/*
 * CVideoHandler.cpp, part of VCMI engine
 *
 * Authors: listed in file AUTHORS in main folder
 *
 * License: GNU General Public License v2.0 or later
 * Full text of license available in license.txt file, in main folder
 *
 */
#include "StdInc.h"
#include <SDL.h>
#include "CVideoHandler.h"

#include "gui/CGuiHandler.h"
#include "gui/SDL_Extensions.h"
#include "CPlayerInterface.h"
#include "../lib/filesystem/Filesystem.h"

extern CGuiHandler GH; //global gui handler

#ifndef DISABLE_VIDEO
//reads events and returns true on key down
static bool keyDown()
{
	SDL_Event ev;
	while(SDL_PollEvent(&ev))
	{
		if(ev.type == SDL_KEYDOWN || ev.type == SDL_MOUSEBUTTONDOWN)
			return true;
	}
	return false;
}

#ifdef _MSC_VER
#pragma comment(lib, "avcodec.lib")
#pragma comment(lib, "avutil.lib")
#pragma comment(lib, "avformat.lib")
#pragma comment(lib, "swscale.lib")
#endif // _MSC_VER

// Define a set of functions to read data
static int lodRead(void* opaque, uint8_t* buf, int size)
{
	auto video = reinterpret_cast<CVideoPlayer *>(opaque);

	return static_cast<int>(video->data->read(buf, size));
}

static si64 lodSeek(void * opaque, si64 pos, int whence)
{
	auto video = reinterpret_cast<CVideoPlayer *>(opaque);

	if (whence & AVSEEK_SIZE)
		return video->data->getSize();

	return video->data->seek(pos);
}

CVideoPlayer::CVideoPlayer()
{
	stream = -1;
	format = nullptr;
	codecContext = nullptr;
	codec = nullptr;
	frame = nullptr;
	sws = nullptr;
	context = nullptr;
	texture = nullptr;
	dest = nullptr;
	destRect = genRect(0,0,0,0);
	pos = genRect(0,0,0,0);
	refreshWait = 0;
	refreshCount = 0;
	doLoop = false;
}

bool CVideoPlayer::open(std::string fname, bool scale)
{
	return open(fname, true, false);
}

// loop = to loop through the video
// useOverlay = directly write to the screen.
bool CVideoPlayer::open(std::string fname, bool loop, bool useOverlay, bool scale)
{
	close();

	this->fname = fname;
	refreshWait = 3;
	refreshCount = -1;
	doLoop = loop;

	ResourceID resource(std::string("Video/") + fname, EResType::VIDEO);

	if (!CResourceHandler::get()->existsResource(resource))
	{
		logGlobal->error("Error: video %s was not found", resource.getName());
		return false;
	}

	data = CResourceHandler::get()->load(resource);

	static const int BUFFER_SIZE = 4096;

	unsigned char * buffer  = (unsigned char *)av_malloc(BUFFER_SIZE);// will be freed by ffmpeg
	context = avio_alloc_context( buffer, BUFFER_SIZE, 0, (void *)this, lodRead, nullptr, lodSeek);

	format = avformat_alloc_context();
	format->pb = context;
	// filename is not needed - file was already open and stored in this->data;
	int avfopen = avformat_open_input(&format, "dummyFilename", nullptr, nullptr);

	if (avfopen != 0)
	{
		return false;
	}
	// Retrieve stream information
	if (avformat_find_stream_info(format, nullptr) < 0)
		return false;

	// Find the first video stream
	stream = -1;
	for(ui32 i=0; i<format->nb_streams; i++)
	{
		if (format->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO)
		{
			stream = i;
			break;
		}
	}

	if (stream < 0)
		// No video stream in that file
		return false;

	// Find the decoder for the video stream
	codec = avcodec_find_decoder(format->streams[stream]->codecpar->codec_id);

	if (codec == nullptr)
	{
		// Unsupported codec
		return false;
	}

	codecContext = avcodec_alloc_context3(codec);
	if(!codecContext)
		return false;
	// Get a pointer to the codec context for the video stream
	int ret = avcodec_parameters_to_context(codecContext, format->streams[stream]->codecpar);
	if (ret < 0)
	{
		//We cannot get codec from parameters
		avcodec_free_context(&codecContext);
		return false;
	}

