/*
  * OpenEXR (.exr) image decoder
  * Copyright (c) 2009 Jimmy Christensen
  *
  * 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

  * OpenEXR decoder
  * @author Jimmy Christensen
  *
  * For more information on the OpenEXR format, visit:
  *  http://openexr.com/
  *
  * exr_flt2uint() and exr_halflt2uint() is credited to  Reimar Döffinger
  */
 

 #include <zlib.h>
 

 #include "avcodec.h"
 #include "bytestream.h"

 #include "mathops.h"

 #include "thread.h"

 #include "libavutil/imgutils.h"
 
 enum ExrCompr {
     EXR_RAW   = 0,
     EXR_RLE   = 1,
     EXR_ZIP1  = 2,
     EXR_ZIP16 = 3,
     EXR_PIZ   = 4,

     EXR_B44   = 6,
     EXR_B44A  = 7,

 };
 
 typedef struct EXRContext {
     AVFrame picture;
     int compr;
     int bits_per_color_id;

     int channel_offsets[4]; // 0 = red, 1 = green, 2 = blue and 3 = alpha

 
     uint8_t *uncompressed_data;
     int uncompressed_size;
 
     uint8_t *tmp;

     int tmp_size;

 } EXRContext;
 
 /**
  * Converts from 32-bit float as uint32_t to uint16_t
  *
  * @param v 32-bit float
  * @return normalized 16-bit unsigned int
  */
 static inline uint16_t exr_flt2uint(uint32_t v)
 {
     unsigned int exp = v >> 23;
     // "HACK": negative values result in exp<  0, so clipping them to 0
     // is also handled by this condition, avoids explicit check for sign bit.
     if (exp<= 127 + 7 - 24) // we would shift out all bits anyway
         return 0;
     if (exp >= 127)
         return 0xffff;
     v &= 0x007fffff;
     return (v + (1 << 23)) >> (127 + 7 - exp);
 }
 
 /**
  * Converts from 16-bit float as uint16_t to uint16_t
  *
  * @param v 16-bit float
  * @return normalized 16-bit unsigned int
  */
 static inline uint16_t exr_halflt2uint(uint16_t v)
 {

     unsigned exp = 14 - (v >> 10);
     if (exp >= 14) {
         if (exp == 14) return (v >> 9) & 1;
         else           return (v & 0x8000) ? 0 : 0xffff;
     }

     v <<= 6;

     return (v + (1 << 16)) >> (exp + 1);

 }
 
 /**
  * Gets the size of the header variable
  *
  * @param **buf the current pointer location in the header where
  * the variable data starts
  * @param *buf_end pointer location of the end of the buffer
  * @return size of variable data
  */
 static unsigned int get_header_variable_length(const uint8_t **buf,
                                                const uint8_t *buf_end)
 {
     unsigned int variable_buffer_data_size = bytestream_get_le32(buf);
     if (variable_buffer_data_size >= buf_end - *buf)
         return 0;
     return variable_buffer_data_size;
 }
 
 /**
  * Checks if the variable name corresponds with it's data type
  *
  * @param *avctx the AVCodecContext
  * @param **buf the current pointer location in the header where
  * the variable name starts
  * @param *buf_end pointer location of the end of the buffer
  * @param *value_name name of the varible to check
  * @param *value_type type of the varible to check
  * @param minimum_length minimum length of the variable data
  * @param variable_buffer_data_size variable length read from the header
  * after it's checked

  * @return negative if variable is invalid

  */

 static int check_header_variable(AVCodecContext *avctx,

                                               const uint8_t **buf,
                                               const uint8_t *buf_end,
                                               const char *value_name,
                                               const char *value_type,
                                               unsigned int minimum_length,
                                               unsigned int *variable_buffer_data_size)
 {
     if (buf_end - *buf >= minimum_length && !strcmp(*buf, value_name)) {
         *buf += strlen(value_name)+1;
         if (!strcmp(*buf, value_type)) {
             *buf += strlen(value_type)+1;
             *variable_buffer_data_size = get_header_variable_length(buf, buf_end);
             if (!*variable_buffer_data_size)

                 av_log(avctx, AV_LOG_ERROR, "Incomplete header\n");
             if (*variable_buffer_data_size > buf_end - *buf)
                 return -1;

             return 1;
         }
         *buf -= strlen(value_name)+1;
         av_log(avctx, AV_LOG_WARNING, "Unknown data type for header variable %s\n", value_name);
     }

     return -1;

