/*!
 * MPEG  video encoder.
 */

#![deny(non_camel_case_types)]
#![deny(unused_parens)]
#![deny(non_upper_case_globals)]
#![deny(unused_qualifications)]
#![deny(missing_docs)]
#![deny(unused_results)]

extern crate libc;
extern crate ffmpeg_sys;

// Inspired by the muxing sample: http://ffmpeg.org/doxygen/trunk/muxing_8c-source.html

use libc::c_void;
use ffmpeg_sys::{SwsContext, AVCodec, AVCodecContext, AVPacket, AVFormatContext, AVStream,
                 AVFrame, AVRational, AVPixelFormat, AVPicture, AVCodecID};
use std::ptr;
use std::mem;
use std::iter;
use std::path::{Path, PathBuf};
use std::ffi::CString;
use std::iter::FromIterator;
use std::sync::{Once, ONCE_INIT};

static mut avformat_init: Once = ONCE_INIT;

/// MPEG video recorder.
pub struct Encoder {
    tmp_frame_buf:    Vec<u8>,
    frame_buf:        Vec<u8>,
    curr_frame_index: usize,
    initialized:      bool,
    bit_rate:         usize,
    target_width:     usize,
    target_height:    usize,
    time_base:        (usize, usize),
    gop_size:         usize,
    max_b_frames:     usize,
    pix_fmt:          AVPixelFormat,
    tmp_frame:        *mut AVFrame,
    frame:            *mut AVFrame,
    context:          *mut AVCodecContext,
    format_context:   *mut AVFormatContext,
    video_st:         *mut AVStream,
    scale_context:    *mut SwsContext,
    path:             PathBuf
}

impl Encoder {
    /// Creates a new video recorder.
    ///
    /// # Arguments:
    /// * `path`   - path to the output file.
    /// * `width`  - width of the recorded video.
    /// * `height` - height of the recorded video.
    pub fn new<P: AsRef<Path>>(path: P, width: usize, height: usize) -> Encoder {
        Encoder::new_with_params(path, width, height, None, None, None, None, None)
    }

    /// Creates a new video recorder with custom recording parameters.
    ///
    /// # Arguments:
    /// * `path`         - path to the output file.
    /// * `width`        - width of the recorded video.
    /// * `height`       - height of the recorded video.
    /// * `bit_rate`     - the average bit rate. Default value: 400000.
    /// * `time_base`    - this is the fundamental unit of time (in seconds) in terms of which
    ///                    frame timestamps are represented. Default value: (1, 60), i-e, 60fps.
    /// * `gop_size`     - the number of pictures in a group of pictures. Default value: 10.
    /// * `max_b_frames` - maximum number of B-frames between non-B-frames. Default value: 1.
    /// * `pix_fmt`      - pixel format. Default value: `AVPixelFormat::PIX_FMT_YUV420P`.
    pub fn new_with_params<P: AsRef<Path>>(path:         P,
                                           width:        usize,
                                           height:       usize,
                                           bit_rate:     Option<usize>,
                                           time_base:    Option<(usize, usize)>,
                                           gop_size:     Option<usize>,
                                           max_b_frames: Option<usize>,
                                           pix_fmt:      Option<AVPixelFormat>)
                                           -> Encoder {
        unsafe {
            avformat_init.call_once(|| {
                ffmpeg_sys::av_register_all();
            });
        }

        let bit_rate     = bit_rate.unwrap_or(400000); // FIXME
        let time_base    = time_base.unwrap_or((1, 60));
        let gop_size     = gop_size.unwrap_or(10);
        let max_b_frames = max_b_frames.unwrap_or(1);
        let pix_fmt      = pix_fmt.unwrap_or(AVPixelFormat::AV_PIX_FMT_YUV420P);
        // width and height must be a multiple of two.
        let width        = if width  % 2 == 0 { width }  else { width + 1 };
        let height       = if height % 2 == 0 { height } else { height + 1 };

        let mut pathbuf = PathBuf::new();
        pathbuf.push(path);

