use arc_swap::{access::Map, ArcSwap};
use futures_util::Stream;
use helix_core::{diagnostic::Severity, pos_at_coords, syntax, Selection};
use helix_lsp::{
    lsp::{self, notification::Notification},
    util::lsp_range_to_range,
    LanguageServerId, LspProgressMap,
};
use helix_stdx::path::get_relative_path;
use helix_view::{
    align_view,
    document::{DocumentOpenError, DocumentSavedEventResult},
    editor::{ConfigEvent, EditorEvent},
    events::DiagnosticsDidChange,
    graphics::Rect,
    theme,
    tree::Layout,
    Align, Editor,
};
use serde_json::json;
use tui::backend::Backend;

use crate::{
    args::Args,
    compositor::{Compositor, Event},
    config::Config,
    handlers,
    job::Jobs,
    keymap::Keymaps,
    ui::{self, overlay::overlaid},
};

use log::{debug, error, info, warn};
#[cfg(not(feature = "integration"))]
use std::io::stdout;
use std::{collections::btree_map::Entry, io::stdin, path::Path, sync::Arc};

#[cfg(not(windows))]
use anyhow::Context;
use anyhow::Error;

use crossterm::{event::Event as CrosstermEvent, tty::IsTty};
#[cfg(not(windows))]
use {signal_hook::consts::signal, signal_hook_tokio::Signals};
#[cfg(windows)]
type Signals = futures_util::stream::Empty<()>;

#[cfg(not(feature = "integration"))]
use tui::backend::CrosstermBackend;

#[cfg(feature = "integration")]
use tui::backend::TestBackend;

#[cfg(not(feature = "integration"))]
type TerminalBackend = CrosstermBackend<std::io::Stdout>;

#[cfg(feature = "integration")]
type TerminalBackend = TestBackend;

type Terminal = tui::terminal::Terminal<TerminalBackend>;

pub struct Application {
    compositor: Compositor,
    terminal: Terminal,
    pub editor: Editor,

    config: Arc<ArcSwap<Config>>,

    #[allow(dead_code)]
    theme_loader: Arc<theme::Loader>,
    #[allow(dead_code)]
    syn_loader: Arc<ArcSwap<syntax::Loader>>,

    signals: Signals,
    jobs: Jobs,
    lsp_progress: LspProgressMap,
}

#[cfg(feature = "integration")]
fn setup_integration_logging() {
    let level = std::env::var("HELIX_LOG_LEVEL")
        .map(|lvl| lvl.parse().unwrap())
        .unwrap_or(log::LevelFilter::Info);

    // Separate file config so we can include year, month and day in file logs
    let _ = fern::Dispatch::new()
        .format(|out, message, record| {
            out.finish(format_args!(
                "{} {} [{}] {}",
                chrono::Local::now().format("%Y-%m-%dT%H:%M:%S%.3f"),
                record.target(),
                record.level(),
                message
            ))
        })
        .level(level)
        .chain(std::io::stdout())
        .apply();
}

impl Application {
    pub fn new(args: Args, config: Config, lang_loader: syntax::Loader) -> Result<Self, Error> {
        #[cfg(feature = "integration")]
        setup_integration_logging();

        use helix_view::editor::Action;

        let mut theme_parent_dirs = vec![helix_loader::config_dir()];
        theme_parent_dirs.extend(helix_loader::runtime_dirs().iter().cloned());
        let theme_loader = std::sync::Arc::new(theme::Loader::new(&theme_parent_dirs));

        let true_color = config.editor.true_color || crate::true_color();
        let theme = config
            .theme
            .as_ref()
            .and_then(|theme| {
                theme_loader
                    .load(theme)
                    .map_err(|e| {
                        log::warn!("failed to load theme `{}` - {}", theme, e);
                        e
                    })
                    .ok()
                    .filter(|theme| (true_color || theme.is_16_color()))
            })
            .unwrap_or_else(|| theme_loader.default_theme(true_color));

        let syn_loader = Arc::new(ArcSwap::from_pointee(lang_loader));

        #[cfg(not(feature = "integration"))]
        let backend = CrosstermBackend::new(stdout(), &config.editor);

        #[cfg(feature = "integration")]
        let backend = TestBackend::new(120, 150);

        let terminal = Terminal::new(backend)?;
        let area = terminal.size().expect("couldn't get terminal size");
        let mut compositor = Compositor::new(area);
        let config = Arc::new(ArcSwap::from_pointee(config));
        let handlers = handlers::setup(config.clone());
        let mut editor = Editor::new(
            area,
            theme_loader.clone(),
            syn_loader.clone(),
            Arc::new(Map::new(Arc::clone(&config), |config: &Config| {
                &config.editor
            })),
            handlers,
        );

        let keys = Box::new(Map::new(Arc::clone(&config), |config: &Config| {
            &config.keys
        }));
        let editor_view = Box::new(ui::EditorView::new(Keymaps::new(keys)));
        compositor.push(editor_view);

        if args.load_tutor {
            let path = helix_loader::runtime_file(Path::new("tutor"));
            editor.open(&path, Action::VerticalSplit)?;
            // Unset path to prevent accidentally saving to the original tutor file.
            doc_mut!(editor).set_path(None);
        } else if !args.files.is_empty() {
            let mut files_it = args.files.into_iter().peekable();

