// Straightaway clear the Bible action for this chapter.
// This atomic operation enables new edits from the user in this chapter to be recorded straightaway,
// even during the time that this chapter is still being sent.
// In the face of a slow network at times, this does occur in practise.
// Examples have been seen.
$database_bibleactions->delete($bible, $book, $chapter);
// If old USFM and new USFM differ, and the new USFM is not empty, send it to the server.
if ($newusfm != $oldusfm && $newusfm != "") {
$checksum = Checksum_Logic::get($oldusfm . $newusfm);
// It used to send the old and new USFM in compressed form.
// But the server failed to decompress it.
// That means that compression is not a good option.
// Generate a POST request.
$post = array("u" => bin2hex($user), "p" => $hash, "bi" => $bible, "bo" => $book, "ch" => $chapter, "o" => $oldusfm, "n" => $newusfm, "s" => $checksum);
$url = "{$address}/sync/bible.php";
$response = Sync_Logic::post($post, $url);
if ($response === false) {
// Communication error.
$communication_errors = true;
$database_logs->log("Failure sending Bibles", Filter_Roles::TRANSLATOR_LEVEL);
// Restore the Bible action for this chapter.
$database_bibleactions->delete($bible, $book, $chapter);
$database_bibleactions->record($bible, $book, $chapter, $oldusfm);
} else {
if ($response != "") {
// The first line of the response can contain a message as a string.
// This is what the server says to the client in case of an error.
// Normally the first line of the response contains a numerical value.
// This value is the checksum of the data that the server returns in the subsequent lines.
// This data would be the updated USFM for the chapter.
$response = explode("\n", $response);
// Get checksum for the chapter on client and on server.
// If both are the same, it means the USFM in both is the same, and we're done.
$client_checksum = Checksum_Logic::getChapter($bible, $book, $chapter);
$post = array("b" => $bible, "bk" => $book, "c" => $chapter, "a" => "chapter");
$server_checksum = Sync_Logic::post($post, $url);
if ($server_checksum === false) {
$database_logs->log(Locale_Translate::_("Failure getting checksum:") . " {$bible} {$book_name} {$chapter}", Filter_Roles::TRANSLATOR_LEVEL);
continue;
}
if ($client_checksum == $server_checksum) {
continue;
}
// Different checksums: Get the USFM for the chapter as it is on the server.
$database_logs->log(Locale_Translate::_("Getting chapter:") . " {$bible} {$book_name} {$chapter}", Filter_Roles::TRANSLATOR_LEVEL);
$post = array("b" => $bible, "bk" => $book, "c" => $chapter, "a" => "get");
$server_usfm = Sync_Logic::post($post, $url);
if ($server_usfm === false) {
$database_logs->log(Locale_Translate::_("Failure getting chapter:") . " {$bible} {$book_name} {$chapter}", Filter_Roles::TRANSLATOR_LEVEL);
continue;
}
// Verify the checksum of the chapter on the server, to be sure there's no corruption during transmission.
$server_usfm = explode("\n", $server_usfm);
$checksum = array_shift($server_usfm);
$server_usfm = implode("\n", $server_usfm);
if (!Checksum_Logic::get($server_usfm) == $checksum) {
$database_logs->log(Locale_Translate::_("Checksum error while receiving chapter from server:") . " {$bible} {$book_name} {$chapter}", Filter_Roles::TRANSLATOR_LEVEL);
continue;
}
// Check whether the user on the client has made changes in this chapter since the edits were sent to the server.
// If there are none, then the client stores the chapter as it gets it from the server, and is done.
$old_usfm = $database_bibleactions->getUsfm($bible, $book, $chapter);
