<?php
  // Buffer anything db.php prints so a later HTTP 500 still reaches PayPal.
  ob_start();
  $noSession = 1;
  require("db.php");

  date_default_timezone_set("Canada/Pacific");

  if (!is_array($_POST) || count($_POST) == 0) {
    $contents = file_get_contents("/m/data1/app.hotlunches.net/ppPaymentHotLunch.log");
    echo(nl2br(htmlentities($contents)));
    exit();
  }

  function saveOutput($contents) {
    $f = fopen("/m/data1/app.hotlunches.net/ppPaymentHotLunch.log", "w");
    fwrite($f, $contents);
    fclose($f);

    $f = fopen("/m/data1/app.hotlunches.net/ppPaymentHotLunch.trx.log", "a");
    fwrite($f, $contents);
    fclose($f);

    return nl2br(htmlentities($contents));
  }

  function hotlunches_paypal_extract_status($body) {
    $body = trim($body);
    if ($body === 'VERIFIED' || $body === 'INVALID') return $body;
    if (preg_match('/(?:^|\r\n|\n)(VERIFIED|INVALID)\s*$/', $body, $m)) return $m[1];
    return $body;
  }

  function hotlunches_paypal_postback_curl($url, $req) {
    if (!function_exists('curl_init')) {
      return array('ok' => false, 'status' => '', 'error' => 'cURL is not available');
    }

    $ch = curl_init($url);
    curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
    curl_setopt($ch, CURLOPT_SSLVERSION, 6); // TLS 1.2
    curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
    curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
    curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
      curl_setopt($ch, CURLOPT_CONNECTTIMEOUT, 3);
      curl_setopt($ch, CURLOPT_TIMEOUT, 6);
    if (defined('CURL_IPRESOLVE_V4')) {
      curl_setopt($ch, CURLOPT_IPRESOLVE, CURL_IPRESOLVE_V4);
    }
    curl_setopt($ch, CURLOPT_HTTPHEADER, array(
      'User-Agent: PHP-IPN-VerificationScript',
      'Connection: Close'
    ));
    $body = curl_exec($ch);
    $errno = curl_errno($ch);
    $errstr = curl_error($ch);
    $http_code = (int)curl_getinfo($ch, CURLINFO_HTTP_CODE);
    curl_close($ch);

    if ($body === false || $errno) {
      return array('ok' => false, 'status' => '', 'error' => $errno . ' - ' . $errstr);
    }
    if ($http_code !== 200) {
      return array('ok' => false, 'status' => hotlunches_paypal_extract_status($body), 'error' => 'PayPal HTTP ' . $http_code);
    }
    return array('ok' => true, 'status' => hotlunches_paypal_extract_status($body), 'error' => '');
  }

  function hotlunches_paypal_postback_socket($url, $req) {
    $url_parts = parse_url($url);
    $host = isset($url_parts['host']) ? $url_parts['host'] : '';
    $path = isset($url_parts['path']) && $url_parts['path'] !== '' ? $url_parts['path'] : '/cgi-bin/webscr';
    if ($host === '') {
      return array('ok' => false, 'status' => '', 'error' => 'Invalid PayPal URL');
    }

    $ssl = array(
      'verify_peer' => true,
      'verify_peer_name' => true,
      'peer_name' => $host
    );
    if (defined('STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT')) {
      $ssl['crypto_method'] = STREAM_CRYPTO_METHOD_TLSv1_2_CLIENT;
    }
    $ctx = stream_context_create(array('ssl' => $ssl));
    $fp = @stream_socket_client('ssl://' . $host . ':443', $errno, $errstr, 5, STREAM_CLIENT_CONNECT, $ctx);
    if ($fp === false) {
      return array('ok' => false, 'status' => '', 'error' => $errno . ' - ' . $errstr);
    }

    // HTTP/1.0 avoids chunked encoding so the body is exactly VERIFIED/INVALID
    $header  = "POST " . $path . " HTTP/1.0\r\n";
    $header .= "Host: " . $host . "\r\n";
    $header .= "User-Agent: PHP-IPN-VerificationScript\r\n";
    $header .= "Content-Type: application/x-www-form-urlencoded\r\n";
    $header .= "Content-Length: " . strlen($req) . "\r\n";
    $header .= "Connection: close\r\n\r\n";
    fwrite($fp, $header . $req);
    $response = '';
    while (!feof($fp)) {
      $response .= fgets($fp, 1024);
    }
    fclose($fp);

    $header_body = preg_split("/\r\n\r\n|\n\n/", $response, 2);
    $status = isset($header_body[1]) ? hotlunches_paypal_extract_status($header_body[1]) : '';
    if ($status === 'VERIFIED' || $status === 'INVALID') {
      return array('ok' => true, 'status' => $status, 'error' => '');
    }
    return array('ok' => false, 'status' => $status, 'error' => 'Unexpected socket response from PayPal');
  }

