Craft\AmForms_ExportsService::runExport PHP Method

    public function runExport(AmForms_ExportModel $export, $limit = null, $offset = null)
    {
        // Validate export file (if send by task)
        if (!IOHelper::fileExists($export->file) && !$export->startRightAway) {
            return false;
        }
        // Get submissions
        $params = array('formId' => $export->formId, 'limit' => $limit, 'offset' => $offset);
        // Are there manually given submissions?
        if ($export->submissions) {
            $params['id'] = $export->submissions;
        }
        $criteria = craft()->amForms_submissions->getCriteria($params);
        $this->_addExportCriteria($export, $criteria);
        $submissions = $criteria->find();
        // Add submissions to export file
        if ($submissions && count($submissions) > 0) {
            // Get form
            $form = craft()->amForms_forms->getFormById($export->formId);
            if (!$form) {
                return false;
            }
            // Get field types
            $fields = $this->getExportFields($form);
            // Export submission to a zip file?
            if ($export->submissions) {
                // Add all fields
                $this->_exportFields[$export->id] = $fields;
                // Export submission
                foreach ($submissions as $submission) {
                    $this->_exportSubmissionToZip($export, $submission);
                }
            } else {
                // Get the export file
                if ($export->startRightAway) {
                    // Open output buffer
                    ob_start();
                    // Write to output stream
                    $this->_exportFiles['manual'] = fopen('php://output', 'w');
                    // Create columns
                    fputcsv($this->_exportFiles['manual'], $this->_getExportColumns($export, $form), $this->_delimiter);
                } else {
                    $this->_exportFiles[$export->id] = fopen($export->file, 'a');
                }
                // Get field handles and columns that should be included
                $columnCounter = 0;
                $this->_exportFields[$export->id] = array();
                foreach ($export->map['fields'] as $fieldHandle => $columnName) {
                    if ($export->map['included'][$fieldHandle] && isset($fields[$fieldHandle])) {
                        // Add field to export fields
                        $field = $fields[$fieldHandle];
                        if (is_array($field)) {
                            $field = (object) $field;
                            // Fix standard fields
                        }
                        $this->_exportFields[$export->id][$fieldHandle] = $field;
                        // Remember how much space this field is taking
                        $spaceCounter = 0;
                        // Add column so we know where to place the data later
                        switch ($field->type) {
                            case 'Matrix':
                                $blockTypes = $field->getFieldType()->getSettings()->getBlockTypes();
                                foreach ($blockTypes as $blockType) {
                                    $blockTypeFields = $blockType->getFields();
                                    $this->_exportColumns[$export->id][$field->handle . ':' . $blockType->handle] = $columnCounter;
                                    $columnCounter += count($blockTypeFields);
                                    $spaceCounter += count($blockTypeFields);
                                }
                                break;
                            default:
                                $this->_exportColumns[$export->id][$field->handle] = $columnCounter;
                                $spaceCounter++;
                                break;
                        }
                        $columnCounter++;
                        $this->_exportSpaceCounter[$export->id][$field->handle] = $spaceCounter;
                    }
                }
                // Export submission model
                foreach ($submissions as $submission) {
                    $this->_exportSubmission($export, $submission);
                }
                // Close export file
                fclose($this->_exportFiles[$export->startRightAway ? 'manual' : $export->id]);
                if ($export->startRightAway) {
                    // Close buffer and return data
                    $data = ob_get_clean();
                    // Use windows friendly newlines
                    $data = str_replace("\n", "\r\n", $data);
                    return $data;
                }
            }
        }
        return true;
    }