Final

.gitignore

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+tests

.htaccess

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+RewriteEngine On
+RewriteRule . index.php
+ErrorDocument 404 /error/not_found.php

api/APIHandler.php

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+<?php
+
+class APIHandler {
+    public static function handle_request($url_parts) {
+        if (count($url_parts) < 2) {
+            http_response_code(400);
+            exit;
+        }
+
+        switch ($url_parts[1]) {
+            case "tenis":
+                return APIHandler::handle_tenis_request(array_slice($url_parts, 1));
+            default:
+                http_response_code(400);
+                exit;
+        }
+    }
+
+    private static function handle_tenis_request($url_parts) {
+        if (count($url_parts) < 2) {
+            http_response_code(400);
+            exit;
+        }
+
+        $pdo = new PDO("sqlite:tenis.db");
+
+        try {
+            switch ($url_parts[1]) {
+                case "reservation":
+                    $reservation = new Reservation($pdo);
+                    echo $reservation->process($_SERVER["REQUEST_METHOD"]);
+                    break;
+                case "court":
+                    $court = new Court($pdo);
+                    echo $court->process($_SERVER["REQUEST_METHOD"]);
+                    break;
+                default:
+                    http_response_code(400);
+                    exit;
+            }
+        }
+        catch (InvalidArgumentException $e) {
+            http_response_code(400);
+            echo json_encode([
+                "message" => $e->getMessage()
+            ]);
+        }
+        catch (Throwable $e) {
+            http_response_code(500);
+            echo json_encode([
+                "message" => $e->getMessage(),
+                "code" => $e->getCode(),
+                "line" => $e->getLine()
+            ]);
+        }
+    }
+}

api/Court.php

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+<?php
+
+class Court {
+    private PDO $pdo;
+
+    public function __construct(PDO $pdo) {
+        $this->pdo = $pdo;
+    }
+
+    public function process(string $request) {
+        switch ($request) {
+            case "GET":
+                return $this->get_all();
+            default:
+                throw new Exception();
+        }
+    }
+        
+    private function get_all() {
+        $query = $this->pdo->query("SELECT * FROM courts");
+        $rows = $query->fetchAll(PDO::FETCH_ASSOC);
+        return json_encode($rows);
+    }
+}

api/Pricing.php

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+<?php
+
+class Pricing {
+    // should rather be in db
+    private static int $TENIS_PRICE = 500;
+    private static $TENIS_GAME = array(1, 1.5);
+    private static $SURFACE_PRICING = array(1, 1.5, 2);
+
+    public static function for_tenis(int $duration, int $game, int $surface) {
+        return intdiv($duration, 3600) * Pricing::$TENIS_PRICE 
+                                        * Pricing::$TENIS_GAME[$game]
+                                        * Pricing::$SURFACE_PRICING[$surface];
+    }
+
+    public static function get_games_count() {
+        return count(Pricing::$TENIS_GAME);
+    }
+
+    public static function get_surfaces_count() {
+        return count(Pricing::$SURFACE_PRICING);
+    }
+}

