char-rtc-obs/rtc-backend/src/ffi/output.rs

use crate::output::{EncodedPacket, EncodedPacketType, OutputStream, OutputStreamError};
use anyhow::Result;
use log::{error, info};
use std::{
    os::raw::{c_char, c_void},
    slice,
    time::Duration,
};
use tokio::runtime::Runtime;

pub struct RTCOutput {
    stream: OutputStream,
    runtime: Runtime,
}
/// cbindgen:prefix-with-name
#[repr(C)]
pub enum RTCOutputError {
    ConnectFailed,
    NetworkError,
}

impl From<OutputStreamError> for RTCOutputError {
    fn from(ose: OutputStreamError) -> Self {
        match ose {
            OutputStreamError::ConnectFailed => RTCOutputError::ConnectFailed,
            OutputStreamError::NetworkError => RTCOutputError::NetworkError,
            OutputStreamError::WriteError(_) => RTCOutputError::NetworkError,
        }
    }
}

// You must call `char_rtc_output_free` on the returned value
#[no_mangle]
pub extern "C" fn char_rtc_output_new() -> *mut RTCOutput {
    (|| -> Result<*mut RTCOutput> {
        let runtime = tokio::runtime::Runtime::new()?;
        let stream = runtime.block_on(OutputStream::new())?;
        Ok(Box::into_raw(Box::new(RTCOutput { stream, runtime })))
    })()
    .unwrap_or_else(|e| {
        error!("Unable to create whip output: {e:?}");
        std::ptr::null_mut::<RTCOutput>()
    })
}

#[no_mangle]
pub unsafe extern "C" fn char_rtc_output_free(output: *mut RTCOutput) {
    info!("Freeing whip output");
    if !output.is_null() {
        drop(Box::from_raw(output));
    }
}

#[no_mangle]
pub unsafe extern "C" fn char_rtc_output_bytes_sent(output: *const RTCOutput) -> u64 {
    let output = output.as_ref().unwrap();
    output.stream.bytes_sent()
}

#[no_mangle]
pub unsafe extern "C" fn char_rtc_output_dropped_frames(output: *const RTCOutput) -> i32 {
    let output = output.as_ref().unwrap();
    output.stream.dropped_frames()
}

#[no_mangle]
pub unsafe extern "C" fn char_rtc_output_congestion(output: *const RTCOutput) -> f64 {
    let output = output.as_ref().unwrap();
    output.stream.congestion()
}

#[no_mangle]
pub unsafe extern "C" fn char_rtc_output_connect_time_ms(output: *const RTCOutput) -> i32 {
    let output = output.as_ref().unwrap();
    output.stream.connect_time().as_millis() as i32
}

#[no_mangle]
pub unsafe extern "C" fn char_rtc_output_connect(
    output: *const RTCOutput,
    url: *const c_char,
    bearer_token: *const c_char,
) {
    let output = output.as_ref().unwrap();

    let url = std::ffi::CStr::from_ptr(url).to_str().unwrap().to_owned();
    let bearer_token = if !bearer_token.is_null() {
        Some(
            std::ffi::CStr::from_ptr(bearer_token)
                .to_str()
                .unwrap()
                .to_owned(),
        )
    } else {
        None
    };

    output.runtime.spawn(async move {
        output.stream.connect(&url, bearer_token.as_deref()).await;
    });
}

// Once closed, you cannot call `char_rtc_output_connect` again
#[no_mangle]
pub unsafe extern "C" fn char_rtc_output_close(output: *const RTCOutput) {
    let output = output.as_ref().unwrap();

    info!("Closing whip output");
    output
        .runtime
        .block_on(async {
            info!("I'm on a thread!");
            output.stream.close().await
        })
        .unwrap_or_else(|e| error!("Failed closing whip output: {e:?}"))
}

/// Write an audio or video packet to the whip output
#[no_mangle]
pub unsafe extern "C" fn char_rtc_output_write(
    output: *const RTCOutput,
    data: *const u8,
    size: usize,
    duration: u64,
    is_audio: bool,
) -> bool {
    let output = output.as_ref().unwrap();

    let slice: &[u8] = slice::from_raw_parts(data, size);
    let encoded_packet = EncodedPacket {
        data: slice.to_owned(),
        duration: Duration::from_micros(duration),
        typ: if is_audio {
            EncodedPacketType::Audio
        } else {
            EncodedPacketType::Video
        },
    };

    output
        .stream
        .write(encoded_packet)
        .map(|_| true)
        .unwrap_or_else(|e| {
            error!("Failed to write packets to whip output: {e:?}");
            false
        })
}

pub struct ErrorCallbackUserdata(*mut c_void);
unsafe impl Send for ErrorCallbackUserdata {}
unsafe impl Sync for ErrorCallbackUserdata {}

impl ErrorCallbackUserdata {
    fn as_ptr(&self) -> *mut c_void {
        self.0
    }
}

type RTCOutputErrorCallback = unsafe extern "C" fn(user_data: *mut c_void, error: RTCOutputError);

#[no_mangle]
pub unsafe extern "C" fn char_rtc_output_set_error_callback(
    output: *const RTCOutput,
    cb: RTCOutputErrorCallback,
    user_data: *mut c_void,
) {
    let output = output.as_ref().unwrap();

    let user_data = ErrorCallbackUserdata(user_data);
    output
        .stream
        .set_error_callback(Box::new(move |error| cb(user_data.as_ptr(), error.into())))
}