/*
  * Vidvox Hap encoder
  * Copyright (C) 2015 Vittorio Giovara <vittorio.giovara@gmail.com>

  * Copyright (C) 2015 Tom Butterworth <bangnoise@gmail.com>

  *

  * 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
  * Hap encoder
  *
  * Fourcc: Hap1, Hap5, HapY
  *
  * https://github.com/Vidvox/hap/blob/master/documentation/HapVideoDRAFT.md
  */
 
 #include <stdint.h>
 #include "snappy-c.h"
 
 #include "libavutil/frame.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/intreadwrite.h"
 #include "libavutil/opt.h"
 
 #include "avcodec.h"
 #include "bytestream.h"
 #include "hap.h"
 #include "internal.h"
 #include "texturedsp.h"
 

 #define HAP_MAX_CHUNKS 64
 
 enum HapHeaderLength {

     /* Short header: four bytes with a 24 bit size value */
     HAP_HDR_SHORT = 4,
     /* Long header: eight bytes with a 32 bit size value */
     HAP_HDR_LONG = 8,

 };

 static int compress_texture(AVCodecContext *avctx, uint8_t *out, int out_length, const AVFrame *f)

 {
     HapContext *ctx = avctx->priv_data;
     int i, j;
 

     if (ctx->tex_size > out_length)
         return AVERROR_BUFFER_TOO_SMALL;
 

     for (j = 0; j < avctx->height; j += 4) {
         for (i = 0; i < avctx->width; i += 4) {
             uint8_t *p = f->data[0] + i * 4 + j * f->linesize[0];
             const int step = ctx->tex_fun(out, f->linesize[0], p);
             out += step;
         }
     }

 
     return 0;

 }
 

 /* section_length does not include the header */
 static void hap_write_section_header(PutByteContext *pbc,
                                      enum HapHeaderLength header_length,
                                      int section_length,
                                      enum HapSectionType section_type)
 {
     /* The first three bytes are the length of the section (not including the
      * header) or zero if using an eight-byte header.
      * For an eight-byte header, the length is in the last four bytes.
      * The fourth byte stores the section type. */

     bytestream2_put_le24(pbc, header_length == HAP_HDR_LONG ? 0 : section_length);

     bytestream2_put_byte(pbc, section_type);
 

     if (header_length == HAP_HDR_LONG) {

         bytestream2_put_le32(pbc, section_length);
     }
 }
 
 static int hap_compress_frame(AVCodecContext *avctx, uint8_t *dst)
 {
     HapContext *ctx = avctx->priv_data;
     int i, final_size = 0;
 
     for (i = 0; i < ctx->chunk_count; i++) {
         HapChunk *chunk = &ctx->chunks[i];
         uint8_t *chunk_src, *chunk_dst;
         int ret;
 
         if (i == 0) {
             chunk->compressed_offset = 0;
         } else {
             chunk->compressed_offset = ctx->chunks[i-1].compressed_offset
                                        + ctx->chunks[i-1].compressed_size;
         }
         chunk->uncompressed_size = ctx->tex_size / ctx->chunk_count;
         chunk->uncompressed_offset = i * chunk->uncompressed_size;
         chunk->compressed_size = ctx->max_snappy;
         chunk_src = ctx->tex_buf + chunk->uncompressed_offset;
         chunk_dst = dst + chunk->compressed_offset;
 
         /* Compress with snappy too, write directly on packet buffer. */
         ret = snappy_compress(chunk_src, chunk->uncompressed_size,
                               chunk_dst, &chunk->compressed_size);
         if (ret != SNAPPY_OK) {
             av_log(avctx, AV_LOG_ERROR, "Snappy compress error.\n");
             return AVERROR_BUG;
         }
 
         /* If there is no gain from snappy, just use the raw texture. */
         if (chunk->compressed_size >= chunk->uncompressed_size) {
             av_log(avctx, AV_LOG_VERBOSE,

                    "Snappy buffer bigger than uncompressed (%"SIZE_SPECIFIER" >= %"SIZE_SPECIFIER" bytes).\n",

                    chunk->compressed_size, chunk->uncompressed_size);
             memcpy(chunk_dst, chunk_src, chunk->uncompressed_size);
             chunk->compressor = HAP_COMP_NONE;
             chunk->compressed_size = chunk->uncompressed_size;
         } else {
             chunk->compressor = HAP_COMP_SNAPPY;
         }
 
         final_size += chunk->compressed_size;
     }
 
     return final_size;
 }
 
 static int hap_decode_instructions_length(HapContext *ctx)
 {

     /*    Second-Stage Compressor Table (one byte per entry)
      *  + Chunk Size Table (four bytes per entry)
      *  + headers for both sections (short versions)
      *  = chunk_count + (4 * chunk_count) + 4 + 4 */

     return (5 * ctx->chunk_count) + 8;
 }
 
 static int hap_header_length(HapContext *ctx)
 {
     /* Top section header (long version) */

     int length = HAP_HDR_LONG;

 
     if (ctx->chunk_count > 1) {
         /* Decode Instructions header (short) + Decode Instructions Container */

         length += HAP_HDR_SHORT + hap_decode_instructions_length(ctx);

