// Take a look at the license at the top of the repository in the LICENSE file.

use std::{mem, ptr};

use glib::{prelude::*, translate::*};

use crate::{
    utils::HasStreamLock,
    video_codec_state::{InNegotiation, Readable, VideoCodecState, VideoCodecStateContext},
    VideoCodecFrame, VideoEncoder,
};
mod sealed {
    pub trait Sealed {}
    impl<T: super::IsA<super::VideoEncoder>> Sealed for T {}
}

pub trait VideoEncoderExtManual: sealed::Sealed + IsA<VideoEncoder> + 'static {
    /// Helper function that allocates a buffer to hold an encoded video frame for `self`'s
    /// current [`VideoCodecState`][crate::VideoCodecState]. Subclass should already have configured video
    /// state and set src pad caps.
    ///
    /// The buffer allocated here is owned by the frame and you should only
    /// keep references to the frame, not the buffer.
    /// ## `frame`
    /// a [`VideoCodecFrame`][crate::VideoCodecFrame]
    /// ## `size`
    /// size of the buffer
    ///
    /// # Returns
    ///
    /// [`gst::FlowReturn::Ok`][crate::gst::FlowReturn::Ok] if an output buffer could be allocated
    #[doc(alias = "gst_video_encoder_allocate_output_frame")]
    fn allocate_output_frame(
        &self,
        frame: &mut VideoCodecFrame,
        size: usize,
    ) -> Result<gst::FlowSuccess, gst::FlowError> {
        unsafe {
            try_from_glib(ffi::gst_video_encoder_allocate_output_frame(
                self.as_ref().to_glib_none().0,
                frame.to_glib_none().0,
                size,
            ))
        }
    }

    /// Get a pending unfinished [`VideoCodecFrame`][crate::VideoCodecFrame]
    /// ## `frame_number`
    /// system_frame_number of a frame
    ///
    /// # Returns
    ///
    /// pending unfinished [`VideoCodecFrame`][crate::VideoCodecFrame] identified by `frame_number`.
    #[doc(alias = "get_frame")]
    #[doc(alias = "gst_video_encoder_get_frame")]
    fn frame(&self, frame_number: i32) -> Option<VideoCodecFrame> {
        let frame = unsafe {
            ffi::gst_video_encoder_get_frame(self.as_ref().to_glib_none().0, frame_number)
        };

        if frame.is_null() {
            None
        } else {
            unsafe { Some(VideoCodecFrame::new(frame, self.as_ref())) }
        }
    }

    /// Get all pending unfinished [`VideoCodecFrame`][crate::VideoCodecFrame]
    ///
    /// # Returns
    ///
    /// pending unfinished [`VideoCodecFrame`][crate::VideoCodecFrame].
    #[doc(alias = "get_frames")]
    #[doc(alias = "gst_video_encoder_get_frames")]
    fn frames(&self) -> Vec<VideoCodecFrame> {
        unsafe {
            let frames = ffi::gst_video_encoder_get_frames(self.as_ref().to_glib_none().0);
            let mut iter: *const glib::ffi::GList = frames;
            let mut vec = Vec::new();

            while !iter.is_null() {
                let frame_ptr = Ptr::from((*iter).data);
                /* transfer ownership of the frame */
                let frame = VideoCodecFrame::new(frame_ptr, self.as_ref());
                vec.push(frame);
                iter = (*iter).next;
            }

            glib::ffi::g_list_free(frames);
            vec
        }
    }

    /// Get the oldest unfinished pending [`VideoCodecFrame`][crate::VideoCodecFrame]
    ///
    /// # Returns
    ///
    /// oldest unfinished pending [`VideoCodecFrame`][crate::VideoCodecFrame]
    #[doc(alias = "get_oldest_frame")]
    #[doc(alias = "gst_video_encoder_get_oldest_frame")]
    fn oldest_frame(&self) -> Option<VideoCodecFrame> {
        let frame =
            unsafe { ffi::gst_video_encoder_get_oldest_frame(self.as_ref().to_glib_none().0) };

        if frame.is_null() {
            None
        } else {
            unsafe { Some(VideoCodecFrame::new(frame, self.as_ref())) }
        }
    }

    /// Lets [`VideoEncoder`][crate::VideoEncoder] sub-classes to know the memory `allocator`
    /// used by the base class and its `params`.
    ///
    /// Unref the `allocator` after use it.
    ///
    /// # Returns
    ///
    ///
    /// ## `allocator`
    /// the [`gst::Allocator`][crate::gst::Allocator]
    /// used
    ///
    /// ## `params`
    /// the
    /// [`gst::AllocationParams`][crate::gst::AllocationParams] of `allocator`
    #[doc(alias = "get_allocator")]
    #[doc(alias = "gst_video_encoder_get_allocator")]
    fn allocator(&self) -> (Option<gst::Allocator>, gst::AllocationParams) {
        unsafe {
            let mut allocator = ptr::null_mut();
            let mut params = mem::MaybeUninit::uninit();
            ffi::gst_video_encoder_get_allocator(
                self.as_ref().to_glib_none().0,
                &mut allocator,
                params.as_mut_ptr(),
            );
            (from_glib_full(allocator), params.assume_init().into())
        }
    }