 }
 

 static void predictor(uint8_t *src, int size)
 {
     uint8_t *t = src + 1;
     uint8_t *stop = src + size;
 
     while (t < stop) {
         int d = (int)t[-1] + (int)t[0] - 128;
         t[0] = d;
         ++t;
     }
 }
 
 static void reorder_pixels(uint8_t *src, uint8_t *dst, int size)
 {
     const int8_t *t1 = src;
     const int8_t *t2 = src + (size + 1) / 2;
     int8_t *s = dst;
     int8_t *stop = s + size;
 
     while (1) {
         if (s < stop)
             *(s++) = *(t1++);
         else
             break;
 
         if (s < stop)
             *(s++) = *(t2++);
         else
             break;
     }
 }
 

 static int rle_uncompress(const uint8_t *src, int ssize, uint8_t *dst, int dsize)
 {
     int8_t *d = (int8_t *)dst;
     int8_t *s = (int8_t *)src;
     int8_t *dend = d + dsize;
     int count;
 
     while (ssize > 0) {
         count = *s++;
 
         if (count < 0) {
             count = -count;
 
             if ((dsize -= count    ) < 0 ||
                 (ssize -= count + 1) < 0)
                 return -1;
 
             while (count--)
                 *d++ = *s++;
         } else {
             count++;
 
             if ((dsize -= count) < 0 ||
                 (ssize -= 2    ) < 0)
                 return -1;
 
             while (count--)
                 *d++ = *s;
 
             s++;
         }
     }
 
     return dend != d;
 }
 

 static int decode_frame(AVCodecContext *avctx,
                         void *data,

                         int *got_frame,

                         AVPacket *avpkt)
 {
     const uint8_t *buf      = avpkt->data;
     unsigned int   buf_size = avpkt->size;
     const uint8_t *buf_end  = buf + buf_size;
 

     const AVPixFmtDescriptor *desc;

     EXRContext *const s = avctx->priv_data;
     AVFrame *picture  = data;
     AVFrame *const p = &s->picture;
     uint8_t *ptr;
 

     int i, x, y, stride, magic_number, version_flag, ret;

     int w = 0;
     int h = 0;
     unsigned int xmin   = ~0;
     unsigned int xmax   = ~0;
     unsigned int ymin   = ~0;
     unsigned int ymax   = ~0;
     unsigned int xdelta = ~0;
 

     int out_line_size;
     int bxmin, axmax;

     int scan_lines_per_block;
     unsigned long scan_line_size;
     unsigned long uncompressed_size;
 

     unsigned int current_channel_offset = 0;
 
     s->channel_offsets[0] = -1;
     s->channel_offsets[1] = -1;
     s->channel_offsets[2] = -1;

     s->channel_offsets[3] = -1;

     s->bits_per_color_id = -1;
 

     if (buf_size < 10) {

         av_log(avctx, AV_LOG_ERROR, "Too short header to parse\n");

         return AVERROR_INVALIDDATA;

     }
 

     magic_number = bytestream_get_le32(&buf);
     if (magic_number != 20000630) { // As per documentation of OpenEXR it's supposed to be int 20000630 little-endian

         av_log(avctx, AV_LOG_ERROR, "Wrong magic number %d\n", magic_number);

         return AVERROR_INVALIDDATA;

     }
 
     version_flag = bytestream_get_le32(&buf);
     if ((version_flag & 0x200) == 0x200) {

         av_log(avctx, AV_LOG_ERROR, "Tile based images are not supported\n");

         return AVERROR_PATCHWELCOME;

