save_bilingual_txt.php

<?php

/**
 * Saves bilingual TXT file with alternating paragraphs from two input TXT files.
 *
 * @param  string $fileAddress1 Path to TXT file 1.
 * @param  string $fileAddress2 Path to TXT file 2.
 * @param  string $outputFileAddress Path to output bilingual TXT file.
 * @return void
 */
function saveBilingualTxt ($fileAddress1, $fileAddress2,
    $outputFileAddress = './bilingual.txt') {

    if (!file_exists($fileAddress1) && !file_exists($fileAddress2)) {
        throw new Exception("Files $fileAddress1 and $fileAddress2 not found!");
    } else if (!file_exists($fileAddress1)) {
        throw new Exception("File $fileAddress1 not found!");
    } else if (!file_exists($fileAddress2)) {
        throw new Exception("File $fileAddress2 not found!");
    }

    $outputDirectory = explode('/', $outputFileAddress);
    $outputDirectory = array_slice($outputDirectory, 0, count($outputDirectory) - 1);
    $outputDirectory = implode('/', $outputDirectory);
    
    if (!is_dir($outputDirectory)) {
        throw new Exception("Directory $outputDirectory not found!");
    }

    $fileContent1 = file_get_contents($fileAddress1);
    $fileContent2 = file_get_contents($fileAddress2);

    $fileCoding1 = mb_detect_encoding($fileContent1, ['UTF-8', 'ASCII', 'CP1251']);
    $fileCoding2 = mb_detect_encoding($fileContent2, ['UTF-8', 'ASCII', 'CP1251']);

    $textArray1 = preg_split("/[\r]*[\n]+/", iconv($fileCoding1, 'UTF-8', $fileContent1));
    $textArray2 = preg_split("/[\r]*[\n]+/", iconv($fileCoding2, 'UTF-8', $fileContent2));

    $maxLength = max(count($textArray1), count($textArray2));
    $txtContent = '';

    for ($i = 0; $i < $maxLength; $i++) {
        $txtContent .= trim(@$textArray1[$i]) . PHP_EOL . PHP_EOL;
        $txtContent .= trim(@$textArray2[$i]) . PHP_EOL . PHP_EOL;
    }

    $txtContent = preg_replace("/<\/?(h1|b|i|img[0-9]+)>/i", '', $txtContent);
    $txtContent = str_replace('<delimiter>', PHP_EOL, $txtContent);
    $txtContent = preg_replace("/" . PHP_EOL . "{4,6}/", str_repeat(PHP_EOL, 2), $txtContent);

    file_put_contents($outputFileAddress, trim($txtContent));
}