/*

 * hbuf.c       -- History buffer implementation

 *

 * Copyright (C) 2005-2010 Mikael Berthe <mikael@lilotux.net>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or (at

 * your option) any later version.

 *

 * This program 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

 * General Public License for more details.

 *

 * You should have received a copy of the GNU General Public License

 * along with this program; if not, see <http://www.gnu.org/licenses/>.

 */

#include <string.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

#include "hbuf.h"

#include "utils.h"

#include "utf8.h"

#include "screen.h"

/* This is a private structure type */

typedef struct {

  char *ptr;

  char *ptr_end;        // beginning of the block

  char *ptr_end_alloc;  // end of the current persistent block

  guchar flags;

  // XXX This should certainly be a pointer, and be allocated only when needed

  // (for ex. when HBB_FLAG_PERSISTENT is set).

  struct { // hbuf_line_info

    time_t timestamp;

    unsigned mucnicklen;

    guint  flags;

    gpointer xep184;

  } prefix;

//  do_wrap(p_hbuf, first_hbuf_elt, width)

// Wrap hbuf lines with the specified width.

// '\n' are handled by this routine (they are removed and persistent lines

// are created).

// All hbuf elements are processed, starting from first_hbuf_elt.

static inline void do_wrap(GList **p_hbuf, GList *first_hbuf_elt,

                           unsigned int width)

{

  GList *curr_elt = first_hbuf_elt;

  // Let's add non-persistent blocs if necessary

  // - If there are '\n' in the string

  // - If length > width (and width != 0)

  while (curr_elt) {

    char *c, *end;

    char *br = NULL; // break pointer

    char *cr = NULL; // CR pointer

    unsigned int cur_w = 0;

    // We want to break where we can find a space char or a CR

    hbuf_b_prev = hbuf_b_curr;

    c = hbuf_b_curr->ptr;

    while (*c && (!width || cur_w <= width)) {

      if (*c == '\n') {

        br = cr = c;

        *c = 0;

        break;

      }

      if (iswblank(get_char(c)))

        br = c;

      cur_w += get_char_width(c);

      c = next_char(c);

    }

    if (cr || (*c && cur_w > width)) {

      if (!br || br == hbuf_b_curr->ptr)

        br = c;

      else

        br = next_char(br);

      end = hbuf_b_curr->ptr_end;

      hbuf_b_curr->ptr_end = br;

      // Create another block

      // The block must be persistent after a CR

      if (cr) {

        hbuf_b_curr->ptr    = hbuf_b_prev->ptr_end + 1; // == cr+1

        hbuf_b_curr->flags  = HBB_FLAG_PERSISTENT;

      } else {

        hbuf_b_curr->ptr    = hbuf_b_prev->ptr_end; // == br

        hbuf_b_curr->flags    = 0;

      }

      hbuf_b_curr->ptr_end  = end;

      hbuf_b_curr->ptr_end_alloc = hbuf_b_prev->ptr_end_alloc;

      // This is OK because insert_before(NULL) == append():

      *p_hbuf = g_list_insert_before(*p_hbuf, curr_elt->next, hbuf_b_curr);

    }

    curr_elt = g_list_next(curr_elt);

  }

}

//  hbuf_add_line(p_hbuf, text, prefix_flags, width, maxhbufblocks)

// Add a line to the given buffer.  If width is not null, then lines are

// wrapped at this length.

// maxhbufblocks is the maximum number of hbuf blocks we can allocate.  If

// null, there is no limit.  If non-null, it should be >= 2.

//

// Note 1: Splitting according to width won't work if there are tabs; they

//         should be expanded before.

// Note 2: width does not include the ending \0.

void hbuf_add_line(GList **p_hbuf, const char *text, time_t timestamp,

        guint prefix_flags, guint width, guint maxhbufblocks,

        unsigned mucnicklen, gpointer xep184)

{

  GList *curr_elt;

  char *line;

  guint hbb_blocksize, textlen;

  if (!text) return;

  prefix_flags |= (xep184 ? HBB_PREFIX_RECEIPT : 0);

  textlen = strlen(text);

  hbb_blocksize = MAX(textlen+1, HBB_BLOCKSIZE);

  hbuf_block_elt->prefix.timestamp  = timestamp;

  hbuf_block_elt->prefix.flags      = prefix_flags;

  hbuf_block_elt->prefix.mucnicklen = mucnicklen;

  hbuf_block_elt->prefix.xep184     = xep184;

  if (!*p_hbuf) {

    hbuf_block_elt->ptr  = g_new(char, hbb_blocksize);

    if (!hbuf_block_elt->ptr) {

      g_free(hbuf_block_elt);

      return;