     }
 
     // Parse the header

     while (buf < buf_end && buf[0]) {

         unsigned int variable_buffer_data_size;
         // Process the channel list

         if (check_header_variable(avctx, &buf, buf_end, "channels", "chlist", 38, &variable_buffer_data_size) >= 0) {

             const uint8_t *channel_list_end;
             if (!variable_buffer_data_size)

                 return AVERROR_INVALIDDATA;

             channel_list_end = buf + variable_buffer_data_size;

             while (channel_list_end - buf >= 19) {
                 int current_bits_per_color_id = -1;
                 int channel_index = -1;
 
                 if (!strcmp(buf, "R"))
                     channel_index = 0;

                 else if (!strcmp(buf, "G"))

                     channel_index = 1;

                 else if (!strcmp(buf, "B"))

                     channel_index = 2;

                 else if (!strcmp(buf, "A"))

                     channel_index = 3;

                 else
                     av_log(avctx, AV_LOG_WARNING, "Unsupported channel %.256s\n", buf);

 
                 while (bytestream_get_byte(&buf) && buf < channel_list_end)
                     continue; /* skip */
 
                 if (channel_list_end - * &buf < 4) {

                     av_log(avctx, AV_LOG_ERROR, "Incomplete header\n");

                     return AVERROR_INVALIDDATA;

                 }
 
                 current_bits_per_color_id = bytestream_get_le32(&buf);
                 if (current_bits_per_color_id > 2) {

                     av_log(avctx, AV_LOG_ERROR, "Unknown color format\n");

                     return AVERROR_INVALIDDATA;

                 }
 
                 if (channel_index >= 0) {
                     if (s->bits_per_color_id != -1 && s->bits_per_color_id != current_bits_per_color_id) {

                         av_log(avctx, AV_LOG_ERROR, "RGB channels not of the same depth\n");

                         return AVERROR_INVALIDDATA;

                     }
                     s->bits_per_color_id  = current_bits_per_color_id;
                     s->channel_offsets[channel_index] = current_channel_offset;
                 }
 
                 current_channel_offset += 1 << current_bits_per_color_id;
                 buf += 12;
             }
 
             /* Check if all channels are set with an offset or if the channels
              * are causing an overflow  */
 
             if (FFMIN3(s->channel_offsets[0],
                        s->channel_offsets[1],
                        s->channel_offsets[2]) < 0) {
                 if (s->channel_offsets[0] < 0)

                     av_log(avctx, AV_LOG_ERROR, "Missing red channel\n");

                 if (s->channel_offsets[1] < 0)

                     av_log(avctx, AV_LOG_ERROR, "Missing green channel\n");

                 if (s->channel_offsets[2] < 0)

                     av_log(avctx, AV_LOG_ERROR, "Missing blue channel\n");

                 return AVERROR_INVALIDDATA;

             }
 
             buf = channel_list_end;
             continue;
         }
 
         // Process the dataWindow variable

         if (check_header_variable(avctx, &buf, buf_end, "dataWindow", "box2i", 31, &variable_buffer_data_size) >= 0) {

             if (!variable_buffer_data_size)

                 return AVERROR_INVALIDDATA;

 
             xmin = AV_RL32(buf);
             ymin = AV_RL32(buf + 4);
             xmax = AV_RL32(buf + 8);
             ymax = AV_RL32(buf + 12);
             xdelta = (xmax-xmin) + 1;
 
             buf += variable_buffer_data_size;
             continue;
         }
 
         // Process the displayWindow variable

         if (check_header_variable(avctx, &buf, buf_end, "displayWindow", "box2i", 34, &variable_buffer_data_size) >= 0) {

             if (!variable_buffer_data_size)

                 return AVERROR_INVALIDDATA;

 
             w = AV_RL32(buf + 8) + 1;
             h = AV_RL32(buf + 12) + 1;
 
             buf += variable_buffer_data_size;
             continue;
         }
 
         // Process the lineOrder variable

         if (check_header_variable(avctx, &buf, buf_end, "lineOrder", "lineOrder", 25, &variable_buffer_data_size) >= 0) {

             if (!variable_buffer_data_size)

                 return AVERROR_INVALIDDATA;

 
             if (*buf) {

                 av_log(avctx, AV_LOG_ERROR, "Doesn't support this line order : %d\n", *buf);

                 return AVERROR_PATCHWELCOME;

