[PATCH v1 13/13] index: Make sure there is no duplicate submission in the same day

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

It's possible that a user resubmit the same data in the same day.
Avoid it!

Co-authored-by: Muhammad Fitrah Pandjalu <pandjalu9j@gmail.com>
Signed-off-by: Muhammad Fitrah Pandjalu <pandjalu9j@gmail.com>
Co-authored-by: Taufiq Pohan <m.taufiq30s@hotmail.com>
Signed-off-by: Taufiq Pohan <m.taufiq30s@hotmail.com>
Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 public/api.php   | 21 ++++++++++++++++++++-
 public/index.php |  2 +-
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/public/api.php b/public/api.php
index 8305552..7250075 100644
--- a/public/api.php
+++ b/public/api.php
@@ -2,7 +2,7 @@
 
 require __DIR__."/../helpers.php";
 
-date_default_timezone_set("UTC");
+date_default_timezone_set("Asia/Jakarta");
 
 function err_msg(int $code, string $msg): array
 {
@@ -25,6 +25,21 @@ const SOCIAL_MEDIA = [
 	"github_username",
 ];
 
+function has_email_been_saved(PDO $pdo, string $email): bool
+{
+	$st = $pdo->prepare(<<<SQL
+		SELECT EXISTS (
+			SELECT * FROM attendances WHERE
+			email = ?
+			AND DAY(created_at) = ?
+			AND MONTH(created_at) = ?
+			AND YEAR(created_at) = ?
+		);
+	SQL);
+	$st->execute([$email, (int)date("d"), (int)date("m"), date("Y")]);
+	return (bool)(int)$st->fetch(PDO::FETCH_NUM)[0];
+}
+
 function submit_attendance(): array
 {
 	if ($_SERVER["REQUEST_METHOD"] !== "POST")
@@ -62,6 +77,10 @@ function submit_attendance(): array
 
 	try {
 		$pdo = pdo();
+
+		if (has_email_been_saved($pdo, $j["email"]))
+			return [400, err_msg(400, "Your data has already been recorded, please don't submit a duplicate submission!")];
+
 		$st = $pdo->prepare(<<<SQL
 			INSERT INTO `attendances`
 			(
diff --git a/public/index.php b/public/index.php
index e07f750..b297f56 100644
--- a/public/index.php
+++ b/public/index.php
@@ -160,7 +160,7 @@
 					let j = res.responseJSON;
 
 					if ("error" in j)
-						form_err(j.error, "Server Error");
+						form_err(j.error, "Bad Request");
 					else
 						form_err("Unknown error!", "Server Error");
 				}
-- 
Ammar Faizi