Login/Register/confirm and new comment feature

tasks/guestBookDB/actions/login.php

@@ -0,0 +1,74 @@
+<?php
+include_once "../../../base/settings.php";
+include_once "../../../base/headers.php";
+include_once "../../../base/database.php";
+include_once "../queries.php";
+
+session_name("PHP_SESSION_guestBook");
+session_start();
+
+if (isset($_SESSION["user"])) {
+  Headers::redirect("../");
+  return;
+}
+
+$_SESSION["error"] = [];
+unset($_SESSION["user"]);
+
+if (!isset($_POST["username"])) {
+  array_push($_SESSION["error"], "username was not among the data sent.");
+}
+if (!isset($_POST["password"])) {
+  array_push($_SESSION["error"], "password was not among the data sent.");
+}
+
+$username = trim($_POST["username"]);
+$password = trim($_POST["password"]);
+
+if ($username === "") {
+  array_push($_SESSION["error"], "The username was empty.");
+}
+if ($password === "") {
+  array_push($_SESSION["error"], "The password was empty.");
+}
+
+if (count($_SESSION["error"]) > 0) {
+  Headers::redirect("../login");
+  return;
+}
+
+$db = DB::openConnection();
+
+$stmt = $db->prepare($loginQuery);
+$stmt->bindValue(":USR", $username);
+$stmt->execute();
+$user = $stmt->fetch();
+
+if ($user) {
+  if (password_verify($password, $user["passwort"])) {
+    $_SESSION["user"] = $user;
+    // REHASH for safety should it somehow change
+    if (password_needs_rehash($user["passwort"], PASSWORD_DEFAULT)) {
+      $newHash = password_hash($password, PASSWORD_DEFAULT);
+      $stmt = $db->prepare($updatePasswordQuery);
+      $stmt->bindValue(":PAS", $newHash);
+      $stmt->bindValue(":UID", $user["id"]);
+      $stmt->execute();
+    }
+    unset($_SESSION["user"]["passwort"]);
+    unset($_SESSION["user"]["confirmationcode"]);
+  } else {
+    array_push($_SESSION["error"], "Username or Password incorrect.");
+  }
+} else {
+  array_push($_SESSION["error"], "Username or Password incorrect.");
+}
+
+DB::closeConnection($db);
+
+if (count($_SESSION["error"]) > 0) {
+  Headers::redirect("../login");
+  return;
+}
+
+Headers::redirect("../");