/*
 * hbuf.c       -- History buffer implementation
 *
 * Copyright (C) 2005-2008 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
 * USA
 */

#include <string.h>

#include "hbuf.h"
#include "utils.h"
#include "utf8.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;
  } prefix;
} hbuf_block;


//  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) {
    hbuf_block *hbuf_b_curr, *hbuf_b_prev;
    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_curr = (hbuf_block*)(curr_elt->data);
    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
      hbuf_b_curr = g_new0(hbuf_block, 1);
      // 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)
{
  GList *curr_elt;
  char *line;
  guint hbb_blocksize, textlen;
  hbuf_block *hbuf_block_elt;

  if (!text) return;

  textlen = strlen(text);
  hbb_blocksize = MAX(textlen+1, HBB_BLOCKSIZE);

  hbuf_block_elt = g_new0(hbuf_block, 1);
  hbuf_block_elt->prefix.timestamp  = timestamp;
  hbuf_block_elt->prefix.flags      = prefix_flags;
  hbuf_block_elt->prefix.mucnicklen = mucnicklen;
  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 {
    hbuf_block *hbuf_b_prev;
    // 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;
      hbuf_block *hbuf_b_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)) {
        hbuf_b_elt = (hbuf_block*)(hbuf_elt->data);
        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) {
            hbuf_b_elt = (hbuf_block*)(hbuf_elt->data);
            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)
{
  hbuf_block *hbuf_b_elt;
  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)) {
    hbuf_b_elt = (hbuf_block*)(hbuf_elt->data);
    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;
  hbuf_block *hbuf_b_curr, *hbuf_b_next;

  // *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;
    hbuf_b_curr = (hbuf_block*)(curr_elt->data);
    hbuf_b_next = (hbuf_block*)(next_elt->data);
    // 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)
{
  hbuf_block *hbuf_b_elt;

  while (l_line) {
    hbuf_b_elt = (hbuf_block*)l_line->data;
    if (hbuf_b_elt->flags & HBB_FLAG_PERSISTENT)
      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;
  hbuf_block *blk;
  guint last_persist_prefixflags = 0;
  GList *last_persist;  // last persistent flags
  hbb_line **array, **array_elt;

  // 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.
  last_persist = hbuf_previous_persistent(hbuf);
  while (last_persist) {
    blk = (hbuf_block*)last_persist->data;
    if ((blk->flags & HBB_FLAG_PERSISTENT) && blk->prefix.flags) {
      last_persist_prefixflags = blk->prefix.flags;
      break;
    }
    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;
      blk = (hbuf_block*)(hbuf->data);
      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) {
        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);
        //Continuation of a message - omit the prefix
        (*array_elt)->flags |= HBB_PREFIX_CONT;
        (*array_elt)->mucnicklen = 0;//The nick is in the first one
      }

      hbuf = g_list_next(hbuf);
    } else
      break;

    array_elt++;
  }

  return array;
}

//  hbuf_search(hbuf, direction, string)
// Look backward/forward for a line containing string in the history buffer
// Search starts at hbuf, and goes forward if direction == 1, backward if -1
GList *hbuf_search(GList *hbuf, int direction, const char *string)
{
  hbuf_block *blk;

  for (;;) {
    if (direction > 0)
      hbuf = g_list_next(hbuf);
    else
      hbuf = g_list_previous(hbuf);

    if (!hbuf) break;

    blk = (hbuf_block*)(hbuf->data);
    // XXX blk->ptr is (maybe) not really correct, because the match should
    // not be after ptr_end.  We should check that...
    if (strcasestr(blk->ptr, string))
      break;
  }

  return hbuf;
}

//  hbuf_jump_date(hbuf, t)
// Return a pointer to the first line after date t in the history buffer
GList *hbuf_jump_date(GList *hbuf, time_t t)
{
  hbuf_block *blk;

  hbuf = g_list_first(hbuf);

  for ( ; hbuf && g_list_next(hbuf); hbuf = g_list_next(hbuf)) {
    blk = (hbuf_block*)(hbuf->data);
    if (blk->prefix.timestamp >= t) break;
  }

  return hbuf;
}

//  hbuf_jump_percent(hbuf, pc)
// Return a pointer to the line at % pc of the history buffer
GList *hbuf_jump_percent(GList *hbuf, int pc)
{
  guint hlen;

  hbuf = g_list_first(hbuf);
  hlen = g_list_length(hbuf);

  return g_list_nth(hbuf, pc*hlen/100);
}

#ifdef DEBUG_ENABLE
//  hbuf_get_blocks_number()
// Returns the number of allocated hbuf_block's.
guint hbuf_get_blocks_number(GList *hbuf)
{
  hbuf_block *hbuf_b_elt;
  guint count = 0U;

  for (hbuf = g_list_first(hbuf); hbuf; hbuf = g_list_next(hbuf)) {
    hbuf_b_elt = (hbuf_block*)(hbuf->data);
    if (hbuf_b_elt->flags & HBB_FLAG_ALLOC)
      count++;
  }
  return count;
}
#endif

/* vim: set expandtab cindent cinoptions=>2\:2(0:  For Vim users... */