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/*

 * Copyright (c) 2000 Fabrice Bellard

 * Copyright (c) 2002 Francois Revol

 * Copyright (c) 2006 Baptiste Coudurier

 *

 * first version by Francois Revol 

 *

 * 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

 * GIF encoder

 * @see http://www.w3.org/Graphics/GIF/spec-gif89a.txt

 */

#define BITSTREAM_WRITER_LE

#include "libavutil/opt.h"

#include "libavutil/imgutils.h"

#include "avcodec.h"

#include "bytestream.h"

#include "internal.h"

#include "lzw.h"

#include "gif.h"

#include "put_bits.h"

typedef struct {

    const AVClass *class;

    LZWState *lzw;

    uint8_t *buf;

    AVFrame *last_frame;

    int flags;

    uint32_t palette[AVPALETTE_COUNT];  ///< local reference palette for !pal8

    uint8_t *tmpl;                      ///< temporary line buffer

} GIFContext;

enum {

    GF_OFFSETTING = 1<<0,

    GF_TRANSDIFF  = 1<<1,

};

static int pick_palette_entry(const uint8_t *buf, int linesize, int w, int h)

{

    int histogram[AVPALETTE_COUNT] = {0};

    int x, y, i;

    for (y = 0; y < h; y++) {

        for (x = 0; x < w; x++)

            histogram[buf[x]]++;

        buf += linesize;

    }

    for (i = 0; i < FF_ARRAY_ELEMS(histogram); i++)

        if (!histogram[i])

            return i;

    return -1;

}

static int gif_image_write_image(AVCodecContext *avctx,

                                 uint8_t **bytestream, uint8_t *end,

                                 const uint32_t *palette,

                                 const uint8_t *buf, const int linesize,

                                 AVPacket *pkt)

{

    GIFContext *s = avctx->priv_data;

    int len = 0, height = avctx->height, width = avctx->width, x, y;

    int x_start = 0, y_start = 0, trans = -1;

    const uint8_t *ptr;

    /* Crop image */

    // TODO support with palette change

    if ((s->flags & GF_OFFSETTING) && s->last_frame && !palette) {

        const uint8_t *ref = s->last_frame->data[0];

        const int ref_linesize = s->last_frame->linesize[0];

        int x_end = avctx->width  - 1,

            y_end = avctx->height - 1;

        /* skip common lines */

        while (y_start < y_end) {

            if (memcmp(ref + y_start*ref_linesize, buf + y_start*linesize, width))

                break;

            y_start++;

        }

        while (y_end > y_start) {

            if (memcmp(ref + y_end*ref_linesize, buf + y_end*linesize, width))

                break;

            y_end--;

        }

        height = y_end + 1 - y_start;

        /* skip common columns */

        while (x_start < x_end) {

            int same_column = 1;

            for (y = y_start; y < y_end; y++) {

                if (ref[y*ref_linesize + x_start] != buf[y*linesize + x_start]) {

                    same_column = 0;

                    break;

                }

            }

            if (!same_column)

                break;

            x_start++;

        }

        while (x_end > x_start) {

            int same_column = 1;

            for (y = y_start; y < y_end; y++) {

                if (ref[y*ref_linesize + x_end] != buf[y*linesize + x_end]) {

                    same_column = 0;

                    break;

                }

            }

            if (!same_column)

                break;

            x_end--;

        }

        width = x_end + 1 - x_start;

        av_log(avctx, AV_LOG_DEBUG,"%dx%d image at pos (%d;%d) [area:%dx%d]\n",

               width, height, x_start, y_start, avctx->width, avctx->height);

    }

    /* image block */

    bytestream_put_byte(bytestream, GIF_IMAGE_SEPARATOR);

    bytestream_put_le16(bytestream, x_start);

    bytestream_put_le16(bytestream, y_start);

    bytestream_put_le16(bytestream, width);

    bytestream_put_le16(bytestream, height);

    if (!palette) {

        bytestream_put_byte(bytestream, 0x00); /* flags */

    } else {

        unsigned i;

        bytestream_put_byte(bytestream, 1<<7 | 0x7); /* flags */

        for (i = 0; i < AVPALETTE_COUNT; i++) {

            const uint32_t v = palette[i];

            bytestream_put_be24(bytestream, v);

        }

    }

    /* TODO: support with palette change (pal8) */

    if ((s->flags & GF_TRANSDIFF) && s->last_frame && !palette) {

        trans = pick_palette_entry(buf + y_start*linesize + x_start,

                                   linesize, width, height);

        if (trans < 0) { // TODO, patch welcome

            av_log(avctx, AV_LOG_DEBUG, "No available color, can not use transparency\n");

        } else {

            uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);

            if (!pal_exdata)

                return AVERROR(ENOMEM);

            memcpy(pal_exdata, s->palette, AVPALETTE_SIZE);

            pal_exdata[trans*4 + 3*!HAVE_BIGENDIAN] = 0x00;

        }

    }

    bytestream_put_byte(bytestream, 0x08);

    ff_lzw_encode_init(s->lzw, s->buf, 2 * width * height,

                       12, FF_LZW_GIF, put_bits);

    ptr = buf + y_start*linesize + x_start;

    if (trans >= 0) {

        const int ref_linesize = s->last_frame->linesize[0];

        const uint8_t *ref = s->last_frame->data[0] + y_start*ref_linesize + x_start;

        for (y = 0; y < height; y++) {

            memcpy(s->tmpl, ptr, width);

            for (x = 0; x < width; x++)

                if (ref[x] == ptr[x])

                    s->tmpl[x] = trans;

            len += ff_lzw_encode(s->lzw, s->tmpl, width);

            ptr += linesize;

            ref += ref_linesize;

