use crate::{theme::Theme, tree::Tree, Document, DocumentId, View, ViewId};
use tui::layout::Rect;

use std::path::PathBuf;

use slotmap::SlotMap;

use anyhow::Error;

pub struct Editor {
    pub tree: Tree,
    pub documents: SlotMap<DocumentId, Document>,
    pub count: Option<usize>,
    pub theme: Theme,
    pub language_servers: helix_lsp::Registry,
    pub executor: &'static smol::Executor<'static>,
}

pub enum Action {
    Replace,
    HorizontalSplit,
    VerticalSplit,
}

impl Editor {
    pub fn new(executor: &'static smol::Executor<'static>, mut area: tui::layout::Rect) -> Self {
        let theme = Theme::default();
        let language_servers = helix_lsp::Registry::new();

        // HAXX: offset the render area height by 1 to account for prompt/commandline
        area.height -= 1;

        Self {
            tree: Tree::new(area),
            documents: SlotMap::with_key(),
            count: None,
            theme,
            language_servers,
            executor,
        }
    }

    fn _refresh(&mut self) {
        for (view, _) in self.tree.views_mut() {
            let doc = &self.documents[view.doc];
            view.ensure_cursor_in_view(doc)
        }
    }

    pub fn open(&mut self, path: PathBuf, action: Action) -> Result<DocumentId, Error> {
        let id = self
            .documents()
            .find(|doc| doc.path() == Some(&path))
            .map(|doc| doc.id);

        let id = if let Some(id) = id {
            id
        } else {
            let mut doc = Document::load(path, self.theme.scopes())?;

            // try to find a language server based on the language name
            let language_server = doc
                .language
                .as_ref()
                .and_then(|language| self.language_servers.get(language, self.executor));

            if let Some(language_server) = language_server {
                doc.set_language_server(Some(language_server.clone()));

                let language_id = doc
                    .language()
                    .and_then(|s| s.split('.').last()) // source.rust
                    .map(ToOwned::to_owned)
                    .unwrap_or_default();

                smol::block_on(language_server.text_document_did_open(
                    doc.url().unwrap(),
                    doc.version(),
                    doc.text(),
                    language_id,
                ))
                .unwrap();
            }

            let id = self.documents.insert(doc);
            self.documents[id].id = id;
            id
        };

        use crate::tree::Layout;
        match action {
            Action::Replace => {
                self.view_mut().doc = id;
                // TODO: reset selection?
                return Ok(id);
            }
            Action::HorizontalSplit => {
                let view = View::new(id)?;
                self.tree.split(view, Layout::Horizontal);
            }
            Action::VerticalSplit => {
                let view = View::new(id)?;
                self.tree.split(view, Layout::Vertical);
            }
        }

        self._refresh();

        Ok(id)
    }

    pub fn close(&mut self, id: ViewId) {
        let view = self.tree.get(self.tree.focus);
        // get around borrowck issues
        let language_servers = &mut self.language_servers;
        let executor = self.executor;

        let doc = &self.documents[view.doc];

        let language_server = doc
            .language
            .as_ref()
            .and_then(|language| language_servers.get(language, executor));

        if let Some(language_server) = language_server {
            smol::block_on(language_server.text_document_did_close(doc.identifier())).unwrap();
        }

        // self.documents.remove(view.doc);
        self.tree.remove(id);
        self._refresh();
    }

    pub fn resize(&mut self, area: Rect) {
        self.tree.resize(area);
        self._refresh();
    }

    pub fn focus_next(&mut self) {
        self.tree.focus_next();
    }

    pub fn should_close(&self) -> bool {
        self.tree.is_empty()
    }

    pub fn view(&self) -> &View {
        self.tree.get(self.tree.focus)
    }

    pub fn view_mut(&mut self) -> &mut View {
        self.tree.get_mut(self.tree.focus)
    }

    pub fn ensure_cursor_in_view(&mut self, id: ViewId) {
        let view = self.tree.get_mut(id);
        let doc = &self.documents[view.doc];
        view.ensure_cursor_in_view(doc)
    }

    pub fn document(&self, id: DocumentId) -> Option<&Document> {
        self.documents.get(id)
    }

    pub fn documents(&self) -> impl Iterator<Item = &Document> {
        self.documents.iter().map(|(_id, doc)| doc)
    }

    pub fn cursor_position(&self) -> Option<helix_core::Position> {
        const OFFSET: u16 = 7; // 1 diagnostic + 5 linenr + 1 gutter
        let view = self.view();
        let doc = &self.documents[view.doc];
        let cursor = doc.selection().cursor();
        if let Some(mut pos) = view.screen_coords_at_pos(doc, doc.text().slice(..), cursor) {
            pos.col += view.area.x as usize + OFFSET as usize;
            pos.row += view.area.y as usize;
            return Some(pos);
        }
        None
    }
}