        Encoder {
            initialized:      false,
            curr_frame_index: 0,
            bit_rate:         bit_rate,
            target_width:     width,
            target_height:    height,
            time_base:        time_base,
            gop_size:         gop_size,
            max_b_frames:     max_b_frames,
            pix_fmt:          pix_fmt,
            frame:            ptr::null_mut(),
            tmp_frame:        ptr::null_mut(),
            context:          ptr::null_mut(),
            scale_context:    ptr::null_mut(),
            format_context:   ptr::null_mut(),
            video_st:         ptr::null_mut(),
            path:             pathbuf,
            frame_buf:        Vec::new(),
            tmp_frame_buf:    Vec::new()
        }
    }

    /// Adds a image with a RGB pixel format to the video.
    pub fn encode_rgb(&mut self, width: usize, height: usize, data: &[u8], vertical_flip: bool) {
        assert!(data.len() == width * height * 3);
        self.encode(width, height, data, false, vertical_flip)
    }

    /// Adds a image with a RGBA pixel format to the video.
    pub fn encode_rgba(&mut self, width: usize, height: usize, data: &[u8], vertical_flip: bool) {
        assert!(data.len() == width * height * 4);
        self.encode(width, height, data, true, vertical_flip)
    }

    fn encode(&mut self, width: usize, height: usize, data: &[u8], rgba: bool, vertical_flip: bool) {
        assert!((rgba && data.len() == width * height * 4) || (!rgba && data.len() == width * height * 3));

        self.init();

        let mut pkt: AVPacket = unsafe { mem::uninitialized() };

        unsafe {
            ffmpeg_sys::av_init_packet(&mut pkt);
        }

        pkt.data = ptr::null_mut();  // packet data will be allocated by the encoder
        pkt.size = 0;

        /*
         *
         * Fill the snapshot frame.
         *
         */
        self.tmp_frame_buf.resize(width * height * 3, 0);

        if rgba {
            for (i, pixel) in data.chunks(4).enumerate() {
                self.tmp_frame_buf[i * 3 + 0] = pixel[0];
                self.tmp_frame_buf[i * 3 + 1] = pixel[1];
                self.tmp_frame_buf[i * 3 + 2] = pixel[2];
            }
        }
        else {
            self.tmp_frame_buf.clone_from_slice(data);
        }

        if vertical_flip {
            vflip(self.tmp_frame_buf.as_mut_slice(), width as usize * 3, height as usize);
        }

        unsafe {
            (*self.frame).pts += ffmpeg_sys::av_rescale_q(1, (*self.context).time_base, (*self.video_st).time_base);
            self.curr_frame_index = self.curr_frame_index + 1;
        }

        unsafe {

            (*self.tmp_frame).width  = width as i32;
            (*self.tmp_frame).height = height as i32;

            let _ = ffmpeg_sys::avpicture_fill(self.tmp_frame as *mut AVPicture,
                                               self.tmp_frame_buf.get(0).unwrap(),
                                               AVPixelFormat::AV_PIX_FMT_RGB24,
                                               width as i32,
                                               height as i32);
        }

        /*
         * Convert the snapshot frame to the right format for the destination frame.
         */
        unsafe {
            self.scale_context = ffmpeg_sys::sws_getCachedContext(
                self.scale_context, width as i32, height as i32, AVPixelFormat::AV_PIX_FMT_RGB24,
                self.target_width as i32, self.target_height as i32, AVPixelFormat::AV_PIX_FMT_YUV420P,
                ffmpeg_sys::SWS_BICUBIC as i32, ptr::null_mut(), ptr::null_mut(), ptr::null());

            let _ = ffmpeg_sys::sws_scale(self.scale_context,
                                          mem::transmute(&(*self.tmp_frame).data[0]), &(*self.tmp_frame).linesize[0],
                                          0, height as i32,
                                          mem::transmute(&(*self.frame).data[0]), &mut (*self.frame).linesize[0]);
        }


        // Encode the image.