            // If the first file is a directory, skip it and open a picker
            if let Some((first, _)) = files_it.next_if(|(p, _)| p.is_dir()) {
                let picker = ui::file_picker(first, &config.load().editor);
                compositor.push(Box::new(overlaid(picker)));
            }

            // If there are any more files specified, open them
            if files_it.peek().is_some() {
                let mut nr_of_files = 0;
                for (file, pos) in files_it {
                    nr_of_files += 1;
                    if file.is_dir() {
                        return Err(anyhow::anyhow!(
                            "expected a path to file, found a directory. (to open a directory pass it as first argument)"
                        ));
                    } else {
                        // If the user passes in either `--vsplit` or
                        // `--hsplit` as a command line argument, all the given
                        // files will be opened according to the selected
                        // option. If neither of those two arguments are passed
                        // in, just load the files normally.
                        let action = match args.split {
                            _ if nr_of_files == 1 => Action::VerticalSplit,
                            Some(Layout::Vertical) => Action::VerticalSplit,
                            Some(Layout::Horizontal) => Action::HorizontalSplit,
                            None => Action::Load,
                        };
                        let doc_id = match editor.open(&file, action) {
                            // Ignore irregular files during application init.
                            Err(DocumentOpenError::IrregularFile) => {
                                nr_of_files -= 1;
                                continue;
                            }
                            Err(err) => return Err(anyhow::anyhow!(err)),
                            Ok(doc_id) => doc_id,
                        };
                        // with Action::Load all documents have the same view
                        // NOTE: this isn't necessarily true anymore. If
                        // `--vsplit` or `--hsplit` are used, the file which is
                        // opened last is focused on.
                        let view_id = editor.tree.focus;
                        let doc = doc_mut!(editor, &doc_id);
                        let pos = Selection::point(pos_at_coords(doc.text().slice(..), pos, true));
                        doc.set_selection(view_id, pos);
                    }
                }

                // if all files were invalid, replace with empty buffer
                if nr_of_files == 0 {
                    editor.new_file(Action::VerticalSplit);
                } else {
                    editor.set_status(format!(
                        "Loaded {} file{}.",
                        nr_of_files,
                        if nr_of_files == 1 { "" } else { "s" } // avoid "Loaded 1 files." grammo
                    ));
                    // align the view to center after all files are loaded,
                    // does not affect views without pos since it is at the top
                    let (view, doc) = current!(editor);
                    align_view(doc, view, Align::Center);
                }
            } else {
                editor.new_file(Action::VerticalSplit);
            }
        } else if stdin().is_tty() || cfg!(feature = "integration") {
            editor.new_file(Action::VerticalSplit);
        } else {
            editor
                .new_file_from_stdin(Action::VerticalSplit)
                .unwrap_or_else(|_| editor.new_file(Action::VerticalSplit));
        }

        editor.set_theme(theme);

        #[cfg(windows)]
        let signals = futures_util::stream::empty();
        #[cfg(not(windows))]
        let signals = Signals::new([
            signal::SIGTSTP,
            signal::SIGCONT,
            signal::SIGUSR1,
            signal::SIGTERM,
            signal::SIGINT,
        ])
        .context("build signal handler")?;

        let app = Self {
            compositor,
            terminal,
            editor,

            config,

            theme_loader,
            syn_loader,

            signals,
            jobs: Jobs::new(),
            lsp_progress: LspProgressMap::new(),
        };

        Ok(app)
    }

    async fn render(&mut self) {
        if self.compositor.full_redraw {
            self.terminal.clear().expect("Cannot clear the terminal");
            self.compositor.full_redraw = false;
        }

        let mut cx = crate::compositor::Context {
            editor: &mut self.editor,
            jobs: &mut self.jobs,
            scroll: None,
        };

        helix_event::start_frame();
        cx.editor.needs_redraw = false;

        let area = self
            .terminal
            .autoresize()
            .expect("Unable to determine terminal size");

        // TODO: need to recalculate view tree if necessary

        let surface = self.terminal.current_buffer_mut();

        self.compositor.render(area, surface, &mut cx);
        let (pos, kind) = self.compositor.cursor(area, &self.editor);
        // reset cursor cache
        self.editor.cursor_cache.reset();

        let pos = pos.map(|pos| (pos.col as u16, pos.row as u16));
        self.terminal.draw(pos, kind).unwrap();
    }

    pub async fn event_loop<S>(&mut self, input_stream: &mut S)
    where
        S: Stream<Item = std::io::Result<crossterm::event::Event>> + Unpin,
    {
        self.render().await;

        loop {
            if !self.event_loop_until_idle(input_stream).await {
                break;
            }
        }
    }

    pub async fn event_loop_until_idle<S>(&mut self, input_stream: &mut S) -> bool
    where
        S: Stream<Item = std::io::Result<crossterm::event::Event>> + Unpin,
    {
        loop {
            if self.editor.should_close() {
                return false;
            }

            use futures_util::StreamExt;

            tokio::select! {
                biased;

