/*
 *  Copyright (C) 2013-2017 Savoir-faire Linux Inc.
 *
 *  Author: Guillaume Roguez <Guillaume.Roguez@savoirfairelinux.com>
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA.
 */

#include "libav_deps.h" // MUST BE INCLUDED FIRST
#include "libav_utils.h"
#include "video_scaler.h"
#include "media_buffer.h"
#include "logger.h"

#include <cassert>

namespace ring { namespace video {

VideoScaler::VideoScaler()
    : ctx_(0), mode_(SWS_FAST_BILINEAR), tmp_data_()
{}

VideoScaler::~VideoScaler()
{
    sws_freeContext(ctx_);
}

void
VideoScaler::scale(const VideoFrame& input, VideoFrame& output)
{
    const auto input_frame = input.pointer();
    auto output_frame = output.pointer();

    ctx_ = sws_getCachedContext(ctx_,
                                input_frame->width,
                                input_frame->height,
                                (AVPixelFormat) input_frame->format,
                                output_frame->width,
                                output_frame->height,
                                (AVPixelFormat) output_frame->format,
                                mode_,
                                NULL, NULL, NULL);
    if (!ctx_) {
        RING_ERR("Unable to create a scaler context");
        return;
    }

    sws_scale(ctx_, input_frame->data, input_frame->linesize, 0,
              input_frame->height, output_frame->data,
              output_frame->linesize);
}

void
VideoScaler::scale_with_aspect(const VideoFrame& input, VideoFrame& output)
{
    auto output_frame = output.pointer();
    scale_and_pad(input, output, 0, 0, output_frame->width,
                  output_frame->height, true);
}

void
VideoScaler::scale_and_pad(const VideoFrame& input, VideoFrame& output,
                           unsigned xoff, unsigned yoff,
                           unsigned dest_width, unsigned dest_height,
                           bool keep_aspect)
{
    const auto input_frame = input.pointer();
    auto output_frame = output.pointer();

    /* Correct destination width/height and offset if we need to keep input
     * frame aspect.
     */
    if (keep_aspect) {
        const float local_ratio = (float)dest_width / dest_height;
        const float input_ratio = (float)input_frame->width / input_frame->height;

        if (local_ratio > input_ratio) {
            auto old_dest_width = dest_width;
            dest_width = dest_height * input_ratio;
            xoff += (old_dest_width - dest_width) / 2;
        } else {
            auto old_dest_heigth = dest_height;
            dest_height = dest_width / input_ratio;
            yoff += (old_dest_heigth - dest_height) / 2;
        }
    }

    // buffer overflow checks
    assert(xoff + dest_width <= (unsigned)output_frame->width);
    assert(yoff + dest_height <= (unsigned)output_frame->height);

    ctx_ = sws_getCachedContext(ctx_,
                                input_frame->width,
                                input_frame->height,
                                (AVPixelFormat) input_frame->format,
                                dest_width,
                                dest_height,
                                (AVPixelFormat) output_frame->format,
                                mode_,
                                NULL, NULL, NULL);
    if (!ctx_) {
        RING_ERR("Unable to create a scaler context");
        return;
    }

    // Make an offset'ed copy of output data from xoff and yoff
    const auto out_desc = av_pix_fmt_desc_get((AVPixelFormat)output_frame->format);
    memset(tmp_data_, 0, sizeof(tmp_data_));
    for (int i = 0; i < 4 && output_frame->linesize[i]; i++) {
        signed x_shift=xoff, y_shift=yoff;
        if (i == 1 || i == 2) {
            x_shift = -((-x_shift) >> out_desc->log2_chroma_w);
            y_shift = -((-y_shift) >> out_desc->log2_chroma_h);
        }
#if LIBAVUTIL_VERSION_MAJOR < 56
        auto x_step = out_desc->comp[i].step_minus1 + 1; // using deprecated api
#else
        auto x_step = out_desc->comp[i].step;
#endif
        tmp_data_[i] = output_frame->data[i] + y_shift * output_frame->linesize[i] + x_shift * x_step;
    }

    sws_scale(ctx_, input_frame->data, input_frame->linesize, 0,
              input_frame->height, tmp_data_, output_frame->linesize);
}

void VideoScaler::reset()
{
    if (ctx_) {
        sws_freeContext(ctx_);
        ctx_ = nullptr;
    }
}

}} // namespace ring::video