     }
 
     return length;
 }
 
 static void hap_write_frame_header(HapContext *ctx, uint8_t *dst, int frame_length)
 {
     PutByteContext pbc;
     int i;
 
     bytestream2_init_writer(&pbc, dst, frame_length);
     if (ctx->chunk_count == 1) {
         /* Write a simple header */

         hap_write_section_header(&pbc, HAP_HDR_LONG, frame_length - 8,

                                  ctx->chunks[0].compressor | ctx->opt_tex_fmt);
     } else {
         /* Write a complex header with Decode Instructions Container */

         hap_write_section_header(&pbc, HAP_HDR_LONG, frame_length - 8,

                                  HAP_COMP_COMPLEX | ctx->opt_tex_fmt);

         hap_write_section_header(&pbc, HAP_HDR_SHORT, hap_decode_instructions_length(ctx),

                                  HAP_ST_DECODE_INSTRUCTIONS);

         hap_write_section_header(&pbc, HAP_HDR_SHORT, ctx->chunk_count,

                                  HAP_ST_COMPRESSOR_TABLE);
 
         for (i = 0; i < ctx->chunk_count; i++) {
             bytestream2_put_byte(&pbc, ctx->chunks[i].compressor >> 4);
         }
 

         hap_write_section_header(&pbc, HAP_HDR_SHORT, ctx->chunk_count * 4,

                                  HAP_ST_SIZE_TABLE);
 
         for (i = 0; i < ctx->chunk_count; i++) {
             bytestream2_put_le32(&pbc, ctx->chunks[i].compressed_size);
         }
     }
 }
 

 static int hap_encode(AVCodecContext *avctx, AVPacket *pkt,
                       const AVFrame *frame, int *got_packet)
 {
     HapContext *ctx = avctx->priv_data;

     int header_length = hap_header_length(ctx);
     int final_data_size, ret;
     int pktsize = FFMAX(ctx->tex_size, ctx->max_snappy * ctx->chunk_count) + header_length;

 
     /* Allocate maximum size packet, shrink later. */

     ret = ff_alloc_packet2(avctx, pkt, pktsize, header_length);

     if (ret < 0)
         return ret;
 

     if (ctx->opt_compressor == HAP_COMP_NONE) {
         /* DXTC compression directly to the packet buffer. */
         ret = compress_texture(avctx, pkt->data + header_length, pkt->size - header_length, frame);
         if (ret < 0)
             return ret;
 
         ctx->chunks[0].compressor = HAP_COMP_NONE;
         final_data_size = ctx->tex_size;
     } else {
         /* DXTC compression. */
         ret = compress_texture(avctx, ctx->tex_buf, ctx->tex_size, frame);
         if (ret < 0)
             return ret;
 
         /* Compress (using Snappy) the frame */
         final_data_size = hap_compress_frame(avctx, pkt->data + header_length);
         if (final_data_size < 0)
             return final_data_size;
     }

 
     /* Write header at the start. */

     hap_write_frame_header(ctx, pkt->data, final_data_size + header_length);

     av_shrink_packet(pkt, final_data_size + header_length);

     pkt->flags |= AV_PKT_FLAG_KEY;
     *got_packet = 1;
     return 0;
 }
 
 static av_cold int hap_init(AVCodecContext *avctx)
 {
     HapContext *ctx = avctx->priv_data;
     int ratio;

     int corrected_chunk_count;

     int ret = av_image_check_size(avctx->width, avctx->height, 0, avctx);
 
     if (ret < 0) {
         av_log(avctx, AV_LOG_ERROR, "Invalid video size %dx%d.\n",
                avctx->width, avctx->height);
         return ret;
     }
 
     if (avctx->width % 4 || avctx->height % 4) {
         av_log(avctx, AV_LOG_ERROR, "Video size %dx%d is not multiple of 4.\n",
                avctx->width, avctx->height);
         return AVERROR_INVALIDDATA;
     }
 
     ff_texturedspenc_init(&ctx->dxtc);
 

     switch (ctx->opt_tex_fmt) {

     case HAP_FMT_RGBDXT1:
         ratio = 8;
         avctx->codec_tag = MKTAG('H', 'a', 'p', '1');

         avctx->bits_per_coded_sample = 24;

         ctx->tex_fun = ctx->dxtc.dxt1_block;
         break;
     case HAP_FMT_RGBADXT5:
         ratio = 4;
         avctx->codec_tag = MKTAG('H', 'a', 'p', '5');

         avctx->bits_per_coded_sample = 32;

         ctx->tex_fun = ctx->dxtc.dxt5_block;
         break;
     case HAP_FMT_YCOCGDXT5:
         ratio = 4;
         avctx->codec_tag = MKTAG('H', 'a', 'p', 'Y');

         avctx->bits_per_coded_sample = 24;

         ctx->tex_fun = ctx->dxtc.dxt5ys_block;
         break;
     default:

         av_log(avctx, AV_LOG_ERROR, "Invalid format %02X\n", ctx->opt_tex_fmt);

