/* infohelp.c -- Functions which build documentation nodes. */

/* This file is part of GNU Info, a program for reading online documentation
   stored in Info format.

   Copyright (C) 1993 Free Software Foundation, Inc.

   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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.

   Written by Brian Fox (bfox@ai.mit.edu). */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "info.h"

/* **************************************************************** */
/*								    */
/*			  Info Help Windows			    */
/*								    */
/* **************************************************************** */

/* The name of the node used in the help window. */
static char *info_help_nodename = "*Info Help*";

/* A node containing printed key bindings and their documentation. */
static NODE *internal_info_help_node = (NODE *)NULL;

/* The static text which appears in the internal info help node. */
static char *info_internal_help_text[] = {
  "Basic Commands in Info Windows",
  "******************************",
  "",
  "  h   Invoke the Info tutorial.",
  "",
  "Selecting other nodes:",
  "----------------------",
  "  n   Move to the \"next\" node of this node.",
  "  p   Move to the \"previous\" node of this node.",
  "  u   Move \"up\" from this node.",
  "  m   Pick menu item specified by name.",
  "      Picking a menu item causes another node to be selected.",
  "  f   Follow a cross reference.  Reads name of reference.",
  "  l   Move to the last node seen in this window.",
  "  d   Move to the `directory' node.  Equivalent to `g(DIR)'.",
  "",
  "Moving within a node:",
  "---------------------",
  "  SPC Scroll forward a page.",
  "  DEL Scroll backward a page.",
  "  b   Go to the beginning of this node.",
  "  e   Go to the end of this node.",
  "",
  "\"Advanced\" commands:",
  "--------------------",
  "  q   Quit Info.",
  "  1   Pick first item in node's menu.",
  "  2-9 Pick second ... ninth item in node's menu.",
  "  0   Pick last item in node's menu.",
  "  g   Move to node specified by name.",
  "      You may include a filename as well, as in (FILENAME)NODENAME.",
  "  s   Search through this Info file for a specified string,",
  "      and select the node in which the next occurrence is found.",
  (char *)NULL
};

void
dump_map_to_message_buffer (prefix, map)
     char *prefix;
     Keymap map;
{
  register int i;

  for (i = 0; i < 256; i++)
    {
      if (map[i].type == ISKMAP)
	{
	  char *new_prefix, *keyname;

	  keyname = pretty_keyname (i);
	  new_prefix = (char *)
	    xmalloc (3 + strlen (prefix) + strlen (keyname));
	  sprintf (new_prefix, "%s%s%s ", prefix, *prefix ? " " : "", keyname);

	  dump_map_to_message_buffer (new_prefix, (Keymap)map[i].function);
	  free (new_prefix);
	}
      else if (map[i].function)
	{
	  register int last;
	  char *doc, *name;

	  doc = function_documentation (map[i].function);
	  name = function_name (map[i].function);

	  if (!*doc)
	    continue;

	  /* Find out if there is a series of identical functions, as in
	     ea_insert (). */
	  for (last = i + 1; last < 256; last++)
	    if ((map[last].type != ISFUNC) ||
		(map[last].function != map[i].function))
	      break;

	  if (last - 1 != i)
	    {
	      printf_to_message_buffer
		("%s%s .. ", prefix, pretty_keyname (i));
	      printf_to_message_buffer
		("%s%s\t", prefix, pretty_keyname (last - 1));
	      i = last - 1;
	    }
	  else
	    printf_to_message_buffer ("%s%s\t", prefix, pretty_keyname (i));

#if defined (NAMED_FUNCTIONS)
	  /* Print the name of the function, and some padding before the
	     documentation string is printed. */
	  {
	    int length_so_far;
	    int desired_doc_start = 40;	/* Must be multiple of 8. */

	    printf_to_message_buffer ("(%s)", name);
	    length_so_far = message_buffer_length_this_line ();

	    if ((desired_doc_start + strlen (doc)) >= the_screen->width)
	      printf_to_message_buffer ("\n     ");
	    else
	      {
		while (length_so_far < desired_doc_start)
		  {
		    printf_to_message_buffer ("\t");
		    length_so_far += character_width ('\t', length_so_far);
		  }
	      }
	  }
#endif /* NAMED_FUNCTIONS */
	  printf_to_message_buffer ("%s\n", doc);
	}
    }
}

