use crate::av::as_ptr::{AsMutPtr, AsPtr};
use crate::av::decoder::Decoder;
use crate::av::encoder::Encoder;
use crate::av::frame::Frame;
use crate::av::xcoder::XCoder;
use ffmpeg_sys_next::{
    swr_alloc, swr_alloc_set_opts, swr_convert_frame, swr_get_delay, AVFrame, SwrContext,
};
use std::ptr::{null, null_mut};

pub struct Resampler {
    ptr: *mut SwrContext,
    output_sample_rate: i64,
}

impl Resampler {
    pub fn from_coder(decoder: &Decoder, encoder: &Encoder) -> Resampler {
        unsafe {
            let swr = swr_alloc();
            swr_alloc_set_opts(
                swr,
                encoder.channel_layout() as i64,
                encoder.sample_format(),
                encoder.sample_rate(),
                decoder.channel_layout() as i64,
                decoder.sample_format(),
                decoder.sample_rate(),
                0,
                null_mut(),
            );

            Resampler {
                ptr: swr,
                output_sample_rate: encoder.sample_rate() as i64,
            }
        }
    }

    pub fn convert(&self, input: Frame) -> Frame {
        let output = Frame::alloc();
        unsafe {
            swr_convert_frame(self.ptr, output.as_mut_ptr(), input.as_ptr());
        }

        output
    }

    pub fn drain(&self) -> Option<Frame> {
        if 0 < unsafe { swr_get_delay(self.ptr, self.output_sample_rate) } {
            let output = Frame::alloc();
            unsafe {
                swr_convert_frame(self.ptr, output.as_mut_ptr(), null());
            }

            Some(output)
        } else {
            None
        }
    }
}