        let mut got_output = 0;
        let ret;

        unsafe {
            ret = ffmpeg_sys::avcodec_encode_video2(self.context, &mut pkt, self.frame, &mut got_output);
        }

        if ret < 0 {
            panic!("Error encoding frame.");
        }

        if got_output != 0 {
            unsafe {
                let _ = ffmpeg_sys::av_interleaved_write_frame(self.format_context, &mut pkt);
                ffmpeg_sys::av_free_packet(&mut pkt);
            }
        }
    }

    /// Initializes the recorder if needed.
    ///
    /// This is automatically called when the first snapshot is made. Call this explicitly if you
    /// do not want the extra time overhead when the first snapshot is made.
    pub fn init(&mut self) {
        if self.initialized {
            return;
        }
        
        let path_str = CString::new(self.path.to_str().unwrap()).unwrap();

        unsafe {
            // try to guess the container type from the path.
            let mut fmt = ptr::null_mut();
            

            let _ = ffmpeg_sys::avformat_alloc_output_context2(&mut fmt, ptr::null_mut(), ptr::null(), path_str.as_ptr());

            if self.format_context.is_null() {
                // could not guess, default to MPEG
                let mpeg = CString::new(&b"mpeg"[..]).unwrap();
                
                let _ = ffmpeg_sys::avformat_alloc_output_context2(&mut fmt, ptr::null_mut(), mpeg.as_ptr(), path_str.as_ptr());
            }

            self.format_context = fmt;

            if self.format_context.is_null() {
                panic!("Unable to create the output context.");
            }

            let fmt = (*self.format_context).oformat;

            if (*fmt).video_codec == AVCodecID::AV_CODEC_ID_NONE {
                panic!("The selected output container does not support video encoding.")
            }

            let codec: *mut AVCodec;

            let ret: i32 = 0;

            codec = ffmpeg_sys::avcodec_find_encoder((*fmt).video_codec);

            if codec.is_null() {
                panic!("Codec not found.");
            }

            self.video_st = ffmpeg_sys::avformat_new_stream(self.format_context, codec);

            if self.video_st.is_null() {
                panic!("Failed to allocate the video stream.");
            }

            (*self.video_st).id = ((*self.format_context).nb_streams - 1) as i32;

            self.context = (*self.video_st).codec;

            let _ = ffmpeg_sys::avcodec_get_context_defaults3(self.context, codec);

            if self.context.is_null() {
                panic!("Could not allocate video codec context.");
            }

            // sws scaling context
            self.scale_context = ffmpeg_sys::sws_getContext(
                self.target_width as i32, self.target_height as i32, AVPixelFormat::AV_PIX_FMT_RGB24,
                self.target_width as i32, self.target_height as i32, self.pix_fmt,
                ffmpeg_sys::SWS_BICUBIC as i32, ptr::null_mut(), ptr::null_mut(), ptr::null());

            // Put sample parameters.
            (*self.context).bit_rate = self.bit_rate as i32;

            // Resolution must be a multiple of two.
            (*self.context).width    = self.target_width  as i32;
            (*self.context).height   = self.target_height as i32;

            // frames per second.
            let (tnum, tdenum)           = self.time_base;
            (*self.context).time_base    = AVRational { num: tnum as i32, den: tdenum as i32 };
            (*self.video_st).time_base   = (*self.context).time_base;
            (*self.context).gop_size     = self.gop_size as i32;
            (*self.context).max_b_frames = self.max_b_frames as i32;
            (*self.context).pix_fmt      = self.pix_fmt;

            if (*self.context).codec_id == AVCodecID::AV_CODEC_ID_MPEG1VIDEO {
                // Needed to avoid using macroblocks in which some coeffs overflow.
                // This does not happen with normal video, it just happens here as
                // the motion of the chroma plane does not match the luma plane.
                (*self.context).mb_decision = 2;
            }

            /*
            if (*fmt).flags & ffmpeg_sys::AVFMT_GLOBALHEADER != 0 {
                (*self.context).flags = (*self.context).flags | CODEC_FLAG_GLOBAL_HEADER;
            }
            */