/* How to create internal_info_help_node. */
static void
create_internal_info_help_node ()
{
  register int i;

  initialize_message_buffer ();

  for (i = 0; info_internal_help_text[i]; i++)
    printf_to_message_buffer ("%s\n", info_internal_help_text[i]);

  printf_to_message_buffer ("---------------------\n\n");
  printf_to_message_buffer ("The current search path is:\n");
  printf_to_message_buffer ("  \"%s\"\n", infopath);
  printf_to_message_buffer ("---------------------\n\n");
  printf_to_message_buffer ("Commands available in Info windows:\n\n");
  dump_map_to_message_buffer ("", info_keymap);
  printf_to_message_buffer ("---------------------\n\n");
  printf_to_message_buffer ("Commands available in the echo area:\n\n");
  dump_map_to_message_buffer ("", echo_area_keymap);

  {
    char *message;

    message = replace_in_documentation
      ("--- Use `\\[history-node]' or `\\[kill-node]' to exit ---\n");
    printf_to_message_buffer ("%s", message);
  }

  internal_info_help_node = message_buffer_to_node ();
  add_gcable_pointer (internal_info_help_node->contents);
  name_internal_node (internal_info_help_node, info_help_nodename);

  /* Even though this is an internal node, we don't want the window
     system to treat it specially.  So we turn off the internalness
     of it here. */
  internal_info_help_node->flags &= ~N_IsInternal;
}

/* Return a window which is the window showing help in this Info. */
static WINDOW *
info_find_or_create_help_window ()
{
  WINDOW *help_window;

  help_window = get_internal_info_window (info_help_nodename);

  /* If we couldn't find the help window, then make it. */
  if (!help_window)
    {
      WINDOW *window, *eligible = (WINDOW *)NULL;
      int max = 0;

      for (window = windows; window; window = window->next)
	{
	  if (window->height > max)
	    {
	      max = window->height;
	      eligible = window;
	    }
	}

      if (!eligible)
	return ((WINDOW *)NULL);
      else
	{
	  /* Make a new node containing the help text.  Split the largest
	     window into 2 windows, and show the help text in that window. */
	  if (!internal_info_help_node)
	    create_internal_info_help_node ();

	  if (eligible->height > 30)
	    {
	      active_window = eligible;
	      help_window = window_make_window (internal_info_help_node);
	    }
	  else
	    {
	      set_remembered_pagetop_and_point (active_window);
	      window_set_node_of_window
		(active_window, internal_info_help_node);
	      help_window = active_window;
	    }

	  remember_window_and_node (help_window, help_window->node);
	}
    }
  return (help_window);
}

/* Create or move to the help window. */
DECLARE_INFO_COMMAND (info_get_help_window, "Display help message")
{
  WINDOW *help_window;

  help_window = info_find_or_create_help_window ();
  if (help_window)
    {
      active_window = help_window;
      active_window->flags |= W_UpdateWindow;
    }
  else
    {
      info_error (CANT_MAKE_HELP);
    }
}

/* Show the Info help node.  This means that the "info" file is installed
   where it can easily be found on your system. */
DECLARE_INFO_COMMAND (info_get_info_help_node, "Visit Info node `(info)Help'")
{
  NODE *node;
  char *nodename;

  /* If there is a window on the screen showing the node "(info)Help" or
     the node "(info)Help-Small-Screen", simply select that window. */
  {
    WINDOW *win;

    for (win = windows; win; win = win->next)
      {
	if (win->node && win->node->filename &&
	    (stricmp
	     (filename_non_directory (win->node->filename), "info") == 0) &&
	    ((strcmp (win->node->nodename, "Help") == 0) ||
	     (strcmp (win->node->nodename, "Help-Small-Screen") == 0)))
	  {
	    active_window = win;
	    return;
	  }
      }
  }

  /* If the current window is small, show the small screen help. */
  if (active_window->height < 24)
    nodename = "Help-Small-Screen";
  else
    nodename = "Help";

  /* Try to get the info file for Info. */
  node = info_get_node ("Info", nodename);

  if (!node)
    {
      if (info_recent_file_error)
	info_error (info_recent_file_error);
      else
	info_error (CANT_FILE_NODE, "Info", nodename);
    }
  else
    {
      /* If the current window is very large (greater than 45 lines),
	 then split it and show the help node in another window.
	 Otherwise, use the current window. */

      if (active_window->height > 45)
	active_window = window_make_window (node);
      else
	{
	  set_remembered_pagetop_and_point (active_window);
	  window_set_node_of_window (active_window, node);
	}

      remember_window_and_node (active_window, node);
    }
}

/* **************************************************************** */
/*								    */
/*		     Groveling Info Keymaps and Docs		    */
/*								    */
/* **************************************************************** */

