<?php
header('Content-Type: application/json');
require_once __DIR__ . '/../db/config.php';
session_start();

$user_id = $_SESSION['user_id'] ?? null;
if (!$user_id) {
    echo json_encode(['success' => false, 'error' => 'Not logged in']);
    exit;
}

$startup_id = $_POST['startup_id'] ?? null;
$action = $_POST['action'] ?? 'follow'; // 'follow' or 'unfollow'

if (!$startup_id) {
    echo json_encode(['success' => false, 'error' => 'Startup ID is required']);
    exit;
}

try {
    if ($action === 'follow') {
        $stmt = db()->prepare("INSERT IGNORE INTO startup_followers (startup_id, user_id) VALUES (?, ?)");
        $stmt->execute([$startup_id, $user_id]);
        
        // Update denormalized count
        $stmt = db()->prepare("UPDATE startups SET followers_count = (SELECT COUNT(*) FROM startup_followers WHERE startup_id = ?) WHERE id = ?");
        $stmt->execute([$startup_id, $startup_id]);
    } else {
        $stmt = db()->prepare("DELETE FROM startup_followers WHERE startup_id = ? AND user_id = ?");
        $stmt->execute([$startup_id, $user_id]);
        
        // Update denormalized count
        $stmt = db()->prepare("UPDATE startups SET followers_count = (SELECT COUNT(*) FROM startup_followers WHERE startup_id = ?) WHERE id = ?");
        $stmt->execute([$startup_id, $startup_id]);
    }
    
    // Get new count
    $stmt = db()->prepare("SELECT followers_count FROM startups WHERE id = ?");
    $stmt->execute([$startup_id]);
    $new_count = $stmt->fetchColumn();
    
    echo json_encode(['success' => true, 'new_count' => $new_count]);
} catch (Exception $e) {
    echo json_encode(['success' => false, 'error' => $e->getMessage()]);
}