#include "exportthread.h"

#include "project/sequence.h"

#include "panels/panels.h"
#include "panels/timeline.h"
#include "panels/viewer.h"
#include "ui/viewerwidget.h"
#include "ui/renderthread.h"
#include "ui/renderfunctions.h"
#include "playback/playback.h"
#include "playback/audio.h"
#include "dialogs/exportdialog.h"
#include "mainwindow.h"
#include "debug.h"

extern "C" {
	#include <libavformat/avformat.h>
	#include <libavutil/opt.h>
	#include <libswresample/swresample.h>
	#include <libswscale/swscale.h>
}

#include <QApplication>
#include <QOffscreenSurface>
#include <QOpenGLFramebufferObject>
#include <QOpenGLPaintDevice>
#include <QPainter>

ExportThread::ExportThread(const ExportParams &iparams,
                           const VideoCodecParams& ivparams,
                           QObject *parent) :
    params(iparams),
    vcodec_params(ivparams),
	QThread(parent),
	continueEncode(true)
{
	surface.create();

	fmt_ctx = nullptr;
	video_stream = nullptr;
	vcodec = nullptr;
	vcodec_ctx = nullptr;
	video_frame = nullptr;
	sws_ctx = nullptr;
	audio_stream = nullptr;
	acodec = nullptr;
	audio_frame = nullptr;
	swr_frame = nullptr;
	acodec_ctx = nullptr;
	swr_ctx = nullptr;

	vpkt_alloc = false;
	apkt_alloc = false;
}

bool ExportThread::encode(AVFormatContext* ofmt_ctx, AVCodecContext* codec_ctx, AVFrame* frame, AVPacket* packet, AVStream* stream, bool rescale) {
	ret = avcodec_send_frame(codec_ctx, frame);
	if (ret < 0) {
		qCritical() << "Failed to send frame to encoder." << ret;
		ed->export_error = tr("failed to send frame to encoder (%1)").arg(QString::number(ret));
		return false;
	}

	while (ret >= 0) {
		ret = avcodec_receive_packet(codec_ctx, packet);
		if (ret == AVERROR(EAGAIN)) {
			return true;
		} else if (ret < 0) {
			if (ret != AVERROR_EOF) {
				qCritical() << "Failed to receive packet from encoder." << ret;
				ed->export_error = tr("failed to receive packet from encoder (%1)").arg(QString::number(ret));
			}
			return false;
		}

		packet->stream_index = stream->index;
		if (rescale) av_packet_rescale_ts(packet, codec_ctx->time_base, stream->time_base);
		av_interleaved_write_frame(ofmt_ctx, packet);
		av_packet_unref(packet);
	}
	return true;
}

bool ExportThread::setupVideo() {
	// if video is disabled, no setup necessary
    if (!params.video_enabled) return true;

	// find video encoder
    vcodec = avcodec_find_encoder(static_cast<enum AVCodecID>(params.video_codec));
    if (!vcodec) {
		qCritical() << "Could not find video encoder";
        ed->export_error = tr("could not video encoder for %1").arg(QString::number(params.video_codec));
		return false;
	}

	// create video stream
	video_stream = avformat_new_stream(fmt_ctx, vcodec);
	video_stream->id = 0;
	if (!video_stream) {
		qCritical() << "Could not allocate video stream";
		ed->export_error = tr("could not allocate video stream");
		return false;
	}

	// allocate context
//	vcodec_ctx = video_stream->codec;
	vcodec_ctx = avcodec_alloc_context3(vcodec);
	if (!vcodec_ctx) {
		qCritical() << "Could not allocate video encoding context";
		ed->export_error = tr("could not allocate video encoding context");
		return false;
	}

