<?php
$pageTitle = "Announcements";
include_once('includes/header.php');

// Check if user is logged in
if (!isset($_SESSION['user_id']) || $_SESSION['role'] !== 'student') {
    header("Location: ../login.php");
    exit();
}

// Get student ID
$student_id = $_SESSION['user_id'];

// Handle marking announcements as read
if (isset($_GET['mark_read']) && is_numeric($_GET['mark_read'])) {
    $announcement_id = intval($_GET['mark_read']);
    
    // Check if already read
    $check_read = $conn->prepare("SELECT * FROM announcement_reads WHERE announcement_id = ? AND user_id = ?");
    $check_read->bind_param("ii", $announcement_id, $student_id);
    $check_read->execute();
    $already_read = $check_read->get_result()->num_rows > 0;
    
    if (!$already_read) {
        // Mark as read
        $mark_read = $conn->prepare("INSERT INTO announcement_reads (announcement_id, user_id, read_date) VALUES (?, ?, NOW())");
        $mark_read->bind_param("ii", $announcement_id, $student_id);
        $mark_read->execute();
        
        // Set success message
        $_SESSION['success_message'] = "Announcement marked as read.";
    }
    
    // Redirect to refresh the page
    header("Location: announcements.php");
    exit();
}

// Handle marking all announcements as read
if (isset($_GET['mark_all_read'])) {
    // Get all unread announcements for this student
    $get_unread = $conn->prepare("
        SELECT a.id 
        FROM announcements a
        LEFT JOIN announcement_reads ar ON ar.announcement_id = a.id AND ar.user_id = ?
        LEFT JOIN course_enrollments ce ON ce.student_id = ? AND (a.course_id = ce.course_id OR a.course_id IS NULL)
        WHERE ar.id IS NULL
        AND (a.target_type = 'all' OR (a.target_type = 'course' AND ce.course_id IS NOT NULL))
    ");
    $get_unread->bind_param("ii", $student_id, $student_id);
    $get_unread->execute();
    $unread_result = $get_unread->get_result();
    
    if ($unread_result->num_rows > 0) {
        // Prepare batch insert query
        $insert_values = [];
        $current_time = date('Y-m-d H:i:s');
        
        while ($row = $unread_result->fetch_assoc()) {
            $announcement_id = $row['id'];
            // Mark each announcement as read
            $mark_read = $conn->prepare("INSERT INTO announcement_reads (announcement_id, user_id, read_date) VALUES (?, ?, NOW())");
            $mark_read->bind_param("ii", $announcement_id, $student_id);
            $mark_read->execute();
        }
        
        // Set success message
        $_SESSION['success_message'] = "All announcements marked as read.";
    } else {
        $_SESSION['info_message'] = "No unread announcements found.";
    }
    
    // Redirect to refresh the page
    header("Location: announcements.php");
    exit();
}

// Check if we need to create the announcement tables
$tableExists = $conn->query("SHOW TABLES LIKE 'announcements'")->num_rows > 0;
if (!$tableExists) {
    // Create announcements table
    $conn->query("
        CREATE TABLE IF NOT EXISTS `announcements` (
          `id` int(11) NOT NULL AUTO_INCREMENT,
          `title` varchar(255) NOT NULL,
          `content` text NOT NULL,
          `created_by` int(11) NOT NULL,
          `created_at` datetime NOT NULL,
          `updated_at` datetime DEFAULT NULL,
          `start_date` date DEFAULT NULL,
          `end_date` date DEFAULT NULL,
          `target_type` enum('all','course','user') NOT NULL DEFAULT 'all',
          `course_id` int(11) DEFAULT NULL,
          `importance` enum('normal','important','urgent') NOT NULL DEFAULT 'normal',
          `status` enum('active','inactive') NOT NULL DEFAULT 'active',
          `attachment` varchar(255) DEFAULT NULL,
          PRIMARY KEY (`id`),
          KEY `created_by` (`created_by`),
          KEY `course_id` (`course_id`)
        ) ENGINE=InnoDB DEFAULT CHARSET=utf8
    ");
    
    // Create announcement_reads table
    $conn->query("
        CREATE TABLE IF NOT EXISTS `announcement_reads` (
          `id` int(11) NOT NULL AUTO_INCREMENT,
          `announcement_id` int(11) NOT NULL,
          `user_id` int(11) NOT NULL,
          `read_date` datetime NOT NULL,
          PRIMARY KEY (`id`),
          UNIQUE KEY `unique_read` (`announcement_id`,`user_id`),
          KEY `announcement_id` (`announcement_id`),
          KEY `user_id` (`user_id`)
        ) ENGINE=InnoDB DEFAULT CHARSET=utf8
    ");
}

