Module:Footnotes/anchor id list

require('strict');
local data = mw.loadData ('Module:Footnotes/anchor id list/data');
local whitelist = mw.loadData ('Module:Footnotes/whitelist');
local Lang_obj = mw.language.getContentLanguage();        -- used by template_list_add() to uppercase first letter of template name TODO: better way to do that?

local redirects_date = {
 ['date'] = true,
 ['datetomos'] = true,
 ['formatdate'] = true,
 ['isotodmymdy'] = true,
 ['isotomos'] = true,
 }
local redirects_patent = {              -- special case cs1-like templates because uses different parameters for name and date in anchor ID
 ['Cite patent'] = true,
 ['Citeref patent'] = true,
 ['Ref patent'] = true,
 }
local redirects_sfnref = {
 ['sfnref'] = true,
 ['harvid'] = true,
 }
local aliases_author = {              -- these use pseudo-patterns in the same way as cs1|2; '#' represents 1 or more enumerator digits
 'last#',
 'author#',
 'surname#',
 'author-last#',
 'author#-last',
 'subject#',
 'host#',
 }
local aliases_contributor = {
 'contributor#',
 'contributor-last#',
 'contributor#-last',
 'contributor-surname#',
 'contributor#-surname',
 }
local aliases_editor = {
 'editor#',
 'editor-last#',
 'editor#-last',
 'editor-surname#',
 'editor#-surname',
 }
local aliases_harvc_author = {
 'last#',
 'author#',
 }
local aliases_inventor = {              -- cite patent
 'inventor#',
 'inventor-last#',
 'inventor#-last',
 'inventor-surname#',
 'inventor#-surname',
 'invent#',
 'invent-#',
 }
local alias_patterns_date = {             -- normal lua patterns for most cs1|2-like templates
 '|%s*year%s*=%s*',
 '|%s*date%s*=%s*',
 '|%s*publication%-?date%s*=%s*',
 '|%s*air%-?date%s*=%s*',
 }
local alias_patterns_harvc_date = {            -- normal lua patterns for harvc template
 '|%s*anchor%-year%s*=%s*',
 '|%s*year%s*=%s*',
 }
local alias_patterns_patent_date = {           -- normal lua patterns for cite patent templates
 '|%s*issue%-date%s*=%s*',
 '|%s*gdate%s*=%s*',
 '|%s*publication%-date%s*=%s*',
 '|%s*pubdate%s*=%s*',
 }
local patterns_date = {               -- normal lua patterns
-- '(%d%d%d%d–%d%d%d%d%l?)$',             -- YYYY–YYYY four-digit year range at end (Season YYYY–YYYY); with or without dab
 '(%d%d%d%d)%D+(%d%d%d%d%l?)$',            -- any range with four-digit years; with or without dab; not two captures
 '^(%d%d%d%d–%d%d%l?)$',              -- YYYY–YY two-digit year range; with or without dab
 '^(c%. %d%d%d%d?%l?)$',              -- three- or four-digit circa year; with or without dab
 '(%d%d%d%d?%l?)$',               -- three- or four-digit year at end of date (dmy or mdy); with or without dab
 '^(%d%d%d%d?%l?)',               -- three- or four-digit year at beginning of date (ymd or YYYY); with or without dab
 '^(n%.d%.%l?)$',               -- 'no date' with dots; with or without dab
 '^(nd%l?)$',                -- 'no date' without dots; with or without dab
 }
local patterns_tags = {
 '<nowiki>.-</nowiki>',
 '<!%-%-.-%-%->',
 '<pre>.-</pre>',
 '<syntaxhighlight.->.-</syntaxhighlight>',
 '<source.->.-</source>',             -- deprecated alias of syntaxhighlight tag
 }
local template_skip = {               -- templates to be skipped for whatever reason; mostly because they resemble cs1-like templates
 ['Citation-attribution'] = true,
 }
local Article_content;

local anchor_id_list = {};              -- exported tables
local template_list = {};
local article_whitelist = {};


--[[--------------------------< A R T I C L E _ C O N T E N T _ G E T >----------------------------------------

get article content, remove certain html-like tags and their content so that this code doesn't include any citation
templates inside the tags as valid tagets; they are not.

