#include "playback.h"

#include "project/clip.h"
#include "project/sequence.h"
#include "io/media.h"
#include "playback/audio.h"
#include "playback/cacher.h"
#include "panels/panels.h"
#include "panels/timeline.h"
#include "panels/viewer.h"
#include "effects/effect.h"

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

#include <algorithm>
#include <QObject>
#include <QOpenGLTexture>
#include <QDebug>
#include <QOpenGLPixelTransferOptions>
#include <QOpenGLFramebufferObject>

bool texture_failed = false;

void open_clip(Clip* clip, bool multithreaded) {
	if (clip->media_type == MEDIA_TYPE_FOOTAGE) {
		if (multithreaded) {
			if (clip->open_lock.tryLock()) {
				clip->multithreaded = true;

				// maybe keep cacher instance in memory while clip exists for performance?
				clip->cacher = new Cacher(clip);
				QObject::connect(clip->cacher, SIGNAL(finished()), clip->cacher, SLOT(deleteLater()));

				clip->cacher->start(QThread::LowPriority);
			}
		} else {
			clip->multithreaded = false;
			clip->finished_opening = false;
			clip->open = true;

			open_clip_worker(clip);
		}
	} else if (clip->media_type == MEDIA_TYPE_SEQUENCE) {
		clip->open = true;
	}
}

void close_clip(Clip* clip) {
	// destroy opengl texture in main thread
	if (clip->texture != NULL) {
		clip->texture->destroy();
		clip->texture = NULL;
	}

	if (clip->fbo != NULL) {
		delete clip->fbo;
		clip->fbo = NULL;
	}

	if (clip->media_type == MEDIA_TYPE_FOOTAGE) {
		if (clip->multithreaded) {
			clip->cacher->caching = false;
			clip->can_cache.wakeAll();
		} else {
			close_clip_worker(clip);
		}
	} else if (clip->media_type == MEDIA_TYPE_SEQUENCE) {
		closeActiveClips(static_cast<Sequence*>(clip->media), false);
		clip->open = false;
	}
}

void cache_clip(Clip* clip, long playhead, bool write_A, bool write_B, bool reset, Clip* nest) {
	if (clip->multithreaded) {
		clip->cacher->playhead = playhead;
		clip->cacher->write_A = write_A;
		clip->cacher->write_B = write_B;
		clip->cacher->reset = reset;
        clip->cacher->nest = nest;

		clip->can_cache.wakeAll();
	} else {
        cache_clip_worker(clip, playhead, write_A, write_B, reset, nest);
	}
}

bool get_clip_frame(Clip* c, long playhead) {
	if (c->open) {
		long sequence_clip_time = playhead - c->timeline_in + c->clip_in;
		long clip_time = refactor_frame_number(sequence_clip_time, c->sequence->frame_rate, av_q2d(av_guess_frame_rate(c->formatCtx, c->stream, c->frame)));

		// do we need to update the texture?
        MediaStream* ms = static_cast<Media*>(c->media)->get_stream_from_file_index(c->track < 0, c->media_stream);

		AVFrame* current_frame = NULL;
		bool no_frame = false;

		// get frame data
		if (ms->infinite_length) { // if clip is a still frame, we only need one
			if (c->cache_A.written) {
				// retrieve cached frame
				current_frame = c->cache_A.frames[0];
			} else if (c->lock.tryLock()) {
				// grab image
				cache_clip(c, 0, true, false, false, NULL);
				c->lock.unlock();
			}
		} else {
			// keeping a RAM cache improves performance, however it's detrimental when rendering
			// determine which cache contains the requested frame
			bool using_cache_A = false;
			bool using_cache_B = false;
			AVFrame** cache = NULL;
			long cache_offset = 0;
			bool cache_needs_reset = false;

			if (c->cache_A.written && clip_time >= c->cache_A.offset && clip_time < c->cache_A.offset + c->cache_size) {
				if (clip_time < c->cache_A.offset + c->cache_A.write_count) {
					if (c->cache_A.mutex.tryLock()) { // lock in case cacher is still writing to it
						using_cache_A = true;
						c->cache_A.unread = false;
						cache = c->cache_A.frames;
						cache_offset = c->cache_A.offset;
						c->cache_A.mutex.unlock();
					}
				} else {
					no_frame = true;
				}
			} else if (c->cache_B.written && clip_time >= c->cache_B.offset && clip_time < c->cache_B.offset + c->cache_size) {
				if (clip_time < c->cache_B.offset + c->cache_B.write_count) {
					if (c->cache_B.mutex.tryLock()) { // lock in case cacher is still writing to it
						using_cache_B = true;
						c->cache_B.unread = false;
						cache = c->cache_B.frames;
						cache_offset = c->cache_B.offset;
						c->cache_B.mutex.unlock();
					}
				} else {
					no_frame = true;
				}
			} else {
				// this is technically bad, unless we just seeked
				c->cache_A.unread = c->cache_B.unread = false;
				cache_needs_reset = true;
			}

			if (!no_frame) {
				if (cache != NULL) {
					current_frame = cache[clip_time - cache_offset];
				}