api/Reservation.php

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+<?php
+
+class Reservation {
+    private PDO $pdo;
+    private int $MAX_DURATION = 36000;
+    private int $MIN_DURATION = 3600;
+
+    public function __construct(PDO $pdo) {
+        $this->pdo = $pdo;
+    }
+
+    public function process(string $request) {
+        // null will become empty array
+        $data = (array) json_decode(file_get_contents("php://input"), true);
+        switch ($request) {
+            case "GET":
+                return $this->get_data($data);
+            case "POST":
+                return $this->create_reservation($data);
+            case "DELETE":
+                $this->delete($data);
+                return null;
+            default:
+                throw new Exception("Unknown request");
+        }
+    }
+
+    private function get_data($data) {
+        $stmt = null;
+        if (empty($data)) {
+            $stmt = $this->get_all();
+        }
+        elseif (isset($data["court"])) {
+            $stmt = $this->get_by_court($data["court"]);
+        }
+        elseif (isset($data["phone"])) {
+            $stmt = $this->get_by_phone($data["phone"]);
+        }
+        else {
+            throw new InvalidArgumentException("Expected court id or phone number got none");
+        }
+
+        $stmt->execute();
+        $result = $stmt->fetchAll(PDO::FETCH_ASSOC);
+        return json_encode($result ? $result : []);
+    }
+    
+    private function get_all() {
+        return $this->pdo->prepare("SELECT * FROM reservations");
+    }
+
+    private function get_by_court(int $id) {
+        if (!is_int($id)) {
+            throw new InvalidArgumentException("id not an integer");
+        }
+
+        $query = "SELECT * FROM reservations WHERE court_id=:id";
+        $stmt = $this->pdo->prepare($query);
+        $stmt->bindValue(":id", $id, PDO::PARAM_INT);
+        return $stmt;
+    }
+
+    private function get_by_phone(string $phone_number) {
+        if (!Security::is_phone_number($phone_number)) {
+            throw new InvalidArgumentException("phone number not in valid format");
+        }
+
+        $query = "SELECT * FROM reservations WHERE phone_number=:phone";
+        $stmt = $this->pdo->prepare($query);
+        $stmt->bindValue(":phone", $phone_number, PDO::PARAM_STR);
+        return $stmt;
+    }
+
+    private function create_reservation($data) {
+        $this->verify_create_data($data);
+
+        $stmt = $this->pdo->prepare("SELECT surface FROM courts WHERE id=:id");
+        $stmt->bindValue(":id", $data["court_id"], PDO::PARAM_INT);
+        $stmt->execute();
+        $surface = $stmt->fetchAll()[0][0];
+        $price = Pricing::for_tenis((int)$data["end"] - (int)$data["start"], $data["game"], $surface);
+        
+        $password = Security::generate_password(6);
+        $password_hash = hash("sha256", $password);
+        
+        $phone = preg_replace('/\s*/', '', $data["phone"]);
+        $phone_hash = hash("sha256", $phone);
+
+        $query = "INSERT INTO reservations VALUES (NULL, :court_id, :phone, :password, :game, :start, :end)";
+        $stmt = $this->pdo->prepare($query);
+
+        $stmt->bindValue(":court_id", $data["court_id"], PDO::PARAM_INT);
+        $stmt->bindValue(":phone", $phone_hash, PDO::PARAM_STR);
+        $stmt->bindValue(":password", $password_hash, PDO::PARAM_STR);
+        $stmt->bindValue(":game", $data["game"], PDO::PARAM_INT);
+        $stmt->bindValue(":start", $data["start"], PDO::PARAM_INT);
+        $stmt->bindValue(":end", $data["end"], PDO::PARAM_INT);
+
+        $result = $stmt->execute();
+        if ($result) {
+            http_response_code(201);
+            echo json_encode([
+                "price" => $price,
+                "password" => $password
+            ]);
+            return;
+        }
+
+        http_response_code(500);
+        exit;
+    }
+
+    private function verify_create_data($data) {
+        if (!isset($data["court_id"], $data["phone"], $data["game"], $data["start"], $data["end"])) {
+            throw new InvalidArgumentException("some arguments are missing");
+        }
+        
+        if (!is_int($data["court_id"])) {
+            throw new InvalidArgumentException("court id not in correct format");
+        }
+
+        $court_id = (int)$data["court_id"];
+        $court_count = $this->pdo->query("SELECT COUNT(*) FROM courts")->fetchAll()[0][0];
+
+        if ($court_id < 1 || $court_id > $court_count) {
+            throw new InvalidArgumentException("court id is not valid");