// Get all announcements visible to this student
$query = "
    SELECT a.*, u.first_name, u.last_name, c.title as course_title,
           (SELECT COUNT(*) FROM announcement_reads ar WHERE ar.announcement_id = a.id AND ar.user_id = ?) as is_read
    FROM announcements a
    LEFT JOIN users u ON a.created_by = u.id
    LEFT JOIN courses c ON a.course_id = c.id
    LEFT JOIN enrollments e ON (a.course_id = e.course_id AND e.user_id = ?)
    WHERE a.status = 'active'
    AND (a.target_type = 'all' OR (a.target_type = 'course' AND e.id IS NOT NULL))
    AND (a.end_date IS NULL OR a.end_date >= CURDATE())
    ORDER BY a.created_at DESC
";

$stmt = $conn->prepare($query);
$stmt->bind_param("ii", $student_id, $student_id);
$stmt->execute();
$result = $stmt->get_result();
$announcements = [];

while ($row = $result->fetch_assoc()) {
    $announcements[] = $row;
}

// Count unread announcements
$unread_count = 0;
foreach ($announcements as $announcement) {
    if ($announcement['is_read'] == 0) {
        $unread_count++;
    }
}
?>

<div class="container py-4">
    <div class="d-flex justify-content-between align-items-center mb-4">
        <h2><?php echo $pageTitle; ?></h2>
        <?php if ($unread_count > 0): ?>
        <a href="announcements.php?mark_all_read=1" class="btn btn-primary">
            <i class="fas fa-check-double me-2"></i> Mark All as Read
        </a>
        <?php endif; ?>
    </div>
    
    <?php if (isset($_SESSION['success_message'])): ?>
    <div class="alert alert-success alert-dismissible fade show" role="alert">
        <i class="fas fa-check-circle me-2"></i> <?php echo $_SESSION['success_message']; ?>
        <button type="button" class="btn-close" data-bs-dismiss="alert" aria-label="Close"></button>
    </div>
    <?php unset($_SESSION['success_message']); endif; ?>
    
    <?php if (isset($_SESSION['info_message'])): ?>
    <div class="alert alert-info alert-dismissible fade show" role="alert">
        <i class="fas fa-info-circle me-2"></i> <?php echo $_SESSION['info_message']; ?>
        <button type="button" class="btn-close" data-bs-dismiss="alert" aria-label="Close"></button>
    </div>
    <?php unset($_SESSION['info_message']); endif; ?>
    
    <?php if (isset($_SESSION['error_message'])): ?>
    <div class="alert alert-danger alert-dismissible fade show" role="alert">
        <i class="fas fa-exclamation-circle me-2"></i> <?php echo $_SESSION['error_message']; ?>
        <button type="button" class="btn-close" data-bs-dismiss="alert" aria-label="Close"></button>
    </div>
    <?php unset($_SESSION['error_message']); endif; ?>
    
    <?php if (empty($announcements)): ?>
    <div class="alert alert-info">
        <div class="d-flex">
            <div class="me-3">
                <i class="fas fa-info-circle fa-2x"></i>
            </div>
            <div>
                <h5>No Announcements</h5>
                <p class="mb-0">There are no announcements available at this time. Check back later for updates.</p>
            </div>
        </div>
    </div>
    <?php else: ?>
    
    <!-- Announcements Filter -->
    <div class="card mb-4">
        <div class="card-body">
            <div class="row align-items-center">
                <div class="col-md-3 mb-3 mb-md-0">
                    <div class="form-check form-switch">
                        <input class="form-check-input" type="checkbox" id="showUnreadOnly">
                        <label class="form-check-label" for="showUnreadOnly">Show unread only</label>
                    </div>
                </div>
                <div class="col-md-9">
                    <div class="d-flex align-items-center justify-content-md-end">
                        <div class="me-3">
                            <select id="announcementFilter" class="form-select form-select-sm">
                                <option value="all">All Announcements</option>
                                <option value="course">Course Announcements</option>
                                <option value="general">General Announcements</option>
                                <option value="important">Important Announcements</option>
                                <option value="urgent">Urgent Announcements</option>
                            </select>
                        </div>
                        <div>
                            <span class="badge bg-primary"><?php echo count($announcements); ?> announcements</span>
                            <?php if ($unread_count > 0): ?>
                            <span class="badge bg-danger ms-2"><?php echo $unread_count; ?> unread</span>
                            <?php endif; ?>
                        </div>
                    </div>
                </div>
            </div>
        </div>
    </div>
    
