fetch_chirps.php

<?php
session_start();

// Function to make URLs clickable, embed images, and handle mentions
function makeLinksClickable($text) {
    // Pattern for URLs
    $urlPattern = '/\b((https?:\/\/)?([a-z0-9-]+\.)+[a-z]{2,6}(\/[^\s]*)?(\?[^\s]*)?)/i';

    // Replace URLs with clickable links or images
    $text = preg_replace_callback($urlPattern, function($matches) {
        $url = $matches[1];

        // Parse URL and query string
        $parsedUrl = parse_url($url);
        $path = isset($parsedUrl['path']) ? $parsedUrl['path'] : '';
        $query = isset($parsedUrl['query']) ? $parsedUrl['query'] : '';

        // Strip "https://" and "www." from the display
        $displayUrl = preg_replace('/^https?:\/\/(www\.)?/i', '', $url);

        // Check for image extension in the path or query string
        $imageExtensions = ['jpg', 'jpeg', 'png', 'gif', 'bmp', 'webp'];
        $fileExtension = pathinfo($path, PATHINFO_EXTENSION);

        // Check if the query string contains an image format
        foreach ($imageExtensions as $extension) {
            if (stripos($query, 'format=' . $extension) !== false) {
                $fileExtension = $extension;
                break;
            }
        }

        if (in_array(strtolower($fileExtension), $imageExtensions)) {
            // If it's an image, embed it
            return '<div class="chirpImageContainer"><img class="imageInChirp" src="' . $url . '" alt="Photo"></div>';
        } else {
            // Otherwise, create a clickable link
            return '<a class="linkInChirp" href="' . htmlspecialchars($url, ENT_QUOTES) . '" target="_blank" rel="noopener noreferrer">' . htmlspecialchars($displayUrl, ENT_QUOTES) . '</a>';
        }
    }, $text);

    // Pattern for @mentions, ensuring it doesn't match inside URLs
    $mentionPattern = '/(?<!\S)@([a-zA-Z0-9_]+)(?!\S)/';

    // Replace mentions with clickable profile links
    $text = preg_replace_callback($mentionPattern, function($matches) {
        $username = $matches[1];
        $profileUrl = '/user/?id=' . htmlspecialchars($username, ENT_QUOTES);
        return '<a class="linkInChirp" href="' . $profileUrl . '">@' . htmlspecialchars($username, ENT_QUOTES) . '</a>';
    }, $text);

    return $text;
}


// Improved error handling
try {
    // Set up PDO with error mode to exception
    $db = new PDO('sqlite:' . __DIR__ . '/../chirp.db');
    $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);

    // Validate and sanitize inputs
    $offset = isset($_GET['offset']) ? max((int)$_GET['offset'], 0) : 0;
    $limit = 12;
    $currentUserId = isset($_SESSION['user_id']) ? (int)$_SESSION['user_id'] : null;

    // Single query to fetch chirps with user info and interaction counts
    $query = '
        SELECT chirps.*, users.username, users.name, users.profilePic, users.isVerified,
               (SELECT COUNT(*) FROM likes WHERE chirp_id = chirps.id) AS like_count,
               (SELECT COUNT(*) FROM rechirps WHERE chirp_id = chirps.id) AS rechirp_count,
               (SELECT COUNT(*) FROM chirps AS replies WHERE replies.parent = chirps.id AND replies.type = "reply") AS reply_count,
               (SELECT COUNT(*) FROM likes WHERE chirp_id = chirps.id AND user_id = :user_id) AS liked_by_current_user,
               (SELECT COUNT(*) FROM rechirps WHERE chirp_id = chirps.id AND user_id = :user_id) AS rechirped_by_current_user
        FROM chirps
        INNER JOIN users ON chirps.user = users.id
        WHERE chirps.type = "post"
        ORDER BY chirps.timestamp DESC
        LIMIT :limit OFFSET :offset';

    $stmt = $db->prepare($query);
    $stmt->bindValue(':limit', $limit, PDO::PARAM_INT);
    $stmt->bindValue(':offset', $offset, PDO::PARAM_INT);
    $stmt->bindValue(':user_id', $currentUserId, PDO::PARAM_INT);
    $stmt->execute();

    $chirps = [];

    while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
        // Sanitize output
        $row['chirp'] = makeLinksClickable(nl2br(htmlspecialchars($row['chirp'])));
        $row['username'] = htmlspecialchars($row['username']);
        $row['name'] = htmlspecialchars($row['name']);
        $row['profilePic'] = htmlspecialchars($row['profilePic']);
        $row['isVerified'] = (bool)$row['isVerified'];
        
        // Convert the interaction counts to booleans
        $row['liked_by_current_user'] = (bool)$row['liked_by_current_user'];
        $row['rechirped_by_current_user'] = (bool)$row['rechirped_by_current_user'];

        $chirps[] = $row;
    }

    // Set JSON header and output
    header('Content-Type: application/json');
    echo json_encode($chirps);
    
} catch (PDOException $e) {
    // Log error details for debugging purposes
    error_log($e->getMessage());
    http_response_code(500); // Set HTTP response code to 500 for server error
    echo json_encode(['error' => 'An error occurred while fetching chirps. Please try again later.']);
}