<?php
include('inc/check_login.php');
require_once('inc/db.php');

$is_admin = ($_SESSION['role'] === 'admin');

$message = '';
$message_type = '';
$edit_mode = false;
$edit_meeting = null;

// --- Funktion: Zufallsfarbe mit inverser Gewichtung (alle Termine, keine Sonderfarben) ---
function get_weighted_random_color($conn)
{
    // Zählt ALLE Termine (vergangen + geplant) für jede reguläre Farbe
    $colors = [];
    $result = mysqli_query($conn, "
        SELECT 
            c.id, 
            c.name, 
            COUNT(m.id) AS usage_count
        FROM colors c
        LEFT JOIN meetings m ON c.id = m.color_id
        WHERE c.is_special = 0
        GROUP BY c.id, c.name
    ");

    if (!$result || mysqli_num_rows($result) === 0) {
        return null;
    }

    while ($row = mysqli_fetch_assoc($result)) {
        $colors[] = [
            'id' => (int)$row['id'],
            'usage' => (int)$row['usage_count']
        ];
    }

    $max_usage = max(array_column($colors, 'usage'));
    $color_pool = [];

    foreach ($colors as $color) {
        $weight = ($max_usage - $color['usage'] + 1) ** 2;
        for ($i = 0; $i < $weight; $i++) {
            $color_pool[] = $color['id'];
        }
    }

    if (empty($color_pool)) {
        return null;
    }

    return $color_pool[array_rand($color_pool)];
}

// --- Nur Admins: Löschen ---
if ($is_admin && isset($_GET['action']) && $_GET['action'] == 'delete' && isset($_GET['id'])) {
    $id = (int)$_GET['id'];
    $stmt = mysqli_prepare($conn, "DELETE FROM meetings WHERE id = ?");
    mysqli_stmt_bind_param($stmt, "i", $id);
    if (mysqli_stmt_execute($stmt)) {
        $message = "Termin erfolgreich gelöscht!";
        $message_type = 'success';
    } else {
        $message = "Fehler beim Löschen des Termins.";
        $message_type = 'danger';
    }
    mysqli_stmt_close($stmt);
    header("Location: planning.php");
    exit();
}

// --- Nur Admins: Bearbeiten ---
if ($is_admin && isset($_GET['action']) && $_GET['action'] == 'edit' && isset($_GET['id'])) {
    $id = (int)$_GET['id'];
    $stmt = mysqli_prepare($conn, "SELECT id, meeting_date, color_id, reason FROM meetings WHERE id = ?");
    mysqli_stmt_bind_param($stmt, "i", $id);
    mysqli_stmt_execute($stmt);
    $result = mysqli_stmt_get_result($stmt);
    $edit_meeting = mysqli_fetch_assoc($result);
    mysqli_stmt_close($stmt);
    $edit_mode = true;

    if ($edit_meeting) {
        $edit_dt = new DateTime($edit_meeting['meeting_date']);
        $edit_meeting['meeting_date_only'] = $edit_dt->format('Y-m-d');
        $edit_meeting['meeting_time_only'] = $edit_dt->format('H:i');
    } else {
        $message = "Termin nicht gefunden.";
        $message_type = 'warning';
    }
}

// --- Nur Admins: Speichern (POST) ---
if ($is_admin && $_SERVER["REQUEST_METHOD"] == "POST") {
    $meeting_date_only = $_POST['meeting_date'] ?? '';
    $meeting_time_only = $_POST['meeting_time'] ?? '12:00';
    $color_id = (int)($_POST['color_id'] ?? 0);
    $reason = trim($_POST['reason'] ?? 'Zufallsfarbe');
    $id = !empty($_POST['id']) ? (int)$_POST['id'] : null;

    if (empty($meeting_date_only) || !$color_id) {
        $message = "Datum und Farbe sind erforderlich.";
        $message_type = 'danger';
    } else {
        $meeting_date = $meeting_date_only . ' ' . $meeting_time_only;
        if ($id) {
            $stmt = mysqli_prepare($conn, "UPDATE meetings SET meeting_date = ?, color_id = ?, reason = ? WHERE id = ?");
            mysqli_stmt_bind_param($stmt, "sisi", $meeting_date, $color_id, $reason, $id);
        } else {
            $stmt = mysqli_prepare($conn, "INSERT INTO meetings (meeting_date, color_id, reason) VALUES (?, ?, ?)");
            mysqli_stmt_bind_param($stmt, "sis", $meeting_date, $color_id, $reason);
        }

        if (mysqli_stmt_execute($stmt)) {
            $message = $id ? "Termin aktualisiert!" : "Neuer Termin hinzugefügt!";
            $message_type = 'success';
        } else {
            $message = "Fehler beim Speichern.";
            $message_type = 'danger';
        }
        mysqli_stmt_close($stmt);
        header("Location: planning.php");
        exit();
    }
}