         return AVERROR_INVALIDDATA;
     }
 
     /* Texture compression ratio is constant, so can we computer
      * beforehand the final size of the uncompressed buffer. */
     ctx->tex_size   = FFALIGN(avctx->width,  TEXTURE_BLOCK_W) *
                       FFALIGN(avctx->height, TEXTURE_BLOCK_H) * 4 / ratio;

     switch (ctx->opt_compressor) {
     case HAP_COMP_NONE:
         /* No benefit chunking uncompressed data */
         corrected_chunk_count = 1;
 
         ctx->max_snappy = ctx->tex_size;
         ctx->tex_buf = NULL;
         break;
     case HAP_COMP_SNAPPY:
         /* Round the chunk count to divide evenly on DXT block edges */
         corrected_chunk_count = av_clip(ctx->opt_chunk_count, 1, HAP_MAX_CHUNKS);
         while ((ctx->tex_size / (64 / ratio)) % corrected_chunk_count != 0) {
             corrected_chunk_count--;
         }
 
         ctx->max_snappy = snappy_max_compressed_length(ctx->tex_size / corrected_chunk_count);
         ctx->tex_buf = av_malloc(ctx->tex_size);
         if (!ctx->tex_buf) {
             return AVERROR(ENOMEM);
         }
         break;
     default:
         av_log(avctx, AV_LOG_ERROR, "Invalid compresor %02X\n", ctx->opt_compressor);
         return AVERROR_INVALIDDATA;

     }
     if (corrected_chunk_count != ctx->opt_chunk_count) {
         av_log(avctx, AV_LOG_INFO, "%d chunks requested but %d used.\n",
                                     ctx->opt_chunk_count, corrected_chunk_count);
     }
     ret = ff_hap_set_chunk_count(ctx, corrected_chunk_count, 1);
     if (ret != 0)
         return ret;
 

     return 0;
 }
 
 static av_cold int hap_close(AVCodecContext *avctx)
 {
     HapContext *ctx = avctx->priv_data;
 

     ff_hap_free_context(ctx);

 
     return 0;
 }
 
 #define OFFSET(x) offsetof(HapContext, x)
 #define FLAGS     AV_OPT_FLAG_VIDEO_PARAM | AV_OPT_FLAG_ENCODING_PARAM
 static const AVOption options[] = {

     { "format", NULL, OFFSET(opt_tex_fmt), AV_OPT_TYPE_INT, { .i64 = HAP_FMT_RGBDXT1 }, HAP_FMT_RGBDXT1, HAP_FMT_YCOCGDXT5, FLAGS, "format" },

         { "hap",       "Hap 1 (DXT1 textures)", 0, AV_OPT_TYPE_CONST, { .i64 = HAP_FMT_RGBDXT1   }, 0, 0, FLAGS, "format" },
         { "hap_alpha", "Hap Alpha (DXT5 textures)", 0, AV_OPT_TYPE_CONST, { .i64 = HAP_FMT_RGBADXT5  }, 0, 0, FLAGS, "format" },
         { "hap_q",     "Hap Q (DXT5-YCoCg textures)", 0, AV_OPT_TYPE_CONST, { .i64 = HAP_FMT_YCOCGDXT5 }, 0, 0, FLAGS, "format" },

     { "chunks", "chunk count", OFFSET(opt_chunk_count), AV_OPT_TYPE_INT, {.i64 = 1 }, 1, HAP_MAX_CHUNKS, FLAGS, },

     { "compressor", "second-stage compressor", OFFSET(opt_compressor), AV_OPT_TYPE_INT, { .i64 = HAP_COMP_SNAPPY }, HAP_COMP_NONE, HAP_COMP_SNAPPY, FLAGS, "compressor" },
         { "none",       "None", 0, AV_OPT_TYPE_CONST, { .i64 = HAP_COMP_NONE }, 0, 0, FLAGS, "compressor" },
         { "snappy",     "Snappy", 0, AV_OPT_TYPE_CONST, { .i64 = HAP_COMP_SNAPPY }, 0, 0, FLAGS, "compressor" },

     { NULL },
 };
 
 static const AVClass hapenc_class = {
     .class_name = "Hap encoder",
     .item_name  = av_default_item_name,
     .option     = options,
     .version    = LIBAVUTIL_VERSION_INT,
 };
 
 AVCodec ff_hap_encoder = {
     .name           = "hap",

     .long_name      = NULL_IF_CONFIG_SMALL("Vidvox Hap"),

     .type           = AVMEDIA_TYPE_VIDEO,
     .id             = AV_CODEC_ID_HAP,
     .priv_data_size = sizeof(HapContext),
     .priv_class     = &hapenc_class,
     .init           = hap_init,
     .encode2        = hap_encode,
     .close          = hap_close,
     .pix_fmts       = (const enum AVPixelFormat[]) {
         AV_PIX_FMT_RGBA, AV_PIX_FMT_NONE,
     },
     .caps_internal  = FF_CODEC_CAP_INIT_THREADSAFE |
                       FF_CODEC_CAP_INIT_CLEANUP,
 };