    }

    hbuf_block_elt->flags  = HBB_FLAG_ALLOC | HBB_FLAG_PERSISTENT;

    hbuf_block_elt->ptr_end_alloc = hbuf_block_elt->ptr + hbb_blocksize;

  } else {

    // Set p_hbuf to the end of the list, to speed up history loading

    // (or CPU time will be used by g_list_last() for each line)

    *p_hbuf = g_list_last(*p_hbuf);

    hbuf_b_prev = (*p_hbuf)->data;

    hbuf_block_elt->ptr    = hbuf_b_prev->ptr_end;

    hbuf_block_elt->flags  = HBB_FLAG_PERSISTENT;

    hbuf_block_elt->ptr_end_alloc = hbuf_b_prev->ptr_end_alloc;

  }

  *p_hbuf = g_list_append(*p_hbuf, hbuf_block_elt);

  if (hbuf_block_elt->ptr + textlen >= hbuf_block_elt->ptr_end_alloc) {

    // Too long for the current allocated bloc, we need another one

    if (!maxhbufblocks || textlen >= HBB_BLOCKSIZE) {

      // No limit, let's allocate a new block

      // If the message text is big, we won't bother to reuse an old block

      // as well (it could be too small and cause a segfault).

      hbuf_block_elt->ptr  = g_new0(char, hbb_blocksize);

      hbuf_block_elt->ptr_end_alloc = hbuf_block_elt->ptr + hbb_blocksize;

      // XXX We should check the return value.

    } else {

      GList *hbuf_head, *hbuf_elt;

      guint n = 0;

      hbuf_head = g_list_first(*p_hbuf);

      // We need at least 2 allocated blocks

      if (maxhbufblocks == 1)

        maxhbufblocks = 2;

      // Let's count the number of allocated areas

      for (hbuf_elt = hbuf_head; hbuf_elt; hbuf_elt = g_list_next(hbuf_elt)) {

        if (hbuf_b_elt->flags & HBB_FLAG_ALLOC)

          n++;

      }

      // If we can't allocate a new area, reuse the previous block(s)

      if (n < maxhbufblocks) {

        hbuf_block_elt->ptr  = g_new0(char, hbb_blocksize);

        hbuf_block_elt->ptr_end_alloc = hbuf_block_elt->ptr + hbb_blocksize;

      } else {

        // Let's use an old block, and free the extra blocks if needed

        char *allocated_block = NULL;

        char *end_of_allocated_block = NULL;

        while (n >= maxhbufblocks) {

          int start_of_block = 1;

          for (hbuf_elt = hbuf_head; hbuf_elt; hbuf_elt = hbuf_head) {

            if (hbuf_b_elt->flags & HBB_FLAG_ALLOC) {

              if (start_of_block-- == 0)

                break;

              if (n == maxhbufblocks) {

                allocated_block = hbuf_b_elt->ptr;

                end_of_allocated_block = hbuf_b_elt->ptr_end_alloc;

              } else {

                g_free(hbuf_b_elt->ptr);

              }

            }

            g_free(hbuf_b_elt);

            hbuf_head = *p_hbuf = g_list_delete_link(hbuf_head, hbuf_elt);

          }

          n--;

        }

        memset(allocated_block, 0, end_of_allocated_block-allocated_block);

        hbuf_block_elt->ptr = allocated_block;

        hbuf_block_elt->ptr_end_alloc = end_of_allocated_block;

      }

    }

    hbuf_block_elt->flags  = HBB_FLAG_ALLOC | HBB_FLAG_PERSISTENT;

  }

  line = hbuf_block_elt->ptr;

  // Ok, now we can copy the text..

  strcpy(line, text);

  hbuf_block_elt->ptr_end = line + textlen + 1;

  curr_elt = g_list_last(*p_hbuf);

  // Wrap lines and handle CRs ('\n')

  do_wrap(p_hbuf, curr_elt, width);

}

//  hbuf_free()

// Destroys all hbuf list.

void hbuf_free(GList **p_hbuf)

{

  GList *hbuf_elt;

  GList *first_elt = g_list_first(*p_hbuf);

  for (hbuf_elt = first_elt; hbuf_elt; hbuf_elt = g_list_next(hbuf_elt)) {

    if (hbuf_b_elt->flags & HBB_FLAG_ALLOC) {

      g_free(hbuf_b_elt->ptr);

    }

    g_free(hbuf_b_elt);

  }

  g_list_free(first_elt);

  *p_hbuf = NULL;

}

//  hbuf_rebuild()

// Rebuild all hbuf list, with the new width.