	// setup context
    vcodec_ctx->codec_id = static_cast<enum AVCodecID>(params.video_codec);
	vcodec_ctx->codec_type = AVMEDIA_TYPE_VIDEO;
    vcodec_ctx->width = params.video_width;
    vcodec_ctx->height = params.video_height;
	vcodec_ctx->sample_aspect_ratio = {1, 1};
    vcodec_ctx->pix_fmt = static_cast<AVPixelFormat>(vcodec_params.pix_fmt);
    vcodec_ctx->framerate = av_d2q(params.video_frame_rate, INT_MAX);
    if (params.video_compression_type == COMPRESSION_TYPE_CBR) {
        vcodec_ctx->bit_rate = qRound(params.video_bitrate * 1000000);
    }
	vcodec_ctx->time_base = av_inv_q(vcodec_ctx->framerate);
	video_stream->time_base = vcodec_ctx->time_base;

	if (fmt_ctx->oformat->flags & AVFMT_GLOBALHEADER) {
		vcodec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
	}

	switch (vcodec_ctx->codec_id) {
	case AV_CODEC_ID_H264:
        switch (params.video_compression_type) {
		case COMPRESSION_TYPE_CFR:
            av_opt_set(vcodec_ctx->priv_data, "crf", QString::number(static_cast<int>(params.video_bitrate)).toUtf8(), AV_OPT_SEARCH_CHILDREN);
			break;
		}
		break;
	}

	AVDictionary* opts = nullptr;
	av_dict_set(&opts, "threads", "auto", 0);

	ret = avcodec_open2(vcodec_ctx, vcodec, &opts);
	if (ret < 0) {
		qCritical() << "Could not open output video encoder." << ret;
		ed->export_error = tr("could not open output video encoder (%1)").arg(QString::number(ret));
		return false;
	}

	// copy video encoder parameters to output stream
	ret = avcodec_parameters_from_context(video_stream->codecpar, vcodec_ctx);
	if (ret < 0) {
		qCritical() << "Could not copy video encoder parameters to output stream." << ret;
		ed->export_error = tr("could not copy video encoder parameters to output stream (%1)").arg(QString::number(ret));
		return false;
	}

	// create AVFrame
	video_frame = av_frame_alloc();
	av_frame_make_writable(video_frame);
	video_frame->format = AV_PIX_FMT_RGBA;
	video_frame->width = sequence->width;
	video_frame->height = sequence->height;
	av_frame_get_buffer(video_frame, 0);

	av_init_packet(&video_pkt);

	sws_ctx = sws_getContext(
				sequence->width,
				sequence->height,
				AV_PIX_FMT_RGBA,
                params.video_width,
                params.video_height,
				vcodec_ctx->pix_fmt,
				SWS_FAST_BILINEAR,
				nullptr,
				nullptr,
				nullptr
			);

	return true;
}

bool ExportThread::setupAudio() {
	// if audio is disabled, no setup necessary
    if (!params.audio_enabled) return true;

	// find encoder
    acodec = avcodec_find_encoder(static_cast<AVCodecID>(params.audio_codec));
	if (!acodec) {
		qCritical() << "Could not find audio encoder";
        ed->export_error = tr("could not audio encoder for %1").arg(QString::number(params.audio_codec));
		return false;
	}

	// allocate audio stream
	audio_stream = avformat_new_stream(fmt_ctx, acodec);
	audio_stream->id = 1;
	if (!audio_stream) {
		qCritical() << "Could not allocate audio stream";
		ed->export_error = tr("could not allocate audio stream");
		return false;
	}

	// allocate context
//	acodec_ctx = audio_stream->codec;
	acodec_ctx = avcodec_alloc_context3(acodec);
	if (!acodec_ctx) {
		qCritical() << "Could not find allocate audio encoding context";
		ed->export_error = tr("could not allocate audio encoding context");
		return false;
	}

