use crate::border::BorderBuilder;
use crate::draw::Draw;
use crate::{
    brush::Brush,
    core::{color::Color, pool::Handle},
    draw::{CommandTexture, DrawingContext},
    message::{
        DecoratorMessage, ListViewMessage, MessageData, MessageDirection, UiMessage, UiMessageData,
        WidgetMessage,
    },
    scroll_viewer::ScrollViewerBuilder,
    stack_panel::StackPanelBuilder,
    widget::{Widget, WidgetBuilder},
    BuildContext, Control, NodeHandleMapping, Thickness, UINode, UserInterface, BRUSH_DARK,
    BRUSH_LIGHT,
};
use std::ops::{Deref, DerefMut};

#[derive(Clone)]
pub struct ListView<M: MessageData, C: Control<M, C>> {
    widget: Widget<M, C>,
    selected_index: Option<usize>,
    item_containers: Vec<Handle<UINode<M, C>>>,
    panel: Handle<UINode<M, C>>,
    items: Vec<Handle<UINode<M, C>>>,
}

crate::define_widget_deref!(ListView<M, C>);

impl<M: MessageData, C: Control<M, C>> ListView<M, C> {
    pub fn new(widget: Widget<M, C>, items: Vec<Handle<UINode<M, C>>>) -> Self {
        Self {
            widget,
            selected_index: None,
            item_containers: items,
            panel: Default::default(),
            items: Default::default(),
        }
    }

    pub fn selected(&self) -> Option<usize> {
        self.selected_index
    }

    pub fn item_containers(&self) -> &[Handle<UINode<M, C>>] {
        &self.item_containers
    }

    pub fn items(&self) -> &[Handle<UINode<M, C>>] {
        &self.items
    }

    fn sync_decorators(&self, ui: &UserInterface<M, C>) {
        if let Some(selected_index) = self.selected_index {
            for (i, &container) in self.item_containers.iter().enumerate() {
                let select = i == selected_index;
                if let UINode::ListViewItem(container) = ui.node(container) {
                    let mut stack = container.children().to_vec();
                    while let Some(handle) = stack.pop() {
                        let node = ui.node(handle);
                        match node {
                            UINode::ListView(_) => {}
                            UINode::Decorator(_) => {
                                ui.send_message(DecoratorMessage::select(
                                    handle,
                                    MessageDirection::ToWidget,
                                    select,
                                ));
                            }
                            _ => stack.extend_from_slice(node.children()),
                        }
                    }
                }
            }
        }
    }
}

#[derive(Clone)]
pub struct ListViewItem<M: MessageData, C: Control<M, C>> {
    widget: Widget<M, C>,
    index: usize,
}

crate::define_widget_deref!(ListViewItem<M, C>);

impl<M: MessageData, C: Control<M, C>> ListViewItem<M, C> {
    pub fn index(&self) -> usize {
        self.index
    }
}

impl<M: MessageData, C: Control<M, C>> Control<M, C> for ListViewItem<M, C> {
    fn draw(&self, drawing_context: &mut DrawingContext) {
        // Emit transparent geometry so item container can be picked by hit test.
        drawing_context.push_rect_filled(&self.widget.screen_bounds(), None);
        drawing_context.commit(
            self.clip_bounds(),
            Brush::Solid(Color::TRANSPARENT),
            CommandTexture::None,
            None,
        );
    }

    fn handle_routed_message(
        &mut self,
        ui: &mut UserInterface<M, C>,
        message: &mut UiMessage<M, C>,
    ) {
        self.widget.handle_routed_message(ui, message);

        let items_control =
            self.find_by_criteria_up(ui, |node| matches!(node, UINode::ListView(_)));

        if let UiMessageData::Widget(WidgetMessage::MouseUp { .. }) = &message.data() {
            if !message.handled() {
                // Explicitly set selection on parent items control. This will send
                // SelectionChanged message and all items will react.
                ui.send_message(ListViewMessage::selection(
                    items_control,
                    MessageDirection::ToWidget,
                    Some(self.index),
                ));
                message.set_handled(true);
            }
        }
    }
}

impl<M: MessageData, C: Control<M, C>> Control<M, C> for ListView<M, C> {
    fn resolve(&mut self, node_map: &NodeHandleMapping<M, C>) {
        node_map.resolve(&mut self.panel);
        node_map.resolve_slice(&mut self.items);
        node_map.resolve_slice(&mut self.item_containers);
    }

    fn handle_routed_message(
        &mut self,
        ui: &mut UserInterface<M, C>,
        message: &mut UiMessage<M, C>,
    ) {
        self.widget.handle_routed_message(ui, message);

        if let UiMessageData::ListView(msg) = &message.data() {
            if message.destination() == self.handle()
                && message.direction() == MessageDirection::ToWidget
            {
                match msg {
                    ListViewMessage::Items(items) => {
                        // Remove previous items.
                        for child in ui.node(self.panel).children().to_vec() {
                            ui.send_message(WidgetMessage::remove(
                                child,
                                MessageDirection::ToWidget,
                            ));
                        }