    /// If multiple subframes are produced for one input frame then use this method
    /// for each subframe, except for the last one. Before calling this function,
    /// you need to fill frame->output_buffer with the encoded buffer to push.
    ///
    /// You must call [`VideoEncoderExt::finish_frame()`][crate::prelude::VideoEncoderExt::finish_frame()] for the last sub-frame
    /// to tell the encoder that the frame has been fully encoded.
    ///
    /// This function will change the metadata of `frame` and frame->output_buffer
    /// will be pushed downstream.
    /// ## `frame`
    /// a [`VideoCodecFrame`][crate::VideoCodecFrame] being encoded
    ///
    /// # Returns
    ///
    /// a [`gst::FlowReturn`][crate::gst::FlowReturn] resulting from pushing the buffer downstream.
    #[cfg(feature = "v1_18")]
    #[cfg_attr(docsrs, doc(cfg(feature = "v1_18")))]
    #[doc(alias = "gst_video_encoder_finish_subframe")]
    fn finish_subframe(&self, frame: &VideoCodecFrame) -> Result<gst::FlowSuccess, gst::FlowError> {
        unsafe {
            try_from_glib(ffi::gst_video_encoder_finish_subframe(
                self.as_ref().to_glib_none().0,
                frame.to_glib_none().0,
            ))
        }
    }

    /// Query the configured encoding latency. Results will be returned via
    /// `min_latency` and `max_latency`.
    ///
    /// # Returns
    ///
    ///
    /// ## `min_latency`
    /// address of variable in which to store the
    ///  configured minimum latency, or [`None`]
    ///
    /// ## `max_latency`
    /// address of variable in which to store the
    ///  configured maximum latency, or [`None`]
    #[doc(alias = "get_latency")]
    #[doc(alias = "gst_video_encoder_get_latency")]
    fn latency(&self) -> (gst::ClockTime, Option<gst::ClockTime>) {
        let mut min_latency = gst::ffi::GST_CLOCK_TIME_NONE;
        let mut max_latency = gst::ffi::GST_CLOCK_TIME_NONE;

        unsafe {
            ffi::gst_video_encoder_get_latency(
                self.as_ref().to_glib_none().0,
                &mut min_latency,
                &mut max_latency,
            );

            (
                try_from_glib(min_latency).expect("undefined min_latency"),
                from_glib(max_latency),
            )
        }
    }

    /// Informs baseclass of encoding latency. If the provided values changed from
    /// previously provided ones, this will also post a LATENCY message on the bus
    /// so the pipeline can reconfigure its global latency.
    /// ## `min_latency`
    /// minimum latency
    /// ## `max_latency`
    /// maximum latency
    #[doc(alias = "gst_video_encoder_set_latency")]
    fn set_latency(
        &self,
        min_latency: gst::ClockTime,
        max_latency: impl Into<Option<gst::ClockTime>>,
    ) {
        unsafe {
            ffi::gst_video_encoder_set_latency(
                self.as_ref().to_glib_none().0,
                min_latency.into_glib(),
                max_latency.into().into_glib(),
            );
        }
    }
    /// Get the current [`VideoCodecState`][crate::VideoCodecState]
    ///
    /// # Returns
    ///
    /// [`VideoCodecState`][crate::VideoCodecState] describing format of video data.
    #[doc(alias = "get_output_state")]
    #[doc(alias = "gst_video_encoder_get_output_state")]
    fn output_state(&self) -> Option<VideoCodecState<'static, Readable>> {
        let state =
            unsafe { ffi::gst_video_encoder_get_output_state(self.as_ref().to_glib_none().0) };

        if state.is_null() {
            None
        } else {
            unsafe { Some(VideoCodecState::<Readable>::new(state)) }
        }
    }

