use std::marker::PhantomData;

use gpui3::{div, Div};

use crate::prelude::*;
use crate::theme::theme;
use crate::{
    h_stack, token, v_stack, Avatar, Icon, IconColor, IconElement, IconSize, Label, LabelColor,
    LabelSize,
};

#[derive(Clone, Copy, Default, Debug, PartialEq)]
pub enum ListItemVariant {
    /// The list item extends to the far left and right of the list.
    FullWidth,
    #[default]
    Inset,
}

#[derive(Element, Clone)]
pub struct ListHeader<S: 'static + Send + Sync + Clone> {
    state_type: PhantomData<S>,
    label: &'static str,
    left_icon: Option<Icon>,
    variant: ListItemVariant,
    state: InteractionState,
    toggleable: Toggleable,
}

impl<S: 'static + Send + Sync + Clone> ListHeader<S> {
    pub fn new(label: &'static str) -> Self {
        Self {
            state_type: PhantomData,
            label,
            left_icon: None,
            variant: ListItemVariant::default(),
            state: InteractionState::default(),
            toggleable: Toggleable::Toggleable(ToggleState::Toggled),
        }
    }

    pub fn set_toggle(mut self, toggle: ToggleState) -> Self {
        self.toggleable = toggle.into();
        self
    }

    pub fn set_toggleable(mut self, toggleable: Toggleable) -> Self {
        self.toggleable = toggleable;
        self
    }

    pub fn set_left_icon(mut self, left_icon: Option<Icon>) -> Self {
        self.left_icon = left_icon;
        self
    }

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

    fn disclosure_control(&self) -> Div<S> {
        let is_toggleable = self.toggleable != Toggleable::NotToggleable;
        let is_toggled = Toggleable::is_toggled(&self.toggleable);

        match (is_toggleable, is_toggled) {
            (false, _) => div(),
            (_, true) => div().child(
                IconElement::new(Icon::ChevronDown)
                    .color(IconColor::Muted)
                    .size(IconSize::Small),
            ),
            (_, false) => div().child(
                IconElement::new(Icon::ChevronRight)
                    .color(IconColor::Muted)
                    .size(IconSize::Small),
            ),
        }
    }

    fn label_color(&self) -> LabelColor {
        match self.state {
            InteractionState::Disabled => LabelColor::Disabled,
            _ => Default::default(),
        }
    }

    fn icon_color(&self) -> IconColor {
        match self.state {
            InteractionState::Disabled => IconColor::Disabled,
            _ => Default::default(),
        }
    }

    fn render(&mut self, _view: &mut S, cx: &mut ViewContext<S>) -> impl Element<ViewState = S> {
        let theme = theme(cx);
        let token = token();
        let system_color = SystemColor::new();
        let color = ThemeColor::new(cx);

        let is_toggleable = self.toggleable != Toggleable::NotToggleable;
        let is_toggled = Toggleable::is_toggled(&self.toggleable);

        let disclosure_control = self.disclosure_control();

        h_stack()
            .flex_1()
            .w_full()
            .fill(color.surface)
            .when(self.state == InteractionState::Focused, |this| {
                this.border().border_color(color.border_focused)
            })
            .relative()
            .child(
                div()
                    .h_5()
                    .when(self.variant == ListItemVariant::Inset, |this| this.px_2())
                    .flex()
                    .flex_1()
                    .w_full()
                    .gap_1()
                    .items_center()
                    .child(
                        div()
                            .flex()
                            .gap_1()
                            .items_center()
                            .children(self.left_icon.map(|i| {
                                IconElement::new(i)
                                    .color(IconColor::Muted)
                                    .size(IconSize::Small)
                            }))
                            .child(
                                Label::new(self.label)
                                    .color(LabelColor::Muted)
                                    .size(LabelSize::Small),
                            ),
                    )
                    .child(disclosure_control),
            )
    }
}

#[derive(Element, Clone)]
pub struct ListSubHeader<S: 'static + Send + Sync + Clone> {
    state_type: PhantomData<S>,
    label: &'static str,
    left_icon: Option<Icon>,
    variant: ListItemVariant,
}

impl<S: 'static + Send + Sync + Clone> ListSubHeader<S> {
    pub fn new(label: &'static str) -> Self {
        Self {
            state_type: PhantomData,
            label,
            left_icon: None,
            variant: ListItemVariant::default(),
        }
    }

    pub fn left_icon(mut self, left_icon: Option<Icon>) -> Self {
        self.left_icon = left_icon;
        self
    }

    fn render(&mut self, _view: &mut S, cx: &mut ViewContext<S>) -> impl Element<ViewState = S> {
        let theme = theme(cx);
        let token = token();

        h_stack().flex_1().w_full().relative().py_1().child(
            div()
                .h_6()
                .when(self.variant == ListItemVariant::Inset, |this| this.px_2())
                .flex()
                .flex_1()
                .w_full()
                .gap_1()
                .items_center()
                .justify_between()
                .child(
                    div()
                        .flex()
                        .gap_1()
                        .items_center()
                        .children(self.left_icon.map(|i| {
                            IconElement::new(i)
                                .color(IconColor::Muted)
                                .size(IconSize::Small)
                        }))
                        .child(
                            Label::new(self.label)
                                .color(LabelColor::Muted)
                                .size(LabelSize::Small),
                        ),
                ),
        )
    }
}