	// Open codec
	if ( avcodec_open2(codecContext, codec, nullptr) < 0 )
	{
		// Could not open codec
		codec = nullptr;
		return false;
	}
	// Allocate video frame
	frame = av_frame_alloc();

	//setup scaling
	if(scale)
	{
		pos.w = screen->w;
		pos.h = screen->h;
	}
	else
	{
		pos.w  = codecContext->width;
		pos.h = codecContext->height;
	}

	// Allocate a place to put our YUV image on that screen
	if (useOverlay)
	{
		texture = SDL_CreateTexture( mainRenderer, SDL_PIXELFORMAT_IYUV, SDL_TEXTUREACCESS_STATIC, pos.w, pos.h);
	}
	else
	{
		dest = CSDL_Ext::newSurface(pos.w, pos.h);
		destRect.x = destRect.y = 0;
		destRect.w = pos.w;
		destRect.h = pos.h;
	}

	if (texture == nullptr && dest == nullptr)
		return false;

	if (texture)
	{ // Convert the image into YUV format that SDL uses
		sws = sws_getContext(codecContext->width, codecContext->height, codecContext->pix_fmt,
							 pos.w, pos.h,
							 AV_PIX_FMT_YUV420P,
							 SWS_BICUBIC, nullptr, nullptr, nullptr);
	}
	else
	{
		AVPixelFormat screenFormat = AV_PIX_FMT_NONE;
		if (screen->format->Bshift > screen->format->Rshift)
		{
			// this a BGR surface
			switch (screen->format->BytesPerPixel)
			{
				case 2: screenFormat = AV_PIX_FMT_BGR565; break;
				case 3: screenFormat = AV_PIX_FMT_BGR24; break;
				case 4: screenFormat = AV_PIX_FMT_BGR32; break;
				default: return false;
			}
		}
		else
		{
			// this a RGB surface
			switch (screen->format->BytesPerPixel)
			{
				case 2: screenFormat = AV_PIX_FMT_RGB565; break;
				case 3: screenFormat = AV_PIX_FMT_RGB24; break;
				case 4: screenFormat = AV_PIX_FMT_RGB32; break;
				default: return false;
			}
		}

		sws = sws_getContext(codecContext->width, codecContext->height, codecContext->pix_fmt,
							 pos.w, pos.h, screenFormat,
							 SWS_BICUBIC, nullptr, nullptr, nullptr);
	}

	if (sws == nullptr)
		return false;

	return true;
}

// Read the next frame. Return false on error/end of file.
bool CVideoPlayer::nextFrame()
{
	AVPacket packet;
	int frameFinished = 0;
	bool gotError = false;

	if (sws == nullptr)
		return false;

	while(!frameFinished)
	{
		int ret = av_read_frame(format, &packet);
		if (ret < 0)
		{
			// Error. It's probably an end of file.
			if (doLoop && !gotError)
			{
				// Rewind
				if (av_seek_frame(format, stream, 0, AVSEEK_FLAG_BYTE) < 0)
					break;
				gotError = true;
			}
			else
			{
				break;
			}
		}
		else
		{
			// Is this a packet from the video stream?
			if (packet.stream_index == stream)
			{
				// Decode video frame
				int rc = avcodec_send_packet(codecContext, &packet);
				if (rc >=0)
					packet.size = 0;
				rc = avcodec_receive_frame(codecContext, frame);
				if (rc >= 0)
					frameFinished = 1;
				// Did we get a video frame?
				if (frameFinished)
				{
					uint8_t *data[4];
					int linesize[4];

					if (texture) {
						av_image_alloc(data, linesize, pos.w, pos.h, AV_PIX_FMT_YUV420P, 1);

						sws_scale(sws, frame->data, frame->linesize,
								  0, codecContext->height, data, linesize);

