Sort algorithm: Magento checkout totals sorted wrongly causing wrong shipping tax calculation

Question

In Magento there is a functionality where you can define the order of total calculation by specifing before and after which totals a total should be run.

I added a c

Answer 1

Well was stucked at this for years!!!+

Now i know why some projects of the past were so difficult to adjust regarding wee and tax combinations a nightmare i could say, never got to understand why, yesterday i found why, later i found this article, a real shame.. but most of the time i need to know the response to be capable of search the question..

And the obvius solution at least for linux heads without fear, is the code below, basically i make use of the ancient linux command tsort that especifically does a topolocical order in the way we need here..

For the entomological and archeologist souls among us some pointers http://www.gnu.org/software/coreutils/manual/html_node/tsort-invocation.html,I am using authentic 80's technology... yummmm

    /**
 * Aggregate before/after information from all items and sort totals based on this data
 *
 * @return array
 */
protected function _getSortedCollectorCodes() {
    if (Mage::app()->useCache('config')) {
        $cachedData = Mage::app()->loadCache($this->_collectorsCacheKey);
        if ($cachedData) {
            return unserialize($cachedData);
        }
    }
    $configArray = $this->_modelsConfig;
    // invoke simple sorting if the first element contains the "sort_order" key
    reset($configArray);
    $element = current($configArray);
    if (isset($element['sort_order'])) {
        uasort($configArray, array($this, '_compareSortOrder'));
        $sortedCollectors = array_keys($configArray);
    } else {
        foreach ($configArray as $code => $data) {
            foreach ($data['before'] as $beforeCode) {
                if (!isset($configArray[$beforeCode])) {
                    continue;
                }
                $configArray[$code]['before'] = array_merge(
                        $configArray[$code]['before'],
                        $configArray[$beforeCode]['before']);
                $configArray[$code]['before'] = array_unique(
                        $configArray[$code]['before']);
                $configArray[$beforeCode]['after'] = array_merge(
                        $configArray[$beforeCode]['after'], array($code),
                        $data['after']);
                $configArray[$beforeCode]['after'] = array_unique(
                        $configArray[$beforeCode]['after']);
            }
            foreach ($data['after'] as $afterCode) {
                if (!isset($configArray[$afterCode])) {
                    continue;
                }
                $configArray[$code]['after'] = array_merge(
                        $configArray[$code]['after'],
                        $configArray[$afterCode]['after']);
                $configArray[$code]['after'] = array_unique(
                        $configArray[$code]['after']);
                $configArray[$afterCode]['before'] = array_merge(
                        $configArray[$afterCode]['before'], array($code),
                        $data['before']);
                $configArray[$afterCode]['before'] = array_unique(
                        $configArray[$afterCode]['before']);
            }
        }
        //uasort($configArray, array($this, '_compareTotals'));
        $res = "";
        foreach ($configArray as $code => $data) {
            foreach ($data['before'] as $beforeCode) {
                if (!isset($configArray[$beforeCode])) {
                    continue;
                }
                $res = $res . "$code $beforeCode\n";
            }
            foreach ($data['after'] as $afterCode) {
                if (!isset($configArray[$afterCode])) {
                    continue;
                }
                $res = $res . "$afterCode $code\n";
            }
        }
        file_put_contents(Mage::getBaseDir('tmp')."/graph.txt", $res);
        $sortedCollectors=explode("\n",shell_exec('tsort '.Mage::getBaseDir('tmp')."/graph.txt"),-1);           
    }
    if (Mage::app()->useCache('config')) {
        Mage::app()
                ->saveCache(serialize($sortedCollectors),
                        $this->_collectorsCacheKey,
                        array(Mage_Core_Model_Config::CACHE_TAG));
    }
    return $sortedCollectors;
}

I've posted the complete funcion for the sake of completeness, and of course is working like a charm for me at least...