            // Open the codec.
            if ffmpeg_sys::avcodec_open2(self.context, codec, ptr::null_mut()) < 0 {
                panic!("Could not open the codec.");
            }

            /*
             * Init the destination video frame.
             */
            self.frame = ffmpeg_sys::avcodec_alloc_frame();

            if self.frame.is_null() {
                panic!("Could not allocate the video frame.");
            }

            (*self.frame).format = (*self.context).pix_fmt as i32;
            (*self.frame).width  = (*self.context).width;
            (*self.frame).height = (*self.context).height;
            (*self.frame).pts    = 0;

            // alloc the buffer
            let nframe_bytes = ffmpeg_sys::avpicture_get_size(self.pix_fmt,
                                                              self.target_width as i32,
                                                              self.target_height as i32);
            
            let reps = iter::repeat(0u8).take(nframe_bytes as usize);
            self.frame_buf = Vec::<u8>::from_iter(reps);
            //self.frame_buf = Vec::from_elem(nframe_bytes as usize, 0u8);

            let _ = ffmpeg_sys::avpicture_fill(self.frame as *mut AVPicture,
                                               self.frame_buf.get(0).unwrap(),
                                               self.pix_fmt,
                                               self.target_width as i32,
                                               self.target_height as i32);

            /*
             * Init the temporary video frame.
             */
            self.tmp_frame = ffmpeg_sys::avcodec_alloc_frame();

            if self.tmp_frame.is_null() {
                panic!("Could not allocate the video frame.");
            }

            (*self.frame).format = (*self.context).pix_fmt as i32;
            // the rest (width, height, data, linesize) are set at the moment of the snapshot.

            // Open the output file.
            static AVIO_FLAG_WRITE: i32 = 2; // XXX: this should be defined by the bindings.
            if ffmpeg_sys::avio_open(&mut (*self.format_context).pb, path_str.as_ptr(), AVIO_FLAG_WRITE) < 0 {
                panic!("Failed to open the output file.");
            }

            if ffmpeg_sys::avformat_write_header(self.format_context, ptr::null_mut()) < 0 {
                panic!("Failed to open the output file.");
            }

            if ret < 0 {
                panic!("Could not allocate raw picture buffer");
            }
        }

        self.initialized = true;
    }
}

impl Drop for Encoder {
    fn drop(&mut self) {
        if self.initialized {
            // Get the delayed frames.
            let mut pkt: AVPacket = unsafe { mem::uninitialized() };
            let mut got_output = 1;
            while got_output != 0 {
                let ret;

                unsafe {
                    ffmpeg_sys::av_init_packet(&mut pkt);
                }

                pkt.data = ptr::null_mut();  // packet data will be allocated by the encoder
                pkt.size = 0;

                unsafe {
                    ret = ffmpeg_sys::avcodec_encode_video2(self.context, &mut pkt, ptr::null(), &mut got_output);
                }

                if ret < 0 {
                    panic!("Error encoding frame.");
                }

                if got_output != 0 {
                    unsafe {
                        let _ = ffmpeg_sys::av_interleaved_write_frame(self.format_context, &mut pkt);
                        ffmpeg_sys::av_free_packet(&mut pkt);
                    }
                }
            }

            // Free things and stuffs.
            unsafe {
                let _ = ffmpeg_sys::avcodec_close(self.context);
                ffmpeg_sys::av_free(self.context as *mut c_void);
                // ffmpeg_sys::av_freep((*self.frame).data[0] as *mut c_void);
                ffmpeg_sys::avcodec_free_frame(&mut self.frame);
                ffmpeg_sys::avcodec_free_frame(&mut self.tmp_frame);
            }
        }
    }
}

fn vflip(vec: &mut [u8], width: usize, height: usize) {
    for j in 0 .. height / 2 {
        for i in 0 .. width {
            vec.swap((height - j - 1) * width + i, j * width + i);
        }
    }
}