    <!-- Announcements List -->
    <div class="announcements-container">
        <?php foreach ($announcements as $announcement): ?>
        <div class="card mb-3 announcement-card <?php echo $announcement['is_read'] ? 'read' : 'unread'; ?>" 
             data-importance="<?php echo $announcement['importance']; ?>"
             data-type="<?php echo $announcement['target_type'] == 'course' ? 'course' : 'general'; ?>">
            <div class="card-header d-flex align-items-center justify-content-between 
                        <?php if ($announcement['importance'] == 'urgent'): ?>bg-danger text-white
                        <?php elseif ($announcement['importance'] == 'important'): ?>bg-warning
                        <?php else: ?>bg-light<?php endif; ?>">
                <h5 class="mb-0 card-title">
                    <?php if ($announcement['is_read'] == 0): ?>
                    <span class="badge bg-primary me-2">New</span>
                    <?php endif; ?>
                    <?php echo htmlspecialchars($announcement['title']); ?>
                </h5>
                <div>
                    <?php if ($announcement['target_type'] == 'course'): ?>
                    <span class="badge bg-info me-2">Course</span>
                    <?php endif; ?>
                    <?php if ($announcement['is_read'] == 0): ?>
                    <a href="announcements.php?mark_read=<?php echo $announcement['id']; ?>" class="btn btn-sm btn-outline-secondary">
                        <i class="fas fa-check"></i> Mark Read
                    </a>
                    <?php endif; ?>
                </div>
            </div>
            <div class="card-body">
                <div class="mb-3">
                    <?php echo nl2br(htmlspecialchars($announcement['content'])); ?>
                </div>
                
                <?php if (!empty($announcement['attachment'])): ?>
                <div class="mb-3">
                    <a href="../<?php echo htmlspecialchars($announcement['attachment']); ?>" class="btn btn-sm btn-outline-primary" target="_blank">
                        <i class="fas fa-paperclip me-2"></i> View Attachment
                    </a>
                </div>
                <?php endif; ?>
                
                <div class="d-flex justify-content-between text-muted small">
                    <div>
                        <i class="fas fa-user me-1"></i> 
                        <?php echo htmlspecialchars($announcement['first_name'] . ' ' . $announcement['last_name']); ?>
                        
                        <?php if ($announcement['target_type'] == 'course'): ?>
                        <span class="mx-2">|</span>
                        <i class="fas fa-book me-1"></i> 
                        <?php echo htmlspecialchars($announcement['course_title']); ?>
                        <?php endif; ?>
                    </div>
                    <div>
                        <i class="far fa-calendar-alt me-1"></i> 
                        <?php echo date('M d, Y', strtotime($announcement['created_at'])); ?>
                        
                        <?php if (!empty($announcement['end_date'])): ?>
                        <span class="mx-2">|</span>
                        <i class="fas fa-hourglass-end me-1"></i> 
                        <span title="Expires on">Until <?php echo date('M d, Y', strtotime($announcement['end_date'])); ?></span>
                        <?php endif; ?>
                    </div>
                </div>
            </div>
        </div>
        <?php endforeach; ?>
    </div>
    <?php endif; ?>
</div>

<style>
.announcement-card.unread {
    border-left: 4px solid #0d6efd;
}
.announcement-card.read {
    opacity: 0.8;
}
</style>

<script>
document.addEventListener('DOMContentLoaded', function() {
    const showUnreadOnlyCheckbox = document.getElementById('showUnreadOnly');
    const announcementFilterSelect = document.getElementById('announcementFilter');
    const announcementCards = document.querySelectorAll('.announcement-card');
    
    // Function to filter announcements
    function filterAnnouncements() {
        const showUnreadOnly = showUnreadOnlyCheckbox.checked;
        const filterValue = announcementFilterSelect.value;
        
        announcementCards.forEach(card => {
            let showCard = true;
            
            // Filter by read status
            if (showUnreadOnly && card.classList.contains('read')) {
                showCard = false;
            }
            
            // Filter by type
            if (filterValue !== 'all') {
                if (filterValue === 'course' && card.dataset.type !== 'course') {
                    showCard = false;
                } else if (filterValue === 'general' && card.dataset.type !== 'general') {
                    showCard = false;
                } else if (filterValue === 'important' && card.dataset.importance !== 'important') {
                    showCard = false;
                } else if (filterValue === 'urgent' && card.dataset.importance !== 'urgent') {
                    showCard = false;
                }
            }
            
            // Show or hide the card
            card.style.display = showCard ? 'block' : 'none';
        });
        
        // Show message if no results
        const visibleCards = document.querySelectorAll('.announcement-card[style="display: block;"]');
        const noResultsMsg = document.querySelector('.no-results-message');
        
        if (visibleCards.length === 0 && announcementCards.length > 0) {
            // Create no results message if it doesn't exist
            if (!noResultsMsg) {
                const container = document.querySelector('.announcements-container');
                const message = document.createElement('div');
                message.className = 'alert alert-info no-results-message';
                message.innerHTML = '<i class="fas fa-info-circle me-2"></i> No announcements match your filter criteria.';
                container.appendChild(message);
            } else {
                noResultsMsg.style.display = 'block';
            }
        } else if (noResultsMsg) {
            noResultsMsg.style.display = 'none';
        }
    }
    
    // Add event listeners
    if (showUnreadOnlyCheckbox) {
        showUnreadOnlyCheckbox.addEventListener('change', filterAnnouncements);
    }
    
    if (announcementFilterSelect) {
        announcementFilterSelect.addEventListener('change', filterAnnouncements);
    }
});
</script>

<?php include_once('includes/footer.php'); ?>