]]

local function article_content_get ()
 if not Article_content then
  Article_content = mw.title.getCurrentTitle():getContent() or '';  -- get the content of the article or ''; new pages edited w/ve do not have 'content' until saved; ve does not preview; phab:T221625
  for _, tag in ipairs (patterns_tags) do
   Article_content = Article_content:gsub (tag, '');     -- remove certain html-like tags and their content
  end
 end
end


--[[--------------------------< S F N R E F _ G E T >----------------------------------------------------------

make an anchor id from the contents of {{sfnref}} or {{harvid}}.  this function assumes that {{sfnref}} and {{harvid}}
are correctly formed.

]]

local function sfnref_get (template)
 template = template:gsub ('{{%s*(.-)%s*}}', '%1');       -- strip bounding template markup and trim
 local parts = mw.text.split (template, '%s*|%s*');       -- split at the pipe and remove extraneous space characters
 local anchor_id = {};

 if redirects_sfnref[parts[1]:lower()] then
  anchor_id[1] = 'CITEREF';
 else
  return nil;                -- not an sfnref or harvid template
 end
 
 local i = 2;                -- indexer into parts{} table
 local j = 2;                -- indexer into anchor_id{} table which already has 'CITEREF' at [1]
 while parts[i] and 7 > j do             -- loop through what should be just positional parameters for names and year (2-6 four names and a date)
  if not parts[i]:find ('=') then           -- look for equal sign (named paraneter in a template that doesn't support named parameters)
   anchor_id[j] = parts[i];           -- positional parameters are saved
   j = j+1;               -- bump the anchor_id{} indexer
  end
  i = i+ 1;                -- bump the parts{} indexer
 end

 return table.concat (anchor_id, '');
end


--[[--------------------------< D A T E _ G E T >--------------------------------------------------------------

extract year from one of |year=, |date=, |publicationdate=, or |publication-date in that order.  Does not error
check (that is left to the cs1|2 templates to do)

also gets date from |<date alias>={{date|...}}

]]

local function date_get (template, aliases)
 local rvalue;

 for _, pattern in ipairs (aliases) do          -- spin through the date alias patterns
  rvalue = tostring(template):match (pattern);       -- is this |<date alias>= used (tostring() because something makes match() think template is a table)
  if rvalue then
   rvalue = tostring(template):match (pattern .. '(%b{})');   -- is rvalue a template?
   if rvalue then
    rvalue = rvalue:gsub ('{{%s*(.-)%s*}}', '%1');     -- strip bounding template markup and trim
    local parts = mw.text.split (rvalue, '%s*|%s*');    -- split at the pipe and remove extraneous space characters

    if redirects_date[parts[1]:lower()] then      -- if parts[1] names {{date}} or redirect
     rvalue = parts[2];           -- assume that date template is properly formed, first positional parameter is the date
    else
     return '';             -- |date= holds some other template than {{date}} or redirect
    end
   else
    rvalue = template:match (pattern .. '([^|}]+)');
    if rvalue then             -- if rvalue is something
     rvalue = mw.text.trim (rvalue);        -- trim it
    end
    
    if not rvalue or '' == rvalue then        -- if rvale was nothing or trimed to nothing
     rvalue = nil;            -- ensure that it is unset so we can try the next parameter in the list
    end
   end

   if rvalue then
    for _, pattern in ipairs (patterns_date) do      -- spin through the recognized date formats
--     date = rvalue:match (pattern);        -- attempt to extract year portion according to the pattern
     local date, date2 = rvalue:match (pattern);     -- attempt to extract year portion according to the pattern; <date2> gets second year in any range
     if date then
      if date2 then           -- when a second year
       date = table.concat ({date, '–', date2});   -- build a date range
      end
      return date;           -- matched so return;
     end
    end
    break;               -- found a date but it was malformed so abandon
   end
  end
 end

 return '';                 -- no date param or date param doesn't hold a recognized date; empty string for concatenation
end

 
--[[--------------------------< V N A M E S _ G E T >----------------------------------------------------------

extract names from |vauthors= or |veditors=; there is no |vcontributors= parameter.

splits the v parameter value at the comma; correctly handles accept-as-witten markup when used to wrap a comma-
separated names (corporate)

]]

local function vnames_get (params, vparam)
 local vnames = {};               -- first four author or editor names go here
 local split = {};               -- temp table to assist in decoding accept-as-witten-markup

 if params[vparam] then              -- test for |vauthors= or |veditor=
  split = mw.text.split (params[vparam], '%s*,%s*');      -- this will separate portions of ((Black, Brown, White, an Co.))
 
