<?php
$servername = "db";
$username = "uzivatel";
$password = "heslo";
$dbname = 'vyvoj';

// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);

// Check connection
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}

echo '<form action="tabulka.php" method="get">
    <select name="trida" id="trida">';
$selected = $_GET['trida'] ?? ''; 
$sql = "SELECT * FROM tridy;";
$result = mysqli_query($conn, $sql);
while ($row = mysqli_fetch_assoc($result)) {
    $isSelected = ($selected == $row['tridaID']) ? 'selected' : '';
    echo '<option value="' . $row['tridaID'] . '"+ ' . $isSelected . ' >' . $row['cislo'] . '</option>';
}
echo '</select><input type="submit"/></form>';

if (isset($_GET["trida"])) {
$dny = ["Pondělí", "Úterý", "Středa", "Čtvrtek", "Pátek"];
echo '<table border = "1">';
//Vypis zahlavi tabulky
echo '<tr>
<th>Rozvrh</th>';
for ($i = 1; $i <= 9; $i++)
{
    echo "<th>$i. hodina</th>\n";
}
echo '
</tr>';

//Vypis jednotlivych dnu
$den_v_tydnu = 0;
foreach ($dny as $den)
{
    $den_v_tydnu++;
    echo '<tr>';
    echo "<th>$den</th>";
    for ($i = 1; $i <= 9; $i++)
    {
        $sql = "SELECT * FROM Plan pl LEFT JOIN Predmety p ON pl.predmetId = p.predmetId LEFT JOIN Vyucujici v ON pl.vyucujiciId = v.vyucujiciId LEFT JOIN Ucebny u ON pl.ucebnaId = u.ucebnaId WHERE tridaId = {$_GET["trida"]} AND hodinaId = $i AND denId = $den_v_tydnu";
        $result = mysqli_query($conn, $sql);
        if (mysqli_num_rows($result))
        {
            $hodina = mysqli_fetch_assoc($result);
            $predmet = $hodina["predmetNazev"];
            echo "<td>$predmet<br>";
            $vyucujicij = $hodina["jmeno"];
            $vyucujicip = $hodina["prijmeni"];
            echo "$vyucujicij ";
            echo "$vyucujicip<br>";
            $ucebna = $hodina["nazev"];
            echo "$ucebna</td>\n";
        } 
        else
        {
            echo "<td></td>\n";
        }
    }
    echo '</tr>';
}


echo '</table>';
}

//$sql = "SELECT *
//FROM Plan pl
//LEFT JOIN Ucebny u ON pl.ucebnaId = u.ucebnaId
//LEFT JOIN Predmety p ON pl.predmetId = p.predmetId
//WHERE hodinaId = 1 AND denId = 1;";

//$vysledek_dotazu = mysqli_query($conn, $sql);

//provede se pokud jsou nějaké řádky ve výsledku
//if (mysqli_num_rows($vysledek_dotazu))
//{
//$hodina = mysqli_fetch_assoc($vysledek_dotazu);
//}
//provede se pokud je nula řádku ve výsledku
//else
//{
//echo "<td>Volná hodina</td>";
//}
?>