				// determine whether we should start filling the other cache
				if (!using_cache_A || !using_cache_B) {
					if (c->lock.tryLock()) {
						bool write_A = (!using_cache_A && !c->cache_A.unread);
						bool write_B = (!using_cache_B && !c->cache_B.unread);
						if (write_A || write_B) {
							// if we have no cache and need to seek, start us at the current playhead, otherwise start at the end of the current cache
							cache_clip(c, (cache_needs_reset) ? clip_time : cache_offset + c->cache_size, write_A, write_B, cache_needs_reset, NULL);
						}
						c->lock.unlock();
					}
				}
			}
		}

		if (current_frame != NULL) {
			// set up opengl texture
			if (c->texture == NULL) {
				c->texture = new QOpenGLTexture(QOpenGLTexture::Target2D);
				c->texture->setSize(current_frame->width, current_frame->height);
				c->texture->setFormat(QOpenGLTexture::RGBA8_UNorm);
				c->texture->setMipLevels(c->texture->maximumMipLevels());
				c->texture->setMinMagFilters(QOpenGLTexture::Linear, QOpenGLTexture::Linear);
				c->texture->allocateStorage(QOpenGLTexture::RGBA, QOpenGLTexture::UInt8);
			}

			memcpy(c->comp_frame, current_frame->data[0], c->comp_frame_size);
			for (int i=0;i<c->effects.size();i++) {
                if (c->effects.at(i)->is_enabled() && c->effects.at(i)->enable_image) {
					c->effects.at(i)->process_image(sequence_clip_time, c->comp_frame, current_frame->width, current_frame->height);
				}
			}

			c->texture->setData(0, QOpenGLTexture::RGBA, QOpenGLTexture::UInt8, c->comp_frame);
			c->texture_frame = clip_time;

			return true;
		} else if (!no_frame) {
			texture_failed = true;
			qDebug() << "[ERROR] Failed to retrieve frame from cache (R:" << clip_time << "| A:" << c->cache_A.offset << "-" << c->cache_A.offset+c->cache_size-1 << "| B:" << c->cache_B.offset << "-" << c->cache_B.offset+c->cache_size-1 << "| WA:" << c->cache_A.written << "| WB:" << c->cache_B.written << ")";
		}
	}
    return false;
}

double playhead_to_seconds(Clip* c, long playhead) {
	// returns time in seconds
    return (qMax((long) 0, playhead - c->timeline_in) + c->clip_in)/c->sequence->frame_rate;
}

long seconds_to_clip_frame(Clip* c, double seconds) {
	// returns time as frame number (according to clip's frame rate)
	if (c->stream->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
		return floor(seconds*av_q2d(av_guess_frame_rate(c->formatCtx, c->stream, c->frame)));
	} else {
		qDebug() << "[ERROR] seconds_to_clip_frame only works on video streams";
		return 0;
	}
}

double clip_frame_to_seconds(Clip* c, long clip_frame) {
    // returns frame number in decimal seconds
	return (double) clip_frame / av_q2d(av_guess_frame_rate(c->formatCtx, c->stream, c->frame));
}

int retrieve_next_frame(Clip* c, AVFrame* f) {
	int result = 0;
    int receive_ret;

	// do we need to retrieve a new packet for a new frame?
    while ((receive_ret = avcodec_receive_frame(c->codecCtx, f)) == AVERROR(EAGAIN)) {
		int read_ret = 0;
		do {
			if (c->pkt_written) {
				av_packet_unref(c->pkt);
			}
			read_ret = av_read_frame(c->formatCtx, c->pkt);
			c->pkt_written = true;
        } while (read_ret >= 0 && c->pkt->stream_index != c->media_stream);

		if (read_ret >= 0) {
			int send_ret = avcodec_send_packet(c->codecCtx, c->pkt);
			if (send_ret < 0) {
				qDebug() << "[ERROR] Failed to send packet to decoder." << send_ret;
                return send_ret;
			}
        } else {
			if (read_ret != AVERROR_EOF) qDebug() << "[ERROR] Could not read frame." << read_ret;
			return read_ret; // skips trying to find a frame at all
		}
	}
	if (receive_ret < 0) {
		qDebug() << "[ERROR] Failed to receive packet from decoder." << receive_ret;
		result = receive_ret;
	}

	return result;
}

void retrieve_next_frame_raw_data(Clip* c, AVFrame* output) {
    if (c->reached_end) {
        qDebug() << "[WARNING] Attempted to retrieve frame of stream with no frames left";
    } else {
        int ret = retrieve_next_frame(c, c->frame);
        if (ret >= 0) {
            if (c->stream->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
				sws_scale(c->sws_ctx, c->frame->data, c->frame->linesize, 0, c->stream->codecpar->height, output->data, output->linesize);
//				output->pts = c->frame->best_effort_timestamp;
            } else if (c->stream->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
                output->pts = c->frame->pts;
                ret = swr_convert_frame(c->swr_ctx, output, c->frame);
                if (ret < 0) {
                    qDebug() << "[ERROR] Failed to resample audio." << ret;
                }
            }
        } else if (ret == AVERROR_EOF) {
            c->reached_end = true;
        } else {
            qDebug() << "[WARNING] Raw frame data could not be retrieved." << ret;
        }
    }
}

bool is_clip_active(Clip* c, long playhead) {
    return c->enabled
            && c->timeline_in < playhead + ceil(c->sequence->frame_rate)
            && c->timeline_out > playhead
            && playhead - c->timeline_in + c->clip_in < c->getMediaLength(c->sequence->frame_rate);
}

void set_sequence(Sequence* s) {
	closeActiveClips(sequence, true);
    sequence = s;
    panel_timeline->update_sequence();
    panel_viewer->update_sequence();
    panel_timeline->setFocus();
}

void closeActiveClips(Sequence *s, bool wait) {
	if (s != NULL) {
		for (int i=0;i<s->clip_count();i++) {
			Clip* c = s->get_clip(i);
			if (c != NULL) {
				if (c->media_type == MEDIA_TYPE_SEQUENCE) {
					closeActiveClips(static_cast<Sequence*>(c->media), wait);
					close_clip(c);
				} else if (c->media_type == MEDIA_TYPE_FOOTAGE && c->open) {
					close_clip(c);
					if (c->multithreaded && wait) c->cacher->wait();
				}
			}
		}
	}
}