// --- 🔁 Automatische Planung: 4 Donnerstage, max. 1 pro Woche ---
if ($is_admin) {
    $today = new DateTime('today');
    $existing_weeks = [];
    $result_existing = mysqli_query($conn, "SELECT meeting_date FROM meetings");
    while ($row = mysqli_fetch_assoc($result_existing)) {
        $dt = new DateTime($row['meeting_date']);
        $year = $dt->format('o');
        $week = $dt->format('W');
        $existing_weeks["$year-$week"] = true;
    }

    $date = clone $today;
    for ($i = 0; $i < 4; $i++) {
        $date->modify($i === 0 ? 'next thursday' : 'next thursday');
        $year = $date->format('o');
        $week = $date->format('W');
        $week_key = "$year-$week";

        if (!isset($existing_weeks[$week_key])) {
            $new_date = $date->format('Y-m-d') . ' 12:00:00';
            $color_id = get_weighted_random_color($conn);
            if ($color_id) {
                $check = mysqli_prepare($conn, "SELECT id FROM meetings WHERE meeting_date = ?");
                mysqli_stmt_bind_param($check, "s", $new_date);
                mysqli_stmt_execute($check);
                $exists = mysqli_fetch_assoc(mysqli_stmt_get_result($check));
                mysqli_stmt_close($check);

                if (!$exists) {
                    $default_reason = "Zufallsfarbe";
                    $ins = mysqli_prepare($conn, "INSERT INTO meetings (meeting_date, color_id, reason) VALUES (?, ?, ?)");
                    mysqli_stmt_bind_param($ins, "sis", $new_date, $color_id, $default_reason);
                    mysqli_stmt_execute($ins);
                    mysqli_stmt_close($ins);
                    $existing_weeks[$week_key] = true;
                }
            }
        }
    }
}

// --- Daten für Anzeige laden ---
$all_colors = [];
if ($is_admin) {
    $result_colors = mysqli_query($conn, "SELECT id, name, hex_code FROM colors ORDER BY name");
    while ($row = mysqli_fetch_assoc($result_colors)) {
        $all_colors[] = $row;
    }
}

$meetings = [];
$result_meetings = mysqli_query($conn, "
    SELECT m.id, m.meeting_date, m.reason, c.name AS color_name, c.hex_code 
    FROM meetings m 
    JOIN colors c ON m.color_id = c.id 
    WHERE m.is_completed = 0 
    ORDER BY m.meeting_date
");
while ($row = mysqli_fetch_assoc($result_meetings)) {
    $meetings[] = $row;
}

require_once 'inc/header.php';
?>

<div class="container mt-5">
    <?php if ($message): ?>
        <div class="alert alert-<?= htmlspecialchars($message_type) ?> alert-dismissible fade show" role="alert">
            <?= htmlspecialchars($message) ?>
            <button type="button" class="btn-close" data-bs-dismiss="alert"></button>
        </div>
    <?php endif; ?>

    <div class="d-flex justify-content-between align-items-center mb-4">
        <h2 class="mb-0">Terminübersicht</h2>
    </div>

