//
use std::{path::PathBuf, sync::mpsc::Receiver};

use anyhow::Context;
use kameo::{mailbox::unbounded::UnboundedMailbox, message::Message, Actor};
use notify::{event::ModifyKind, RecommendedWatcher, Watcher};
use tracing::{error, info};

use git_next_core::message;

use crate::{
    default_on_actor_link_died, default_on_actor_panic, default_on_actor_stop, on_actor_start,
    publish, tell, MessageBus,
};

message!(
    FileUpdated,
    "Notification that watched file has been updated"
);

message!(Watch, "Watch for the next event on the file");

pub struct FileWatcherActor {
    file_updates_bus: MessageBus<FileUpdated>,
    file: PathBuf,
    event_receiver: Option<Receiver<Result<notify::Event, notify::Error>>>,
    watcher: Option<RecommendedWatcher>,
}

impl FileWatcherActor {
    pub const fn new(file_updates_bus: MessageBus<FileUpdated>, file: PathBuf) -> Self {
        Self {
            file_updates_bus,
            file,
            event_receiver: None,
            watcher: None,
        }
    }
}

impl Actor for FileWatcherActor {
    type Mailbox = UnboundedMailbox<Self>;

    on_actor_start!(this, actor_ref, {
        //
        let (tx, rx) = std::sync::mpsc::channel();
        this.event_receiver.replace(rx);

        let mut watcher = notify::recommended_watcher(tx).context("file watcher")?;
        watcher
            .watch(&this.file, notify::RecursiveMode::NonRecursive)
            .with_context(|| format!("Watching: {:?}", this.file))?;
        this.watcher.replace(watcher);

        tell!("file_watcher", actor_ref, Watch)?;

        Ok(())
    });

    default_on_actor_panic!(this, actor_ref, err);
    default_on_actor_link_died!(this, actor_ref, id, reason);
    default_on_actor_stop!(this, actor_ref, reason);
}

impl Message<Watch> for FileWatcherActor {
    type Reply = color_eyre::Result<()>;

    async fn handle(
        &mut self,
        msg: Watch,
        ctx: kameo::message::Context<'_, Self, Self::Reply>,
    ) -> Self::Reply {
        if let Some(rx) = &self.event_receiver {
            while let Ok(result) = rx.recv() {
                match result {
                    Ok(event) => match event.kind {
                        notify::EventKind::Modify(ModifyKind::Data(_)) => {
                            info!("===================================================================================");
                            info!(?event, "File modified");
                            publish!("file_updates_bus", self.file_updates_bus, FileUpdated)?;
                            break;
                        }
                        notify::EventKind::Modify(_)
                        | notify::EventKind::Create(_)
                        | notify::EventKind::Remove(_)
                        | notify::EventKind::Any
                        | notify::EventKind::Access(_)
                        | notify::EventKind::Other => { /* do nothing */ }
                    },
                    Err(err) => {
                        error!(?err, "Watching file: {:?}", self.file);
                    }
                }
            }
        }
        tell!("file_watcher", ctx.actor_ref(), msg)?;
        Ok(())
    }
}