                Some(signal) = self.signals.next() => {
                    if !self.handle_signals(signal).await {
                        return false;
                    };
                }
                Some(event) = input_stream.next() => {
                    self.handle_terminal_events(event).await;
                }
                Some(callback) = self.jobs.callbacks.recv() => {
                    self.jobs.handle_callback(&mut self.editor, &mut self.compositor, Ok(Some(callback)));
                    self.render().await;
                }
                Some(msg) = self.jobs.status_messages.recv() => {
                    let severity = match msg.severity{
                        helix_event::status::Severity::Hint => Severity::Hint,
                        helix_event::status::Severity::Info => Severity::Info,
                        helix_event::status::Severity::Warning => Severity::Warning,
                        helix_event::status::Severity::Error => Severity::Error,
                    };
                    // TODO: show multiple status messages at once to avoid clobbering
                    self.editor.status_msg = Some((msg.message, severity));
                    helix_event::request_redraw();
                }
                Some(callback) = self.jobs.wait_futures.next() => {
                    self.jobs.handle_callback(&mut self.editor, &mut self.compositor, callback);
                    self.render().await;
                }
                event = self.editor.wait_event() => {
                    let _idle_handled = self.handle_editor_event(event).await;

                    #[cfg(feature = "integration")]
                    {
                        if _idle_handled {
                            return true;
                        }
                    }
                }
            }

            // for integration tests only, reset the idle timer after every
            // event to signal when test events are done processing
            #[cfg(feature = "integration")]
            {
                self.editor.reset_idle_timer();
            }
        }
    }

    pub fn handle_config_events(&mut self, config_event: ConfigEvent) {
        match config_event {
            ConfigEvent::Refresh => self.refresh_config(),

            // Since only the Application can make changes to Editor's config,
            // the Editor must send up a new copy of a modified config so that
            // the Application can apply it.
            ConfigEvent::Update(editor_config) => {
                let mut app_config = (*self.config.load().clone()).clone();
                app_config.editor = *editor_config;
                if let Err(err) = self.terminal.reconfigure(app_config.editor.clone().into()) {
                    self.editor.set_error(err.to_string());
                };
                self.config.store(Arc::new(app_config));
            }
        }

        // Update all the relevant members in the editor after updating
        // the configuration.
        self.editor.refresh_config();

        // reset view position in case softwrap was enabled/disabled
        let scrolloff = self.editor.config().scrolloff;
        for (view, _) in self.editor.tree.views() {
            let doc = doc_mut!(self.editor, &view.doc);
            view.ensure_cursor_in_view(doc, scrolloff);
        }
    }

    /// refresh language config after config change
    fn refresh_language_config(&mut self) -> Result<(), Error> {
        let lang_loader = helix_core::config::user_lang_loader()?;

        self.syn_loader.store(Arc::new(lang_loader));
        self.editor.syn_loader = self.syn_loader.clone();
        for document in self.editor.documents.values_mut() {
            document.detect_language(self.syn_loader.clone());
            let diagnostics = Editor::doc_diagnostics(
                &self.editor.language_servers,
                &self.editor.diagnostics,
                document,
            );
            document.replace_diagnostics(diagnostics, &[], None);
        }

        Ok(())
    }

    /// Refresh theme after config change
    fn refresh_theme(&mut self, config: &Config) -> Result<(), Error> {
        let true_color = config.editor.true_color || crate::true_color();
        let theme = config
            .theme
            .as_ref()
            .and_then(|theme| {
                self.theme_loader
                    .load(theme)
                    .map_err(|e| {
                        log::warn!("failed to load theme `{}` - {}", theme, e);
                        e
                    })
                    .ok()
                    .filter(|theme| (true_color || theme.is_16_color()))
            })
            .unwrap_or_else(|| self.theme_loader.default_theme(true_color));

        self.editor.set_theme(theme);
        Ok(())
    }

    fn refresh_config(&mut self) {
        let mut refresh_config = || -> Result<(), Error> {
            let default_config = Config::load_default()
                .map_err(|err| anyhow::anyhow!("Failed to load config: {}", err))?;
            self.refresh_language_config()?;
            self.refresh_theme(&default_config)?;
            self.terminal
                .reconfigure(default_config.editor.clone().into())?;
            // Store new config
            self.config.store(Arc::new(default_config));
            Ok(())
        };

        match refresh_config() {
            Ok(_) => {
                self.editor.set_status("Config refreshed");
            }
            Err(err) => {
                self.editor.set_error(err.to_string());
            }
        }
    }

    #[cfg(windows)]
    // no signal handling available on windows
    pub async fn handle_signals(&mut self, _signal: ()) -> bool {
        true
    }

    #[cfg(not(windows))]
    pub async fn handle_signals(&mut self, signal: i32) -> bool {
        match signal {
            signal::SIGTSTP => {
                self.restore_term().unwrap();

