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/*
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 * Beam Software VB decoder
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 * Copyright (c) 2007 Konstantin Shishkov
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 *
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 * This file is part of Libav.
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 *
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 * Libav is free software; you can redistribute it and/or
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 * modify it under the terms of the GNU Lesser General Public
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 * License as published by the Free Software Foundation; either
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 * version 2.1 of the License, or (at your option) any later version.
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 *
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 * Libav is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 * Lesser General Public License for more details.
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 *
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 * You should have received a copy of the GNU Lesser General Public
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 * License along with Libav; if not, write to the Free Software
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 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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 */
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/**
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 * @file
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 * VB Video decoder
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 */
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#include <stdio.h>
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#include <stdlib.h>
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#include "avcodec.h"
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#include "bytestream.h"
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enum VBFlags{
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    VB_HAS_GMC     = 0x01,
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    VB_HAS_AUDIO   = 0x04,
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    VB_HAS_VIDEO   = 0x08,
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    VB_HAS_PALETTE = 0x10,
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    VB_HAS_LENGTH  = 0x20
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};
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typedef struct VBDecContext {
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    AVCodecContext *avctx;
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    AVFrame pic;
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    uint8_t *frame, *prev_frame;
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    uint32_t pal[AVPALETTE_COUNT];
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    const uint8_t *stream;
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} VBDecContext;
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static const uint16_t vb_patterns[64] = {
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    0x0660, 0xFF00, 0xCCCC, 0xF000, 0x8888, 0x000F, 0x1111, 0xFEC8,
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    0x8CEF, 0x137F, 0xF731, 0xC800, 0x008C, 0x0013, 0x3100, 0xCC00,
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    0x00CC, 0x0033, 0x3300, 0x0FF0, 0x6666, 0x00F0, 0x0F00, 0x2222,
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    0x4444, 0xF600, 0x8CC8, 0x006F, 0x1331, 0x318C, 0xC813, 0x33CC,
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    0x6600, 0x0CC0, 0x0066, 0x0330, 0xF900, 0xC88C, 0x009F, 0x3113,
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    0x6000, 0x0880, 0x0006, 0x0110, 0xCC88, 0xFC00, 0x00CF, 0x88CC,
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    0x003F, 0x1133, 0x3311, 0xF300, 0x6FF6, 0x0603, 0x08C6, 0x8C63,
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    0xC631, 0x6310, 0xC060, 0x0136, 0x136C, 0x36C8, 0x6C80, 0x324C
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};
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static void vb_decode_palette(VBDecContext *c, int data_size)
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{
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    int start, size, i;
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    start = bytestream_get_byte(&c->stream);
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    size = (bytestream_get_byte(&c->stream) - 1) & 0xFF;
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    if(start + size > 255){
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        av_log(c->avctx, AV_LOG_ERROR, "Palette change runs beyond entry 256\n");
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        return;
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    }
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    if(size*3+2 > data_size){
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        av_log(c->avctx, AV_LOG_ERROR, "Palette data runs beyond chunk size\n");
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        return;
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    }
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    for(i = start; i <= start + size; i++)
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        c->pal[i] = bytestream_get_be24(&c->stream);
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}
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static inline int check_pixel(uint8_t *buf, uint8_t *start, uint8_t *end)
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{
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    return buf >= start && buf < end;
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}
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static inline int check_line(uint8_t *buf, uint8_t *start, uint8_t *end)
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{
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    return buf >= start && (buf + 4) <= end;
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}
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static int vb_decode_framedata(VBDecContext *c, const uint8_t *buf, int data_size, int offset)
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{
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    uint8_t *prev, *cur;
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    const uint8_t* data_end = buf + data_size;
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    int blk, blocks, t, blk2;
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    int blocktypes = 0;
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    int x, y, a, b;
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    int pattype, pattern;
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    const int width = c->avctx->width;
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    uint8_t *pstart = c->prev_frame;
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    uint8_t *pend = c->prev_frame + width*c->avctx->height;
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    prev = c->prev_frame + offset;
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    cur = c->frame;
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    blocks = (c->avctx->width >> 2) * (c->avctx->height >> 2);
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    blk2 = 0;
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    for(blk = 0; blk < blocks; blk++){
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        if(!(blk & 3)) {
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            if(buf >= data_end){
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                av_log(c->avctx, AV_LOG_ERROR, "Data pointer out of bounds\n");
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                return -1;
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            }
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            blocktypes = bytestream_get_byte(&buf);
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        }
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        switch(blocktypes & 0xC0){
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        case 0x00: //skip
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            for(y = 0; y < 4; y++)
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                if(check_line(prev + y*width, pstart, pend))
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                    memcpy(cur + y*width, prev + y*width, 4);
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                else
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                    memset(cur + y*width, 0, 4);
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            break;
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        case 0x40:
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            t = bytestream_get_byte(&buf);
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            if(!t){ //raw block
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                if(buf + 16 > data_end){
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                    av_log(c->avctx, AV_LOG_ERROR, "Insufficient data\n");
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                    return -1;
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                }
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                for(y = 0; y < 4; y++)
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                    memcpy(cur + y*width, buf + y*4, 4);
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                buf += 16;
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            }else{ // motion compensation
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                x = ((t & 0xF)^8) - 8;
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                y = ((t >> 4) ^8) - 8;
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                t = x + y*width;
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                for(y = 0; y < 4; y++)
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                    if(check_line(prev + t + y*width, pstart, pend))
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                        memcpy(cur + y*width, prev + t + y*width, 4);
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                    else
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                        memset(cur + y*width, 0, 4);
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            }
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            break;
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        case 0x80: // fill
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            t = bytestream_get_byte(&buf);
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            for(y = 0; y < 4; y++)
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                memset(cur + y*width, t, 4);
