-- TIME_STAMP   2021-11-26 13:52:54   v 0.2

--[[    History
    v 0.2
    added:      Multiple UDF files for the same prefix
                i.e.: "udf.path._OL_=C:\Code\AutoIt\udf\OutlookEX 1.7.0.0\OutlookEX.au3|C:\Code\AutoIt\udf\OutlookEX 1.7.0.0\OutlookEX_Base.au3"
    changed:    This script is now called from an executable *.au3 file.
                Therefore, the resulting command line for calling the respective help is passed to the calling program for execution.
]]


local tAU3Help = {}

do
    tAU3Help.pattFunc = '([Ff][Uu][Nn][Cc]%s+[%w_]+%s-%b())'
    tAU3Help.pattFuncName = '([Ff][Uu][Nn][Cc]%s+)([%w_]+)(%s-%b())'
    tAU3Help.t_names = {}

    tAU3Help.Split = function(self, _s, _delim)
        if not _s:find(_delim) then return {_s} end
        local t_res = {}
        for v in (_s.._delim):gmatch("(.-)".._delim) do
            table.insert(t_res, v)
        end
        return t_res
    end

    tAU3Help.GetItemHelp = function(self, _item)
        local prefix = _item:match('^(_%w+_)')
        if prefix ~= nil then
            if self:Extract(prefix) then
                if self.t_names[_item:upper()] then
                    self:CallHelp(prefix, _item)
                    return
                end
            end
        end
        self:CallHelp('AU3', _item)
    end

    tAU3Help.Extract = function(self, _prefix)
        self.t_names = {}
	    local func, fname, err, s, a, e = '', '', 0
        local t_udfpath = self:Split(props['udf.path.'.._prefix:upper()], '|')
        if #t_udfpath == 0 then return false end
        for i=1, #t_udfpath do
            local fh = io.open(t_udfpath[i])
            if fh == nil then
                err = err + 1
            else
                s = fh:read('*a') fh:close() e = 1
                while e do
                    a, e, func = s:find(self.pattFunc , e)
                    if a then
                        _, _, _, fname = func:find(self.pattFuncName)
                        if fname:sub(1, _prefix:len()):upper() == _prefix:upper() then
                            self.t_names[fname:upper()] = true
                        end
                    end
                end
            end
        end
        if err == #t_udfpath then return false end
        return true
	end

    tAU3Help.CallHelp = function(self, _prefix, _item)
        local path, cmd = props['chm.path.'.._prefix:upper()]
        if _prefix == 'AU3' then
            cmd = '"'..props['autoit3dir']..'\\Autoit3Help.exe" "'.._item..'"'
        else
            cmd = 'mk:@MSITStore:'..path..'::/funcs/'.._item..'.htm'
        end
        props['extender.result'] = cmd  -- Runtime property, is queried by the calling Au3 script.
    end

end


tAU3Help:GetItemHelp(props['CurrentWord'])