             }
 
             buf += variable_buffer_data_size;
             continue;
         }
 

         // Process the pixelAspectRatio variable
         if (check_header_variable(avctx, &buf, buf_end, "pixelAspectRatio", "float", 31, &variable_buffer_data_size) >= 0) {
             if (!variable_buffer_data_size)

                 return AVERROR_INVALIDDATA;

 
             avctx->sample_aspect_ratio = av_d2q(av_int2float(AV_RL32(buf)), 255);
 
             buf += variable_buffer_data_size;
             continue;
         }
 

         // Process the compression variable

         if (check_header_variable(avctx, &buf, buf_end, "compression", "compression", 29, &variable_buffer_data_size) >= 0) {

             if (!variable_buffer_data_size)

                 return AVERROR_INVALIDDATA;

             if (s->compr == -1)
                 s->compr = *buf;
             else
                 av_log(avctx, AV_LOG_WARNING, "Found more than one compression attribute\n");

 
             buf += variable_buffer_data_size;
             continue;
         }
 
         // Check if there is enough bytes for a header
         if (buf_end - buf <= 9) {

             av_log(avctx, AV_LOG_ERROR, "Incomplete header\n");

             return AVERROR_INVALIDDATA;

         }
 
         // Process unknown variables

         for (i = 0; i < 2; i++) {

             // Skip variable name/type

             while (++buf < buf_end)

                 if (buf[0] == 0x0)
                     break;
         }
         buf++;
         // Skip variable length
         if (buf_end - buf >= 5) {
             variable_buffer_data_size = get_header_variable_length(&buf, buf_end);
             if (!variable_buffer_data_size) {

                 av_log(avctx, AV_LOG_ERROR, "Incomplete header\n");

                 return AVERROR_INVALIDDATA;

             }
             buf += variable_buffer_data_size;
         }
     }
 

     if (s->compr == -1) {
         av_log(avctx, AV_LOG_ERROR, "Missing compression attribute\n");
         return AVERROR_INVALIDDATA;
     }
 

     if (buf >= buf_end) {

         av_log(avctx, AV_LOG_ERROR, "Incomplete frame\n");

         return AVERROR_INVALIDDATA;

     }
     buf++;
 
     switch (s->bits_per_color_id) {
     case 2: // 32-bit
     case 1: // 16-bit

         if (s->channel_offsets[3] >= 0)

             avctx->pix_fmt = AV_PIX_FMT_RGBA64;

         else

             avctx->pix_fmt = AV_PIX_FMT_RGB48;

         break;
     // 8-bit
     case 0:
         av_log_missing_feature(avctx, "8-bit OpenEXR", 1);

         return AVERROR_PATCHWELCOME;

     default:

         av_log(avctx, AV_LOG_ERROR, "Unknown color format : %d\n", s->bits_per_color_id);

         return AVERROR_INVALIDDATA;

     }
 

     switch (s->compr) {
     case EXR_RAW:

     case EXR_RLE:

     case EXR_ZIP1:
         scan_lines_per_block = 1;
         break;
     case EXR_ZIP16:
         scan_lines_per_block = 16;
         break;

     default:
         av_log(avctx, AV_LOG_ERROR, "Compression type %d is not supported\n", s->compr);
         return AVERROR_PATCHWELCOME;

     }
 

     if (s->picture.data[0])

         ff_thread_release_buffer(avctx, &s->picture);

     if (av_image_check_size(w, h, 0, avctx))

         return AVERROR_INVALIDDATA;

 
     // Verify the xmin, xmax, ymin, ymax and xdelta before setting the actual image size

     if (xmin > xmax || ymin > ymax || xdelta != xmax - xmin + 1 || xmax >= w || ymax >= h) {

         av_log(avctx, AV_LOG_ERROR, "Wrong sizing or missing size information\n");

         return AVERROR_INVALIDDATA;