/* Return the documentation associated with the Info command FUNCTION. */
char *
function_documentation (function)
     VFunction *function;
{
  register int i;

  for (i = 0; function_doc_array[i].func; i++)
    if (function == function_doc_array[i].func)
      break;

  return (replace_in_documentation (function_doc_array[i].doc));
}

#if defined (NAMED_FUNCTIONS)
/* Return the user-visible name of the function associated with the
   Info command FUNCTION. */
char *
function_name (function)

     VFunction *function;
{
  register int i;

  for (i = 0; function_doc_array[i].func; i++)
    if (function == function_doc_array[i].func)
      break;

  return (function_doc_array[i].func_name);
}

/* Return a pointer to the function named NAME. */
VFunction *
named_function (name)
     char *name;
{
  register int i;

  for (i = 0; function_doc_array[i].func; i++)
    if (strcmp (function_doc_array[i].func_name, name) == 0)
      break;

  return (function_doc_array[i].func);
}
#endif /* NAMED_FUNCTIONS */

/* Return the documentation associated with KEY in MAP. */
char *
key_documentation (key, map)
     char key;
     Keymap map;
{
  VFunction *function = map[key].function;

  if (function)
    return (function_documentation (function));
  else
    return ((char *)NULL);
}

DECLARE_INFO_COMMAND (describe_key, "Print documentation for KEY")
{
  char keyname[50];
  int keyname_index = 0;
  unsigned char keystroke;
  char *rep;
  Keymap map;

  keyname[0] = '\0';
  map = window->keymap;

  while (1)
    {
      message_in_echo_area ("Describe key: %s", keyname);
      keystroke = info_get_input_char ();
      unmessage_in_echo_area ();

      if (Meta_p (keystroke) && (!ISO_Latin_p || key < 160))
	{
	  if (map[ESC].type != ISKMAP)
	    {
	      window_message_in_echo_area
		("ESC %s is undefined.", pretty_keyname (UnMeta (keystroke)));
	      return;
	    }

	  strcpy (keyname + keyname_index, "ESC ");
	  keyname_index = strlen (keyname);
	  keystroke = UnMeta (keystroke);
	  map = (Keymap)map[ESC].function;
	}

      /* Add the printed representation of KEYSTROKE to our keyname. */
      rep = pretty_keyname (keystroke);
      strcpy (keyname + keyname_index, rep);
      keyname_index = strlen (keyname);

      if (map[keystroke].function == (VFunction *)NULL)
	{
	  message_in_echo_area ("%s is undefined.", keyname);
	  return;
	}
      else if (map[keystroke].type == ISKMAP)
	{
	  map = (Keymap)map[keystroke].function;
	  strcat (keyname, " ");
	  keyname_index = strlen (keyname);
	  continue;
	}
      else
	{
	  char *message, *fundoc, *funname = "";

#if defined (NAMED_FUNCTIONS)
	  funname = function_name (map[keystroke].function);
#endif /* NAMED_FUNCTIONS */

	  fundoc = function_documentation (map[keystroke].function);

	  message = (char *)xmalloc
	    (10 + strlen (keyname) + strlen (fundoc) + strlen (funname));

#if defined (NAMED_FUNCTIONS)
	  sprintf (message, "%s (%s): %s.", keyname, funname, fundoc);
#else
	  sprintf (message, "%s is defined to %s.", keyname, fundoc);
#endif /* !NAMED_FUNCTIONS */

	  window_message_in_echo_area ("%s", message);
	  free (message);
	  break;
	}
    }
}

/* How to get the pretty printable name of a character. */
static char rep_buffer[30];

char *
pretty_keyname (key)
     unsigned char key;
{
  char *rep;

  if (Meta_p (key))
    {
      char temp[20];

      rep = pretty_keyname (UnMeta (key));

      sprintf (temp, "ESC %s", rep);
      strcpy (rep_buffer, temp);
      rep = rep_buffer;
    }
  else if (Control_p (key))
    {
      switch (key)
	{
	case '\n': rep = "LFD"; break;
	case '\t': rep = "TAB"; break;
	case '\r': rep = "RET"; break;
	case ESC:  rep = "ESC"; break;

	default:
	  sprintf (rep_buffer, "C-%c", UnControl (key));
	  rep = rep_buffer;
	}
    }
  else
    {
      switch (key)
	{
	case ' ': rep = "SPC"; break;
	case DEL: rep = "DEL"; break;
	default:
	  rep_buffer[0] = key;
	  rep_buffer[1] = '\0';
	  rep = rep_buffer;
	}
    }
  return (rep);
}

