<?php
/**
 * Module D: Timeline Feed Compilation Engine (Database Driven)
 * Target Path: htdocs/api/v1/feed/timeline.php
 */

// Inherit the universal configuration hub
require_once __DIR__ . '/../../../config.php';

// Instagram 6.20.2 requests timeline data streams using GET
if ($_SERVER['REQUEST_METHOD'] !== 'GET') {
    http_response_code(405);
    die(json_encode(["status" => "fail", "message" => "Method not allowed. Use GET query pipeline."]));
}

// 1. Optional Session Catching (For custom tailored feeds or liking flags later)
$sessionCookie = $_COOKIE['sessionid'] ?? '';
$currentUserId = 0;
if (!empty($sessionCookie) && strpos($sessionCookie, 'nostolga_sess_') === 0) {
    $currentUserId = (int)str_replace('nostolga_sess_', '', $sessionCookie);
}

$db = getDB();

try {
    /**
     * 2. Pull Live Posts Linked with Creator Profiles
     * 
     * NOTE: As you expand your database schema, ensure you create a `posts` table containing:
     * id (INT AUTO_INCREMENT), user_id (INT), media_url (VARCHAR), caption (TEXT), created_at (INT)
     * 
     * This query falls back gracefully to standard dummy content if your live table is empty.
     */
    $posts = [];
    
    // Check if the posts table exists in phpMyAdmin before running
    $tableCheck = $db->query("SHOW TABLES LIKE 'posts'")->rowCount();
    
    if ($tableCheck > 0) {
        $query = "SELECT p.*, u.username, u.full_name, u.profile_pic 
                  FROM posts p 
                  JOIN users u ON p.user_id = u.id 
                  ORDER BY p.id DESC LIMIT 30";
        $stmt = $db->query($query);
        $posts = $stmt->fetchAll();
    }

    $feedItems = [];

    // 3. Loop through your live data records and structuralize them for Instagram 6.20.2
    foreach ($posts as $post) {
        $feedItems[] = [
            "pk"               => (int)$post['id'],
            "id"               => $post['id'] . "_" . $post['user_id'],
            "device_timestamp" => (int)$post['created_at'],
            "media_type"       => 1, // 1 = Standard Square Photo Image Layout
            "code"             => "post_" . $post['id'],
            "image_versions2" => [
                "candidates" => [
                    [
                        "url"    => $post['media_url'],
                        "width"  => 600,
                        "height" => 600
                    ]
                ]
            ],
            "user" => [
                "pk"              => (int)$post['user_id'],
                "username"        => $post['username'],
                "full_name"       => $post['full_name'],
                "profile_pic_url" => $post['profile_pic'] ?? 'https://picsum.photos/150/150',
                "is_private"      => false
            ],
            "caption" => [
                "text"       => $post['caption'] ?? '',
                "created_at" => (int)$post['created_at']
            ],
            "like_count"    => 0, // Expand later via a likes mapping table
            "has_liked"     => false,
            "comment_count" => 0
        ];
    }

    // 4. Fallback Architecture: Show an initial welcome item if your database table is still empty
    if (empty($feedItems)) {
        $feedItems[] = [
            "pk"               => 999999999,
            "id"               => "999999999_1",
            "device_timestamp" => time(),
            "media_type"       => 1,
            "code"             => "welcome_post",
            "image_versions2" => [
                "candidates" => [
                    [
                        "url"    => "https://res.cloudinary.com/demo/image/upload/c_fill,g_auto,w_600,h_600/sample.jpg",
                        "width"  => 600,
                        "height" => 600
                    ]
                ]
            ],
            "user" => [
                "pk"              => 1,
                "username"        => "nostolgagram_system",
                "full_name"       => "System Hub Core",
                "profile_pic_url" => "https://picsum.photos/150/150",
                "is_private"      => false
            ],
            "caption" => [
                "text"       => "Welcome to NostolgaGram! Your dynamic timeline engine is completely online. Start posting media to fill up your feed!",
                "created_at" => time()
            ],
            "like_count"    => 1337,
            "has_liked"     => false,
            "comment_count" => 0
        ];
    }

    // 5. Package output matching legacy format structures
    http_response_code(200);
    echo json_encode([
        "items"          => $feedItems,
        "num_results"    => count($feedItems),
        "more_available" => false,
        "status"         => "ok"
    ]);
    exit;

} catch (PDOException $e) {
    http_response_code(500);
    die(json_encode(["status" => "fail", "message" => "Feed matrix assembly array sequence dropped."]));
}