     }
 
     if (w != avctx->width || h != avctx->height) {
         avcodec_set_dimensions(avctx, w, h);
     }
 

     desc = av_pix_fmt_desc_get(avctx->pix_fmt);
     bxmin = xmin * 2 * desc->nb_components;
     axmax = (avctx->width - (xmax + 1)) * 2 * desc->nb_components;
     out_line_size = avctx->width * 2 * desc->nb_components;

     scan_line_size = xdelta * current_channel_offset;

     uncompressed_size = scan_line_size * scan_lines_per_block;
 
     if (s->compr != EXR_RAW) {
         av_fast_padded_malloc(&s->uncompressed_data, &s->uncompressed_size, uncompressed_size);
         av_fast_padded_malloc(&s->tmp, &s->tmp_size, uncompressed_size);
         if (!s->uncompressed_data || !s->tmp)
             return AVERROR(ENOMEM);
     }
 

     if ((ret = ff_thread_get_buffer(avctx, p)) < 0) {

         av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");

         return ret;

     }
 
     ptr    = p->data[0];
     stride = p->linesize[0];
 
     // Zero out the start if ymin is not 0
     for (y = 0; y < ymin; y++) {

         memset(ptr, 0, out_line_size);

         ptr += stride;
     }
 

     // Process the actual scan line blocks
     for (y = ymin; y <= ymax; y += scan_lines_per_block) {

         uint16_t *ptr_x = (uint16_t *)ptr;
         if (buf_end - buf > 8) {
             /* Read the lineoffset from the line offset table and add 8 bytes
                to skip the coordinates and data size fields */
             const uint64_t line_offset = bytestream_get_le64(&buf) + 8;

             int32_t data_size;
 

             // Check if the buffer has the required bytes needed from the offset

             if ((line_offset > buf_size) ||
                 (s->compr == EXR_RAW && line_offset > avpkt->size - xdelta * current_channel_offset) ||
                 (s->compr != EXR_RAW && line_offset > buf_size - (data_size = AV_RL32(avpkt->data + line_offset - 4)))) {

                 // Line offset is probably wrong and not inside the buffer
                 av_log(avctx, AV_LOG_WARNING, "Line offset for line %d is out of reach setting it to black\n", y);

                 for (i = 0; i < scan_lines_per_block && y + i <= ymax; i++, ptr += stride) {
                     ptr_x = (uint16_t *)ptr;

                     memset(ptr_x, 0, out_line_size);

                 }

             } else {

                 const uint8_t *red_channel_buffer, *green_channel_buffer, *blue_channel_buffer, *alpha_channel_buffer = 0;
 

                 if (scan_lines_per_block > 1)
                     uncompressed_size = scan_line_size * FFMIN(scan_lines_per_block, ymax - y + 1);

                 if ((s->compr == EXR_ZIP1 || s->compr == EXR_ZIP16) && data_size < uncompressed_size) {

                     unsigned long dest_len = uncompressed_size;
 
                     if (uncompress(s->tmp, &dest_len, avpkt->data + line_offset, data_size) != Z_OK ||
                         dest_len != uncompressed_size) {

                         av_log(avctx, AV_LOG_ERROR, "error during zlib decompression\n");
                         return AVERROR(EINVAL);

                     }

                 } else if (s->compr == EXR_RLE && data_size < uncompressed_size) {
                     if (rle_uncompress(avpkt->data + line_offset, data_size, s->tmp, uncompressed_size)) {
                         av_log(avctx, AV_LOG_ERROR, "error during rle decompression\n");
                         return AVERROR(EINVAL);
                     }
                 }

                 if (s->compr != EXR_RAW && data_size < uncompressed_size) {

                     predictor(s->tmp, uncompressed_size);
                     reorder_pixels(s->tmp, s->uncompressed_data, uncompressed_size);
 
                     red_channel_buffer   = s->uncompressed_data + xdelta * s->channel_offsets[0];
                     green_channel_buffer = s->uncompressed_data + xdelta * s->channel_offsets[1];
                     blue_channel_buffer  = s->uncompressed_data + xdelta * s->channel_offsets[2];
                     if (s->channel_offsets[3] >= 0)
                         alpha_channel_buffer = s->uncompressed_data + xdelta * s->channel_offsets[3];

