        if let Some(ix) = self.selected_index {
            if ix == 0 {
                self.handle_select_last(&SelectLast, window, cx);
            } else {
                for (ix, item) in self.items.iter().enumerate().take(ix).rev() {
                    if item.is_selectable() {
                        self.select_index(ix);
                        cx.notify();
                        break;
                    }
                }
            }
        } else {
            self.handle_select_last(&SelectLast, window, cx);
        }
    }

    fn select_index(&mut self, ix: usize) -> Option<usize> {
        self.documentation_aside = None;
        let item = self.items.get(ix)?;
        if item.is_selectable() {
            self.selected_index = Some(ix);
            if let ContextMenuItem::Entry(entry) = item {
                if let Some(callback) = &entry.documentation_aside {
                    self.documentation_aside = Some((ix, callback.clone()));
                }
            }
        }
        Some(ix)
    }

    pub fn on_action_dispatch(
        &mut self,
        dispatched: &dyn Action,
        window: &mut Window,
        cx: &mut Context<Self>,
    ) {
        if self.clicked {
            cx.propagate();
            return;
        }

        if let Some(ix) = self.items.iter().position(|item| {
            if let ContextMenuItem::Entry(ContextMenuEntry {
                action: Some(action),
                disabled: false,
                ..
            }) = item
            {
                action.partial_eq(dispatched)
            } else {
                false
            }
        }) {
            self.select_index(ix);
            self.delayed = true;
            cx.notify();
            let action = dispatched.boxed_clone();
            cx.spawn_in(window, |this, mut cx| async move {
                cx.background_executor()
                    .timer(Duration::from_millis(50))
                    .await;
                cx.update(|window, cx| {
                    this.update(cx, |this, cx| {
                        this.cancel(&menu::Cancel, window, cx);
                        window.dispatch_action(action, cx);
                    })
                })
            })
            .detach_and_log_err(cx);
        } else {
            cx.propagate()
        }
    }

    pub fn on_blur_subscription(mut self, new_subscription: Subscription) -> Self {
        self._on_blur_subscription = new_subscription;
        self
    }
}

impl ContextMenuItem {
    fn is_selectable(&self) -> bool {
        match self {
            ContextMenuItem::Header(_)
            | ContextMenuItem::Separator
            | ContextMenuItem::Label { .. } => false,
            ContextMenuItem::Entry(ContextMenuEntry { disabled, .. }) => !disabled,
            ContextMenuItem::CustomEntry { selectable, .. } => *selectable,
        }
    }
}

impl Render for ContextMenu {
    fn render(&mut self, window: &mut Window, cx: &mut Context<Self>) -> impl IntoElement {
        let ui_font_size = ThemeSettings::get_global(cx).ui_font_size(cx);
        let window_size = window.viewport_size();
        let rem_size = window.rem_size();
        let is_wide_window = window_size.width / rem_size > rems_from_px(800.).0;

        let aside = self
            .documentation_aside
            .as_ref()
            .map(|(_, callback)| callback.clone());

