<?php
function save_computed_data_to_db(string $filename, bool $clear_before, string $userdata = '') {
	try {
		$pdo = new PDO('mysql:host=localhost;dbname=observer', 'observer', '6BjUdh7n');

		$fd = fopen($filename, 'r');

		$columns = fgetcsv($fd);
		$placeholders = array_map(function($_) { return '?'; }, $columns);
		$column_count = count($columns);

		$sql_insert = 'insert into computeddata (' . implode(',', $columns) .
			') values (' . implode(',', $placeholders) . ');';

		$pdo->beginTransaction();

		$statement = $pdo->prepare($sql_insert);
		$nan_to_null = function ($x) {
			if ((gettype($x) === 'double' && is_nan($x)) || $x === 'NaN') {
				return null;
			}
			return $x;
		};
		$insert_data = function ($line) use ($column_count, $statement, $nan_to_null) {
			if (count($line) == $column_count) {
				if (!$statement->execute(array_map($nan_to_null, $line))) {
					HttpResponse::internal_server_error()->set_and_exit();
				}
			} else {
				throw new Exception('Incomplete or overfull line in CSV: '
					. $column_count .  ' expected, ' . count($line)
					. ' given (distance ' . $line['distance'] . ')');
			}
		};

		if ($clear_before) {
			$setup_id_index = array_search('setup_id', array_map('strtolower', $columns));
			$line = fgetcsv($fd);
			$setup_id = $line[$setup_id_index];
			$pdo->exec('delete from computeddata where setup_id = ' . $setup_id . ';');
			$insert_data($line);
			if ($userdata !== '') {
				$pdo->prepare('replace into setup (setup_id, userdata) values (?, ?);')->execute(array($setup_id, $userdata));
			}
		}

		while (($line = fgetcsv($fd)) !== false) {
			$insert_data($line);
		}

		$pdo->commit();
	} catch (Exception $e) {
		// Prevent incomplete dataset insertion
		if (isset($pdo) && $pdo->inTransaction()) {
			$pdo->rollBack();
		}
		// As all we care about is aborting the transaction, we leave taking
		// care of the exception up to the caller
		throw $e;
	} finally {
		if (isset($fd)) {
			fclose($fd);
		}
		unset($statement);
		unset($pdo);
	}
}