	// setup context
    acodec_ctx->codec_id = static_cast<AVCodecID>(params.audio_codec);
	acodec_ctx->codec_type = AVMEDIA_TYPE_AUDIO;
    acodec_ctx->sample_rate = params.audio_sampling_rate;
	acodec_ctx->channel_layout = AV_CH_LAYOUT_STEREO;  // change this to support surround/mono sound in the future (this is what the user sets the output audio to)
	acodec_ctx->channels = av_get_channel_layout_nb_channels(acodec_ctx->channel_layout);
	acodec_ctx->sample_fmt = acodec->sample_fmts[0];
    acodec_ctx->bit_rate = params.audio_bitrate * 1000;

	acodec_ctx->time_base.num = 1;
    acodec_ctx->time_base.den = params.audio_sampling_rate;
	audio_stream->time_base = acodec_ctx->time_base;

	if (fmt_ctx->oformat->flags & AVFMT_GLOBALHEADER) {
		acodec_ctx->flags |= AV_CODEC_FLAG_GLOBAL_HEADER;
	}

	// open encoder
	ret = avcodec_open2(acodec_ctx, acodec, nullptr);
	if (ret < 0) {
		qCritical() << "Could not open output audio encoder." << ret;
		ed->export_error = tr("could not open output audio encoder (%1)").arg(QString::number(ret));
		return false;
	}

	// copy params to output stream
	ret = avcodec_parameters_from_context(audio_stream->codecpar, acodec_ctx);
	if (ret < 0) {
		qCritical() << "Could not copy audio encoder parameters to output stream." << ret;
		ed->export_error = tr("could not copy audio encoder parameters to output stream (%1)").arg(QString::number(ret));
		return false;
	}

	// init audio resampler context
	swr_ctx = swr_alloc_set_opts(
			nullptr,
			acodec_ctx->channel_layout,
			acodec_ctx->sample_fmt,
			acodec_ctx->sample_rate,
			sequence->audio_layout,
			AV_SAMPLE_FMT_S16,
			sequence->audio_frequency,
			0,
			nullptr
		);
	swr_init(swr_ctx);

	// initialize raw audio frame
	audio_frame = av_frame_alloc();
	audio_frame->sample_rate = sequence->audio_frequency;
	audio_frame->nb_samples = acodec_ctx->frame_size;
	if (audio_frame->nb_samples == 0) audio_frame->nb_samples = 256; // should possibly be smaller?
	audio_frame->format = AV_SAMPLE_FMT_S16;
	audio_frame->channel_layout = AV_CH_LAYOUT_STEREO; // change this to support surround/mono sound in the future (this is whatever format they're held in the internal buffer)
	audio_frame->channels = av_get_channel_layout_nb_channels(audio_frame->channel_layout);
	av_frame_make_writable(audio_frame);
	ret = av_frame_get_buffer(audio_frame, 0);
	if (ret < 0) {
		qCritical() << "Could not allocate audio buffer." << ret;
		ed->export_error = tr("could not allocate audio buffer (%1)").arg(QString::number(ret));
		return false;
	}
	aframe_bytes = av_samples_get_buffer_size(nullptr, audio_frame->channels, audio_frame->nb_samples, static_cast<AVSampleFormat>(audio_frame->format), 0);

	// init converted audio frame
	swr_frame = av_frame_alloc();
	swr_frame->channel_layout = acodec_ctx->channel_layout;
	swr_frame->channels = acodec_ctx->channels;
	swr_frame->sample_rate = acodec_ctx->sample_rate;
	swr_frame->format = acodec_ctx->sample_fmt;
	av_frame_make_writable(swr_frame);

	av_init_packet(&audio_pkt);

	return true;
}

bool ExportThread::setupContainer() {
	avformat_alloc_output_context2(&fmt_ctx, nullptr, nullptr, c_filename);
	if (!fmt_ctx) {
		qCritical() << "Could not create output context";
		ed->export_error = tr("could not create output format context");
		return false;
	}

	//av_dump_format(fmt_ctx, 0, c_filename, 1);

	ret = avio_open(&fmt_ctx->pb, c_filename, AVIO_FLAG_WRITE);
	if (ret < 0) {
		qCritical() << "Could not open output file." << ret;
		ed->export_error = tr("could not open output file (%1)").arg(QString::number(ret));
		return false;
	}

	return true;
}

void ExportThread::run() {
	panel_sequence_viewer->pause();
    panel_sequence_viewer->seek(params.start_frame);

