/*
  * 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 <stdarg.h>
 #include <stdio.h>
 #include <string.h>

 #include <time.h>

 #include "avassert.h"

 #include "avstring.h"

 #include "bprint.h"
 #include "common.h"

 #include "compat/va_copy.h"

 #include "error.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 == 1)
         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)
 {
     buf->str      = buffer;
     buf->len      = 0;
     buf->size     = size;
     buf->size_max = size;
     *buf->str = 0;
 }
 

 void av_bprintf(AVBPrint *buf, const char *fmt, ...)
 {
     unsigned room;
     char *dst;
     va_list vl;
     int extra_len;
 
     while (1) {
         room = av_bprint_room(buf);
         dst = room ? buf->str + buf->len : NULL;
         va_start(vl, fmt);
         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_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_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;
 
     if (!*fmt)
         return;
     while (1) {
         room = av_bprint_room(buf);
         if (room && (l = strftime(buf->str + buf->len, room, fmt, tm)))
             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 ? strlen(fmt) + 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 ? 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_malloc(real_size);
             if (str)
                 memcpy(str, buf->str, real_size);
             else
                 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_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;
     }
 }