  local i = 1;               -- an indexer
  
  while split[i] do
   if split[i]:match ('^%(%(.*[^%)][^%)]$') then      -- first segment of comma-separated accept-as-witten; this segment has the opening doubled parens
    local name = split[i];
    i=i+1;               -- bump indexer to next segment
    while split[i] do
     name = name .. ', ' .. split[i];       -- concatenate with previous segments
     if split[i]:match ('^.*%)%)$') then       -- if this table member has the closing doubled parens
      break;             -- and done reassembling so
     end
     i=i+1;              -- bump indexer
    end
    table.insert (vnames, name);         -- and add accept-as-witten name to the vnames table
 
   else
    table.insert (vnames, split[i]);        -- and add name to the vnames table
   end
  i=i+1;                 -- bump indexer
  if 5 == i then break; end            -- limit to four names
  end

  for i, vname in ipairs (vnames) do
   if not vname:match ('%(%(.-%)%)') then        -- without accept-this-value-as-written markup
    vnames[i] = vname:gsub ('(.-)%s+%u+$', '%1');     -- extract and save surname(s)
   end
  end
  for i, vname in ipairs (vnames) do          -- repeat, this time for accept-this-value-as-written markup
   vnames[i] = vname:gsub ('%(%((.-)%)%)', '%1');      -- remove markup if present and save the whole name
  end
 end

 return 0 ~= #vnames and table.concat (vnames) or nil      -- return a concatenation of the vnames; nil else
end


--[[--------------------------< N A M E S _ G E T >------------------------------------------------------------

cs1|2 makes anchor id from contributor, author, or editor name-lists in that order

get the names from the cs1|2 template;  if there are no contributor names, try author names, then try editor names.

returns concatenated names in enumeration order when successful; nil else

empty name (nameholding parameter n is present without value) and missing name (nameholding parameter n is not
present) are included as empty string with all other names

]]

local function names_get (params, aliases_list)
 local names = {};               -- first four author or editor names go here
 local enum_alias;               -- alias with '#' replaced with a digit

 for enum=1, 4 do               -- four names only
  for i, alias in ipairs (aliases_list) do
   if not names[enum] then            -- hanven't found a previous alias with this [enum]? see if we can find this alias with this enum
    enum_alias = alias:gsub ('#', enum);       -- replace '#' to make 'lastn'
 
    if 1 == enum then            -- because |last= and last1= are exact aliases
     if params[enum_alias] then         -- test |last1= first
      names[enum] = params[enum_alias];      -- found so save the value assigned to |last1=
      break;             -- next enum
     else
      enum_alias = alias:gsub ('#', '');      -- replace '#' to make 'last'
      if params[enum_alias] then
       names[enum] = params[enum_alias];     -- found so save the value assigned to |last=
       break;            -- next enum
      end
     end
    else               -- here for enum 2, 3, 4
     if params[enum_alias] then
      names[enum] = params[enum_alias];      -- found so save the value assigned to |lastn=
      break;             -- next enum
     end
    end
   end
  end
 end

 for enum=1, 4 do               -- spin through the names table and
  local name = names[enum];
  if not name then              -- when nameholding parameter n is not present (nil)
   name = '';               -- convert to empty string for concatenation
  end
  name = name:gsub('%(%((.-)%)%)', '%1');         -- remove accept-as-written markup if present
  names[enum] = name;              -- save the modified name
 end

 local name_str = table.concat (names);          -- concatenate the names
 return '' ~= name_str and name_str or nil;         -- return the concatenation if not empty string; nil else
end


--[[--------------------------< T E M P L A T E _ S T R I P >--------------------------------------------------

removes the citation or havrc template's {{ and }} markup then removes, in whole, any templates found inside the
citation or harvc template.

Templates are not allowed in parameters that are made part of COinS metadata; yet, they will appear.  cs1|2 does
not see the template markup but instead sees the result of the template as html.  cs1|2 strips the html which
leaves the displayed value for the anchor id.  We can't do that here so, because templates aren't allowed in
parameters, we simply discard any templates found in the cs1|2 template.

this may leave a |lastn= parameter empty which will be treated as if it were really empty as cs1|2 do (three authors,
|last2= empty -> CITEREFLast1Last3YYYY (the harv and sfn render: 'Last1, & Last3 YYYY' with CITEREFLast1Last3YYYY).