	// copy filename
    QByteArray ba = params.filename.toUtf8();
	c_filename = new char[ba.size()+1];
	strcpy(c_filename, ba.data());

	continueEncode = setupContainer();

    if (params.video_enabled && continueEncode) continueEncode = setupVideo();

    if (params.audio_enabled && continueEncode) continueEncode = setupAudio();

	if (continueEncode) {
		ret = avformat_write_header(fmt_ctx, nullptr);
		if (ret < 0) {
			qCritical() << "Could not write output file header." << ret;
			ed->export_error = tr("could not write output file header (%1)").arg(QString::number(ret));
			continueEncode = false;
		}
	}

	long file_audio_samples = 0;
	qint64 start_time, frame_time, avg_time, eta, total_time = 0;
	long remaining_frames, frame_count = 1;

	RenderThread* renderer = panel_sequence_viewer->viewer_widget->get_renderer();
	disconnect(renderer, SIGNAL(ready()), panel_sequence_viewer->viewer_widget, SLOT(queue_repaint()));
	connect(renderer, SIGNAL(ready()), this, SLOT(wake()));

	mutex.lock();

    while (sequence->playhead <= params.end_frame && continueEncode) {
		start_time = QDateTime::currentMSecsSinceEpoch();

        if (params.audio_enabled) {
			compose_audio(nullptr, sequence, true, false);
		}
        if (params.video_enabled) {
			do {
				// TODO optimize by rendering the next frame while encoding the last
                renderer->start_render(nullptr, sequence, nullptr, video_frame->data[0], video_frame->linesize[0]/4);
				waitCond.wait(&mutex);
				if (!continueEncode) break;
			} while (renderer->did_texture_fail());
			if (!continueEncode) break;
		}

		// encode last frame while rendering next frame
        double timecode_secs = double(sequence->playhead - params.start_frame) / sequence->frame_rate;
        if (params.video_enabled) {
			// create sws_frame for converting pixel format

			//
			// - I'm not sure why, but we have to alloc/free sws_frame every frame, or it breaks GIF exporting.
			// - (i.e. GIFs get stuck on the first frame)
			// - The same problem/solution can be seen here: https://stackoverflow.com/a/38997739
			// - Perhaps this is the intended way to use swscale, but it seems inefficient.
			// - Anyway, here we are.
			//

			sws_frame = av_frame_alloc();
			sws_frame->format = vcodec_ctx->pix_fmt;
            sws_frame->width = params.video_width;
            sws_frame->height = params.video_height;
			av_frame_get_buffer(sws_frame, 0);

			// convert pixel format to format expected by the encoder
            sws_scale(sws_ctx, video_frame->data, video_frame->linesize, 0, video_frame->height, sws_frame->data, sws_frame->linesize);
			sws_frame->pts = qRound(timecode_secs/av_q2d(video_stream->time_base));

			// send converted frame to encoder
			if (!encode(fmt_ctx, vcodec_ctx, sws_frame, &video_pkt, video_stream, false)) continueEncode = false;

			av_frame_free(&sws_frame);
		}
        if (params.audio_enabled) {

			// do we need to encode more audio samples?
            while (continueEncode && file_audio_samples <= (timecode_secs*params.audio_sampling_rate)) {

				// copy samples from audio buffer to AVFrame
				int adjusted_read = audio_ibuffer_read%audio_ibuffer_size;
				int copylen = qMin(aframe_bytes, audio_ibuffer_size-adjusted_read);
				memcpy(audio_frame->data[0], audio_ibuffer+adjusted_read, copylen);
				memset(audio_ibuffer+adjusted_read, 0, copylen);
				audio_ibuffer_read += copylen;

				if (copylen < aframe_bytes) {
					// copy remainder
					int remainder_len = aframe_bytes-copylen;
					memcpy(audio_frame->data[0]+copylen, audio_ibuffer, remainder_len);
					memset(audio_ibuffer, 0, remainder_len);
					audio_ibuffer_read += remainder_len;
				}

