use arc_swap::{access::Map, ArcSwap};
use helix_core::{
    config::{default_syntax_loader, user_syntax_loader},
    pos_at_coords, syntax, Selection,
};
use helix_lsp::{lsp, util::lsp_pos_to_pos, LspProgressMap};
use helix_view::{align_view, editor::ConfigEvent, theme, Align, Editor};
use serde_json::json;

use crate::{
    args::Args,
    commands::apply_workspace_edit,
    compositor::Compositor,
    config::Config,
    job::Jobs,
    keymap::Keymaps,
    ui::{self, overlay::overlayed},
};

use log::{error, warn};
use std::{
    io::{stdin, stdout, Write},
    sync::Arc,
    time::{Duration, Instant},
};

use anyhow::Error;

use crossterm::{
    event::{DisableMouseCapture, EnableMouseCapture, Event, EventStream},
    execute, terminal,
    tty::IsTty,
};
#[cfg(not(windows))]
use {
    signal_hook::{consts::signal, low_level},
    signal_hook_tokio::Signals,
};
#[cfg(windows)]
type Signals = futures_util::stream::Empty<()>;

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

    config: Arc<ArcSwap<Config>>,

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

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

impl Application {
    pub fn new(args: Args) -> Result<Self, Error> {
        use helix_view::editor::Action;

        let config_dir = helix_loader::config_dir();
        if !config_dir.exists() {
            std::fs::create_dir_all(&config_dir).ok();
        }

        let config = match std::fs::read_to_string(config_dir.join("config.toml")) {
            Ok(config) => toml::from_str(&config)
                .map(crate::keymap::merge_keys)
                .unwrap_or_else(|err| {
                    eprintln!("Bad config: {}", err);
                    eprintln!("Press <ENTER> to continue with default config");
                    use std::io::Read;
                    // This waits for an enter press.
                    let _ = std::io::stdin().read(&mut []);
                    Config::default()
                }),
            Err(err) if err.kind() == std::io::ErrorKind::NotFound => Config::default(),
            Err(err) => return Err(Error::new(err)),
        };

        let theme_loader = std::sync::Arc::new(theme::Loader::new(
            &config_dir,
            &helix_loader::runtime_dir(),
        ));

        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(|| {
                if true_color {
                    theme_loader.default()
                } else {
                    theme_loader.base16_default()
                }
            });

        let syn_loader_conf = user_syntax_loader().unwrap_or_else(|err| {
            eprintln!("Bad language config: {}", err);
            eprintln!("Press <ENTER> to continue with default language config");
            use std::io::Read;
            // This waits for an enter press.
            let _ = std::io::stdin().read(&mut []);
            default_syntax_loader()
        });
        let syn_loader = std::sync::Arc::new(syntax::Loader::new(syn_loader_conf));

        let mut compositor = Compositor::new()?;
        let config = Arc::new(ArcSwap::from_pointee(config));
        let mut editor = Editor::new(
            compositor.size(),
            theme_loader.clone(),
            syn_loader.clone(),
            Box::new(Map::new(Arc::clone(&config), |config: &Config| {
                &config.editor
            })),
        );

        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_dir().join("tutor.txt");
            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 first = &args.files[0].0; // we know it's not empty
            if first.is_dir() {
                std::env::set_current_dir(&first)?;
                editor.new_file(Action::VerticalSplit);
                let picker = ui::file_picker(".".into(), &config.load().editor);
                compositor.push(Box::new(overlayed(picker)));
            } else {
                let nr_of_files = args.files.len();
                editor.open(first.to_path_buf(), Action::VerticalSplit)?;
                for (file, pos) in args.files {
                    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 {
                        let doc_id = editor.open(file, Action::Load)?;
                        // with Action::Load all documents have the same view
                        let view_id = editor.tree.focus;
                        let doc = editor.document_mut(doc_id).unwrap();
                        let pos = Selection::point(pos_at_coords(doc.text().slice(..), pos, true));
                        doc.set_selection(view_id, pos);
                    }
                }
                editor.set_status(format!("Loaded {} files.", nr_of_files));
                // 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 if stdin().is_tty() {
            editor.new_file(Action::VerticalSplit);
        } else if cfg!(target_os = "macos") {
            // On Linux and Windows, we allow the output of a command to be piped into the new buffer.
            // This doesn't currently work on macOS because of the following issue:
            //   https://github.com/crossterm-rs/crossterm/issues/500
            anyhow::bail!("Piping into helix-term is currently not supported on macOS");
        } 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])?;

        let app = Self {
            compositor,
            editor,

            config,

            theme_loader,
            syn_loader,

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

        Ok(app)
    }

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

        self.compositor.render(&mut cx);
    }

    pub async fn event_loop(&mut self) {
        let mut reader = EventStream::new();
        let mut last_render = Instant::now();
        let deadline = Duration::from_secs(1) / 60;

        self.render();

        loop {
            if self.editor.should_close() {
                break;
            }

            use futures_util::StreamExt;

            tokio::select! {
                biased;