#[derive(Clone)]
pub enum LeftContent {
    Icon(Icon),
    Avatar(&'static str),
}

#[derive(Default, PartialEq, Copy, Clone)]
pub enum ListEntrySize {
    #[default]
    Small,
    Medium,
}

#[derive(Clone, Element)]
pub enum ListItem<S: 'static + Send + Sync + Clone> {
    Entry(ListEntry<S>),
    Separator(ListSeparator<S>),
    Header(ListSubHeader<S>),
}

impl<S: 'static + Send + Sync + Clone> From<ListEntry<S>> for ListItem<S> {
    fn from(entry: ListEntry<S>) -> Self {
        Self::Entry(entry)
    }
}

impl<S: 'static + Send + Sync + Clone> From<ListSeparator<S>> for ListItem<S> {
    fn from(entry: ListSeparator<S>) -> Self {
        Self::Separator(entry)
    }
}

impl<S: 'static + Send + Sync + Clone> From<ListSubHeader<S>> for ListItem<S> {
    fn from(entry: ListSubHeader<S>) -> Self {
        Self::Header(entry)
    }
}

impl<S: 'static + Send + Sync + Clone> ListItem<S> {
    fn render(&mut self, view: &mut S, cx: &mut ViewContext<S>) -> impl Element<ViewState = S> {
        match self {
            ListItem::Entry(entry) => div().child(entry.render(view, cx)),
            ListItem::Separator(separator) => div().child(separator.render(view, cx)),
            ListItem::Header(header) => div().child(header.render(view, cx)),
        }
    }

    pub fn new(label: Label<S>) -> Self {
        Self::Entry(ListEntry::new(label))
    }

    pub fn as_entry(&mut self) -> Option<&mut ListEntry<S>> {
        if let Self::Entry(entry) = self {
            Some(entry)
        } else {
            None
        }
    }
}

#[derive(Element, Clone)]
pub struct ListEntry<S: 'static + Send + Sync + Clone> {
    disclosure_control_style: DisclosureControlVisibility,
    indent_level: u32,
    label: Label<S>,
    left_content: Option<LeftContent>,
    variant: ListItemVariant,
    size: ListEntrySize,
    state: InteractionState,
    toggle: Option<ToggleState>,
}

impl<S: 'static + Send + Sync + Clone> ListEntry<S> {
    pub fn new(label: Label<S>) -> Self {
        Self {
            disclosure_control_style: DisclosureControlVisibility::default(),
            indent_level: 0,
            label,
            variant: ListItemVariant::default(),
            left_content: None,
            size: ListEntrySize::default(),
            state: InteractionState::default(),
            // TODO: Should use Toggleable::NotToggleable
            // or remove Toggleable::NotToggleable from the system
            toggle: None,
        }
    }
    pub fn set_variant(mut self, variant: ListItemVariant) -> Self {
        self.variant = variant;
        self
    }
    pub fn set_indent_level(mut self, indent_level: u32) -> Self {
        self.indent_level = indent_level;
        self
    }

    pub fn set_toggle(mut self, toggle: ToggleState) -> Self {
        self.toggle = Some(toggle);
        self
    }

    pub fn set_left_content(mut self, left_content: LeftContent) -> Self {
        self.left_content = Some(left_content);
        self
    }

    pub fn set_left_icon(mut self, left_icon: Icon) -> Self {
        self.left_content = Some(LeftContent::Icon(left_icon));
        self
    }

    pub fn set_left_avatar(mut self, left_avatar: &'static str) -> Self {
        self.left_content = Some(LeftContent::Avatar(left_avatar));
        self
    }

    pub fn set_state(mut self, state: InteractionState) -> Self {
        self.state = state;
        self
    }

    pub fn set_size(mut self, size: ListEntrySize) -> Self {
        self.size = size;
        self
    }

    pub fn set_disclosure_control_style(
        mut self,
        disclosure_control_style: DisclosureControlVisibility,
    ) -> Self {
        self.disclosure_control_style = disclosure_control_style;
        self
    }

    fn label_color(&self) -> LabelColor {
        match self.state {
            InteractionState::Disabled => LabelColor::Disabled,
            _ => Default::default(),
        }
    }