]]

local function template_strip (template)
 template = template:gsub ('^{{%s*', ''):gsub ('%s*}}$', '', 1);    -- remove outer {{ and }} (cs1|2 template delimiters with trailing/leading whitespace)
 template = template:gsub ('%b{}', '');          -- remove any templates from the cs1|2 template
 return template;
end


--[[--------------------------< E S C A P E _ L U A _ M A G I C _ C H A R S >----------------------------------

Returns a string where all of lua's magic characters have been escaped.  This is important because functions like
string.gsub() treat their pattern and replace strings as patterns, not literal strings.
]]

local function escape_lua_magic_chars (argument)
 argument = argument:gsub("%%", "%%%%");          -- replace % with %%
 argument = argument:gsub("([%^%$%(%)%.%[%]%*%+%-%?])", "%%%1");    -- replace all other lua magic pattern characters
 return argument;
end


--[=[-------------------------< W I K I L I N K _ S T R I P >--------------------------------------------------

Wikilink markup does not belong in an anchor id and can / does confuse the code that parses apart citation and
harvc templates so here we remove any wiki markup:
 [[link|label]] -> label
 [[link]] -> link
 
]=]

local function wikilink_strip (template)
 for wikilink in template:gmatch ('%[%b[]%]') do        -- get a wikilink
  template = template:gsub ('%[%b[]%]', '__57r1P__', 1);     -- install a marker
  if wikilink:match ('%[%[.-|(.-)%]%]') then
   wikilink = wikilink:match ('%[%[.-|(.-)%]%]');      -- extract label from complex [[link|label]] wikilink
  else
   wikilink = wikilink:match ('%[%[(.-)%]%]');       -- extract link from simple [[link]] wikilinks
  end
  wikilink = escape_lua_magic_chars (wikilink);       -- in case there are lua magic characters in wikilink
  template = template:gsub ('__57r1P__', wikilink, 1);     -- replace the marker with the appropriate text
 end

 return template;
end


--[[--------------------------< T E M P L A T E _ N A M E _ G E T >--------------------------------------------

return the citation or harvc template's name; convert to lower case and trim leading and trailing whitespace;

when the template is a sandbox the subpage portion of the template name is omitted from the returned template name
 {{Cite book/new |...}} returns cite book

]]

local function template_name_get (template)
 local template_name = template:match ('^{{%s*([^/|}]+)');     -- get template name; ignore subpages ~/new, ~/sandbox; parser functions

 if not template_name or template_name:match ('^#') then      -- parser functions, magic words don't count as templates
  return nil;                -- could not get template name from (possibly corrupt) template; extraneous opening { mid template can cause this;
 end;
 template_name = template_name:gsub ('%s*$', '');       -- trim trailing whitespace; leading whitespace already removed
 return Lang_obj:ucfirst (template_name);         -- first character in template name must be uppercase (same as canonical template name) TODO: better way to do this?
end


--[[--------------------------< T E M P L A T E _ P A R A M S _ G E T >----------------------------------------

parse apart a template's parameters and store in the params table where key is the parameter's name and value is
the parameter's value; empty parameters are not saved

]]

local function template_params_get (template, params_t)
 template = wikilink_strip (template);          -- because piped wikilinks confuse code that builds params_t{} and because wikilinks not allowed in an anchor id
                    -- strip templates after getting |ref= value because |ref={{sfnref}} and |ref={{harvid}} are allowed
 template = template_strip (template);          -- because template markup can confuse code that builds params_t{} and because templates in name parameters are not allowed

 local temp_t = mw.text.split (template, '%s*|%s*');       --split on the pipe
 for _, param in ipairs (temp_t) do
  if param:find ('=', 1, true) then          -- a named parameter?
   local k, v = param:match ('%s*([^=]-)%s*=%s*([^|}]+)');
   if v then               -- there must be a value
    if '' ~= v and not v:match ('^%s$') then      -- skip when value is empty string or only whitespace
     params_t[k] = mw.text.trim (v);        -- add trimmed value else
    end
   end
  end
 end
end


--[[--------------------------< C I T E R E F _ M A K E _ H A R V C >------------------------------------------

makes anchor_id from {{harvc}} or redirects

]]

local function anchor_id_make_harvc (template)
 local date = date_get (template, alias_patterns_harvc_date);    -- get date; done here because might be in {{date}}; return date if valid; empty string else
 local anchor_id;
 local params = {};               -- table of harvc parameters
 local id;                 -- custom anchor id for this {{harvc}} template

 id = template:match ('|%s*id%s*=%s*(%b{})');        -- in case |id={{sfnref}}; done here because templates will be stripped

 template_params_get (template, params);          -- build a table of template parameters and their values; this strips wikilinks and templates

 if id then                 -- when set is {{sfnref}} or {{harvid}} template
  return sfnref_get (id);             -- returns content of {{sfnref}} or {{harvid}}; nil else
 end
 if params.id then               -- custom anchor for this {{harvc}} template (text)
  return params.id;              -- |id= value as written
 end
 
 anchor_id = names_get (params, aliases_harvc_author);      -- get the harvc contributor names

 if anchor_id then               -- if names were gotten
  return 'CITEREF' .. anchor_id .. date;
 end
 return nil;                 -- no names; no anchor_id
end


