use std::sync::Arc;

use slint::ComponentHandle;
use tokio::sync::mpsc;

use crate::{runtime::spawn, ui};

/// A thing for spawning I/O-tasks and updating the GUI `ConnectionStatus` with the result.
#[derive(Clone)]
pub struct Io {
    state: Arc<State>,
}

struct State {
    status: mpsc::Sender<ui::ConnectionStatus>,
}

impl Io {
    pub fn new(app: &ui::App) -> Self {
        let (tx, mut rx) = mpsc::channel(10);
        let app_weak = app.as_weak();

        spawn(async move {
            loop {
                let Some(status) = rx.recv().await else {
                    return;
                };

                let _ = app_weak.upgrade_in_event_loop(move |app| {
                    app.global::<ui::State>().set_connection_status(status);
                });
            }
        });

        Io {
            state: Arc::new(State { status: tx }),
        }
    }

    /// Spawn a fallible async function.
    ///
    /// Update the `ConnectionStatus` in the GUI depending on whether the result is an error.
    #[cfg(not(target_arch = "wasm32"))]
    pub fn spawn<Fut>(&self, f: impl FnOnce() -> Fut + Send + 'static)
    where
        Fut: Future<Output = anyhow::Result<()>>,
        Fut: Send + 'static,
    {
        let io = self.clone();
        spawn(async move {
            let _ = io.state.status.send(ui::ConnectionStatus::Syncing).await;
            let result = f().await;
            let was_error = result.is_err();
            if let Err(e) = result {
                eprintln!("{e:?}");
            }
            let _ = io
                .state
                .status
                .send(if was_error {
                    ui::ConnectionStatus::Error
                } else {
                    ui::ConnectionStatus::Idle
                })
                .await;
        });
    }

    /// Spawn a fallible async function.
    ///
    /// Update the `ConnectionStatus` in the GUI depending on whether the result is an error.
    // FIXME: this function is duplicated from the one above, but without the `Send` requirement on the future.
    #[cfg(target_arch = "wasm32")]
    pub fn spawn<Fut>(&self, f: impl FnOnce() -> Fut + Send + 'static)
    where
        Fut: Future<Output = anyhow::Result<()>>,
        Fut: 'static,
    {
        let io = self.clone();
        spawn(async move {
            let _ = io.state.status.send(ui::ConnectionStatus::Syncing).await;
            let result = f().await;
            let was_error = result.is_err();
            if let Err(e) = result {
                eprintln!("{e:?}");
            }
            let _ = io
                .state
                .status
                .send(if was_error {
                    ui::ConnectionStatus::Error
                } else {
                    ui::ConnectionStatus::Idle
                })
                .await;
        });
    }
}