## Copyright (C) 2009 Søren Hauberg
##
## 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 3 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; see the file COPYING.  If not, see
## <http://www.gnu.org/licenses/>.

## -*- texinfo -*-
## @deftypefn {Function File} gen_doc_cache ()
## @deftypefnx{Function File} gen_doc_cache (@var{directory})
## Generate documentation caches for all functions in a given directory.
##
## A documentation cache is generated for all functions in @var{directory}. The
## resulting cache is saved in the file @code{help_cache.mat} in @var{directory}.
## The cache is used to speed up @code{lookfor}.
## If no directory is given, all directories in the current path is traversed.
##
## @seealso{lookfor, path}
## @end deftypefn

function gen_doc_cache (p = path ())
  if (!ischar (p))
    print_usage ();
  endif
  
  ## Generate caches for all directories in path
  idx = find (p == pathsep ());
  prev_idx = 1;
  for n = 1:length (idx)
    f = p (prev_idx:idx (n)-1);
    gen_doc_cache_in_dir (f);
    prev_idx = idx (n) + 1;
  endfor
    
  ## Generate cache for keywords, operators, and builtins if we're handling the
  ## entire path
  if (nargin == 0)
    gen_builtin_cache ();
  endif
endfunction

function [text, first_sentence, status] = handle_function (f, text, format)
  first_sentence = "";
  ## Skip functions that start with __ as these shouldn't be searched by lookfor
  if (length (f) > 2 && all (f (1:2) == "_"))
    status = 1;
    return;
  endif

  ## Take action depending on help text format
  switch (lower (format))
    case "plain text"
      status = 0;
    case "texinfo"
      [text, status] = makeinfo (text, "plain text");
    case "html"
      [text, status] = strip_html_tags (text);
    otherwise
      status = 1;
  endswitch
    
  ## Did we get the help text?
  if (status != 0 || isempty (text))
    warning ("gen_doc_cache: unusable help text in '%s'. Ignoring function.", f);
    return;
  endif

  ## Get first sentence of help text
  first_sentence = get_first_help_sentence (f);
endfunction

function cache = create_cache (list)
  cache = {};
  
  ## For each function:
  for n = 1:length (list)
    f = list {n};
    
    ## Get help text
    [text, format] = get_help_text (f);
    
    [text, first_sentence, status] = handle_function (f, text, format);

    ## Did we get the help text?
    if (status != 0)
      continue;
    endif
    
    ## Store the help text
    cache (1, end+1) = f;
    cache (2, end) = text;
    cache (3, end) = first_sentence;
  endfor
endfunction

function gen_doc_cache_in_dir (directory)
  ## If 'directory' is not in the current path, add it so we search it
  dir_in_path = false;
  p = path ();
  idx = find (p == pathsep ());
  prev_idx = 1;
  for n = 1:length (idx)
    f = p (prev_idx:idx (n)-1);
    if (strcmp (f, directory))
      dir_in_path = true;
      break;
    endif
    prev_idx = idx (n) + 1;
  endfor
  
  if (!dir_in_path)
    addpath (directory);
  endif

  ## Get list of functions in directory and create cache
  list = __list_functions__ (directory);
  cache = create_cache (list);
  
  ## Write the cache
  fn = fullfile (directory, "help_cache.mat");
  save ("-binary", fn, "cache"); # FIXME: Should we zip it ?
  
  if (!dir_in_path)
    rmpath (directory);
  endif
endfunction

function gen_builtin_cache ()
  operators = __operators__ ();
  keywords = __keywords__ ();
  builtins = __builtins__ ();
  list = {operators{:}, keywords{:}, builtins{:}};

  cache = create_cache (list);
  
  ## Write the cache
  ## FIXME: Where should we store this cache?
  ## FIXME: if we change it -- update 'lookfor'
  fn = fullfile (octave_config_info.datadir, "builtin_cache.mat"); 
  save ("-binary", fn, "cache"); # FIXME: Should we zip it ?
endfunction

