/*
 * PNM image format
 * Copyright (c) 2002, 2003 Fabrice Bellard
 *
 * 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
 */

#include <stdlib.h>
#include <string.h>

#include "libavutil/avassert.h"
#include "libavutil/imgutils.h"
#include "avcodec.h"
#include "internal.h"
#include "pnm.h"

static inline int pnm_space(int c)
{
    return c == ' ' || c == '\n' || c == '\r' || c == '\t';
}

static void pnm_get(PNMContext *sc, char *str, int buf_size)
{
    char *s;
    int c;
    uint8_t *bs  = sc->bytestream;
    const uint8_t *end = sc->bytestream_end;

    /* skip spaces and comments */
    while (bs < end) {
        c = *bs++;
        if (c == '#')  {
            while (c != '\n' && bs < end) {
                c = *bs++;
            }
        } else if (!pnm_space(c)) {
            break;
        }
    }

    s = str;
    while (bs < end && !pnm_space(c) && (s - str) < buf_size - 1) {
        *s++ = c;
        c = *bs++;
    }
    *s = '\0';
    sc->bytestream = bs;
}

int ff_pnm_decode_header(AVCodecContext *avctx, PNMContext * const s)
{
    char buf1[32], tuple_type[32];
    int h, w, depth, maxval;
    int ret;

    if (s->bytestream_end - s->bytestream < 3 ||
        s->bytestream[0] != 'P' ||
        s->bytestream[1] < '1'  ||
        s->bytestream[1] > '7') {
        s->bytestream += s->bytestream_end > s->bytestream;
        s->bytestream += s->bytestream_end > s->bytestream;
        return AVERROR_INVALIDDATA;
    }
    pnm_get(s, buf1, sizeof(buf1));
    s->type= buf1[1]-'0';

    if (s->type==1 || s->type==4) {
        avctx->pix_fmt = AV_PIX_FMT_MONOWHITE;
    } else if (s->type==2 || s->type==5) {
        if (avctx->codec_id == AV_CODEC_ID_PGMYUV)
            avctx->pix_fmt = AV_PIX_FMT_YUV420P;
        else
            avctx->pix_fmt = AV_PIX_FMT_GRAY8;
    } else if (s->type==3 || s->type==6) {
        avctx->pix_fmt = AV_PIX_FMT_RGB24;
    } else if (s->type==7) {
        w      = -1;
        h      = -1;
        maxval = -1;
        depth  = -1;
        tuple_type[0] = '\0';
        for (;;) {
            pnm_get(s, buf1, sizeof(buf1));
            if (!strcmp(buf1, "WIDTH")) {
                pnm_get(s, buf1, sizeof(buf1));
                w = strtol(buf1, NULL, 10);
            } else if (!strcmp(buf1, "HEIGHT")) {
                pnm_get(s, buf1, sizeof(buf1));
                h = strtol(buf1, NULL, 10);
            } else if (!strcmp(buf1, "DEPTH")) {
                pnm_get(s, buf1, sizeof(buf1));
                depth = strtol(buf1, NULL, 10);
            } else if (!strcmp(buf1, "MAXVAL")) {
                pnm_get(s, buf1, sizeof(buf1));
                maxval = strtol(buf1, NULL, 10);
            } else if (!strcmp(buf1, "TUPLTYPE") ||
                       /* libavcodec used to write invalid files */
                       !strcmp(buf1, "TUPLETYPE")) {
                pnm_get(s, tuple_type, sizeof(tuple_type));
            } else if (!strcmp(buf1, "ENDHDR")) {
                break;
            } else {
                return AVERROR_INVALIDDATA;
            }
        }
        if (!pnm_space(s->bytestream[-1]))
            return AVERROR_INVALIDDATA;