    <?php if ($is_admin): ?>
        <div class="collapse <?= $edit_mode ? 'show' : '' ?>" id="planningFormCollapse">
            <div class="card shadow mb-4">
                <div class="card-header bg-primary-subtle text-secondary">
                    <h4 class="mb-0"><?= $edit_mode ? 'Termin bearbeiten' : 'Neuen Termin hinzufügen'; ?></h4>
                </div>
                <div class="card-body">
                    <form action="planning.php" method="post">
                        <?php if ($edit_mode): ?>
                            <input type="hidden" name="id" value="<?= htmlspecialchars($edit_meeting['id']); ?>">
                        <?php endif; ?>
                        <div class="row g-3">
                            <div class="col-md-4">
                                <label class="form-label">Datum</label>
                                <input type="date" class="form-control" name="meeting_date" value="<?= htmlspecialchars($edit_meeting['meeting_date_only'] ?? ''); ?>" required>
                            </div>
                            <div class="col-md-4">
                                <label class="form-label">Uhrzeit</label>
                                <input type="time" class="form-control" name="meeting_time" value="<?= htmlspecialchars($edit_meeting['meeting_time_only'] ?? '12:00'); ?>" required>
                            </div>
                            <div class="col-md-4">
                                <label class="form-label">Farbe</label>
                                <select class="form-select" name="color_id" required>
                                    <?php foreach ($all_colors as $color): ?>
                                        <option value="<?= $color['id'] ?>" <?= (($edit_meeting['color_id'] ?? 0) == $color['id']) ? 'selected' : '' ?>>
                                            <?= htmlspecialchars($color['name']) ?>
                                        </option>
                                    <?php endforeach; ?>
                                </select>
                            </div>
                            <div class="col-12">
                                <label class="form-label">Grund für die Farbe (optional)</label>
                                <input type="text" class="form-control" name="reason" value="<?= htmlspecialchars($edit_meeting['reason'] ?? ''); ?>">
                                <div class="form-text">Wenn leer, wird „Zufallsfarbe“ eingetragen.</div>
                            </div>
                            <div class="col-12 d-flex justify-content-start">
                                <button type="submit" class="btn btn-sm btn-outline-<?= $edit_mode ? 'success' : 'primary' ?> me-2">
                                    <?= $edit_mode ? 'Speichern' : 'Hinzufügen' ?>
                                </button>
                                <a href="planning.php" class="btn btn-sm btn-outline-secondary">Abbrechen</a>
                            </div>
                        </div>
                    </form>
                </div>
            </div>
        </div>
    <?php endif; ?>

    <div class="card shadow">
        <div class="card-header bg-primary-subtle text-secondary d-flex justify-content-between align-items-center">
            <h4 class="mb-0">Anstehende Termine</h4>
            <?php if ($is_admin): ?>
                <a class="btn btn-sm d-flex align-items-center justify-content-center" data-bs-toggle="collapse" href="#planningFormCollapse" role="button" aria-expanded="false" aria-controls="planningFormCollapse">Add
                    <span class="material-symbols-outlined">add</span>
                </a>
            <?php endif; ?>
        </div>
        <div class="card-body">
            <?php if (empty($meetings)): ?>
                <p class="text-muted text-center">Keine anstehenden Termine.</p>
            <?php else: ?>
                <div class="list-group list-group-flush">
                    <?php foreach ($meetings as $m): ?>
                        <div class="list-group-item">
                            <div class="d-flex justify-content-between align-items-start">
                                <div>
                                    <p class="fw-bold mb-1"><?= date('d.m.Y H:i', strtotime($m['meeting_date'])) ?></p>
                                    <div class="d-flex align-items-center mb-1">
                                        <div class="me-2" style="background-color: <?= htmlspecialchars($m['hex_code']); ?>; width: 20px; height: 20px; border: 1px solid #ccc; border-radius: 2px;"></div> <span><?= htmlspecialchars($m['color_name']); ?></span>
                                    </div>
                                    <p class="text-muted small mb-0">Grund: <?= htmlspecialchars($m['reason']); ?></p>
                                </div>
                                <?php if ($is_admin): ?>
                                    <div class="dropdown ms-2">
                                        <a href="#" class="text-secondary" role="button" data-bs-toggle="dropdown" aria-expanded="false">
                                            <span class="material-icons">more_vert</span>
                                        </a>
                                        <ul class="dropdown-menu dropdown-menu-end">
                                            <li>
                                                <a class="dropdown-item d-flex align-items-center" href="planning.php?action=edit&id=<?= $m['id'] ?>">
                                                    <span class="material-icons me-2">mode_edit_outline</span> Bearbeiten
                                                </a>
                                            </li>
                                            <li>
                                                <a class="dropdown-item d-flex align-items-center text-danger" href="planning.php?action=delete&id=<?= $m['id'] ?>" onclick="return confirm('Wirklich löschen?')">
                                                    <span class="material-icons me-2">delete_outline</span> Löschen
                                                </a>
                                            </li>
                                        </ul>
                                    </div>
                                <?php endif; ?>
                            </div>
                        </div>
                    <?php endforeach; ?>
                </div>
            <?php endif; ?>
        </div>
    </div>
</div>

<?php include('inc/footer.php'); ?>