--[[--------------------------< A N C H O R _ I D _ M A K E _ W R A P P E R >----------------------------------

for wrapper templates

inspect externally visible |ref= to decide what to do:
 |ref=          - empty or missing: get names and date from whitelist defaults; override defaults from externally visible template parameters
 |ref=harv         - same as empty or missing
 |ref={{SfnRef|name|name|name|name|year}} - assemble an anchor id from {{sfnref}} positional parameters
 |ref={{Harvid|name|name|name|name|year}} - assemble an anchor id from {{harvid}} positional parameters
 |ref=none         - skip; do nothing because an anchor id intentionally suppressed; TODO: keep with a type code of '0'?
 |ref=<text>         - save param value because may match an anchor id override value in {{harv}} template |ref= parameter or {{harvc}} |id= parameter

]]

local function anchor_id_make_wrapper (template)
 local ref;                 -- content of |ref=
 local template_name;              -- name of the template
 local anchor_id;               -- the assembled anchor id from this template
 local date;
 local name_default;
 local date_default;
 local vol;
 local params = {};               -- table of template parameters
 
 template_name = template_name_get (template);        -- get first char uppercase trimmed template name; ignore subpages ~/new, ~/sandbox
 if not template_name or template_skip[template_name] then
  return nil;                -- could not extract template name from (possibly corrupted) template (extraneous opening { in the template will cause this)
 end

 date = date_get (template, alias_patterns_date);       -- get date; done here because might be in {{date}}
-- if '' == date then
--  date = whitelist.wrapper_templates[template_name][2] or '';    -- no externally visible date so get default date
-- end

 ref = template:match ('|%s*ref%s*=%s*(%b{})');        -- first look for |ref={{sfnref}} or |ref={{harvid}} because we will strip templates from the wrapper template
 if not ref then
  if template:match ('|%s*ref%s*=([^|}]+)') then       -- |ref={{template}} not found; if there is a |ref= param with an assigned value
   ref = template:match ('|%s*ref%s*=([^|}]+)');      -- get the value; whitespace is a 'value'
   if ref then               -- nil when |ref=|... or when |ref=}} (no spaces between assignment operator and pipe or closing brace)
    ref = mw.text.trim (ref);          -- something, could be just whitespace, so trim leading / trailing whitespace
    if '' == ref then            -- trimming a string of whitespace makes an empty string
     ref = nil;             -- make empty ref same as missing ref
    end
   end
  end
 end

 template_params_get (template, params);          -- build a table of template parameters and their values

 if whitelist.wrapper_templates[template_name][1] then      -- is this wrapper a simple-default wrapper?
  name_default = whitelist.wrapper_templates[template_name][1];   -- get the default names
  date_default = whitelist.wrapper_templates[template_name][2];   -- get the default date
 else
  vol = params['volume'] or 'default';
  if not whitelist.wrapper_templates[template_name][vol] then    -- make sure this volume exists
   vol = 'default';             -- doesn't exist, use default volume
  end
  name_default = whitelist.wrapper_templates[template_name][vol][1];  -- get the default names
  date_default = whitelist.wrapper_templates[template_name][vol][2];  -- get the default date
 end

 if 'harv' == ref  or not ref then           -- |ref=harv specified or |ref= missing or empty
  anchor_id = names_get (params, aliases_contributor) or     -- get contributor, author, or editor names
   names_get (params, aliases_author) or
   vnames_get (params, 'vauthors') or         -- |vauthors=
   names_get (params, aliases_editor) or
   vnames_get (params, 'veditors') or         -- |veditors=
   name_default;              -- default names from whitelist
--   whitelist.wrapper_templates[template_name][1];      -- default names from whitelist

  if '' == date then              -- if date not provided in the template
   date = date_default;            -- use the default date from whitelist
  end

  if anchor_id then              -- if names were gotten
   anchor_id = 'CITEREF' .. anchor_id .. date;
  end

