php-guestbook/persistence.php

<?php

function createDB($db_name = 'guestbook.db'): SQLite3 {
	// Can't create table if it already exists
	$exists = file_exists($db_name);
	$db = new SQLite3($db_name);

	if(!$exists) {
		$db->exec('CREATE TABLE user
					(id_user INTEGER PRIMARY KEY,
					username TEXT NOT NULL UNIQUE,
					password TEXT)'
		);
		$db->exec('CREATE TABLE message
					(id_msg INTEGER PRIMARY KEY,
					id_user INT,
					content TEXT NOT NULL,
					date INT,
					FOREIGN KEY (id_user) REFERENCES user (id_user))'
		);
	}

	return $db;
}

function getMessages(SQLite3 $db, array $filter = [], int $limit = 25) {
	// Apply filters
	$append_string = '';
	$verb = 'WHERE';

	foreach($filter as $key => $value) {
		$to_append = match($key) {
			'id_user' => "$verb $key = :$key",
			// TODO
		};
		if($to_append) {
 			$append_string .= " $to_append";
			$verb = 'AND';
		}
	}

	// Prepare statement
	$query = 'SELECT * FROM message' . $append_string;
	//var_dump($query);
	$statement = $db->prepare($query);

	foreach($filter as $key => $value) {
		$statement->bindParam($key, $value);
	}

	$result = $statement->execute();
	$notnull = true;
	$ret = [];
	while($notnull) {
		$arr = $result->fetchArray(SQLITE3_ASSOC);
		//var_dump($arr);
		if($arr !== false) {
			$ret[] = $arr;
		}
		else $notnull = false;
	}

	return $ret;
}

function storeMessage(SQLite3 $db, string $content, ?int $user_id = null) : bool {
	$query = 'INSERT INTO message(id_user, content, date)
				VALUES (:id_user, :content, :date)';

	$date = (new DateTime('now'))->getTimestamp();
	$statement = $db->prepare($query);
	$statement->bindParam(':id_user', $user_id);
	$statement->bindParam(':content', $content);
	$statement->bindParam(':date', $date);
	$statement->execute();
	return ($db->changes() > 0);
}

function storeUser(SQLite3 $db, string $username, string $password) : bool {
	$query = 'INSERT INTO user(username, password)
				VALUES (:username, :password)';

	$statement = $db->prepare($query);
	$statement->bindParam(':username', $username);
	$statement->bindParam(':password', $password);
	$statement->execute();
	return ($db->changes() > 0);
}

function deleteMessage(SQLite3 $db, int $message_id) : int {
	$query = 'DELETE FROM message
				WHERE id_msg = :id_msg';

	$statement = $db->prepare($query);
	$statement->bindParam(':id_msg', $message_id);
	$result = $statement->execute();
	if($result === false) {
		return -1;
	}
	// Number of changed rows
	return $db->changes();
}

function userFromMessage(SQLite3 $db, int $message_id) {
	$query = 'SELECT user.id_user, user.username
				FROM user, message
				WHERE message.id_user = user.id_user
				AND message.id_msg = :id_msg';

	$statement = $db->prepare($query);
	$statement->bindParam(':id_msg', $message_id);
	$result = $statement->execute();


	$array = $result->fetchArray();
	if(!$array) return null;
	return ['id' => $array['id_user'], 'username' => $array['username']];
}