#![cfg_attr(not(debug_assertions), windows_subsystem = "windows")]

mod editor;
mod events;
mod window;
mod keybindings;
mod renderer;
mod error_handling;
mod ui_commands;

#[macro_use] extern crate derive_new;
#[macro_use] extern crate rust_embed;

use std::sync::{Arc, Mutex};
use std::process::Stdio;

use async_trait::async_trait;
use rmpv::Value;
use nvim_rs::{create::tokio as create, Neovim, UiAttachOptions, Handler, compat::tokio::Compat};
use tokio::process::{ChildStdin, Command};
use tokio::task::spawn_blocking;
use tokio::runtime::Runtime;
use tokio::sync::mpsc::{unbounded_channel, UnboundedSender, UnboundedReceiver};

use window::ui_loop;
use editor::Editor;
use events::parse_neovim_event;
use error_handling::ResultPanicExplanation;
use ui_commands::UiCommand;

const INITIAL_WIDTH: u64 = 100;
const INITIAL_HEIGHT: u64 = 50;

#[cfg(target_os = "windows")]
fn set_windows_creation_flags(cmd: &mut Command) {
    use std::os::windows::process::CommandExt;
    cmd.creation_flags(0x08000000); // CREATE_NO_WINDOW
}

fn create_nvim_command() -> Command {
    let mut cmd = Command::new("nvim");

    cmd.arg("--embed")
        .args(std::env::args().skip(1))
        .stderr(Stdio::inherit());

    #[cfg(target_os = "windows")]
    set_windows_creation_flags(&mut cmd);

    cmd
}

#[derive(Clone)]
struct NeovimHandler(Arc<Mutex<Editor>>);

#[async_trait]
impl Handler for NeovimHandler {
    type Writer = Compat<ChildStdin>;

    async fn handle_notify(&self, event_name: String, arguments: Vec<Value>, _neovim: Neovim<Compat<ChildStdin>>) {
        let parsed_events = parse_neovim_event(event_name, arguments)
            .unwrap_or_explained_panic("Could not parse event", "Could not parse event from neovim");
        for event in parsed_events {
            let mut editor = self.0.lock().unwrap();
            editor.handle_redraw_event(event);
        }
    }
}

async fn start_nvim(editor: Arc<Mutex<Editor>>, mut receiver: UnboundedReceiver<UiCommand>) {
    let (mut nvim, io_handler, _) = create::new_child_cmd(&mut create_nvim_command(), NeovimHandler(editor.clone())).await
        .unwrap_or_explained_panic("Could not create nvim process", "Could not locate or start the neovim process");

    tokio::spawn(async move {
        match io_handler.await {
            Err(join_error) => eprintln!("Error joining IO loop: '{}'", join_error),
            Ok(Err(error)) => eprintln!("Error: '{}'", error),
            Ok(Ok(())) => {}
        };
        std::process::exit(0);
    });

    let mut options = UiAttachOptions::new();
    options.set_linegrid_external(true);
    options.set_rgb(true);
    nvim.set_var("neovide", Value::Boolean(true)).await
        .unwrap_or_explained_panic("Could not communicate.", "Could not communicate with neovim process");
    nvim.ui_attach(INITIAL_WIDTH as i64, INITIAL_HEIGHT as i64, &options).await
        .unwrap_or_explained_panic("Could not attach.", "Could not attach ui to neovim process");

    let nvim = Arc::new(nvim);
    loop {
        let mut commands = Vec::new();
        let mut resize_command = None;
        while let Ok(ui_command) = receiver.try_recv() {
            if let UiCommand::Resize { .. } = ui_command {
                resize_command = Some(ui_command);
            } else {
                commands.push(ui_command);
            }
        }
        if let Some(resize_command) = resize_command {
            commands.push(resize_command);
        }

        for ui_command in commands.into_iter() {
            ui_command.execute(&nvim).await;
        }
    }
}

fn main() {
    let rt = Runtime::new().unwrap();

    let editor = Arc::new(Mutex::new(Editor::new(INITIAL_WIDTH, INITIAL_HEIGHT)));
    let (sender, receiver) = unbounded_channel::<UiCommand>();
    let editor_clone = editor.clone();
    rt.spawn(async move {
        start_nvim(editor_clone, receiver).await;
    });
    ui_loop(editor, sender, (INITIAL_WIDTH, INITIAL_HEIGHT));
}