                // SAFETY:
                //
                // - helix must have permissions to send signals to all processes in its signal
                //   group, either by already having the requisite permission, or by having the
                //   user's UID / EUID / SUID match that of the receiving process(es).
                let res = unsafe {
                    // A pid of 0 sends the signal to the entire process group, allowing the user to
                    // regain control of their terminal if the editor was spawned under another process
                    // (e.g. when running `git commit`).
                    //
                    // We have to send SIGSTOP (not SIGTSTP) to the entire process group, because,
                    // as mentioned above, the terminal will get stuck if `helix` was spawned from
                    // an external process and that process waits for `helix` to complete. This may
                    // be an issue with signal-hook-tokio, but the author of signal-hook believes it
                    // could be a tokio issue instead:
                    // https://github.com/vorner/signal-hook/issues/132
                    libc::kill(0, signal::SIGSTOP)
                };

                if res != 0 {
                    let err = std::io::Error::last_os_error();
                    eprintln!("{}", err);
                    let res = err.raw_os_error().unwrap_or(1);
                    std::process::exit(res);
                }
            }
            signal::SIGCONT => {
                // Copy/Paste from same issue from neovim:
                // https://github.com/neovim/neovim/issues/12322
                // https://github.com/neovim/neovim/pull/13084
                for retries in 1..=10 {
                    match self.claim_term().await {
                        Ok(()) => break,
                        Err(err) if retries == 10 => panic!("Failed to claim terminal: {}", err),
                        Err(_) => continue,
                    }
                }

                // redraw the terminal
                let area = self.terminal.size().expect("couldn't get terminal size");
                self.compositor.resize(area);
                self.terminal.clear().expect("couldn't clear terminal");

                self.render().await;
            }
            signal::SIGUSR1 => {
                self.refresh_config();
                self.render().await;
            }
            signal::SIGTERM | signal::SIGINT => {
                self.restore_term().unwrap();
                return false;
            }
            _ => unreachable!(),
        }

        true
    }

    pub async fn handle_idle_timeout(&mut self) {
        let mut cx = crate::compositor::Context {
            editor: &mut self.editor,
            jobs: &mut self.jobs,
            scroll: None,
        };
        let should_render = self.compositor.handle_event(&Event::IdleTimeout, &mut cx);
        if should_render || self.editor.needs_redraw {
            self.render().await;
        }
    }

    pub fn handle_document_write(&mut self, doc_save_event: DocumentSavedEventResult) {
        let doc_save_event = match doc_save_event {
            Ok(event) => event,
            Err(err) => {
                self.editor.set_error(err.to_string());
                return;
            }
        };

        let doc = match self.editor.document_mut(doc_save_event.doc_id) {
            None => {
                warn!(
                    "received document saved event for non-existent doc id: {}",
                    doc_save_event.doc_id
                );

                return;
            }
            Some(doc) => doc,
        };

        debug!(
            "document {:?} saved with revision {}",
            doc.path(),
            doc_save_event.revision
        );

        doc.set_last_saved_revision(doc_save_event.revision, doc_save_event.save_time);

        let lines = doc_save_event.text.len_lines();
        let bytes = doc_save_event.text.len_bytes();

        self.editor
            .set_doc_path(doc_save_event.doc_id, &doc_save_event.path);
        // TODO: fix being overwritten by lsp
        self.editor.set_status(format!(
            "'{}' written, {}L {}B",
            get_relative_path(&doc_save_event.path).to_string_lossy(),
            lines,
            bytes
        ));
    }

    #[inline(always)]
    pub async fn handle_editor_event(&mut self, event: EditorEvent) -> bool {
        log::debug!("received editor event: {:?}", event);

        match event {
            EditorEvent::DocumentSaved(event) => {
                self.handle_document_write(event);
                self.render().await;
            }
            EditorEvent::ConfigEvent(event) => {
                self.handle_config_events(event);
                self.render().await;
            }
            EditorEvent::LanguageServerMessage((id, call)) => {
                self.handle_language_server_message(call, id).await;
                // limit render calls for fast language server messages
                helix_event::request_redraw();
            }
            EditorEvent::DebuggerEvent(payload) => {
                let needs_render = self.editor.handle_debugger_message(payload).await;
                if needs_render {
                    self.render().await;
                }
            }
            EditorEvent::Redraw => {
                self.render().await;
            }
            EditorEvent::IdleTimer => {
                self.editor.clear_idle_timer();
                self.handle_idle_timeout().await;