        h_flex()
            .when(is_wide_window, |this| {this.flex_row()})
            .when(!is_wide_window, |this| {this.flex_col()})
            .w_full()
            .items_start()
            .gap_1()
            .child(
                div().children(aside.map(|aside|
                    WithRemSize::new(ui_font_size)
                        .occlude()
                        .elevation_2(cx)
                        .p_2()
                        .overflow_hidden()
                        .when(is_wide_window, |this| {this.max_w_96()})
                        .when(!is_wide_window, |this| {this.max_w_48()})
                        .child(aside(cx))
                ))
            )
            .child(
                WithRemSize::new(ui_font_size)
                    .occlude()
                    .elevation_2(cx)
                    .flex()
                    .flex_row()
                    .child(
                        v_flex()
                            .id("context-menu")
                            .min_w(px(200.))
                            .max_h(vh(0.75, window))
                            .flex_1()
                            .overflow_y_scroll()
                            .track_focus(&self.focus_handle(cx))
                            .on_mouse_down_out(cx.listener(|this, _, window, cx| {
                                this.cancel(&menu::Cancel, window, cx)
                            }))
                            .key_context("menu")
                            .on_action(cx.listener(ContextMenu::select_first))
                            .on_action(cx.listener(ContextMenu::handle_select_last))
                            .on_action(cx.listener(ContextMenu::select_next))
                            .on_action(cx.listener(ContextMenu::select_previous))
                            .on_action(cx.listener(ContextMenu::confirm))
                            .on_action(cx.listener(ContextMenu::cancel))
                            .when(!self.delayed, |mut el| {
                                for item in self.items.iter() {
                                    if let ContextMenuItem::Entry(ContextMenuEntry {
                                        action: Some(action),
                                        disabled: false,
                                        ..
                                    }) = item
                                    {
                                        el = el.on_boxed_action(
                                            &**action,
                                            cx.listener(ContextMenu::on_action_dispatch),
                                        );
                                    }
                                }
                                el
                            })
                            .child(List::new().children(self.items.iter_mut().enumerate().map(
                                |(ix, item)| {
                                    match item {
                                        ContextMenuItem::Separator => {
                                            ListSeparator.into_any_element()
                                        }
                                        ContextMenuItem::Header(header) => {
                                            ListSubHeader::new(header.clone())
                                                .inset(true)
                                                .into_any_element()
                                        }
                                        ContextMenuItem::Label(label) => ListItem::new(ix)
                                            .inset(true)
                                            .disabled(true)
                                            .child(Label::new(label.clone()))
                                            .into_any_element(),
                                        ContextMenuItem::Entry(ContextMenuEntry {
                                            toggle,
                                            label,
                                            handler,
                                            icon,
                                            icon_position,
                                            icon_size,
                                            icon_color,
                                            action,
                                            disabled,
                                            documentation_aside,
                                        }) => {
                                            let handler = handler.clone();
                                            let menu = cx.entity().downgrade();

                                            let icon_color = if *disabled {
                                                Color::Muted
                                            } else if toggle.is_some() {
                                                icon_color.unwrap_or(Color::Accent)
                                            } else {
                                                icon_color.unwrap_or(Color::Default)
                                            };

                                            let label_color = if *disabled {
                                                Color::Disabled
                                            } else {
                                                Color::Default
                                            };

                                            let label_element = if let Some(icon_name) = icon {
                                                h_flex()
                                                    .gap_1p5()
                                                    .when(
                                                        *icon_position == IconPosition::Start && toggle.is_none(),
                                                        |flex| {
                                                            flex.child(
                                                                Icon::new(*icon_name)
                                                                    .size(*icon_size)
                                                                    .color(icon_color),
                                                            )
                                                        },
                                                    )
                                                    .child(
                                                        Label::new(label.clone())
                                                            .color(label_color),
                                                    )
                                                    .when(
                                                        *icon_position == IconPosition::End,
                                                        |flex| {
                                                            flex.child(
                                                                Icon::new(*icon_name)
                                                                    .size(*icon_size)
                                                                    .color(icon_color),
                                                            )
                                                        },
                                                    )
                                                    .into_any_element()
                                            } else {
                                                Label::new(label.clone())
                                                    .color(label_color)
                                                    .into_any_element()
                                            };

                                            let documentation_aside_callback =
                                                documentation_aside.clone();

