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//! Manages receiving and sending values across the FFI boundary.

pub use crate::ffi::*;
pub use crate::into_into_dart::IntoIntoDart;
/// The representation of a Dart object outside of the Dart heap.
///
/// Its implementation lies with the Dart language and therefore should not be
/// depended on to be stable.
use std::marker::PhantomData;

/// A wrapper around a Dart [`Isolate`].
#[derive(Clone)]
pub struct Rust2Dart {
    pub(crate) channel: Channel,
}

#[derive(Debug)]
pub enum Rust2DartAction {
    Success = 0,
    Error = 1,
    CloseStream = 2,
    Panic = 3,
}

impl From<&crate::handler::Error> for Rust2DartAction {
    fn from(value: &crate::handler::Error) -> Self {
        match value {
            crate::handler::Error::CustomError(_) => Self::Error,
            crate::handler::Error::Panic(_) => Self::Panic,
        }
    }
}

impl IntoDart for Rust2DartAction {
    fn into_dart(self) -> DartAbi {
        (self as i32).into_dart()
    }
}

// api signatures is similar to Flutter Android's callback https://api.flutter.dev/javadoc/io/flutter/plugin/common/MethodChannel.Result.html
impl Rust2Dart {
    /// Create a new wrapper from a raw port.
    pub fn new(port: MessagePort) -> Self {
        Rust2Dart {
            channel: Channel::new(port),
        }
    }

    /// Send a success message back to the specified port.
    pub fn success(&self, result: impl IntoDart) -> bool {
        self.channel.post(vec![
            Rust2DartAction::Success.into_dart(),
            result.into_dart(),
        ])
    }

    /// Send a panic back to the specified port.
    pub fn panic(&self, e: impl IntoDart) -> bool {
        self.channel
            .post(vec![Rust2DartAction::Panic.into_dart(), e.into_dart()])
    }

    /// Send a detailed error back to the specified port.
    pub fn error(&self, e: impl IntoDart) -> bool {
        self.channel
            .post(vec![Rust2DartAction::Error.into_dart(), e.into_dart()])
    }

    /// Close the stream and ignore further messages.
    pub fn close_stream(&self) -> bool {
        self.channel
            .post(vec![Rust2DartAction::CloseStream.into_dart()])
    }
}

/// A callback that receives the return value of Rust functions.
pub struct TaskCallback {
    rust2dart: Rust2Dart,
}

impl TaskCallback {
    /// Create a new callback from a port wrapper.
    pub fn new(rust2dart: Rust2Dart) -> Self {
        Self { rust2dart }
    }

    /// Create a new [StreamSink] of the specified type.
    pub fn stream_sink<T, D>(&self) -> StreamSink<T>
    where
        T: IntoIntoDart<D>,
        D: IntoDart,
    {
        StreamSink::new(self.rust2dart.clone())
    }
}

/// A handle to a [`web_sys::BroadcastChannel`].
#[derive(Clone)]
pub struct ChannelHandle(pub String);

impl ChannelHandle {
    #[cfg(wasm)]
    pub fn port(&self) -> MessagePort {
        PortLike::broadcast(&self.0)
    }
}

/// A sink to send asynchronous data back to Dart.
/// Represented as a Dart
/// [`Stream`](https://api.dart.dev/stable/dart-async/Stream-class.html).
#[derive(Clone)]
pub struct StreamSink<T> {
    #[cfg(not(wasm))]
    rust2dart: Rust2Dart,
    #[cfg(wasm)]
    handle: ChannelHandle,
    _phantom_data: PhantomData<T>,
}

impl<T> StreamSink<T> {
    /// Create a new sink from a port wrapper.
    pub fn new(rust2dart: Rust2Dart) -> Self {
        #[cfg(wasm)]
        let name = rust2dart
            .channel
            .broadcast_name()
            .expect("Not a BroadcastChannel");
        Self {
            #[cfg(not(wasm))]
            rust2dart,
            #[cfg(wasm)]
            handle: ChannelHandle(name),
            _phantom_data: PhantomData,
        }
    }

    fn rust2dart(&self) -> Rust2Dart {
        #[cfg(not(wasm))]
        return self.rust2dart.clone();

        #[cfg(wasm)]
        Rust2Dart::new(self.handle.port())
    }

    /// Add data to the stream. Returns false when data could not be sent,
    /// or the stream has been closed.
    pub fn add<D: IntoDart>(&self, value: T) -> bool
    where
        T: IntoIntoDart<D>,
    {
        self.rust2dart().success(value.into_into_dart().into_dart())
    }

    /// Close the stream and ignore further messages. Returns false when
    /// the stream could not be closed, or when it has already been closed.
    pub fn close(&self) -> bool {
        self.rust2dart().close_stream()
    }
}

// IntoDart consumes `self` so we need a trait for the `Box` case
pub trait BoxIntoDart {
    fn box_into_dart(self: Box<Self>) -> DartAbi;
}

impl<T: IntoDart> BoxIntoDart for T {
    fn box_into_dart(self: Box<T>) -> DartAbi {
        self.into_dart()
    }
}