PHP engineer challenge

PHP/library-api-php/controllers/LoanController.php

@@ -7,15 +7,15 @@
 class LoanController {
     // GET /loans
     public function index() {
-        // TODO: Implement logic to list active loans with borrower and book details.
         header('Content-Type: application/json');
-        echo json_encode(['message' => 'List active loans functionality to be implemented.']);
+        header('Status: 200');
+        echo json_encode(bookList());
     }
 
     // POST /loans/return
     public function returnBook() {
-        // TODO: Implement logic to process the return of a book and calculate fines if overdue.
         header('Content-Type: application/json');
-        echo json_encode(['message' => 'Return book functionality to be implemented.']);
+        header('Status: 200');
+        echo json_encode(returnBook($_POST['bookId']));
     }
 }

PHP/library-api-php/controllers/ReservationController.php

@@ -6,15 +6,21 @@
 class ReservationController {
     // POST /reservations
     public function reserve() {
-        // TODO: Implement logic to reserve a book currently on loan.
-        header('Content-Type: application/json');
-        echo json_encode(['message' => 'Reserve book functionality to be implemented.']);
+        $reservation = reservation($_POST['bookId'], $_POST['borrowerId']);
+        if ($reservation === NULL) {
+            header('Content-Type: application/json');
+            header('Status: 404');
+        } else {
+            header('Content-Type: application/json');
+            header('Status: 200');
+            echo json_encode($reservation);    
+        }
     }
 
     // GET /reservations
     public function status() {
-        // TODO: Implement logic to return reservation status for a given borrower and book.
         header('Content-Type: application/json');
-        echo json_encode(['message' => 'Reservation status functionality to be implemented.']);
+        header('Status: 200');
+        echo json_encode(reservationStatus($_GET['bookId']));
     }
 }

PHP/library-api-php/data/data.php

@@ -29,3 +29,77 @@
 // Fines and reservations (empty arrays to start)
 $fines = [];
 $reservations = [];
+
+// 
+
+function maxId($a) {
+    return array_reduce(fn($c, $o) => $c > $o->id ? $c : $o->id,$a);
+}
+
+function book($bookId) {
+    return array_first(array_filter(fn($o) => $bookId==$o->bookId,$books));
+}
+
+function bookList() {
+    return array_map(function($o) {
+        $book = book($o->bookId);
+        return ['title' => $book->title, 'isOnLoan'=>$o->isOnLoan,'loanEndDate'=>$o->loanEndDate,'borrowerId'=>$o->borrowerId];
+    },$bookStocks);
+}
+
+function fineAmount($bookStock) {
+    // TODO calculate the fine amount
+}
+
+function fineDetails($bookStock) {
+    // TODO fine details
+}
+
+function returnBook($bookId) {
+    $bookStock = array_first(array_filter(fn($o) => $bookId ==$o->bookId, $bookStocks));
+    $bookStocks = array_filter(fn($o) => $o->$bookId != $bookId,$bookStocks);
+
+    if (strtotime($bookStock->loadEndDate) < strtotime(date('now'))) {
+        return new Fine($id,$bookStock->borrowerId,fineAmount($bookStock), fineDetails($bookStock));
+    } else {
+        return [];
+    }
+}
+
+function reservation($bookId, $borrowerId) {
+    $bookReservations = array_filter(
+        fn($o) => $o->bookId == $bookId
+        ,$reservations
+    );
+
+    if (count($bookReservations)) {
+        $id = maxId($reservations) + 1;
+        $reservation = new Reservation($id, $bookId, $borrowerId, date('now'));
+        $reservations[]=$reservation;
+        return [];
+    }
+
+    return NULL;
+}
+
+function reservationStatus($bookId) {
+    $available = true;
+    $reservedAt = NULL;
+
+    $bookReservations = array_filter(
+        fn($o) => $o->$bookId == $bookId
+        ,$reservations
+    );
+
+    if (count($bookReservations)) {
+        $available = false;
+        $reservedAt = array_reduce(
+            fn($v, $o) => (strtotime($o->reservedAt) > strtotime($v)) ? $o->reservedAt : $v 
+            ,$bookReservations);
+    }
+
+    return [
+        'available' => $available,
+        'reservedAt' => $reservedAt
+    ];
+}