/* Replace the names of functions with the key that invokes them. */
static char *where_is (), *where_is_internal ();

char *
replace_in_documentation (string)
     char *string;
{
  register int i, start, next;
  static char *result = (char *)NULL;

  maybe_free (result);
  result = (char *)xmalloc (1 + strlen (string));

  i = next = start = 0;

  /* Skip to the beginning of a replaceable function. */
  for (i = start; string[i]; i++)
    {
      /* Is this the start of a replaceable function name? */
      if (string[i] == '\\' && string[i + 1] == '[')
	{
	  char *fun_name, *rep;
	  VFunction *function;

	  /* Copy in the old text. */
	  strncpy (result + next, string + start, i - start);
	  next += (i - start);
	  start = i + 2;

	  /* Move to the end of the function name. */
	  for (i = start; string[i] && (string[i] != ']'); i++);

	  fun_name = (char *)xmalloc (1 + i - start);
	  strncpy (fun_name, string + start, i - start);
	  fun_name[i - start] = '\0';

	  /* Find a key which invokes this function in the info_keymap. */
	  function = named_function (fun_name);

	  /* If the internal documentation string fails, there is a 
	     serious problem with the associated command's documentation.
	     We croak so that it can be fixed immediately. */
	  if (!function)
	    abort ();

	  rep = where_is (info_keymap, function);
	  strcpy (result + next, rep);
	  next = strlen (result);

	  start = i;
	  if (string[i])
	    start++;
	}
    }
  strcpy (result + next, string + start);
  return (result);
}

/* Return a string of characters which could be typed from the keymap
   MAP to invoke FUNCTION. */
static char *where_is_rep = (char *)NULL;
static int where_is_rep_index = 0;
static int where_is_rep_size = 0;

static char *
where_is (map, function)
     Keymap map;
     VFunction *function;
{
  char *rep;

  if (!where_is_rep_size)
    where_is_rep = (char *)xmalloc (where_is_rep_size = 100);
  where_is_rep_index = 0;

  rep = where_is_internal (map, function);

  /* If it couldn't be found, return "M-x Foo". */
  if (!rep)
    {
      char *name;

      name = function_name (function);

      if (name)
	sprintf (where_is_rep, "M-x %s", name);

      rep = where_is_rep;
    }
  return (rep);
}

/* Return the printed rep of FUNCTION as found in MAP, or NULL. */
static char *
where_is_internal (map, function)
     Keymap map;
     VFunction *function;
{
  register int i;
  
  /* If the function is directly invokable in MAP, return the representation
     of that keystroke. */
  for (i = 0; i < 256; i++)
    if ((map[i].type == ISFUNC) && map[i].function == function)
      {
	sprintf (where_is_rep + where_is_rep_index, "%s", pretty_keyname (i));
	return (where_is_rep);
      }

  /* Okay, search subsequent maps for this function. */
  for (i = 0; i < 256; i++)
    {
      if (map[i].type == ISKMAP)
	{
	  int saved_index = where_is_rep_index;
	  char *rep;

	  sprintf (where_is_rep + where_is_rep_index, "%s ",
		   pretty_keyname (i));

	  where_is_rep_index = strlen (where_is_rep);
	  rep = where_is_internal ((Keymap)map[i].function, function);

	  if (rep)
	    return (where_is_rep);

	  where_is_rep_index = saved_index;
	}
    }

  return ((char *)NULL);
}

extern char *read_function_name ();

DECLARE_INFO_COMMAND (info_where_is,
   "Show what to type to execute a given command")
{
  char *command_name;

  command_name = read_function_name ("Where is command: ", window);

  if (!command_name)
    {
      info_abort_key (active_window, count, key);
      return;
    }

  if (*command_name)
    {
      VFunction *function;

      function = named_function (command_name);

      if (function)
	{
	  char *location;

	  location = where_is (active_window->keymap, function);

	  if (!location)
	    {
	      info_error ("`%s' is not on any keys", command_name);
	    }
	  else
	    {
	      if (strncmp (location, "M-x ", 4) == 0)
		window_message_in_echo_area
		  ("%s can only be invoked via %s.", command_name, location);
	      else
		window_message_in_echo_area
		  ("%s can be invoked via %s.", command_name, location);
	    }
	}
      else
	info_error ("There is no function named `%s'", command_name);
    }

  free (command_name);
}