 elseif ref:match ('%b{}') then            -- ref holds a template
  anchor_id = sfnref_get (ref);           -- returns content of {{sfnref}} or {{harvid}}; nil else

 elseif 'none' == ref then             -- |ref=none
  return nil;                -- anchor id expicitly suppressed
  
 else
  anchor_id = ref;              -- |ref=<text> may match an anchor id override value in {{harv}} template |ref= parameter
 end
 
 return anchor_id;               -- anchor_id text; nil else
end


--[[--------------------------< A N C H O R _ I D _ M A K E _ C S 1 2 >----------------------------------------

for cs1|2 template and cs1-like templates

inspect |ref= to decide what to do:
 |ref=          - empty or missing: get names and date from template parameters; all cs1|2 create CITEREF anchor IDs
 |ref=harv         - get names and date from template parameters
 |ref={{SfnRef|name|name|name|name|year}} - assemble an anchor id from {{sfnref}} positional parameters
 |ref={{Harvid|name|name|name|name|year}} - assemble an anchor id from {{harvid}} positional parameters
 |ref=none         - skip; do nothing because an anchor id intentionally suppressed; TODO: keep with a type code of '0'?
 |ref=<text>         - save param value because may match an anchor id override value in {{harv}} template |ref= parameter or {{harvc}} |id= parameter

]]

local function anchor_id_make_cs12 (template)
 local ref;                 -- content of |ref=
 local template_name;              -- name of the template
 local anchor_id;               -- the assembled anchor id from this template
 local date;
 local params = {};               -- table of template parameters
 
 template_name = template_name_get (template);        -- get first char uppercase trimmed template name; ignore subpages ~/new, ~/sandbox
 if not template_name or template_skip[template_name] then
  return nil;                -- could not extract template name from (possibly corrupted) template (extraneous opening { in the template will cause this)
 end

 if redirects_patent[template_name] then
  date = date_get (template, alias_patterns_patent_date);     -- get date; done here because might be in {{date}} 
 else
  date = date_get (template, alias_patterns_date);
 end
 
 ref = template:match ('|%s*ref%s*=%s*(%b{})');        -- first look for |ref={{sfnref}} or |ref={{harvid}} because we will strip templates from the cs1|2 template
 if not ref then
  if template:match ('|%s*ref%s*=([^|}]+)') then       -- |ref={{template}} not found; if there is a |ref= param with an assigned value
   ref = template:match ('|%s*ref%s*=([^|}]+)');      -- get the value; whitespace is a 'value'
   if ref then               -- nil when |ref=|... or when |ref=}} (no spaces between assignment operator and pipe or closing brace)
    ref = mw.text.trim (ref);          -- something, could be just whitespace, so trim leading / trailing whitespace
    if '' == ref then            -- trimming a string of whitespace makes an empty string
     ref = nil;             -- make empty ref same as missing ref
    end
   end
  end
 end

 template_params_get (template, params);          -- build a table of template parameters and their values

 if not ref then                -- |ref= not set, might be cite LSA which doesn't support |ref=
  if 'cite lsa' == template_name then
   return 'CITEREF' .. (params.last or '') .. (params.year or '');  -- cite LSA always creates an anchor id using only |last= and |year= (no aliases)
  end
 end

 if 'harv' == ref  or not ref then           -- |ref=harv specified or |ref= missing or empty
  if redirects_patent[template_name] then         -- if this is a cite patent template
   anchor_id = names_get (params, aliases_inventor);     -- inventor names only
  else                 -- cs1|2 template
   anchor_id = names_get (params, aliases_contributor) or    -- get contributor, author, or editor names
    names_get (params, aliases_author) or
    vnames_get (params, 'vauthors') or        -- |vauthors=
    names_get (params, aliases_editor) or
    vnames_get (params, 'veditors');        -- |veditors=
  end

  if anchor_id then              -- if names were gotten
   anchor_id = 'CITEREF' .. anchor_id .. date;
  end

 elseif ref:match ('%b{}') then            -- ref holds a template
  anchor_id = sfnref_get (ref);           -- returns content of {{sfnref}} or {{harvid}}; nil else

 elseif 'none' == ref and not redirects_patent[template_name] then   -- |ref=none; not supported by cite patent
  return nil;                -- anchor id expicitly suppressed
  
 else
  anchor_id = ref;              -- |ref=<text> may match an anchor id override value in {{harv}} template |ref= parameter
 end
 
 return anchor_id;               -- anchor_id text; nil else
end


--[[--------------------------< L I S T _ A D D >--------------------------------------------------------------

adds an <item> to <list> table; for anchor IDs, the boolean <encode> argument must be set true; no return value