                event = reader.next() => {
                    self.handle_terminal_events(event)
                }
                Some(signal) = self.signals.next() => {
                    self.handle_signals(signal).await;
                }
                Some((id, call)) = self.editor.language_servers.incoming.next() => {
                    self.handle_language_server_message(call, id).await;
                    // limit render calls for fast language server messages
                    let last = self.editor.language_servers.incoming.is_empty();
                    if last || last_render.elapsed() > deadline {
                        self.render();
                        last_render = Instant::now();
                    }
                }
                Some(payload) = self.editor.debugger_events.next() => {
                    let needs_render = self.editor.handle_debugger_message(payload).await;
                    if needs_render {
                        self.render();
                    }
                }
                Some(config_event) = self.editor.config_events.1.recv() => {
                    self.handle_config_events(config_event);
                    self.render();
                }
                Some(callback) = self.jobs.futures.next() => {
                    self.jobs.handle_callback(&mut self.editor, &mut self.compositor, callback);
                    self.render();
                }
                Some(callback) = self.jobs.wait_futures.next() => {
                    self.jobs.handle_callback(&mut self.editor, &mut self.compositor, callback);
                    self.render();
                }
                _ = &mut self.editor.idle_timer => {
                    // idle timeout
                    self.editor.clear_idle_timer();
                    self.handle_idle_timeout();
                }
            }
        }
    }

    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;
                self.config.store(Arc::new(app_config));
            }
        }
    }

    fn refresh_config(&mut self) {
        let config = Config::load(helix_loader::config_file()).unwrap_or_else(|err| {
            self.editor.set_error(err.to_string());
            Config::default()
        });

        // Refresh theme
        if let Some(theme) = config.theme.clone() {
            let true_color = self.true_color();
            self.editor.set_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(|| {
                        if true_color {
                            self.theme_loader.default()
                        } else {
                            self.theme_loader.base16_default()
                        }
                    }),
            );
        }
        self.config.store(Arc::new(config));
    }

    fn true_color(&self) -> bool {
        self.config.load().editor.true_color || crate::true_color()
    }

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

    #[cfg(not(windows))]
    pub async fn handle_signals(&mut self, signal: i32) {
        use helix_view::graphics::Rect;
        match signal {
            signal::SIGTSTP => {
                self.compositor.save_cursor();
                self.restore_term().unwrap();
                low_level::emulate_default_handler(signal::SIGTSTP).unwrap();
            }
            signal::SIGCONT => {
                self.claim_term().await.unwrap();
                // redraw the terminal
                let Rect { width, height, .. } = self.compositor.size();
                self.compositor.resize(width, height);
                self.compositor.load_cursor();
                self.render();
            }
            _ => unreachable!(),
        }
    }

    pub fn handle_idle_timeout(&mut self) {
        use crate::compositor::EventResult;
        let editor_view = self
            .compositor
            .find::<ui::EditorView>()
            .expect("expected at least one EditorView");

        let mut cx = crate::compositor::Context {
            editor: &mut self.editor,
            jobs: &mut self.jobs,
            scroll: None,
        };
        if let EventResult::Consumed(_) = editor_view.handle_idle_timeout(&mut cx) {
            self.render();
        }
    }

    pub fn handle_terminal_events(&mut self, event: Option<Result<Event, crossterm::ErrorKind>>) {
        let mut cx = crate::compositor::Context {
            editor: &mut self.editor,
            jobs: &mut self.jobs,
            scroll: None,
        };
        // Handle key events
        let should_redraw = match event {
            Some(Ok(Event::Resize(width, height))) => {
                self.compositor.resize(width, height);

                self.compositor
                    .handle_event(Event::Resize(width, height), &mut cx)
            }
            Some(Ok(event)) => self.compositor.handle_event(event, &mut cx),
            Some(Err(x)) => panic!("{}", x),
            None => panic!(),
        };

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

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

        match call {
            Call::Notification(helix_lsp::jsonrpc::Notification { method, params, .. }) => {
                let notification = match Notification::parse(&method, params) {
                    Some(notification) => notification,
                    None => return,
                };

                match notification {
                    Notification::Initialized => {
                        let language_server =
                            match self.editor.language_servers.get_by_id(server_id) {
                                Some(language_server) => language_server,
                                None => {
                                    warn!("can't find language server with id `{}`", server_id);
                                    return;
                                }
                            };

                        // 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.language_server().map(|server| server.id()) == Some(server_id)
                        });

                        // trigger textDocument/didOpen for docs that are already open
                        for doc in docs {
                            let language_id =
                                doc.language_id().map(ToOwned::to_owned).unwrap_or_default();

                            tokio::spawn(language_server.text_document_did_open(
                                doc.url().unwrap(),
                                doc.version(),
                                doc.text(),
                                language_id,
                            ));
                        }
                    }
                    Notification::PublishDiagnostics(params) => {
                        let path = params.uri.to_file_path().unwrap();
                        let doc = self.editor.document_by_path_mut(&path);

                        if let Some(doc) = doc {
                            let lang_conf = doc.language_config();
                            let text = doc.text();