                #[cfg(feature = "integration")]
                {
                    return true;
                }
            }
        }

        false
    }

    pub async fn handle_terminal_events(&mut self, event: std::io::Result<CrosstermEvent>) {
        let mut cx = crate::compositor::Context {
            editor: &mut self.editor,
            jobs: &mut self.jobs,
            scroll: None,
        };
        // Handle key events
        let should_redraw = match event.unwrap() {
            CrosstermEvent::Resize(width, height) => {
                self.terminal
                    .resize(Rect::new(0, 0, width, height))
                    .expect("Unable to resize terminal");

                let area = self.terminal.size().expect("couldn't get terminal size");

                self.compositor.resize(area);

                self.compositor
                    .handle_event(&Event::Resize(width, height), &mut cx)
            }
            // Ignore keyboard release events.
            CrosstermEvent::Key(crossterm::event::KeyEvent {
                kind: crossterm::event::KeyEventKind::Release,
                ..
            }) => false,
            event => self.compositor.handle_event(&event.into(), &mut cx),
        };

        if should_redraw && !self.editor.should_close() {
            self.render().await;
        }
    }

    pub async fn handle_language_server_message(
        &mut self,
        call: helix_lsp::Call,
        server_id: LanguageServerId,
    ) {
        use helix_lsp::{Call, MethodCall, Notification};

        macro_rules! language_server {
            () => {
                match self.editor.language_server_by_id(server_id) {
                    Some(language_server) => language_server,
                    None => {
                        warn!("can't find language server with id `{}`", server_id);
                        return;
                    }
                }
            };
        }

        match call {
            Call::Notification(helix_lsp::jsonrpc::Notification { method, params, .. }) => {
                let notification = match Notification::parse(&method, params) {
                    Ok(notification) => notification,
                    Err(helix_lsp::Error::Unhandled) => {
                        info!("Ignoring Unhandled notification from Language Server");
                        return;
                    }
                    Err(err) => {
                        error!(
                            "Ignoring unknown notification from Language Server: {}",
                            err
                        );
                        return;
                    }
                };

                match notification {
                    Notification::Initialized => {
                        let language_server = language_server!();

                        // Trigger a workspace/didChangeConfiguration notification after initialization.
                        // This might not be required by the spec but Neovim does this as well, so it's
                        // probably a good idea for compatibility.
                        if let Some(config) = language_server.config() {
                            tokio::spawn(language_server.did_change_configuration(config.clone()));
                        }

                        let docs = self
                            .editor
                            .documents()
                            .filter(|doc| doc.supports_language_server(server_id));

                        // trigger textDocument/didOpen for docs that are already open
                        for doc in docs {
                            let url = match doc.url() {
                                Some(url) => url,
                                None => continue, // skip documents with no path
                            };

                            let language_id =
                                doc.language_id().map(ToOwned::to_owned).unwrap_or_default();

                            tokio::spawn(language_server.text_document_did_open(
                                url,
                                doc.version(),
                                doc.text(),
                                language_id,
                            ));
                        }
                    }
                    Notification::PublishDiagnostics(mut params) => {
                        let uri = match helix_core::Uri::try_from(params.uri) {
                            Ok(uri) => uri,
                            Err(err) => {
                                log::error!("{err}");
                                return;
                            }
                        };
                        let language_server = language_server!();
                        if !language_server.is_initialized() {
                            log::error!("Discarding publishDiagnostic notification sent by an uninitialized server: {}", language_server.name());
                            return;
                        }
                        // have to inline the function because of borrow checking...
                        let doc = self.editor.documents.values_mut()
                            .find(|doc| doc.uri().is_some_and(|u| u == uri))
                            .filter(|doc| {
                                if let Some(version) = params.version {
                                    if version != doc.version() {
                                        log::info!("Version ({version}) is out of date for {uri:?} (expected ({}), dropping PublishDiagnostic notification", doc.version());
                                        return false;
                                    }
                                }
                                true
                            });

                        let mut unchanged_diag_sources = Vec::new();
                        if let Some(doc) = &doc {
                            let lang_conf = doc.language.clone();

                            if let Some(lang_conf) = &lang_conf {
                                if let Some(old_diagnostics) = self.editor.diagnostics.get(&uri) {
                                    if !lang_conf.persistent_diagnostic_sources.is_empty() {
                                        // Sort diagnostics first by severity and then by line numbers.
                                        // Note: The `lsp::DiagnosticSeverity` enum is already defined in decreasing order
                                        params
                                            .diagnostics
                                            .sort_by_key(|d| (d.severity, d.range.start));
                                    }
                                    for source in &lang_conf.persistent_diagnostic_sources {
                                        let new_diagnostics = params
                                            .diagnostics
                                            .iter()
                                            .filter(|d| d.source.as_ref() == Some(source));
                                        let old_diagnostics = old_diagnostics
                                            .iter()
                                            .filter(|(d, d_server)| {
                                                *d_server == server_id
                                                    && d.source.as_ref() == Some(source)
                                            })
                                            .map(|(d, _)| d);
                                        if new_diagnostics.eq(old_diagnostics) {
                                            unchanged_diag_sources.push(source.clone())
                                        }
                                    }
                                }
                            }
                        }

                        let diagnostics = params.diagnostics.into_iter().map(|d| (d, server_id));

                        // Insert the original lsp::Diagnostics here because we may have no open document
                        // for diagnosic message and so we can't calculate the exact position.
                        // When using them later in the diagnostics picker, we calculate them on-demand.
                        let diagnostics = match self.editor.diagnostics.entry(uri) {
                            Entry::Occupied(o) => {
                                let current_diagnostics = o.into_mut();
                                // there may entries of other language servers, which is why we can't overwrite the whole entry
                                current_diagnostics.retain(|(_, lsp_id)| *lsp_id != server_id);
                                current_diagnostics.extend(diagnostics);
                                current_diagnostics
                                // Sort diagnostics first by severity and then by line numbers.
                            }
                            Entry::Vacant(v) => v.insert(diagnostics.collect()),
                        };

