use std::{cell::RefCell, collections::HashSet, rc::Rc, sync::Arc};

use gpui::{
    InteractiveElement, IntoElement, ParentElement, StatefulInteractiveElement, Styled, div, list,
    prelude::FluentBuilder, px,
};

use crate::{
    app,
    component::{
        font_icon::{FontIcon, font_icon},
        text::text,
    },
    util::{
        self,
        file::{FileTreeItem, FileTreeItemKind},
    },
};

#[derive(gpui::IntoElement)]
pub(crate) struct FileTree {
    state: FileTreeState,
    item: Box<dyn Fn(usize, &gpui::Window, &mut gpui::App) -> util::file::FileTreeItem>,
    on_item_click: Option<Rc<dyn Fn(&usize, &mut gpui::Window, &mut gpui::App)>>,
}

#[derive(gpui::IntoElement)]
pub(crate) struct Item {
    item: util::file::FileTreeItem,
    is_expanded: bool,
    on_click: Box<dyn Fn(&mut gpui::Window, &mut gpui::App) + 'static>,
}

#[derive(Clone)]
pub(crate) struct FileTreeState(Rc<RefCell<FileTreeStateInner>>);

struct FileTreeStateInner {
    list_state: gpui::ListState,
    collapsed_dirs: HashSet<Arc<str>>,
    visible_items: Vec<usize>,
}

pub(crate) fn file_tree(
    state: FileTreeState,
    item: impl Fn(usize, &gpui::Window, &mut gpui::App) -> util::file::FileTreeItem + 'static,
) -> FileTree {
    FileTree {
        state,
        item: Box::new(item),
        on_item_click: None,
    }
}

impl FileTreeState {
    pub(crate) fn new() -> Self {
        Self(Rc::new(RefCell::new(FileTreeStateInner {
            list_state: gpui::ListState::new(0, gpui::ListAlignment::Top, px(50.)),
            collapsed_dirs: HashSet::new(),
            visible_items: Vec::new(),
        })))
    }

    pub(crate) fn reset(&self, items: &[util::file::FileTreeItem]) {
        let mut state = self.0.borrow_mut();
        state.list_state.reset(items.len());
        state.visible_items = (0..items.len()).collect::<Vec<_>>();
    }

    pub(crate) fn toggle_directory(
        &mut self,
        dir_path: &Arc<str>,
        items: &[util::file::FileTreeItem],
    ) {
        let mut state = self.0.borrow_mut();
        if !state.collapsed_dirs.remove(dir_path) {
            state.collapsed_dirs.insert(Arc::clone(dir_path));
        }

        state.visible_items.clear();

        let mut hidden_after_level: usize = usize::MAX;
        for (i, item) in items.iter().enumerate() {
            if item.level > hidden_after_level {
                continue;
            }

            hidden_after_level = usize::MAX;

            if item.kind == FileTreeItemKind::Directory
                && state.collapsed_dirs.contains(&item.full_path)
            {
                hidden_after_level = item.level;
            }

            state.visible_items.push(i);
        }

        state.list_state.reset(state.visible_items.len());
    }
}

impl FileTree {
    pub(crate) fn on_item_click(
        mut self,
        f: impl Fn(&usize, &mut gpui::Window, &mut gpui::App) + 'static,
    ) -> Self {
        self.on_item_click = Some(Rc::new(f));
        self
    }
}

impl gpui::RenderOnce for FileTree {
    fn render(
        self,
        _window: &mut gpui::Window,
        _cx: &mut gpui::App,
    ) -> impl gpui::prelude::IntoElement {
        let list_state = self.state.0.borrow().list_state.clone();

        list(list_state, move |i, window, cx| {
            let state = self.state.0.borrow();
            let item_index = state.visible_items[i];
            let on_item_click = self.on_item_click.as_ref().map(Rc::clone);

            let item = (self.item)(item_index, window, cx);
            let item = Item {
                is_expanded: !state.collapsed_dirs.contains(&item.full_path),
                item,
                on_click: Box::new(move |window, cx| {
                    if let Some(f) = &on_item_click {
                        f(&i, window, cx);
                    }
                }),
            };

            item.into_any_element()
        })
        .size_full()
    }
}

impl gpui::RenderOnce for Item {
    fn render(self, _window: &mut gpui::Window, cx: &mut gpui::App) -> impl IntoElement {
        let theme = app::current_theme(cx);
        div()
            .id(gpui::SharedString::new(self.item.full_path))
            .w_full()
            .flex()
            .flex_row()
            .items_center()
            .gap_1p5()
            .pr_2()
            .py_0p5()
            .pl(px(8. + (8 * self.item.level) as f32))
            .rounded_sm()
            .hover(|it| it.bg(theme.colors.surface_hover))
            .on_click(move |_, window, cx| (self.on_click)(window, cx))
            .when(
                matches!(self.item.kind, FileTreeItemKind::Directory),
                |it| {
                    it.child(
                        font_icon(if self.is_expanded {
                            FontIcon::FolderOpen
                        } else {
                            FontIcon::FolderClosed
                        })
                        .size_3(),
                    )
                },
            )
            .when(matches!(self.item.kind, FileTreeItemKind::File), |it| {
                it.child(font_icon(FontIcon::FileBracesCorner).size_3())
            })
            .child(text(gpui::SharedString::new(self.item.name)).text_sm())
    }
}