+        }
+
+        if (!Security::is_phone_number($data["phone"])) {
+            throw new InvalidArgumentException("phone number not in correct format");
+        }
+
+        if (!is_int($data["game"]) || $data["game"] < 0 || $data["game"] >= Pricing::get_games_count()) {
+            throw new InvalidArgumentException("game type is not in valid format");
+        }
+
+        if (!is_int($data["start"]) || !is_int($data["end"]))
+        {
+            throw new InvalidArgumentException("start or end is not in valid format");
+        }
+
+        $start = (int)$data["start"];
+        $end = (int)$data["end"];
+
+        $this->verify_interval($start, $end, $data["court_id"]);
+    }
+
+    private function verify_interval(int $start, int $end, int $id) {
+        if ($start > $end || $end - $start > $this->MAX_DURATION || $end - $start < $this->MIN_DURATION) {
+            throw new InvalidArgumentException("reservation interval not valid");
+        }
+
+        if ($start <= time()) {
+            throw new InvalidArgumentException("can't create reservation in the past");
+        }
+
+        $query = 'SELECT * FROM reservations WHERE court_id=:court_id AND start>=:start AND end<=:end';
+        $stmt = $this->pdo->prepare($query);
+        
+        $stmt->bindValue(":start", $start, PDO::PARAM_INT);
+        $stmt->bindValue(":end", $end, PDO::PARAM_INT);
+        $stmt->bindValue(":court_id", $id, PDO::PARAM_INT);
+        $stmt->execute();
+        
+        $result = $stmt->fetchAll(PDO::FETCH_ASSOC);
+        if ($result) {
+            throw new InvalidArgumentException("reservation in this interval already exists");
+        }
+    }
+
+    private function delete($data) {
+        if (!isset($data["id"], $data["password"], $data["phone"])) {
+            throw new InvalidArgumentException("invalid arguments");
+        }
+
+        if (!is_int($data["id"])) {
+            throw new InvalidArgumentException("id not in correct format");
+        }
+
+        if (!Security::is_phone_number($data["phone"])) {
+            throw new InvalidArgumentException("phone number not in correct format");
+        }
+
+        
+        $phone = preg_replace('/\s*/', '', $data["phone"]);
+        $phone_hash = hash("sha256", $phone);
+        $password_hash = hash("sha256", $data["password"]);
+
+        $query = "SELECT COUNT(*) FROM reservations WHERE id=:id AND phone_number=:phone AND password=:password";
+        $stmt = $this->pdo->prepare($query);
+
+        $stmt->bindValue(":id", $data["id"], PDO::PARAM_INT);
+        $stmt->bindValue(":password", $password_hash, PDO::PARAM_STR);
+        $stmt->bindValue(":phone", $phone_hash, PDO::PARAM_STR);
+
+        $stmt->execute();
+        $count = $stmt->fetchAll()[0][0];
+        if ($count == 0) {
+            throw new InvalidArgumentException("invalid entry (does not exist or not correct information)");
+        }
+
+        $query = "DELETE FROM reservations WHERE id=:id AND phone_number=:phone AND password=:password";
+        $stmt = $this->pdo->prepare($query);
+        
+        $stmt->bindValue(":id", $data["id"], PDO::PARAM_INT);
+        $stmt->bindValue(":password", $password_hash, PDO::PARAM_STR);
+        $stmt->bindValue(":phone", $phone_hash, PDO::PARAM_STR);
+
+        $result = $stmt->execute();
+        if (!$result) {
+            throw new InvalidArgumentException("something went wrong");
+        }
+    }
+}

api/Security.php

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+<?php
+
+class Security {
+    public static function generate_password(int $len) : string {
+        $password = "";
+        for ($i = 0; $i < $len; $i++) {
+            if (random_int(0, 1)) {
+                $password .= chr(random_int(65, 90));
+            }
+            else {
+                $password .= random_int(0, 9);
+            }
+        }
+
+        return $password;
+    }
+
+    public static function is_phone_number(string $phone) : ?string {
+        return !(is_null($phone) || preg_match("/\+[0-9\s]*$/", trim($phone)) == 0);
+    }
+}

index.php

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+<?php
+
+spl_autoload_register(function ($class) {
+    include_once __DIR__ . "/api/$class.php";
+});
+
+header("Content-type: application/json; charset=UTF-8");
+
+$url_parts = explode("/", $_SERVER["REQUEST_URI"]);
+
+switch ($url_parts[2]) {
+    case "api":
+        APIHandler::handle_request(array_slice($url_parts, 2));
+        exit;
+    default:
+        http_response_code(404);
+}