                        // Sort diagnostics first by severity and then by line numbers.
                        // Note: The `lsp::DiagnosticSeverity` enum is already defined in decreasing order
                        diagnostics
                            .sort_by_key(|(d, server_id)| (d.severity, d.range.start, *server_id));

                        if let Some(doc) = doc {
                            let diagnostic_of_language_server_and_not_in_unchanged_sources =
                                |diagnostic: &lsp::Diagnostic, ls_id| {
                                    ls_id == server_id
                                        && diagnostic.source.as_ref().map_or(true, |source| {
                                            !unchanged_diag_sources.contains(source)
                                        })
                                };
                            let diagnostics = Editor::doc_diagnostics_with_filter(
                                &self.editor.language_servers,
                                &self.editor.diagnostics,
                                doc,
                                diagnostic_of_language_server_and_not_in_unchanged_sources,
                            );
                            doc.replace_diagnostics(
                                diagnostics,
                                &unchanged_diag_sources,
                                Some(server_id),
                            );

                            let doc = doc.id();
                            helix_event::dispatch(DiagnosticsDidChange {
                                editor: &mut self.editor,
                                doc,
                            });
                        }
                    }
                    Notification::ShowMessage(params) => {
                        log::warn!("unhandled window/showMessage: {:?}", params);
                    }
                    Notification::LogMessage(params) => {
                        log::info!("window/logMessage: {:?}", params);
                    }
                    Notification::ProgressMessage(params)
                        if !self
                            .compositor
                            .has_component(std::any::type_name::<ui::Prompt>()) =>
                    {
                        let editor_view = self
                            .compositor
                            .find::<ui::EditorView>()
                            .expect("expected at least one EditorView");
                        let lsp::ProgressParams { token, value } = params;

                        let lsp::ProgressParamsValue::WorkDone(work) = value;
                        let parts = match &work {
                            lsp::WorkDoneProgress::Begin(lsp::WorkDoneProgressBegin {
                                title,
                                message,
                                percentage,
                                ..
                            }) => (Some(title), message, percentage),
                            lsp::WorkDoneProgress::Report(lsp::WorkDoneProgressReport {
                                message,
                                percentage,
                                ..
                            }) => (None, message, percentage),
                            lsp::WorkDoneProgress::End(lsp::WorkDoneProgressEnd { message }) => {
                                if message.is_some() {
                                    (None, message, &None)
                                } else {
                                    self.lsp_progress.end_progress(server_id, &token);
                                    if !self.lsp_progress.is_progressing(server_id) {
                                        editor_view.spinners_mut().get_or_create(server_id).stop();
                                    }
                                    self.editor.clear_status();

                                    // we want to render to clear any leftover spinners or messages
                                    return;
                                }
                            }
                        };

                        let token_d: &dyn std::fmt::Display = match &token {
                            lsp::NumberOrString::Number(n) => n,
                            lsp::NumberOrString::String(s) => s,
                        };

                        let status = match parts {
                            (Some(title), Some(message), Some(percentage)) => {
                                format!("[{}] {}% {} - {}", token_d, percentage, title, message)
                            }
                            (Some(title), None, Some(percentage)) => {
                                format!("[{}] {}% {}", token_d, percentage, title)
                            }
                            (Some(title), Some(message), None) => {
                                format!("[{}] {} - {}", token_d, title, message)
                            }
                            (None, Some(message), Some(percentage)) => {
                                format!("[{}] {}% {}", token_d, percentage, message)
                            }
                            (Some(title), None, None) => {
                                format!("[{}] {}", token_d, title)
                            }
                            (None, Some(message), None) => {
                                format!("[{}] {}", token_d, message)
                            }
                            (None, None, Some(percentage)) => {
                                format!("[{}] {}%", token_d, percentage)
                            }
                            (None, None, None) => format!("[{}]", token_d),
                        };

                        if let lsp::WorkDoneProgress::End(_) = work {
                            self.lsp_progress.end_progress(server_id, &token);
                            if !self.lsp_progress.is_progressing(server_id) {
                                editor_view.spinners_mut().get_or_create(server_id).stop();
                            }
                        } else {
                            self.lsp_progress.update(server_id, token, work);
                        }

                        if self.config.load().editor.lsp.display_messages {
                            self.editor.set_status(status);
                        }
                    }
                    Notification::ProgressMessage(_params) => {
                        // do nothing
                    }
                    Notification::Exit => {
                        self.editor.set_status("Language server exited");

                        // LSPs may produce diagnostics for files that haven't been opened in helix,
                        // we need to clear those and remove the entries from the list if this leads to
                        // an empty diagnostic list for said files
                        for diags in self.editor.diagnostics.values_mut() {
                            diags.retain(|(_, lsp_id)| *lsp_id != server_id);
                        }

