/*

 * Copyright (c) 2012 Nicolas George

 *

 * 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 <limits.h>

#include <stdarg.h>

#include <stdio.h>

#include <string.h>

#include <time.h>

#include "avstring.h"

#include "bprint.h"

#include "error.h"

#include "macros.h"

#include "mem.h"

#define av_bprint_room(buf) ((buf)->size - FFMIN((buf)->len, (buf)->size))

#define av_bprint_is_allocated(buf) ((buf)->str != (buf)->reserved_internal_buffer)

static int av_bprint_alloc(AVBPrint *buf, unsigned room)

{

    char *old_str, *new_str;

    unsigned min_size, new_size;

    if (buf->size == buf->size_max)

        return AVERROR(EIO);

    if (!av_bprint_is_complete(buf))

        return AVERROR_INVALIDDATA; /* it is already truncated anyway */

    min_size = buf->len + 1 + FFMIN(UINT_MAX - buf->len - 1, room);

    new_size = buf->size > buf->size_max / 2 ? buf->size_max : buf->size * 2;

    if (new_size < min_size)

        new_size = FFMIN(buf->size_max, min_size);

    old_str = av_bprint_is_allocated(buf) ? buf->str : NULL;

    new_str = av_realloc(old_str, new_size);

    if (!new_str)

        return AVERROR(ENOMEM);

    if (!old_str)

        memcpy(new_str, buf->str, buf->len + 1);

    buf->str  = new_str;

    buf->size = new_size;

    return 0;

}

static void av_bprint_grow(AVBPrint *buf, unsigned extra_len)

{

    /* arbitrary margin to avoid small overflows */

    extra_len = FFMIN(extra_len, UINT_MAX - 5 - buf->len);

    buf->len += extra_len;

    if (buf->size)

        buf->str[FFMIN(buf->len, buf->size - 1)] = 0;

}

void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)

{

    unsigned size_auto = (char *)buf + sizeof(*buf) -

                         buf->reserved_internal_buffer;

    if (size_max == AV_BPRINT_SIZE_AUTOMATIC)

        size_max = size_auto;

    buf->str      = buf->reserved_internal_buffer;

    buf->len      = 0;

    buf->size     = FFMIN(size_auto, size_max);

    buf->size_max = size_max;

    *buf->str = 0;

    if (size_init > buf->size)

        av_bprint_alloc(buf, size_init - 1);

}

void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size)

{

    if (size == 0) {

        av_bprint_init(buf, 0, AV_BPRINT_SIZE_COUNT_ONLY);

        return;

    }

    buf->str      = buffer;

    buf->len      = 0;

    buf->size     = size;

    buf->size_max = size;

    *buf->str = 0;

}

void av_vbprintf(AVBPrint *buf, const char *fmt, va_list vl_arg)

{

    unsigned room;

    char *dst;

    int extra_len;

    va_list vl;

    while (1) {

        room = av_bprint_room(buf);

        dst = room ? buf->str + buf->len : NULL;

        va_copy(vl, vl_arg);

        extra_len = vsnprintf(dst, room, fmt, vl);

        va_end(vl);

        if (extra_len <= 0)

            return;

        if (extra_len < room)

            break;

        if (av_bprint_alloc(buf, extra_len))

            break;

    }

    av_bprint_grow(buf, extra_len);

}

void av_bprintf(AVBPrint *buf, const char *fmt, ...)

{

    va_list vl;

    va_start(vl, fmt);

    av_vbprintf(buf, fmt, vl);

    va_end(vl);

}

void av_bprint_chars(AVBPrint *buf, char c, unsigned n)

{

    unsigned room, real_n;

    while (1) {

        room = av_bprint_room(buf);

        if (n < room)

            break;

        if (av_bprint_alloc(buf, n))

            break;

    }

    if (room) {

        real_n = FFMIN(n, room - 1);

        memset(buf->str + buf->len, c, real_n);

    }

    av_bprint_grow(buf, n);

}

void av_bprint_append_data(AVBPrint *buf, const char *data, unsigned size)

{

    unsigned room, real_n;

    while (1) {

        room = av_bprint_room(buf);

        if (size < room)

            break;

        if (av_bprint_alloc(buf, size))

            break;

    }

    if (room) {

        real_n = FFMIN(size, room - 1);

        memcpy(buf->str + buf->len, data, real_n);

    }

    av_bprint_grow(buf, size);

}

void av_bprint_strftime(AVBPrint *buf, const char *fmt, const struct tm *tm)

{

    unsigned room;

    size_t l;

    size_t fmt_len = strlen(fmt);

    if (!*fmt)

        return;

    while (1) {

        room = av_bprint_room(buf);

        if (room && (l = strftime(buf->str + buf->len, room, fmt, tm)))

            break;

        /* Due to the limitations of strftime() it is not possible to know if

         * the output buffer is too small or the output is empty.