]]

local function list_add (item, list, encode)
 if item then                -- if there was an item
  if encode then               -- for anchor IDs ...
   item = mw.uri.anchorEncode (item);         -- encode to remove wikimarkup, convert spaces to underscores etc
  end
  
  if not list[item] then             -- if not already saved
   list[item] = 1;              -- save it 
  else                 -- here when this item already saved
   list[item] = list[item] + 1;          -- to indicate that there are multiple items
  end
 end
end


--[[--------------------------< A N C H O R _ I D _ M A K E _ A N C H O R >------------------------------------

make anchor IDs from {{anchor}}; there may be more than one because {{anchor}} is not limited to the number of
anchors it may hold.

]]

local function anchor_id_make_anchor (template, anchor_id_list)
 template = template:gsub ('^{{[^|]+|', ''):gsub ('}}$', '', 1);    -- remove outer {{ and }} and template name

 template = wikilink_strip (template);          -- strip any wikilink markup (there shouldn't be any but just in case)
 
 local params = {};
 local anchor_id;
 
 for param in template:gmatch ('%b{}') do         -- loop through the template; remove and save templates (presumed to be sfnref or harvid)
  table.insert (params, param);           -- save it
  template = template:gsub ('%b{}', '', 1);        -- remove it from source template
 end
 
 for _, t in ipairs (params) do            -- spin through the templates in params
  anchor_id = sfnref_get (t);            -- attempt to decode {{sfnref}} and {{harvid}}
  if anchor_id then              -- nil when not {{sfnref}} or {{harvid}}
   list_add (anchor_id, anchor_id_list, true);       -- add anchor ID to the list
  end
 end
 
 template = template:gsub ('|%s*|', '|');         -- when pipe follows pipe with or without white space, remove extraneous pipe
 template = template:gsub ('^|', ''):gsub('|$', '');       -- remove extraneous leading and trailing pipes

 params = mw.text.split (template, '%s*|%s*');        -- split at the pipe and remove extraneous space characters
 
 for _, t in ipairs (params) do            -- spin through the anchor IDs
  anchor_id = mw.text.trim (t);           -- trim white space
  if '' ~= anchor_id then             -- should always have something
   list_add (anchor_id, anchor_id_list, true);       -- add anchor ID to the list
  end
 end
end


--[[--------------------------< T E M P L A T E _ L I S T _ A D D >--------------------------------------------

makes a list of templates use in the article.

]]

local function template_list_add (template)
 local template = template:match ('{{%s*(.-)[|}]');       -- keep the case of the template - this is different from template_name_get()
 if template and not template:match ('^#') then        -- found a template or magic word; ignore magic words
  template=mw.text.trim (template);          -- trim whitespace
  template = Lang_obj:ucfirst (template);         -- first character in template name must be uppercase (same as canonical template name) TODO: better way to do this?
  list_add (template, template_list);          -- add to list with (unused) tally
 end
end


--[[--------------------------< A N C H O R _ I D _ L I S T _ M A K E >----------------------------------------

makes a list of anchor ids from cs1|2, cs1|2-like, vcite xxx, harvc, anchor, wikicite templates

Because cs1|2 wrapper templates can, and often do, hide the author and date parameters inside the wrapper,
these parameters are not available in the article's wikisource so {{harv}}, {{sfn}}, and {{harvc}} templates that
link correctly to those wrapper templates will incorrectly show error messages.  Use |ignore-err=yes in the {{harv}},
{{sfn}}, and {{harvc}} templates to supress the error message.

creates a list of templates used in the article for use with the whitelist

creates a list of article-local whitelisted anchor IDs from {{sfn whitelist}}

]]

local function anchor_id_list_make ()
 article_content_get ();              -- attempt to get this article's content

 if '' == Article_content then            -- when there is no article content
  return '';                -- no point in continuing
 end
 
 local template;                -- place to hold the template that we found
 local template_name;
 local anchor_id;               -- place to hold an anchor id as it is extracted / decoded

 local find_pattern = '%f[{]{{[^{]';
 local tstart, tend = Article_content:find (find_pattern);     -- find the first template; do not find template variables: {{{template var|}}} 

 while tstart do
  template = Article_content:match ('%b{}', tstart);      -- get the whole template
  if not template then
   break;                -- template is nil for some reason (last template missing closing }} for example) so declare ourselves done
  end

