/*
 * Copyright (c) 2013 Stefano Sabatini
 *
 * This file is part of FFmpeg.
 *
 * FFmpeg is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * FFmpeg 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
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with FFmpeg; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
 */

/**
 * @file
 * video quantizer filter based on ELBG
 */

#include "libavcodec/elbg.h"
#include "libavutil/opt.h"
#include "libavutil/pixdesc.h"
#include "libavutil/random_seed.h"

#include "avfilter.h"
#include "drawutils.h"
#include "internal.h"
#include "video.h"

typedef struct ColorContext {
    const AVClass *class;
    AVLFG lfg;
    unsigned int lfg_seed;
    int max_steps_nb;
    int *codeword;
    int codeword_length;
    int *codeword_closest_codebook_idxs;
    int *codebook;
    int codebook_length;
    const AVPixFmtDescriptor *pix_desc;
    uint8_t rgba_map[4];
} ELBGContext;

#define OFFSET(x) offsetof(ELBGContext, x)
#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM

static const AVOption elbg_options[] = {
    { "codebook_length", "set codebook length", OFFSET(codebook_length), AV_OPT_TYPE_INT, { .i64 = 256 }, 1, INT_MAX, FLAGS },
    { "l",               "set codebook length", OFFSET(codebook_length), AV_OPT_TYPE_INT, { .i64 = 256 }, 1, INT_MAX, FLAGS },
    { "nb_steps", "set max number of steps used to compute the mapping", OFFSET(max_steps_nb), AV_OPT_TYPE_INT, { .i64 = 1 }, 1, INT_MAX, FLAGS },
    { "n",        "set max number of steps used to compute the mapping", OFFSET(max_steps_nb), AV_OPT_TYPE_INT, { .i64 = 1 }, 1, INT_MAX, FLAGS },
    { "seed", "set the random seed", OFFSET(lfg_seed), AV_OPT_TYPE_INT, {.i64 = -1}, -1, UINT32_MAX, FLAGS },
    { "s",    "set the random seed", OFFSET(lfg_seed), AV_OPT_TYPE_INT, { .i64 = -1 }, -1, UINT32_MAX, FLAGS },
    { NULL }
};

AVFILTER_DEFINE_CLASS(elbg);

static av_cold int init(AVFilterContext *ctx)
{
    ELBGContext *elbg = ctx->priv;

    if (elbg->lfg_seed == -1)
        elbg->lfg_seed = av_get_random_seed();

    av_lfg_init(&elbg->lfg, elbg->lfg_seed);
    return 0;
}

static int query_formats(AVFilterContext *ctx)
{
    static const enum AVPixelFormat pix_fmts[] = {
        AV_PIX_FMT_ARGB, AV_PIX_FMT_RGBA, AV_PIX_FMT_ABGR, AV_PIX_FMT_BGRA,
        AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24,
        AV_PIX_FMT_NONE
    };
    AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
    if (!fmts_list)
        return AVERROR(ENOMEM);
    return ff_set_common_formats(ctx, fmts_list);
}

#define NB_COMPONENTS 3

static int config_input(AVFilterLink *inlink)
{
    AVFilterContext *ctx = inlink->dst;
    ELBGContext *elbg = ctx->priv;

    elbg->pix_desc = av_pix_fmt_desc_get(inlink->format);
    elbg->codeword_length = inlink->w * inlink->h;
    elbg->codeword = av_realloc_f(elbg->codeword, elbg->codeword_length,
                                  NB_COMPONENTS * sizeof(*elbg->codeword));
    if (!elbg->codeword)
        return AVERROR(ENOMEM);

    elbg->codeword_closest_codebook_idxs =
        av_realloc_f(elbg->codeword_closest_codebook_idxs, elbg->codeword_length,
                     sizeof(*elbg->codeword_closest_codebook_idxs));
    if (!elbg->codeword_closest_codebook_idxs)
        return AVERROR(ENOMEM);

    elbg->codebook = av_realloc_f(elbg->codebook, elbg->codebook_length,
                                  NB_COMPONENTS * sizeof(*elbg->codebook));
    if (!elbg->codebook)
        return AVERROR(ENOMEM);

    ff_fill_rgba_map(elbg->rgba_map, inlink->format);

    return 0;
}

#define R 0
#define G 1
#define B 2

static int filter_frame(AVFilterLink *inlink, AVFrame *frame)
{
    ELBGContext *elbg = inlink->dst->priv;
    int i, j, k;
    uint8_t *p, *p0;

    const uint8_t r_idx  = elbg->rgba_map[R];
    const uint8_t g_idx  = elbg->rgba_map[G];
    const uint8_t b_idx  = elbg->rgba_map[B];

    /* build the codeword */
    p0 = frame->data[0];
    k = 0;
    for (i = 0; i < inlink->h; i++) {
        p = p0;
        for (j = 0; j < inlink->w; j++) {
            elbg->codeword[k++] = p[r_idx];
            elbg->codeword[k++] = p[g_idx];
            elbg->codeword[k++] = p[b_idx];
            p += elbg->pix_desc->nb_components;
        }
        p0 += frame->linesize[0];
    }

    /* compute the codebook */
    avpriv_init_elbg(elbg->codeword, NB_COMPONENTS, elbg->codeword_length,
                     elbg->codebook, elbg->codebook_length, elbg->max_steps_nb,
                     elbg->codeword_closest_codebook_idxs, &elbg->lfg);
    avpriv_do_elbg(elbg->codeword, NB_COMPONENTS, elbg->codeword_length,
                   elbg->codebook, elbg->codebook_length, elbg->max_steps_nb,
                   elbg->codeword_closest_codebook_idxs, &elbg->lfg);

    /* fill the output with the codebook values */
    p0 = frame->data[0];

    k = 0;
    for (i = 0; i < inlink->h; i++) {
        p = p0;
        for (j = 0; j < inlink->w; j++) {
            int cb_idx = NB_COMPONENTS * elbg->codeword_closest_codebook_idxs[k++];
            p[r_idx] = elbg->codebook[cb_idx];
            p[g_idx] = elbg->codebook[cb_idx+1];
            p[b_idx] = elbg->codebook[cb_idx+2];
            p += elbg->pix_desc->nb_components;
        }
        p0 += frame->linesize[0];
    }

    return ff_filter_frame(inlink->dst->outputs[0], frame);
}

static av_cold void uninit(AVFilterContext *ctx)
{
    ELBGContext *elbg = ctx->priv;

    av_freep(&elbg->codebook);
    av_freep(&elbg->codeword);
    av_freep(&elbg->codeword_closest_codebook_idxs);
}

static const AVFilterPad elbg_inputs[] = {
    {
        .name           = "default",
        .type           = AVMEDIA_TYPE_VIDEO,
        .config_props   = config_input,
        .filter_frame   = filter_frame,
        .needs_writable = 1,
    },
    { NULL }
};

static const AVFilterPad elbg_outputs[] = {
    {
        .name = "default",
        .type = AVMEDIA_TYPE_VIDEO,
    },
    { NULL }
};

AVFilter ff_vf_elbg = {
    .name          = "elbg",
    .description   = NULL_IF_CONFIG_SMALL("Apply posterize effect, using the ELBG algorithm."),
    .priv_size     = sizeof(ELBGContext),
    .priv_class    = &elbg_class,
    .query_formats = query_formats,
    .init          = init,
    .uninit        = uninit,
    .inputs        = elbg_inputs,
    .outputs       = elbg_outputs,
};