         * However, a 256x output space requirement compared to the format

         * string length is so unlikely we can safely assume empty output. This

         * allows supporting possibly empty format strings like "%p". */

        if (room >> 8 > fmt_len)

            break;

        /* strftime does not tell us how much room it would need: let us

           retry with twice as much until the buffer is large enough */

        room = !room ? fmt_len + 1 :

               room <= INT_MAX / 2 ? room * 2 : INT_MAX;

        if (av_bprint_alloc(buf, room)) {

            /* impossible to grow, try to manage something useful anyway */

            room = av_bprint_room(buf);

            if (room < 1024) {

                /* if strftime fails because the buffer has (almost) reached

                   its maximum size, let us try in a local buffer; 1k should

                   be enough to format any real date+time string */

                char buf2[1024];

                if ((l = strftime(buf2, sizeof(buf2), fmt, tm))) {

                    av_bprintf(buf, "%s", buf2);

                    return;

                }

            }

            if (room) {

                /* if anything else failed and the buffer is not already

                   truncated, let us add a stock string and force truncation */

                static const char txt[] = "[truncated strftime output]";

                memset(buf->str + buf->len, '!', room);

                memcpy(buf->str + buf->len, txt, FFMIN(sizeof(txt) - 1, room));

                av_bprint_grow(buf, room); /* force truncation */

            }

            return;

        }

    }

    av_bprint_grow(buf, l);

}

void av_bprint_get_buffer(AVBPrint *buf, unsigned size,

                          unsigned char **mem, unsigned *actual_size)

{

    if (size > av_bprint_room(buf))

        av_bprint_alloc(buf, size);

    *actual_size = av_bprint_room(buf);

    *mem = *actual_size ? (unsigned char *) (buf->str + buf->len) : NULL;

}

void av_bprint_clear(AVBPrint *buf)

{

    if (buf->len) {

        *buf->str = 0;

        buf->len  = 0;

    }

}

int av_bprint_finalize(AVBPrint *buf, char **ret_str)

{

    unsigned real_size = FFMIN(buf->len + 1, buf->size);

    char *str;

    int ret = 0;

    if (ret_str) {

        if (av_bprint_is_allocated(buf)) {

            str = av_realloc(buf->str, real_size);

            if (!str)

                str = buf->str;

            buf->str = NULL;

        } else {

            str = av_memdup(buf->str, real_size);

            if (!str)

                ret = AVERROR(ENOMEM);

        }

        *ret_str = str;

    } else {

        if (av_bprint_is_allocated(buf))

            av_freep(&buf->str);

    }

    buf->size = real_size;

    return ret;

}

#define WHITESPACES " \n\t\r"

void av_bprint_escape(AVBPrint *dstbuf, const char *src, const char *special_chars,

                      enum AVEscapeMode mode, int flags)

{

    const char *src0 = src;

    if (mode == AV_ESCAPE_MODE_AUTO)

        mode = AV_ESCAPE_MODE_BACKSLASH; /* TODO: implement a heuristic */

    switch (mode) {

    case AV_ESCAPE_MODE_QUOTE:

        /* enclose the string between '' */

        av_bprint_chars(dstbuf, '\'', 1);

        for (; *src; src++) {

            if (*src == '\'')

                av_bprintf(dstbuf, "'\\''");

            else

                av_bprint_chars(dstbuf, *src, 1);

        }

        av_bprint_chars(dstbuf, '\'', 1);

        break;

    case AV_ESCAPE_MODE_XML:

        /* escape XML non-markup character data as per 2.4 by default: */

        /*  [^<&]* - ([^<&]* ']]>' [^<&]*) */

        /* additionally, given one of the AV_ESCAPE_FLAG_XML_* flags, */

        /* escape those specific characters as required. */

        for (; *src; src++) {

            switch (*src) {

            case '&' : av_bprintf(dstbuf, "%s", "&");  break;

            case '<' : av_bprintf(dstbuf, "%s", "&lt;");   break;

            case '>' : av_bprintf(dstbuf, "%s", ">");   break;

            case '\'':

                if (!(flags & AV_ESCAPE_FLAG_XML_SINGLE_QUOTES))

                    goto XML_DEFAULT_HANDLING;

                av_bprintf(dstbuf, "%s", "'");

                break;

            case '"' :

                if (!(flags & AV_ESCAPE_FLAG_XML_DOUBLE_QUOTES))

                    goto XML_DEFAULT_HANDLING;

                av_bprintf(dstbuf, "%s", """);

                break;

XML_DEFAULT_HANDLING:

            default: av_bprint_chars(dstbuf, *src, 1);

            }

        }

        break;

    /* case AV_ESCAPE_MODE_BACKSLASH or unknown mode */

    default:

        /* \-escape characters */

        for (; *src; src++) {

            int is_first_last       = src == src0 || !*(src+1);

            int is_ws               = !!strchr(WHITESPACES, *src);

            int is_strictly_special = special_chars && strchr(special_chars, *src);

            int is_special          =

                is_strictly_special || strchr("'\\", *src) ||

                (is_ws && (flags & AV_ESCAPE_FLAG_WHITESPACE));

            if (is_strictly_special ||

                (!(flags & AV_ESCAPE_FLAG_STRICT) &&

                 (is_special || (is_ws && is_first_last))))

                av_bprint_chars(dstbuf, '\\', 1);

            av_bprint_chars(dstbuf, *src, 1);

        }

        break;

    }

}