                            let diagnostics = params
                                .diagnostics
                                .into_iter()
                                .filter_map(|diagnostic| {
                                    use helix_core::{
                                        diagnostic::{Range, Severity::*},
                                        Diagnostic,
                                    };
                                    use lsp::DiagnosticSeverity;

                                    let language_server = doc.language_server().unwrap();

                                    // TODO: convert inside server
                                    let start = if let Some(start) = lsp_pos_to_pos(
                                        text,
                                        diagnostic.range.start,
                                        language_server.offset_encoding(),
                                    ) {
                                        start
                                    } else {
                                        log::warn!("lsp position out of bounds - {:?}", diagnostic);
                                        return None;
                                    };

                                    let end = if let Some(end) = lsp_pos_to_pos(
                                        text,
                                        diagnostic.range.end,
                                        language_server.offset_encoding(),
                                    ) {
                                        end
                                    } else {
                                        log::warn!("lsp position out of bounds - {:?}", diagnostic);
                                        return None;
                                    };

                                    let severity =
                                        diagnostic.severity.map(|severity| match severity {
                                            DiagnosticSeverity::ERROR => Error,
                                            DiagnosticSeverity::WARNING => Warning,
                                            DiagnosticSeverity::INFORMATION => Info,
                                            DiagnosticSeverity::HINT => Hint,
                                            severity => unreachable!(
                                                "unrecognized diagnostic severity: {:?}",
                                                severity
                                            ),
                                        });

                                    if let Some(lang_conf) = lang_conf {
                                        if let Some(severity) = severity {
                                            if severity < lang_conf.diagnostic_severity {
                                                return None;
                                            }
                                        }
                                    };

                                    Some(Diagnostic {
                                        range: Range { start, end },
                                        line: diagnostic.range.start.line as usize,
                                        message: diagnostic.message,
                                        severity,
                                        // code
                                        // source
                                    })
                                })
                                .collect();

                            doc.set_diagnostics(diagnostics);
                        }
                    }
                    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
                    }
                }
            }
            Call::MethodCall(helix_lsp::jsonrpc::MethodCall {
                method, params, id, ..
            }) => {
                let call = match MethodCall::parse(&method, params) {
                    Some(call) => call,
                    None => {
                        error!("Method not found {}", method);
                        return;
                    }
                };

                let reply = match call {
                    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)
                    }
                    MethodCall::ApplyWorkspaceEdit(params) => {
                        apply_workspace_edit(
                            &mut self.editor,
                            helix_lsp::OffsetEncoding::Utf8,
                            &params.edit,
                        );

                        Ok(json!(lsp::ApplyWorkspaceEditResponse {
                            applied: true,
                            failure_reason: None,
                            failed_change: None,
                        }))
                    }
                    MethodCall::WorkspaceFolders => {
                        let language_server =
                            self.editor.language_servers.get_by_id(server_id).unwrap();

                        Ok(json!(language_server.workspace_folders()))
                    }
                    MethodCall::WorkspaceConfiguration(params) => {
                        let result: Vec<_> = params
                            .items
                            .iter()
                            .map(|item| {
                                let mut config = match &item.scope_uri {
                                    Some(scope) => {
                                        let path = scope.to_file_path().ok()?;
                                        let doc = self.editor.document_by_path(path)?;
                                        doc.language_config()?.config.as_ref()?
                                    }
                                    None => self
                                        .editor
                                        .language_servers
                                        .get_by_id(server_id)
                                        .unwrap()
                                        .config()?,
                                };
                                if let Some(section) = item.section.as_ref() {
                                    for part in section.split('.') {
                                        config = config.get(part)?;
                                    }
                                }
                                Some(config)
                            })
                            .collect();
                        Ok(json!(result))
                    }
                };

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

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

    async fn claim_term(&mut self) -> Result<(), Error> {
        terminal::enable_raw_mode()?;
        let mut stdout = stdout();
        execute!(stdout, terminal::EnterAlternateScreen)?;
        execute!(stdout, terminal::Clear(terminal::ClearType::All))?;
        if self.config.load().editor.mouse {
            execute!(stdout, EnableMouseCapture)?;
        }
        Ok(())
    }

    fn restore_term(&mut self) -> Result<(), Error> {
        let mut stdout = stdout();
        // reset cursor shape
        write!(stdout, "\x1B[2 q")?;
        // Ignore errors on disabling, this might trigger on windows if we call
        // disable without calling enable previously
        let _ = execute!(stdout, DisableMouseCapture);
        execute!(stdout, terminal::LeaveAlternateScreen)?;
        terminal::disable_raw_mode()?;
        Ok(())
    }

    pub async fn run(&mut self) -> Result<i32, Error> {
        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`s.
            let _ = execute!(std::io::stdout(), DisableMouseCapture);
            let _ = execute!(std::io::stdout(), terminal::LeaveAlternateScreen);
            let _ = terminal::disable_raw_mode();
            hook(info);
        }));

        self.event_loop().await;

        self.jobs.finish().await;

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

        self.restore_term()?;

        Ok(self.editor.exit_code)
    }
}