        }

    } else {

        for (y = 0; y < height; y++) {

            len += ff_lzw_encode(s->lzw, ptr, width);

            ptr += linesize;

        }

    }

    len += ff_lzw_encode_flush(s->lzw, flush_put_bits);

    ptr = s->buf;

    while (len > 0) {

        int size = FFMIN(255, len);

        bytestream_put_byte(bytestream, size);

        if (end - *bytestream < size)

            return -1;

        bytestream_put_buffer(bytestream, ptr, size);

        ptr += size;

        len -= size;

    }

    bytestream_put_byte(bytestream, 0x00); /* end of image block */

    return 0;

}

static av_cold int gif_encode_init(AVCodecContext *avctx)

{

    GIFContext *s = avctx->priv_data;

    if (avctx->width > 65535 || avctx->height > 65535) {

        av_log(avctx, AV_LOG_ERROR, "GIF does not support resolutions above 65535x65535\n");

        return AVERROR(EINVAL);

    }

    s->lzw = av_mallocz(ff_lzw_encode_state_size);

    s->buf = av_malloc(avctx->width*avctx->height*2);

    s->tmpl = av_malloc(avctx->width);

    if (!s->tmpl || !s->buf || !s->lzw)

        return AVERROR(ENOMEM);

    if (avpriv_set_systematic_pal2(s->palette, avctx->pix_fmt) < 0)

        av_assert0(avctx->pix_fmt == AV_PIX_FMT_PAL8);

    return 0;

}

static int gif_encode_frame(AVCodecContext *avctx, AVPacket *pkt,

                            const AVFrame *pict, int *got_packet)

{

    GIFContext *s = avctx->priv_data;

    AVFrame *const p = (AVFrame *)pict;

    uint8_t *outbuf_ptr, *end;

    const uint32_t *palette = NULL;

    int ret;

    if ((ret = ff_alloc_packet2(avctx, pkt, avctx->width*avctx->height*7/5 + FF_MIN_BUFFER_SIZE)) < 0)

        return ret;

    outbuf_ptr = pkt->data;

    end        = pkt->data + pkt->size;

    p->pict_type = AV_PICTURE_TYPE_I;

    p->key_frame = 1;

    if (avctx->pix_fmt == AV_PIX_FMT_PAL8) {

        uint8_t *pal_exdata = av_packet_new_side_data(pkt, AV_PKT_DATA_PALETTE, AVPALETTE_SIZE);

        if (!pal_exdata)

            return AVERROR(ENOMEM);

        memcpy(pal_exdata, p->data[1], AVPALETTE_SIZE);

        palette = (uint32_t*)p->data[1];

    }

    gif_image_write_image(avctx, &outbuf_ptr, end, palette,

                          pict->data[0], pict->linesize[0], pkt);

    if (!s->last_frame) {

        s->last_frame = av_frame_alloc();

        if (!s->last_frame)

            return AVERROR(ENOMEM);

    }

    av_frame_unref(s->last_frame);

    ret = av_frame_ref(s->last_frame, (AVFrame*)pict);

    if (ret < 0)

        return ret;

    pkt->size   = outbuf_ptr - pkt->data;

    pkt->flags |= AV_PKT_FLAG_KEY;

    *got_packet = 1;

    return 0;

}

static int gif_encode_close(AVCodecContext *avctx)

{

    GIFContext *s = avctx->priv_data;

    av_freep(&s->lzw);

    av_freep(&s->buf);

    av_frame_free(&s->last_frame);

    av_freep(&s->tmpl);

    return 0;

}

#define OFFSET(x) offsetof(GIFContext, x)

#define FLAGS AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM

static const AVOption gif_options[] = {

    { "gifflags", "set GIF flags", OFFSET(flags), AV_OPT_TYPE_FLAGS, {.i64 = GF_OFFSETTING|GF_TRANSDIFF}, 0, INT_MAX, FLAGS, "flags" },

        { "offsetting", "enable picture offsetting", 0, AV_OPT_TYPE_CONST, {.i64=GF_OFFSETTING}, INT_MIN, INT_MAX, FLAGS, "flags" },

        { "transdiff", "enable transparency detection between frames", 0, AV_OPT_TYPE_CONST, {.i64=GF_TRANSDIFF}, INT_MIN, INT_MAX, FLAGS, "flags" },

    { NULL }

};

static const AVClass gif_class = {

    .class_name = "GIF encoder",

    .item_name  = av_default_item_name,

    .option     = gif_options,

    .version    = LIBAVUTIL_VERSION_INT,

};

AVCodec ff_gif_encoder = {

    .name           = "gif",

    .long_name      = NULL_IF_CONFIG_SMALL("GIF (Graphics Interchange Format)"),

    .type           = AVMEDIA_TYPE_VIDEO,

    .id             = AV_CODEC_ID_GIF,

    .priv_data_size = sizeof(GIFContext),

    .init           = gif_encode_init,

    .encode2        = gif_encode_frame,

    .close          = gif_encode_close,

    .pix_fmts       = (const enum AVPixelFormat[]){

        AV_PIX_FMT_RGB8, AV_PIX_FMT_BGR8, AV_PIX_FMT_RGB4_BYTE, AV_PIX_FMT_BGR4_BYTE,

        AV_PIX_FMT_GRAY8, AV_PIX_FMT_PAL8, AV_PIX_FMT_NONE

    },

    .priv_class     = &gif_class,

};