  template_name = template_name_get (template);       -- get first char uppercase trimmed template name; ignore subpages ~/new, ~/sandbox
  template_list_add (template);           -- add this template's name to the list

  if data.known_templates_cs12 [template_name] then
   anchor_id = anchor_id_make_cs12 (template);       -- extract an anchor id from this template
   list_add (anchor_id, anchor_id_list, true)

  elseif data.known_templates_vcite [template_name] then
   local ref = template:match ('|%s*ref%s*=%s*(%b{})');    -- first look for |ref={{sfnref}} or |ref={{harvid}} because we will strip templates from the vcite template
   if ref then               -- |ref={{template}}
    anchor_id = sfnref_get (ref);         -- returns content of {{sfnref}} or {{harvid}}; nil else
    list_add (anchor_id, anchor_id_list, true);
   else
    local params = {};

    template_params_get (template, params);       -- build a table of template parameters and their values

    anchor_id = params['ref'];          -- when both set, vcite uses value from |ref=
    if not anchor_id and params['harvid'] then
     anchor_id = 'CITEREF' .. params['harvid'];     -- in vcite, |harvid= auto-adds 'CITEREF' prefix to the value in |harvid=
    end
    list_add (anchor_id, anchor_id_list, true);
   end

  elseif data.known_templates_harvc [template_name] then
   anchor_id = anchor_id_make_harvc (template);      -- extract an anchor id from this template
   list_add (anchor_id, anchor_id_list, true);
   
  elseif data.known_templates_wikicite [template_name] then
   local ref = template:match ('|%s*ref%s*=%s*(%b{})');    -- first look for |ref={{sfnref}} or |ref={{harvid}}
   
   if ref then
    anchor_id = sfnref_get (ref);
 
   elseif template:match ('|%s*ref%s*=([^|}]+)') then
    anchor_id = template:match ('|%s*ref%s*=([^|}]+)');    -- plain-text
 
   elseif template:match ('|%s*id%s*=%s*(%b{})') then
    ref = template:match ('|%s*id%s*=%s*(%b{})');
    anchor_id = 'Reference-' .. sfnref_get (ref);

   elseif template:match ('|%s*id%s*=([^|}]+)') then
    anchor_id = 'Reference-' .. template:match ('|%s*id%s*=([^|}]+)'); -- plain-text

   else
    anchor_id = nil;            -- no matches, ensure that anchor_id has no value
   end
   
   if anchor_id then
    list_add (anchor_id, anchor_id_list, true);
   end

  elseif data.known_templates_anchor [template_name] then
   anchor_id_make_anchor (template, anchor_id_list);     -- extract anchor ids from this template if any
  
  elseif data.known_templates_sfn_whitelist [template_name] then
   template = template:gsub ('^{{[^|]+|', ''):gsub ('}}$', '', 1);  -- remove outer {{ and }} and template name
   template = mw.text.trim (template, '%s|');       -- trim leading trailing white space and pipes
   template = mw.text.split (template, '%s*|%s*');      -- make a table of the template's parameters

   for _, anchor_id in ipairs (template) do       -- spin through this template's parameter
    if '' ~= anchor_id and not article_whitelist[anchor_id] then
     anchor_id = mw.uri.anchorEncode (anchor_id)
     article_whitelist[anchor_id] = 1;       -- add to the whitelist
    end
   end
  
  elseif template_name and whitelist.wrapper_templates[template_name] then
   anchor_id = anchor_id_make_wrapper (template);      -- extract an anchor id from this template if possible
   list_add (anchor_id, anchor_id_list, true);

  elseif template_name and template_name:match ('^Cit[ea]') then   -- not known, not known wrapper; last gasp, try as cs1-like
   anchor_id = anchor_id_make_cs12 (template);       -- extract an anchor id from this template if possible
   list_add (anchor_id, anchor_id_list, true);
  end

  tstart, tend = Article_content:find (find_pattern, tend);    -- search for another template; begin at end of last search
 end

mw.logObject (anchor_id_list, 'anchor_id_list');
mw.logObject (template_list, 'template_list');
mw.logObject (article_whitelist, 'article_whitelist');

 return anchor_id_list;
end


--[[--------------------------< E X P O R T E D _ T A B L E S >------------------------------------------------
]]

return {
 anchor_id_list = anchor_id_list_make(),          -- table of anchor ids available in this article
 article_whitelist = article_whitelist,          -- table of anchor ids with false-positive error message to be suppressed
 template_list = template_list,            -- table of templates used in this article
 }