<?php

/**
 * Routine: merge_column_T_and_U_into_T
 *
 * Purpose:
 * For each imported XLS row:
 * - read the value from column T
 * - read the value from column U
 * - merge both values
 * - save the final value into column T
 *
 * Target:
 * Column T must be mapped to the destination field in the template mapping.
 */

function applyRoutine(&$excelData, $routineData = [])
{
    /*
     * Excel column indexes are zero-based:
     *
     * T = 19
     * U = 20
     */
    $targetColumnIndex = 19; // T
    $firstColumnIndex  = 19; // T
    $secondColumnIndex = 20; // U

    foreach ($excelData as $rowIndex => &$row) {
        if (!isset($row['data']) || !is_array($row['data'])) {
            error_log("Routine merge T+U: invalid row structure at index {$rowIndex}.");
            continue;
        }

        $valueT = trim((string)($row['data'][$firstColumnIndex] ?? ''));
        $valueU = trim((string)($row['data'][$secondColumnIndex] ?? ''));

        /*
         * Merge values, ignoring empty values.
         */
        $mergedValues = [];

        if ($valueT !== '') {
            $mergedValues[] = $valueT;
        }

        if ($valueU !== '') {
            $mergedValues[] = $valueU;
        }

        /*
         * Save final value into column T.
         */
        $row['data'][$targetColumnIndex] = implode(' ', $mergedValues);

        error_log(
            "Routine merge T+U: row " .
                ($row['excelrow'] ?? $rowIndex) .
                " generated value in column T: " .
                $row['data'][$targetColumnIndex]
        );
    }

    unset($row);

    error_log("Routine merge T+U completed.");
}