						SDL_UpdateYUVTexture(texture, NULL, data[0], linesize[0],
								data[1], linesize[1],
								data[2], linesize[2]);
						av_freep(&data[0]);
					}
					else
					{
						/* Avoid buffer overflow caused by sws_scale():
						 *     http://trac.ffmpeg.org/ticket/9254
						 * Currently (ffmpeg-4.4 with SSE3 enabled) sws_scale()
						 * has a few requirements for target data buffers on rescaling:
						 * 1. buffer has to be aligned to be usable for SIMD instructions
						 * 2. buffer has to be padded to allow small overflow by SIMD instructions
						 * Unfortunately SDL_Surface does not provide these guarantees.
						 * This means that atempt to rescale directly into SDL surface causes
						 * memory corruption. Usually it happens on campaign selection screen
						 * where short video moves start spinning on mouse hover.
						 *
						 * To fix [1.] we use av_malloc() for memory allocation.
						 * To fix [2.] we add an `ffmpeg_pad` that provides plenty of space.
						 * We have to use intermdiate buffer and then use memcpy() to land it
						 * to SDL_Surface.
						 */
						size_t pic_bytes = dest->pitch * dest->h;
						size_t ffmped_pad = 1024; /* a few bytes of overflow will go here */
						void * for_sws = av_malloc (pic_bytes + ffmped_pad);
						data[0] = (ui8 *)for_sws;
						linesize[0] = dest->pitch;

						sws_scale(sws, frame->data, frame->linesize,
								  0, codecContext->height, data, linesize);
						memcpy(dest->pixels, for_sws, pic_bytes);
						av_free(for_sws);
					}
				}
			}

			av_packet_unref(&packet);
		}
	}

	return frameFinished != 0;
}

void CVideoPlayer::show( int x, int y, SDL_Surface *dst, bool update )
{
	if (sws == nullptr)
		return;

	pos.x = x;
	pos.y = y;
	CSDL_Ext::blitSurface(dest, &destRect, dst, &pos);

	if (update)
		SDL_UpdateRect(dst, pos.x, pos.y, pos.w, pos.h);
}

void CVideoPlayer::redraw( int x, int y, SDL_Surface *dst, bool update )
{
	show(x, y, dst, update);
}

void CVideoPlayer::update( int x, int y, SDL_Surface *dst, bool forceRedraw, bool update )
{
	if (sws == nullptr)
		return;

	if (refreshCount <= 0)
	{
		refreshCount = refreshWait;
		if (nextFrame())
			show(x,y,dst,update);
		else
		{
			open(fname);
			nextFrame();

			// The y position is wrong at the first frame.
			// Note: either the windows player or the linux player is
			// broken. Compensate here until the bug is found.
			show(x, y--, dst, update);
		}
	}
	else
	{
		redraw(x, y, dst, update);
	}

	refreshCount --;
}

void CVideoPlayer::close()
{
	fname = "";
	if (sws)
	{
		sws_freeContext(sws);
		sws = nullptr;
	}

	if (texture)
	{
		SDL_DestroyTexture(texture);
		texture = nullptr;
	}

	if (dest)
	{
		SDL_FreeSurface(dest);
		dest = nullptr;
	}

	if (frame)
	{
		av_frame_free(&frame);//will be set to null
	}

	if (codec)
	{
		avcodec_close(codecContext);
		codec = nullptr;
	}
	if (codecContext)
	{
		avcodec_free_context(&codecContext);
	}

	if (format)
	{
		avformat_close_input(&format);
	}

	if (context)
	{
		av_free(context);
		context = nullptr;
	}
}

// Plays a video. Only works for overlays.
bool CVideoPlayer::playVideo(int x, int y, bool stopOnKey)
{
	// Note: either the windows player or the linux player is
	// broken. Compensate here until the bug is found.
	y--;

	pos.x = x;
	pos.y = y;

	while(nextFrame())
	{
		if(stopOnKey && keyDown())
			return false;

		SDL_RenderCopy(mainRenderer, texture, nullptr, &pos);
		SDL_RenderPresent(mainRenderer);

		// Wait 3 frames
		GH.mainFPSmng->framerateDelay();
		GH.mainFPSmng->framerateDelay();
		GH.mainFPSmng->framerateDelay();
	}

	return true;
}

bool CVideoPlayer::openAndPlayVideo(std::string name, int x, int y, bool stopOnKey, bool scale)
{
	open(name, false, true, scale);
	bool ret = playVideo(x, y,  stopOnKey);
	close();
	return ret;
}

CVideoPlayer::~CVideoPlayer()
{
	close();
}

#endif