                        // Generate new items.
                        let item_containers = generate_item_containers(&mut ui.build_ctx(), items);

                        for item_container in item_containers.iter() {
                            ui.send_message(WidgetMessage::link(
                                *item_container,
                                MessageDirection::ToWidget,
                                self.panel,
                            ));
                        }

                        self.item_containers = item_containers;
                        self.items = items.clone();

                        // Check if current selection is out-of-bounds.
                        if let Some(selected_index) = self.selected_index {
                            if selected_index >= self.items.len() {
                                let new_selection = if self.items.is_empty() {
                                    None
                                } else {
                                    Some(self.items.len() - 1)
                                };

                                ui.send_message(ListViewMessage::selection(
                                    self.handle,
                                    MessageDirection::ToWidget,
                                    new_selection,
                                ));
                            }
                        }

                        self.sync_decorators(ui);
                    }
                    &ListViewMessage::AddItem(item) => {
                        let item_container =
                            generate_item_container(&mut ui.build_ctx(), item, self.items.len());

                        ui.send_message(WidgetMessage::link(
                            item,
                            MessageDirection::ToWidget,
                            self.panel,
                        ));

                        self.item_containers.push(item_container);
                        self.items.push(item);
                    }
                    &ListViewMessage::SelectionChanged(selection) => {
                        if self.selected_index != selection {
                            self.selected_index = selection;
                            self.sync_decorators(ui);
                            ui.send_message(message.reverse());
                        }
                    }
                }
            }
        }
    }

    fn remove_ref(&mut self, handle: Handle<UINode<M, C>>) {
        self.item_containers.retain(|i| *i != handle);
    }
}

pub struct ListViewBuilder<M: MessageData, C: Control<M, C>> {
    widget_builder: WidgetBuilder<M, C>,
    items: Vec<Handle<UINode<M, C>>>,
    panel: Option<Handle<UINode<M, C>>>,
    scroll_viewer: Option<Handle<UINode<M, C>>>,
}

impl<M: MessageData, C: Control<M, C>> ListViewBuilder<M, C> {
    pub fn new(widget_builder: WidgetBuilder<M, C>) -> Self {
        Self {
            widget_builder,
            items: Vec::new(),
            panel: None,
            scroll_viewer: None,
        }
    }

    pub fn with_items(mut self, items: Vec<Handle<UINode<M, C>>>) -> Self {
        self.items = items;
        self
    }

    pub fn with_items_panel(mut self, panel: Handle<UINode<M, C>>) -> Self {
        self.panel = Some(panel);
        self
    }

    pub fn with_scroll_viewer(mut self, sv: Handle<UINode<M, C>>) -> Self {
        self.scroll_viewer = Some(sv);
        self
    }

    pub fn build(self, ctx: &mut BuildContext<M, C>) -> Handle<UINode<M, C>> {
        let item_containers = generate_item_containers(ctx, &self.items);

        let panel = self.panel.unwrap_or_else(|| {
            StackPanelBuilder::new(WidgetBuilder::new().with_children(&item_containers)).build(ctx)
        });

        let back = BorderBuilder::new(
            WidgetBuilder::new()
                .with_background(BRUSH_DARK)
                .with_foreground(BRUSH_LIGHT),
        )
        .with_stroke_thickness(Thickness::uniform(1.0))
        .build(ctx);

        let scroll_viewer = self.scroll_viewer.unwrap_or_else(|| {
            ScrollViewerBuilder::new(WidgetBuilder::new().with_margin(Thickness::uniform(3.0)))
                .build(ctx)
        });
        if let UINode::ScrollViewer(scroll_viewer) = &mut ctx[scroll_viewer] {
            scroll_viewer.set_content(panel);
            let content_presenter = scroll_viewer.scroll_panel;
            ctx.link(panel, content_presenter);
        } else {
            panic!("must be scroll viewer!");
        }

        ctx.link(scroll_viewer, back);

        let list_box = ListView {
            widget: self.widget_builder.with_child(back).build(),
            selected_index: None,
            item_containers,
            items: self.items,
            panel,
        };

        ctx.add_node(UINode::ListView(list_box))
    }
}

fn generate_item_container<M: MessageData, C: Control<M, C>>(
    ctx: &mut BuildContext<M, C>,
    item: Handle<UINode<M, C>>,
    index: usize,
) -> Handle<UINode<M, C>> {
    let item = ListViewItem {
        widget: WidgetBuilder::new().with_child(item).build(),
        index,
    };

    ctx.add_node(UINode::ListViewItem(item))
}

fn generate_item_containers<M: MessageData, C: Control<M, C>>(
    ctx: &mut BuildContext<M, C>,
    items: &[Handle<UINode<M, C>>],
) -> Vec<Handle<UINode<M, C>>> {
    items
        .iter()
        .enumerate()
        .map(|(index, &item)| generate_item_container(ctx, item, index))
        .collect()
}