                                            div()
                                                .id(("context-menu-child", ix))
                                                .when_some(
                                                    documentation_aside_callback.clone(),
                                                    |this, documentation_aside_callback| {
                                                        this.occlude().on_hover(cx.listener(
                                                            move |menu, hovered, _, cx| {
                                                                if *hovered {
                                                                    menu.documentation_aside = Some((ix, documentation_aside_callback.clone()));
                                                                    cx.notify();
                                                                } else if matches!(menu.documentation_aside, Some((id, _)) if id == ix) {
                                                                    menu.documentation_aside = None;
                                                                    cx.notify();
                                                                }
                                                            },
                                                        ))
                                                    },
                                                )
                                                .child(
                                                    ListItem::new(ix)
                                                        .inset(true)
                                                        .disabled(*disabled)
                                                        .toggle_state(
                                                            Some(ix) == self.selected_index,
                                                        )
                                                        .when_some(
                                                            *toggle,
                                                            |list_item, (position, toggled)| {
                                                                let contents =
                                                                    div().flex_none().child(
                                                                        Icon::new(icon.unwrap_or(IconName::Check))
                                                                            .color(icon_color)
                                                                            .size(*icon_size)
                                                                    )
                                                                    .when(!toggled, |contents|
                                                                        contents.invisible()
                                                                    );

                                                                match position {
                                                                    IconPosition::Start => {
                                                                        list_item
                                                                            .start_slot(contents)
                                                                    }
                                                                    IconPosition::End => {
                                                                        list_item.end_slot(contents)
                                                                    }
                                                                }
                                                            },
                                                        )
                                                        .child(
                                                            h_flex()
                                                                .w_full()
                                                                .justify_between()
                                                                .child(label_element)
                                                                .debug_selector(|| {
                                                                    format!("MENU_ITEM-{}", label)
                                                                })
                                                                .children(
                                                                    action.as_ref().and_then(
                                                                        |action| {
                                                                            self.action_context
                                                                    .as_ref()
                                                                    .map(|focus| {
                                                                        KeyBinding::for_action_in(
                                                                            &**action, focus,
                                                                            window,
                                                                            cx
                                                                        )
                                                                    })
                                                                    .unwrap_or_else(|| {
                                                                        KeyBinding::for_action(
                                                                            &**action, window, cx
                                                                        )
                                                                    })
                                                                    .map(|binding| {
                                                                        div().ml_4().child(binding)
                                                                            .when(*disabled && documentation_aside_callback.is_some(), |parent| {
                                                                                parent.invisible()
                                                                            })
                                                                    })
                                                                        },
                                                                    ),
                                                                )
                                                                .when(*disabled && documentation_aside_callback.is_some(), |parent| {
                                                                    parent.child(Icon::new(IconName::Info).size(IconSize::XSmall).color(Color::Muted))
                                                                }),
                                                        )
                                                        .on_click({
                                                            let context =
                                                                self.action_context.clone();
                                                            move |_, window, cx| {
                                                                handler(
                                                                    context.as_ref(),
                                                                    window,
                                                                    cx,
                                                                );
                                                                menu.update(cx, |menu, cx| {
                                                                    menu.clicked = true;
                                                                    cx.emit(DismissEvent);
                                                                })
                                                                .ok();
                                                            }
                                                        }),
                                                )
                                                .into_any_element()
                                        }
                                        ContextMenuItem::CustomEntry {
                                            entry_render,
                                            handler,
                                            selectable,
                                        } => {
                                            let handler = handler.clone();
                                            let menu = cx.entity().downgrade();
                                            let selectable = *selectable;
                                            ListItem::new(ix)
                                                .inset(true)
                                                .toggle_state(if selectable {
                                                    Some(ix) == self.selected_index
                                                } else {
                                                    false
                                                })
                                                .selectable(selectable)
                                                .when(selectable, |item| {
                                                    item.on_click({
                                                        let context = self.action_context.clone();
                                                        move |_, window, cx| {
                                                            handler(context.as_ref(), window, cx);
                                                            menu.update(cx, |menu, cx| {
                                                                menu.clicked = true;
                                                                cx.emit(DismissEvent);
                                                            })
                                                            .ok();
                                                        }
                                                    })
                                                })
                                                .child(entry_render(window, cx))
                                                .into_any_element()
                                        }
                                    }
                                },
                            )))
                    ),
            )
    }
}