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            break;
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        case 0xC0: // pattern fill
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            if(buf + 2 > data_end){
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                av_log(c->avctx, AV_LOG_ERROR, "Insufficient data\n");
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                return -1;
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            }
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            t = bytestream_get_byte(&buf);
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            pattype = t >> 6;
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            pattern = vb_patterns[t & 0x3F];
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            switch(pattype){
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            case 0:
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                a = bytestream_get_byte(&buf);
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                b = bytestream_get_byte(&buf);
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                for(y = 0; y < 4; y++)
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                    for(x = 0; x < 4; x++, pattern >>= 1)
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                        cur[x + y*width] = (pattern & 1) ? b : a;
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                break;
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            case 1:
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                pattern = ~pattern;
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            case 2:
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                a = bytestream_get_byte(&buf);
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                for(y = 0; y < 4; y++)
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                    for(x = 0; x < 4; x++, pattern >>= 1)
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                        if(pattern & 1 && check_pixel(prev + x + y*width, pstart, pend))
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                            cur[x + y*width] = prev[x + y*width];
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                        else
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                            cur[x + y*width] = a;
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                break;
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            case 3:
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                av_log(c->avctx, AV_LOG_ERROR, "Invalid opcode seen @%d\n",blk);
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                return -1;
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            }
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            break;
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        }
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        blocktypes <<= 2;
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        cur  += 4;
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        prev += 4;
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        blk2++;
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        if(blk2 == (width >> 2)){
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            blk2 = 0;
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            cur  += width * 3;
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            prev += width * 3;
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        }
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    }
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    return 0;
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}
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static int decode_frame(AVCodecContext *avctx, void *data, int *data_size, AVPacket *avpkt)
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{
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    const uint8_t *buf = avpkt->data;
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    int buf_size = avpkt->size;
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    VBDecContext * const c = avctx->priv_data;
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    uint8_t *outptr, *srcptr;
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    int i, j;
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    int flags;
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    uint32_t size;
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    int rest = buf_size;
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    int offset = 0;
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    if(c->pic.data[0])
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        avctx->release_buffer(avctx, &c->pic);
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    c->pic.reference = 1;
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    if(avctx->get_buffer(avctx, &c->pic) < 0){
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        av_log(avctx, AV_LOG_ERROR, "get_buffer() failed\n");
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        return -1;
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    }
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    c->stream = buf;
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    flags = bytestream_get_le16(&c->stream);
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    rest -= 2;
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    if(flags & VB_HAS_GMC){
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        i = (int16_t)bytestream_get_le16(&c->stream);
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        j = (int16_t)bytestream_get_le16(&c->stream);
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        offset = i + j * avctx->width;
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        rest -= 4;
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    }
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    if(flags & VB_HAS_VIDEO){
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        size = bytestream_get_le32(&c->stream);
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        if(size > rest){
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            av_log(avctx, AV_LOG_ERROR, "Frame size is too big\n");
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            return -1;
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        }
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        vb_decode_framedata(c, c->stream, size, offset);
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        c->stream += size - 4;
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        rest -= size;
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    }
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    if(flags & VB_HAS_PALETTE){
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        size = bytestream_get_le32(&c->stream);
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        if(size > rest){
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            av_log(avctx, AV_LOG_ERROR, "Palette size is too big\n");
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            return -1;
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        }
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        vb_decode_palette(c, size);
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        rest -= size;
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    }
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    memcpy(c->pic.data[1], c->pal, AVPALETTE_SIZE);
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    c->pic.palette_has_changed = flags & VB_HAS_PALETTE;
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    outptr = c->pic.data[0];
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    srcptr = c->frame;
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    for(i = 0; i < avctx->height; i++){
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        memcpy(outptr, srcptr, avctx->width);
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        srcptr += avctx->width;
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        outptr += c->pic.linesize[0];
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    }
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    FFSWAP(uint8_t*, c->frame, c->prev_frame);
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    *data_size = sizeof(AVFrame);
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    *(AVFrame*)data = c->pic;
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    /* always report that the buffer was completely consumed */
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    return buf_size;
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}
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static av_cold int decode_init(AVCodecContext *avctx)
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{
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    VBDecContext * const c = avctx->priv_data;
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    c->avctx = avctx;
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    avctx->pix_fmt = PIX_FMT_PAL8;
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    c->frame      = av_mallocz(avctx->width * avctx->height);
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    c->prev_frame = av_mallocz(avctx->width * avctx->height);
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    return 0;
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}
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static av_cold int decode_end(AVCodecContext *avctx)
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{
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    VBDecContext *c = avctx->priv_data;
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    av_freep(&c->frame);
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    av_freep(&c->prev_frame);
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    if(c->pic.data[0])
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        avctx->release_buffer(avctx, &c->pic);
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    return 0;
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}
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AVCodec ff_vb_decoder = {
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    "vb",
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    AVMEDIA_TYPE_VIDEO,
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    CODEC_ID_VB,
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    sizeof(VBDecContext),
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    decode_init,
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    NULL,
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    decode_end,
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    decode_frame,
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    .long_name = NULL_IF_CONFIG_SMALL("Beam Software VB"),
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};
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