                        self.editor.diagnostics.retain(|_, diags| !diags.is_empty());

                        // Clear any diagnostics for documents with this server open.
                        for doc in self.editor.documents_mut() {
                            doc.clear_diagnostics(Some(server_id));
                        }

                        // Remove the language server from the registry.
                        self.editor.language_servers.remove_by_id(server_id);
                    }
                }
            }
            Call::MethodCall(helix_lsp::jsonrpc::MethodCall {
                method, params, id, ..
            }) => {
                let reply = match MethodCall::parse(&method, params) {
                    Err(helix_lsp::Error::Unhandled) => {
                        error!(
                            "Language Server: Method {} not found in request {}",
                            method, id
                        );
                        Err(helix_lsp::jsonrpc::Error {
                            code: helix_lsp::jsonrpc::ErrorCode::MethodNotFound,
                            message: format!("Method not found: {}", method),
                            data: None,
                        })
                    }
                    Err(err) => {
                        log::error!(
                            "Language Server: Received malformed method call {} in request {}: {}",
                            method,
                            id,
                            err
                        );
                        Err(helix_lsp::jsonrpc::Error {
                            code: helix_lsp::jsonrpc::ErrorCode::ParseError,
                            message: format!("Malformed method call: {}", method),
                            data: None,
                        })
                    }
                    Ok(MethodCall::WorkDoneProgressCreate(params)) => {
                        self.lsp_progress.create(server_id, params.token);

                        let editor_view = self
                            .compositor
                            .find::<ui::EditorView>()
                            .expect("expected at least one EditorView");
                        let spinner = editor_view.spinners_mut().get_or_create(server_id);
                        if spinner.is_stopped() {
                            spinner.start();
                        }

                        Ok(serde_json::Value::Null)
                    }
                    Ok(MethodCall::ApplyWorkspaceEdit(params)) => {
                        let language_server = language_server!();
                        if language_server.is_initialized() {
                            let offset_encoding = language_server.offset_encoding();
                            let res = self
                                .editor
                                .apply_workspace_edit(offset_encoding, &params.edit);

                            Ok(json!(lsp::ApplyWorkspaceEditResponse {
                                applied: res.is_ok(),
                                failure_reason: res.as_ref().err().map(|err| err.kind.to_string()),
                                failed_change: res
                                    .as_ref()
                                    .err()
                                    .map(|err| err.failed_change_idx as u32),
                            }))
                        } else {
                            Err(helix_lsp::jsonrpc::Error {
                                code: helix_lsp::jsonrpc::ErrorCode::InvalidRequest,
                                message: "Server must be initialized to request workspace edits"
                                    .to_string(),
                                data: None,
                            })
                        }
                    }
                    Ok(MethodCall::WorkspaceFolders) => {
                        Ok(json!(&*language_server!().workspace_folders().await))
                    }
                    Ok(MethodCall::WorkspaceConfiguration(params)) => {
                        let language_server = language_server!();
                        let result: Vec<_> = params
                            .items
                            .iter()
                            .map(|item| {
                                let mut config = language_server.config()?;
                                if let Some(section) = item.section.as_ref() {
                                    // for some reason some lsps send an empty string (observed in 'vscode-eslint-language-server')
                                    if !section.is_empty() {
                                        for part in section.split('.') {
                                            config = config.get(part)?;
                                        }
                                    }
                                }
                                Some(config)
                            })
                            .collect();
                        Ok(json!(result))
                    }
                    Ok(MethodCall::RegisterCapability(params)) => {
                        if let Some(client) = self.editor.language_servers.get_by_id(server_id) {
                            for reg in params.registrations {
                                match reg.method.as_str() {
                                    lsp::notification::DidChangeWatchedFiles::METHOD => {
                                        let Some(options) = reg.register_options else {
                                            continue;
                                        };
                                        let ops: lsp::DidChangeWatchedFilesRegistrationOptions =
                                            match serde_json::from_value(options) {
                                                Ok(ops) => ops,
                                                Err(err) => {
                                                    log::warn!("Failed to deserialize DidChangeWatchedFilesRegistrationOptions: {err}");
                                                    continue;
                                                }
                                            };
                                        self.editor.language_servers.file_event_handler.register(
                                            client.id(),
                                            Arc::downgrade(client),
                                            reg.id,
                                            ops,
                                        )
                                    }
                                    _ => {
                                        // Language Servers based on the `vscode-languageserver-node` library often send
                                        // client/registerCapability even though we do not enable dynamic registration
                                        // for most capabilities. We should send a MethodNotFound JSONRPC error in this
                                        // case but that rejects the registration promise in the server which causes an
                                        // exit. So we work around this by ignoring the request and sending back an OK
                                        // response.
                                        log::warn!("Ignoring a client/registerCapability request because dynamic capability registration is not enabled. Please report this upstream to the language server");
                                    }
                                }
                            }
                        }

