use std::collections::BTreeMap;
use std::marker::PhantomData;

use egui::*;

use crate::color_hex_utils::*;
use crate::{CategoryTrait, NodeTemplateIter, NodeTemplateTrait};

#[derive(Clone)]
#[cfg_attr(
    feature = "persistence",
    derive(serde::Serialize, serde::Deserialize)
)]
pub struct NodeFinder<NodeTemplate> {
    pub query: String,
    /// Reset every frame. When set, the node finder will be moved at that
    /// position
    pub position: Option<Pos2>,
    pub just_spawned: bool,
    _phantom: PhantomData<NodeTemplate>,
}

impl<NodeTemplate, NodeData, UserState, CategoryType> NodeFinder<NodeTemplate>
where
    NodeTemplate: NodeTemplateTrait<
        NodeData = NodeData,
        UserState = UserState,
        CategoryType = CategoryType,
    >,
    CategoryType: CategoryTrait,
{
    pub fn new_at(pos: Pos2) -> Self {
        NodeFinder {
            query: "".into(),
            position: Some(pos),
            just_spawned: true,
            _phantom: Default::default(),
        }
    }

    /// Shows the node selector panel with a search bar. Returns whether a node
    /// archetype was selected and, in that case, the finder should be hidden on
    /// the next frame.
    pub fn show(
        &mut self,
        ui: &mut Ui,
        all_kinds: impl NodeTemplateIter<Item = NodeTemplate>,
        user_state: &mut UserState,
    ) -> Option<NodeTemplate> {
        let background_color;
        let text_color;

        if ui.visuals().dark_mode {
            background_color = color_from_hex("#3f3f3f").unwrap();
            text_color = color_from_hex("#fefefe").unwrap();
        } else {
            background_color = color_from_hex("#fefefe").unwrap();
            text_color = color_from_hex("#3f3f3f").unwrap();
        }

        ui.visuals_mut().widgets.noninteractive.fg_stroke =
            Stroke::new(2.0, text_color);

        let frame = Frame::dark_canvas(ui.style())
            .fill(background_color)
            .inner_margin(vec2(5.0, 5.0));

        // The archetype that will be returned.
        let mut submitted_archetype = None;
        frame.show(ui, |ui| {
            ui.vertical(|ui| {
                let resp = ui.text_edit_singleline(&mut self.query);
                if self.just_spawned {
                    resp.request_focus();
                    self.just_spawned = false;
                }
                let update_open = resp.changed();

                let mut query_submit = resp.lost_focus()
                    && ui.input(|i| i.key_pressed(Key::Enter));

                let max_height =
                    ui.input(|i| f32::max(i.screen_rect.height() * 0.5, 200.));
                let scroll_area_width = resp.rect.width();

                let all_kinds = all_kinds.all_kinds();
                let mut categories: BTreeMap<String, Vec<&NodeTemplate>> =
                    Default::default();
                let mut orphan_kinds = Vec::new();

                for kind in &all_kinds {
                    let kind_categories =
                        kind.node_finder_categories(user_state);

                    if kind_categories.is_empty() {
                        orphan_kinds.push(kind);
                    } else {
                        for category in kind_categories {
                            categories
                                .entry(category.name())
                                .or_default()
                                .push(kind);
                        }
                    }
                }

                Frame::default().inner_margin(vec2(10.0, 10.0)).show(
                    ui,
                    |ui| {
                        ScrollArea::vertical()
                            .max_height(max_height)
                            .auto_shrink([true, false])
                            .show(ui, |ui| {
                                ui.set_width(scroll_area_width);
                                for (category, kinds) in categories {
                                    let filtered_kinds: Vec<_> = kinds
                                        .into_iter()
                                        .map(|kind| {
                                            let kind_name = kind
                                                .node_finder_label(user_state)
                                                .to_string();
                                            (kind, kind_name)
                                        })
                                        .filter(|(_kind, kind_name)| {
                                            kind_name.to_lowercase().contains(
                                                self.query
                                                    .to_lowercase()
                                                    .as_str(),
                                            )
                                        })
                                        .collect();

                                    if !filtered_kinds.is_empty() {
                                        let default_open =
                                            !self.query.is_empty();

                                        CollapsingHeader::new(&category)
                                            .default_open(default_open)
                                            .open(
                                                update_open
                                                    .then_some(default_open),
                                            )
                                            .show(ui, |ui| {
                                                for (kind, kind_name) in
                                                    filtered_kinds
                                                {
                                                    if ui
                                                        .selectable_label(
                                                            false, kind_name,
                                                        )
                                                        .clicked()
                                                    {
                                                        submitted_archetype =
                                                            Some(kind.clone());
                                                    } else if query_submit {
                                                        submitted_archetype =
                                                            Some(kind.clone());
                                                        query_submit = false;
                                                    }
                                                }
                                            });
                                    }
                                }

                                for kind in orphan_kinds {
                                    let kind_name = kind
                                        .node_finder_label(user_state)
                                        .to_string();

                                    if ui
                                        .selectable_label(false, kind_name)
                                        .clicked()
                                    {
                                        submitted_archetype =
                                            Some(kind.clone());
                                    } else if query_submit {
                                        submitted_archetype =
                                            Some(kind.clone());
                                        query_submit = false;
                                    }
                                }
                            });
                    },
                );
            });
        });

        submitted_archetype
    }
}