    /// Creates a new [`VideoCodecState`][crate::VideoCodecState] with the specified caps as the output state
    /// for the encoder.
    /// Any previously set output state on `self` will be replaced by the newly
    /// created one.
    ///
    /// The specified `caps` should not contain any resolution, pixel-aspect-ratio,
    /// framerate, codec-data, .... Those should be specified instead in the returned
    /// [`VideoCodecState`][crate::VideoCodecState].
    ///
    /// If the subclass wishes to copy over existing fields (like pixel aspect ratio,
    /// or framerate) from an existing [`VideoCodecState`][crate::VideoCodecState], it can be provided as a
    /// `reference`.
    ///
    /// If the subclass wishes to override some fields from the output state (like
    /// pixel-aspect-ratio or framerate) it can do so on the returned [`VideoCodecState`][crate::VideoCodecState].
    ///
    /// The new output state will only take effect (set on pads and buffers) starting
    /// from the next call to [`VideoEncoderExt::finish_frame()`][crate::prelude::VideoEncoderExt::finish_frame()].
    /// ## `caps`
    /// the [`gst::Caps`][crate::gst::Caps] to use for the output
    /// ## `reference`
    /// An optional reference [`VideoCodecState`][crate::VideoCodecState]
    ///
    /// # Returns
    ///
    /// the newly configured output state.
    #[doc(alias = "gst_video_encoder_set_output_state")]
    fn set_output_state(
        &self,
        caps: gst::Caps,
        reference: Option<&VideoCodecState<Readable>>,
    ) -> Result<VideoCodecState<InNegotiation>, gst::FlowError> {
        let state = unsafe {
            let reference = match reference {
                Some(reference) => reference.as_mut_ptr(),
                None => ptr::null_mut(),
            };
            ffi::gst_video_encoder_set_output_state(
                self.as_ref().to_glib_none().0,
                caps.into_glib_ptr(),
                reference,
            )
        };

        if state.is_null() {
            Err(gst::FlowError::NotNegotiated)
        } else {
            unsafe { Ok(VideoCodecState::<InNegotiation>::new(state, self.as_ref())) }
        }
    }

    /// Negotiate with downstream elements to currently configured [`VideoCodecState`][crate::VideoCodecState].
    /// Unmark GST_PAD_FLAG_NEED_RECONFIGURE in any case. But mark it again if
    /// negotiate fails.
    ///
    /// # Returns
    ///
    /// [`true`] if the negotiation succeeded, else [`false`].
    #[doc(alias = "gst_video_encoder_negotiate")]
    fn negotiate<'a>(
        &'a self,
        output_state: VideoCodecState<'a, InNegotiation<'a>>,
    ) -> Result<(), gst::FlowError> {
        // Consume output_state so user won't be able to modify it anymore
        let self_ptr = self.to_glib_none().0 as *const gst::ffi::GstElement;
        assert_eq!(output_state.context.element_as_ptr(), self_ptr);

        let ret = unsafe {
            from_glib(ffi::gst_video_encoder_negotiate(
                self.as_ref().to_glib_none().0,
            ))
        };
        if ret {
            Ok(())
        } else {
            Err(gst::FlowError::NotNegotiated)
        }
    }

    /// Set the codec headers to be sent downstream whenever requested.
    /// ## `headers`
    /// a list of [`gst::Buffer`][crate::gst::Buffer] containing the codec header
    #[doc(alias = "gst_video_encoder_set_headers")]
    fn set_headers(&self, headers: impl IntoIterator<Item = gst::Buffer>) {
        unsafe {
            ffi::gst_video_encoder_set_headers(
                self.as_ref().to_glib_none().0,
                headers
                    .into_iter()
                    .collect::<glib::List<_>>()
                    .into_glib_ptr(),
            );
        }
    }

    fn sink_pad(&self) -> &gst::Pad {
        unsafe {
            let elt = &*(self.as_ptr() as *const ffi::GstVideoEncoder);
            &*(&elt.sinkpad as *const *mut gst::ffi::GstPad as *const gst::Pad)
        }
    }

    fn src_pad(&self) -> &gst::Pad {
        unsafe {
            let elt = &*(self.as_ptr() as *const ffi::GstVideoEncoder);
            &*(&elt.srcpad as *const *mut gst::ffi::GstPad as *const gst::Pad)
        }
    }

    fn input_segment(&self) -> gst::Segment {
        unsafe {
            let ptr: &ffi::GstVideoDecoder = &*(self.as_ptr() as *const _);
            glib::ffi::g_rec_mutex_lock(mut_override(&ptr.stream_lock));
            let segment = ptr.input_segment;
            glib::ffi::g_rec_mutex_unlock(mut_override(&ptr.stream_lock));
            from_glib_none(&segment as *const gst::ffi::GstSegment)
        }
    }

    fn output_segment(&self) -> gst::Segment {
        unsafe {
            let ptr: &ffi::GstVideoDecoder = &*(self.as_ptr() as *const _);
            glib::ffi::g_rec_mutex_lock(mut_override(&ptr.stream_lock));
            let segment = ptr.output_segment;
            glib::ffi::g_rec_mutex_unlock(mut_override(&ptr.stream_lock));
            from_glib_none(&segment as *const gst::ffi::GstSegment)
        }
    }
}

impl<O: IsA<VideoEncoder>> VideoEncoderExtManual for O {}

impl HasStreamLock for VideoEncoder {
    fn stream_lock(&self) -> *mut glib::ffi::GRecMutex {
        let encoder_sys: *const ffi::GstVideoEncoder = self.to_glib_none().0;
        unsafe { mut_override(&(*encoder_sys).stream_lock) }
    }

    fn element_as_ptr(&self) -> *const gst::ffi::GstElement {
        self.as_ptr() as *const gst::ffi::GstElement
    }
}