use std::sync::Arc;

use crate::{
    api, app,
    component::file_tree::{FileTreeState, file_tree},
    query::{self, QueryStatus, read_query, use_query, watch_query},
    screen::dashboard::pull_request_diff_view::PullRequestDiffView,
    util::{
        self,
        file::{FileTreeItem, FileTreeItemKind},
    },
};
use gpui::{AppContext, ParentElement, Styled, div};

pub(crate) struct PullRequestChangeView {
    selected_file_path: Option<Arc<str>>,
    diff_view: gpui::Entity<PullRequestDiffView>,

    file_tree_query: query::Entity<api::issues::FetchPullRequestFileTree>,
    file_tree_state: FileTreeState,
    file_tree_items: Vec<FileTreeItem>,
}

pub(crate) fn new(
    pr_id: api::issues::Id,
    cx: &mut gpui::Context<PullRequestChangeView>,
) -> PullRequestChangeView {
    let mut view = PullRequestChangeView {
        selected_file_path: None,
        diff_view: cx.new(|cx| PullRequestDiffView::new(pr_id.clone(), cx)),

        file_tree_query: use_query(
            api::issues::FetchPullRequestFileTree {
                id: pr_id,
                first: 100,
            },
            cx,
        ),
        file_tree_state: FileTreeState::new(),
        file_tree_items: Vec::new(),
    };
    view.on_create(cx);
    view
}

impl PullRequestChangeView {
    fn on_create(&mut self, cx: &mut gpui::Context<Self>) {
        watch_query(
            &self.file_tree_query,
            |this, query, cx| {
                if let QueryStatus::Loaded(changed_files) = read_query(query, cx) {
                    let tree = util::file::build_file_tree(changed_files, |f| &f.path);
                    this.file_tree_state.reset(&tree);
                    this.file_tree_items = tree;
                    cx.notify();
                };
            },
            cx,
        )
        .detach();
    }

    fn handle_file_tree_item_click(
        &mut self,
        i: usize,
        window: &mut gpui::Window,
        cx: &mut gpui::Context<Self>,
    ) {
        let item = &self.file_tree_items[i];
        match item.kind {
        | FileTreeItemKind::Directory => {
            self.file_tree_state
                .toggle_directory(&item.full_path, &self.file_tree_items);
            cx.notify();
        }
        | FileTreeItemKind::File => {
            self.selected_file_path = Some(Arc::clone(&item.full_path));
            self.file_tree_state.highlight_item(i);
            self.diff_view.update(cx, |diff_view, cx| {
                diff_view.show_diff_for_file(&item.full_path, cx);
            });
            cx.focus_view(&self.diff_view, window);
            cx.notify();
        }
        }
    }
}

impl gpui::Render for PullRequestChangeView {
    fn render(
        &mut self,
        _window: &mut gpui::Window,
        cx: &mut gpui::Context<Self>,
    ) -> impl gpui::IntoElement {
        let theme = app::current_theme(cx);
        let weak = cx.entity();

        div()
            .size_full()
            .flex()
            .flex_row()
            .child(
                div()
                    .flex()
                    .w_80()
                    .h_full()
                    .bg(theme.colors.surface_chrome)
                    .border_r_1()
                    .border_color(theme.colors.border_muted)
                    .child(
                        file_tree(self.file_tree_state.clone(), move |i, _, cx| {
                            weak.read(cx).file_tree_items[i].clone()
                        })
                        .on_item_click(cx.listener(
                            |this, i, window, cx| {
                                this.handle_file_tree_item_click(*i, window, cx);
                            },
                        )),
                    ),
            )
            .child(
                gpui::AnyView::from(self.diff_view.clone())
                    .cached(gpui::StyleRefinement::default().size_full()),
            )
    }
}