                        Ok(serde_json::Value::Null)
                    }
                    Ok(MethodCall::UnregisterCapability(params)) => {
                        for unreg in params.unregisterations {
                            match unreg.method.as_str() {
                                lsp::notification::DidChangeWatchedFiles::METHOD => {
                                    self.editor
                                        .language_servers
                                        .file_event_handler
                                        .unregister(server_id, unreg.id);
                                }
                                _ => {
                                    log::warn!("Received unregistration request for unsupported method: {}", unreg.method);
                                }
                            }
                        }
                        Ok(serde_json::Value::Null)
                    }
                    Ok(MethodCall::ShowDocument(params)) => {
                        let language_server = language_server!();
                        let offset_encoding = language_server.offset_encoding();

                        let result = self.handle_show_document(params, offset_encoding);
                        Ok(json!(result))
                    }
                };

                tokio::spawn(language_server!().reply(id, reply));
            }
            Call::Invalid { id } => log::error!("LSP invalid method call id={:?}", id),
        }
    }

    fn handle_show_document(
        &mut self,
        params: lsp::ShowDocumentParams,
        offset_encoding: helix_lsp::OffsetEncoding,
    ) -> lsp::ShowDocumentResult {
        if let lsp::ShowDocumentParams {
            external: Some(true),
            uri,
            ..
        } = params
        {
            self.jobs.callback(crate::open_external_url_callback(uri));
            return lsp::ShowDocumentResult { success: true };
        };

        let lsp::ShowDocumentParams {
            uri,
            selection,
            take_focus,
            ..
        } = params;

        let uri = match helix_core::Uri::try_from(uri) {
            Ok(uri) => uri,
            Err(err) => {
                log::error!("{err}");
                return lsp::ShowDocumentResult { success: false };
            }
        };
        // If `Uri` gets another variant other than `Path` this may not be valid.
        let path = uri.as_path().expect("URIs are valid paths");

        let action = match take_focus {
            Some(true) => helix_view::editor::Action::Replace,
            _ => helix_view::editor::Action::VerticalSplit,
        };

        let doc_id = match self.editor.open(path, action) {
            Ok(id) => id,
            Err(err) => {
                log::error!("failed to open path: {:?}: {:?}", uri, err);
                return lsp::ShowDocumentResult { success: false };
            }
        };

        let doc = doc_mut!(self.editor, &doc_id);
        if let Some(range) = selection {
            // TODO: convert inside server
            if let Some(new_range) = lsp_range_to_range(doc.text(), range, offset_encoding) {
                let view = view_mut!(self.editor);

                // we flip the range so that the cursor sits on the start of the symbol
                // (for example start of the function).
                doc.set_selection(view.id, Selection::single(new_range.head, new_range.anchor));
                if action.align_view(view, doc.id()) {
                    align_view(doc, view, Align::Center);
                }
            } else {
                log::warn!("lsp position out of bounds - {:?}", range);
            };
        };
        lsp::ShowDocumentResult { success: true }
    }

    async fn claim_term(&mut self) -> std::io::Result<()> {
        let terminal_config = self.config.load().editor.clone().into();
        self.terminal.claim(terminal_config)
    }

    fn restore_term(&mut self) -> std::io::Result<()> {
        let terminal_config = self.config.load().editor.clone().into();
        use helix_view::graphics::CursorKind;
        self.terminal
            .backend_mut()
            .show_cursor(CursorKind::Block)
            .ok();
        self.terminal.restore(terminal_config)
    }

    pub async fn run<S>(&mut self, input_stream: &mut S) -> Result<i32, Error>
    where
        S: Stream<Item = std::io::Result<crossterm::event::Event>> + Unpin,
    {
        self.claim_term().await?;

        // Exit the alternate screen and disable raw mode before panicking
        let hook = std::panic::take_hook();
        std::panic::set_hook(Box::new(move |info| {
            // We can't handle errors properly inside this closure.  And it's
            // probably not a good idea to `unwrap()` inside a panic handler.
            // So we just ignore the `Result`.
            let _ = TerminalBackend::force_restore();
            hook(info);
        }));

        self.event_loop(input_stream).await;

        let close_errs = self.close().await;

        self.restore_term()?;

        for err in close_errs {
            self.editor.exit_code = 1;
            eprintln!("Error: {}", err);
        }

        Ok(self.editor.exit_code)
    }

    pub async fn close(&mut self) -> Vec<anyhow::Error> {
        // [NOTE] we intentionally do not return early for errors because we
        //        want to try to run as much cleanup as we can, regardless of
        //        errors along the way
        let mut errs = Vec::new();

        if let Err(err) = self
            .jobs
            .finish(&mut self.editor, Some(&mut self.compositor))
            .await
        {
            log::error!("Error executing job: {}", err);
            errs.push(err);
        };

        if let Err(err) = self.editor.flush_writes().await {
            log::error!("Error writing: {}", err);
            errs.push(err);
        }

        if self.editor.close_language_servers(None).await.is_err() {
            log::error!("Timed out waiting for language servers to shutdown");
            errs.push(anyhow::format_err!(
                "Timed out waiting for language servers to shutdown"
            ));
        }

        errs
    }
}