                 } else {

                     red_channel_buffer   = avpkt->data + line_offset + xdelta * s->channel_offsets[0];
                     green_channel_buffer = avpkt->data + line_offset + xdelta * s->channel_offsets[1];
                     blue_channel_buffer  = avpkt->data + line_offset + xdelta * s->channel_offsets[2];
                     if (s->channel_offsets[3] >= 0)
                         alpha_channel_buffer = avpkt->data + line_offset + xdelta * s->channel_offsets[3];

                 }
 

                 for (i = 0; i < scan_lines_per_block && y + i <= ymax; i++, ptr += stride) {
                     const uint8_t *r, *g, *b, *a;
 
                     r = red_channel_buffer;
                     g = green_channel_buffer;
                     b = blue_channel_buffer;
                     if (alpha_channel_buffer)
                         a = alpha_channel_buffer;
 
                     ptr_x = (uint16_t *)ptr;
 
                     // Zero out the start if xmin is not 0

                     memset(ptr_x, 0, bxmin);

                     ptr_x += xmin * desc->nb_components;

                     if (s->bits_per_color_id == 2) {
                         // 32-bit
                         for (x = 0; x < xdelta; x++) {
                             *ptr_x++ = exr_flt2uint(bytestream_get_le32(&r));
                             *ptr_x++ = exr_flt2uint(bytestream_get_le32(&g));
                             *ptr_x++ = exr_flt2uint(bytestream_get_le32(&b));
                             if (alpha_channel_buffer)
                                 *ptr_x++ = exr_flt2uint(bytestream_get_le32(&a));
                         }
                     } else {
                         // 16-bit
                         for (x = 0; x < xdelta; x++) {
                             *ptr_x++ = exr_halflt2uint(bytestream_get_le16(&r));
                             *ptr_x++ = exr_halflt2uint(bytestream_get_le16(&g));
                             *ptr_x++ = exr_halflt2uint(bytestream_get_le16(&b));
                             if (alpha_channel_buffer)
                                 *ptr_x++ = exr_halflt2uint(bytestream_get_le16(&a));
                         }
                     }
 
                     // Zero out the end if xmax+1 is not w

                     memset(ptr_x, 0, axmax);

 
                     red_channel_buffer   += scan_line_size;
                     green_channel_buffer += scan_line_size;
                     blue_channel_buffer  += scan_line_size;
                     if (alpha_channel_buffer)
                         alpha_channel_buffer += scan_line_size;
                 }

             }
         }
     }
 
     // Zero out the end if ymax+1 is not h

     for (y = ymax + 1; y < avctx->height; y++) {

         memset(ptr, 0, out_line_size);

         ptr += stride;
     }
 
     *picture   = s->picture;

     *got_frame = 1;

 
     return buf_size;
 }
 
 static av_cold int decode_init(AVCodecContext *avctx)
 {
     EXRContext *s = avctx->priv_data;

     avcodec_get_frame_defaults(&s->picture);
     avctx->coded_frame = &s->picture;

     s->compr = -1;
 

     return 0;
 }
 
 static av_cold int decode_end(AVCodecContext *avctx)
 {
     EXRContext *s = avctx->priv_data;

     if (s->picture.data[0])
         avctx->release_buffer(avctx, &s->picture);
 

     av_freep(&s->uncompressed_data);
     av_freep(&s->tmp);
 

     return 0;
 }
 
 AVCodec ff_exr_decoder = {
     .name               = "exr",
     .type               = AVMEDIA_TYPE_VIDEO,

     .id                 = AV_CODEC_ID_EXR,

     .priv_data_size     = sizeof(EXRContext),
     .init               = decode_init,
     .close              = decode_end,
     .decode             = decode_frame,

     .capabilities       = CODEC_CAP_DR1 | CODEC_CAP_FRAME_THREADS,

     .long_name          = NULL_IF_CONFIG_SMALL("OpenEXR image"),
 };