        /* check that all tags are present */
        if (w <= 0 || h <= 0 || maxval <= 0 || maxval > UINT16_MAX || depth <= 0 || tuple_type[0] == '\0' ||
            av_image_check_size(w, h, 0, avctx) || s->bytestream >= s->bytestream_end)
            return AVERROR_INVALIDDATA;

        ret = ff_set_dimensions(avctx, w, h);
        if (ret < 0)
            return ret;
        s->maxval     = maxval;
        if (depth == 1) {
            if (maxval == 1) {
                avctx->pix_fmt = AV_PIX_FMT_MONOBLACK;
            } else if (maxval < 256) {
                avctx->pix_fmt = AV_PIX_FMT_GRAY8;
            } else {
                avctx->pix_fmt = AV_PIX_FMT_GRAY16;
            }
        } else if (depth == 2) {
            if (maxval < 256) {
                avctx->pix_fmt = AV_PIX_FMT_GRAY8A;
            } else {
                avctx->pix_fmt = AV_PIX_FMT_YA16;
            }
        } else if (depth == 3) {
            if (maxval < 256) {
                avctx->pix_fmt = AV_PIX_FMT_RGB24;
            } else {
                avctx->pix_fmt = AV_PIX_FMT_RGB48;
            }
        } else if (depth == 4) {
            if (maxval < 256) {
                avctx->pix_fmt = AV_PIX_FMT_RGBA;
            } else {
                avctx->pix_fmt = AV_PIX_FMT_RGBA64;
            }
        } else {
            return AVERROR_INVALIDDATA;
        }
        return 0;
    } else {
        av_assert0(0);
    }
    pnm_get(s, buf1, sizeof(buf1));
    w = atoi(buf1);
    pnm_get(s, buf1, sizeof(buf1));
    h = atoi(buf1);
    if(w <= 0 || h <= 0 || av_image_check_size(w, h, 0, avctx) || s->bytestream >= s->bytestream_end)
        return AVERROR_INVALIDDATA;

    ret = ff_set_dimensions(avctx, w, h);
    if (ret < 0)
        return ret;

    if (avctx->pix_fmt != AV_PIX_FMT_MONOWHITE && avctx->pix_fmt != AV_PIX_FMT_MONOBLACK) {
        pnm_get(s, buf1, sizeof(buf1));
        s->maxval = atoi(buf1);
        if (s->maxval <= 0 || s->maxval > UINT16_MAX) {
            av_log(avctx, AV_LOG_ERROR, "Invalid maxval: %d\n", s->maxval);
            s->maxval = 255;
        }
        if (s->maxval >= 256) {
            if (avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
                avctx->pix_fmt = AV_PIX_FMT_GRAY16;
            } else if (avctx->pix_fmt == AV_PIX_FMT_RGB24) {
                avctx->pix_fmt = AV_PIX_FMT_RGB48;
            } else if (avctx->pix_fmt == AV_PIX_FMT_YUV420P && s->maxval < 65536) {
                if (s->maxval < 512)
                    avctx->pix_fmt = AV_PIX_FMT_YUV420P9;
                else if (s->maxval < 1024)
                    avctx->pix_fmt = AV_PIX_FMT_YUV420P10;
                else
                    avctx->pix_fmt = AV_PIX_FMT_YUV420P16;
            } else {
                av_log(avctx, AV_LOG_ERROR, "Unsupported pixel format\n");
                avctx->pix_fmt = AV_PIX_FMT_NONE;
                return AVERROR_INVALIDDATA;
            }
        }
    }else
        s->maxval=1;

    if (!pnm_space(s->bytestream[-1]))
        return AVERROR_INVALIDDATA;

    /* more check if YUV420 */
    if (av_pix_fmt_desc_get(avctx->pix_fmt)->flags & AV_PIX_FMT_FLAG_PLANAR) {
        if ((avctx->width & 1) != 0)
            return AVERROR_INVALIDDATA;
        h = (avctx->height * 2);
        if ((h % 3) != 0)
            return AVERROR_INVALIDDATA;
        h /= 3;
        avctx->height = h;
    }
    return 0;
}