    fn icon_color(&self) -> IconColor {
        match self.state {
            InteractionState::Disabled => IconColor::Disabled,
            _ => Default::default(),
        }
    }

    fn disclosure_control(
        &mut self,
        cx: &mut ViewContext<S>,
    ) -> Option<impl Element<ViewState = S>> {
        let theme = theme(cx);
        let token = token();

        let disclosure_control_icon = if let Some(ToggleState::Toggled) = self.toggle {
            IconElement::new(Icon::ChevronDown)
        } else {
            IconElement::new(Icon::ChevronRight)
        }
        .color(IconColor::Muted)
        .size(IconSize::Small);

        match (self.toggle, self.disclosure_control_style) {
            (Some(_), DisclosureControlVisibility::OnHover) => {
                Some(div().absolute().neg_left_5().child(disclosure_control_icon))
            }
            (Some(_), DisclosureControlVisibility::Always) => {
                Some(div().child(disclosure_control_icon))
            }
            (None, _) => None,
        }
    }

    fn render(&mut self, _view: &mut S, cx: &mut ViewContext<S>) -> impl Element<ViewState = S> {
        let theme = theme(cx);
        let token = token();
        let system_color = SystemColor::new();
        let color = ThemeColor::new(cx);

        let left_content = match self.left_content {
            Some(LeftContent::Icon(i)) => Some(
                h_stack().child(
                    IconElement::new(i)
                        .size(IconSize::Small)
                        .color(IconColor::Muted),
                ),
            ),
            Some(LeftContent::Avatar(src)) => Some(h_stack().child(Avatar::new(src))),
            None => None,
        };

        let sized_item = match self.size {
            ListEntrySize::Small => div().h_6(),
            ListEntrySize::Medium => div().h_7(),
        };

        div()
            .relative()
            .fill(color.surface)
            .when(self.state == InteractionState::Focused, |this| {
                this.border().border_color(color.border_focused)
            })
            .child(
                sized_item
                    .when(self.variant == ListItemVariant::Inset, |this| this.px_2())
                    // .ml(rems(0.75 * self.indent_level as f32))
                    .children((0..self.indent_level).map(|_| {
                        div()
                            .w(token.list_indent_depth)
                            .h_full()
                            .flex()
                            .justify_center()
                            .child(
                                h_stack()
                                    .child(div().w_px().h_full())
                                    .child(div().w_px().h_full().fill(color.border)),
                            )
                    }))
                    .flex()
                    .gap_1()
                    .items_center()
                    .relative()
                    .children(self.disclosure_control(cx))
                    .children(left_content)
                    .child(self.label.clone()),
            )
    }
}

#[derive(Clone, Element)]
pub struct ListSeparator<S: 'static + Send + Sync> {
    state_type: PhantomData<S>,
}

impl<S: 'static + Send + Sync> ListSeparator<S> {
    pub fn new() -> Self {
        Self {
            state_type: PhantomData,
        }
    }

    fn render(&mut self, _view: &mut S, cx: &mut ViewContext<S>) -> impl Element<ViewState = S> {
        let color = ThemeColor::new(cx);

        div().h_px().w_full().fill(color.border)
    }
}

#[derive(Element)]
pub struct List<S: 'static + Send + Sync + Clone> {
    items: Vec<ListItem<S>>,
    empty_message: &'static str,
    header: Option<ListHeader<S>>,
    toggleable: Toggleable,
}

impl<S: 'static + Send + Sync + Clone> List<S> {
    pub fn new(items: Vec<ListItem<S>>) -> Self {
        Self {
            items,
            empty_message: "No items",
            header: None,
            toggleable: Toggleable::default(),
        }
    }

    pub fn empty_message(mut self, empty_message: &'static str) -> Self {
        self.empty_message = empty_message;
        self
    }

    pub fn header(mut self, header: ListHeader<S>) -> Self {
        self.header = Some(header);
        self
    }

    pub fn set_toggle(mut self, toggle: ToggleState) -> Self {
        self.toggleable = toggle.into();
        self
    }

    fn render(&mut self, _view: &mut S, cx: &mut ViewContext<S>) -> impl Element<ViewState = S> {
        let theme = theme(cx);
        let token = token();
        let is_toggleable = self.toggleable != Toggleable::NotToggleable;
        let is_toggled = Toggleable::is_toggled(&self.toggleable);

        let list_content = match (self.items.is_empty(), is_toggled) {
            (_, false) => div(),
            (false, _) => div().children(self.items.iter().cloned()),
            (true, _) => div().child(Label::new(self.empty_message).color(LabelColor::Muted)),
        };

        v_stack()
            .py_1()
            .children(
                self.header
                    .clone()
                    .map(|header| header.set_toggleable(self.toggleable)),
            )
            .child(list_content)
    }
}