// If width == 0, lines are not wrapped.

void hbuf_rebuild(GList **p_hbuf, unsigned int width)

{

  GList *first_elt, *curr_elt, *next_elt;

  // *p_hbuf needs to be the head of the list

  first_elt = *p_hbuf = g_list_first(*p_hbuf);

  // #1 Remove non-persistent blocks (ptr_end should be updated!)

  curr_elt = first_elt;

  while (curr_elt) {

    next_elt = g_list_next(curr_elt);

    // Last element?

    if (!next_elt)

      break;

    // Is next line not-persistent?

    if (!(hbuf_b_next->flags & HBB_FLAG_PERSISTENT)) {

      hbuf_b_curr->ptr_end = hbuf_b_next->ptr_end;

      g_free(hbuf_b_next);

      curr_elt = g_list_delete_link(curr_elt, next_elt);

    } else

      curr_elt = next_elt;

  }

  // #2 Go back to head and create non-persistent blocks when needed

  if (width)

    do_wrap(p_hbuf, first_elt, width);

}

//  hbuf_previous_persistent()

// Returns the previous persistent block (line).  If the given line is

// persistent, then it is returned.

// This function is used for example when resizing a buffer.  If the top of the

// screen is on a non-persistent block, then a screen resize could destroy this

// line...

GList *hbuf_previous_persistent(GList *l_line)

{

  while (l_line) {

    if (hbuf_b_elt->flags & HBB_FLAG_PERSISTENT &&

        (hbuf_b_elt->flags & ~HBB_PREFIX_READMARK))

      return l_line;

    l_line = g_list_previous(l_line);

  }

  return NULL;

}

//  hbuf_get_lines(hbuf, n)

// Returns an array of n hbb_line pointers

// (The first line will be the line currently pointed by hbuf)

// Note: The caller should free the array, the hbb_line pointers and the

// text pointers after use.

hbb_line **hbuf_get_lines(GList *hbuf, unsigned int n)

{

  unsigned int i;

  guint last_persist_prefixflags = 0;

  GList *last_persist;  // last persistent flags

  hbb_line **array, **array_elt;

  hbb_line *prev_array_elt = NULL;

  // To be able to correctly highlight multi-line messages,

  // we need to look at the last non-null prefix, which should be the first

  // line of the message.  We also need to check if there's a readmark flag

  // somewhere in the message.

  last_persist = hbuf_previous_persistent(hbuf);

  while (last_persist) {

    if ((blk->flags & HBB_FLAG_PERSISTENT) && blk->prefix.flags) {

      // This can be either the beginning of the message,

      // or a persistent line with a readmark flag (or both).

      if (blk->prefix.flags & ~HBB_PREFIX_READMARK) { // First message line

        last_persist_prefixflags |= blk->prefix.flags;

        break;

      } else { // Not the first line, but we need to keep the readmark flag

        last_persist_prefixflags = blk->prefix.flags;

      }

    }

    last_persist = g_list_previous(last_persist);

  }

  array = g_new0(hbb_line*, n);

  array_elt = array;

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

    if (hbuf) {

      int maxlen;

      maxlen = blk->ptr_end - blk->ptr;

      *array_elt = (hbb_line*)g_new(hbb_line, 1);

      (*array_elt)->timestamp  = blk->prefix.timestamp;

      (*array_elt)->flags      = blk->prefix.flags;

      (*array_elt)->mucnicklen = blk->prefix.mucnicklen;

      (*array_elt)->text       = g_strndup(blk->ptr, maxlen);

      if ((blk->flags & HBB_FLAG_PERSISTENT) &&

          (blk->prefix.flags & ~HBB_PREFIX_READMARK)) {

        // This is a new message: persistent block flag and no prefix flag

        // (except a possible readmark flag)

        last_persist_prefixflags = blk->prefix.flags;

      } else {

        // Propagate highlighting flags

        (*array_elt)->flags |= last_persist_prefixflags &

                               (HBB_PREFIX_HLIGHT_OUT | HBB_PREFIX_HLIGHT |

                                HBB_PREFIX_INFO | HBB_PREFIX_IN |

                                HBB_PREFIX_READMARK);

        // Continuation of a message - omit the prefix

        (*array_elt)->flags |= HBB_PREFIX_CONT;

        (*array_elt)->mucnicklen = 0; // The nick is in the first one

        // If there is a readmark on this line, update last_persist_prefixflags

        if (blk->flags & HBB_FLAG_PERSISTENT)

          last_persist_prefixflags |= blk->prefix.flags & HBB_PREFIX_READMARK;

        // Remove readmark flag from the previous line

        if (prev_array_elt && last_persist_prefixflags & HBB_PREFIX_READMARK)

          prev_array_elt->flags &= ~HBB_PREFIX_READMARK;

      }

      prev_array_elt = *array_elt;

      hbuf = g_list_next(hbuf);

    } else

      break;

    array_elt++;

  }

  return array;

}