				// convert to export sample format
				swr_convert_frame(swr_ctx, swr_frame, audio_frame);
				swr_frame->pts = file_audio_samples;

				// send to encoder
				if (!encode(fmt_ctx, acodec_ctx, swr_frame, &audio_pkt, audio_stream, true)) continueEncode = false;

				file_audio_samples += swr_frame->nb_samples;
			}
		}

		// generating encoding statistics (time it took to encode this frame/estimated remaining time)
		frame_time = (QDateTime::currentMSecsSinceEpoch()-start_time);
		total_time += frame_time;
        remaining_frames = (params.end_frame - sequence->playhead);
		avg_time = (total_time/frame_count);
		eta = (remaining_frames*avg_time);

        emit progress_changed(qRound((double(sequence->playhead - params.start_frame) / double(params.end_frame - params.start_frame)) * 100.0), eta);
		sequence->playhead++;
		frame_count++;
	}

	disconnect(renderer, SIGNAL(ready()), this, SLOT(wake()));
	connect(renderer, SIGNAL(ready()), panel_sequence_viewer->viewer_widget, SLOT(queue_repaint()));

	mutex.unlock();

	if (continueEncode) {
        if (params.video_enabled) vpkt_alloc = true;
        if (params.audio_enabled) apkt_alloc = true;
	}

	mainWindow->set_rendering_state(false);

    if (params.audio_enabled && continueEncode) {
		// flush swresample
		do {
			swr_convert_frame(swr_ctx, swr_frame, nullptr);
			if (swr_frame->nb_samples == 0) break;
			swr_frame->pts = file_audio_samples;
			if (!encode(fmt_ctx, acodec_ctx, swr_frame, &audio_pkt, audio_stream, true)) continueEncode = false;
			file_audio_samples += swr_frame->nb_samples;
		} while (swr_frame->nb_samples > 0);
	}

	bool continueVideo = true;
	bool continueAudio = true;
	if (continueEncode) {
		// flush remaining packets
		while (continueVideo && continueAudio) {
            if (continueVideo && params.video_enabled) continueVideo = encode(fmt_ctx, vcodec_ctx, nullptr, &video_pkt, video_stream, false);
            if (continueAudio && params.audio_enabled) continueAudio = encode(fmt_ctx, acodec_ctx, nullptr, &audio_pkt, audio_stream, true);
		}

		ret = av_write_trailer(fmt_ctx);
		if (ret < 0) {
			qCritical() << "Could not write output file trailer." << ret;
			ed->export_error = tr("could not write output file trailer (%1)").arg(QString::number(ret));
			continueEncode = false;
		}

		emit progress_changed(100, 0);
	}

	avio_closep(&fmt_ctx->pb);

	if (vpkt_alloc) av_packet_unref(&video_pkt);
	if (video_frame != nullptr) av_frame_free(&video_frame);
	if (vcodec_ctx != nullptr) {
		avcodec_close(vcodec_ctx);
		avcodec_free_context(&vcodec_ctx);
	}

	if (apkt_alloc) av_packet_unref(&audio_pkt);
	if (audio_frame != nullptr) av_frame_free(&audio_frame);
	if (acodec_ctx != nullptr) {
		avcodec_close(acodec_ctx);
		avcodec_free_context(&acodec_ctx);
	}

	avformat_free_context(fmt_ctx);

	if (sws_ctx != nullptr) {
		sws_freeContext(sws_ctx);
	}
	if (swr_ctx != nullptr) {
		swr_free(&swr_ctx);
		av_frame_free(&swr_frame);
	}

	delete [] c_filename;
}

void ExportThread::wake() {
	mutex.lock();
	waitCond.wakeAll();
	mutex.unlock();
}