  // Rebuild the original IPN payload. PayPal requires original field order/encoding.
  $raw_post_data = file_get_contents('php://input');
  if ($raw_post_data === false || $raw_post_data === '') {
    $req = 'cmd=_notify-validate';
    foreach ($_POST as $key => $value) {
      $req .= '&' . $key . '=' . urlencode(stripslashes($value));
    }
  } else {
    $raw_post_array = explode('&', $raw_post_data);
    $myPost = array();
    foreach ($raw_post_array as $keyval) {
      $keyval = explode('=', $keyval, 2);
      if (count($keyval) == 2) {
        if ($keyval[0] === 'payment_date' && substr_count($keyval[1], '+') === 1) {
          $keyval[1] = str_replace('+', '%2B', $keyval[1]);
        }
        $myPost[$keyval[0]] = urldecode($keyval[1]);
      }
    }
    $req = 'cmd=_notify-validate';
    foreach ($myPost as $key => $value) {
      $req .= '&' . $key . '=' . urlencode($value);
    }
  }

  $use_sandbox = array_key_exists('test_ipn', $_POST);
  $paypal_urls = $use_sandbox
    ? array(
        'https://ipnpb.sandbox.paypal.com/cgi-bin/webscr',
        'https://www.sandbox.paypal.com/cgi-bin/webscr'
      )
    : array(
        'https://ipnpb.paypal.com/cgi-bin/webscr',
        'https://www.paypal.com/cgi-bin/webscr'
      );

  $errors = array();
  $unexpectedErrors = 0;
  $paypal_status = '';
  $paypal_error = '';
  $verified = false;

  foreach ($paypal_urls as $url_index => $paypal_url) {
    if ($verified || $paypal_status === 'INVALID') break;

    // Primary endpoint is retried once. The backup endpoint is tried once.
    // Timeouts stay inside PayPal's IPN response window.
    $max_attempts = ($url_index === 0) ? 2 : 1;
    for ($attempt = 1; $attempt <= $max_attempts; $attempt++) {
      $result = hotlunches_paypal_postback_curl($paypal_url, $req);
      $paypal_status = $result['status'];
      $paypal_error = $result['error'];
      if ($result['ok'] && ($paypal_status === 'VERIFIED' || $paypal_status === 'INVALID')) {
        $verified = ($paypal_status === 'VERIFIED');
        break;
      }
    }

    // Socket fallback only when cURL never got a final VERIFIED/INVALID answer.
    if ($verified || $paypal_status === 'INVALID' || $url_index !== 0) continue;

    $result = hotlunches_paypal_postback_socket($paypal_url, $req);
    $paypal_status = $result['status'];
    $paypal_error = $result['error'];
    if ($result['ok'] && $paypal_status === 'VERIFIED') {
      $verified = true;
    }
  }

  // Transport failure must be HTTP 500 so PayPal resends the IPN.
  // INVALID stays HTTP 200 so a rejected notice is not retried.
  if (!$verified && $paypal_status !== 'INVALID') {
    if (function_exists('http_response_code')) {
      http_response_code(500);
    } else {
      header('HTTP/1.1 500 Internal Server Error');
    }
  }

  ob_start("saveOutput");

  echo(date('r') . "\n\n");
  $x = $_POST;
  if (isset($x['callbackPW'])) unset($x['callbackPW']);
  print_r($x);
  echo("\n\n");

  if ($verified) {
    echo("VERIFIED");
  } elseif ($paypal_status === 'INVALID') {
    echo("INVALID");
    $errors[] = "The PayPal server could not validate the IPN.";
    $unexpectedErrors = 1;
  } else {
    echo("ERROR\n" . $paypal_error);
    $errors[] = "Error connecting to PayPal server to validate IPN.";
    $unexpectedErrors = 1;
  }
  echo("\n\n");

  if ($unexpectedErrors == 1) exit();


  extract($_POST,EXTR_PREFIX_ALL,'P');
  $school_num = isset($P_custom) ? intval($P_custom) : 0;

  // Load user information from the database
  $query = "SELECT * FROM schools WHERE record_num = $school_num";
  $r = db_query("SELECT * FROM schools WHERE record_num = {$school_num}");
  if (db_num_rows($r) != 1) {
    echo("Invalid school number: $school_num.\n");
    echo("$query");
    exit();
  } else {
    extract(db_fetch_assoc($r), EXTR_PREFIX_ALL, 's');
  }

  // Check that the payment was made in Canadian funds
  if (!$P_mc_currency || $P_mc_currency != 'CAD') {
    echo("Unexpected currency - payment should be made in $s_paypal_currency");
    exit();
  }

  // Get the invoice number(s)
  $r = db_query("SELECT * FROM invoice_header WHERE status = 'Open' AND school_num = $school_num");
  if (db_num_rows($r) == 0) {
    echo("Error: no open invoices found.\n");
    echo("$query");
    exit();
  }

  $invoices = "";
  while ($row = db_fetch_array($r)) {
    if (strlen($invoices)) $invoices .= ",";
    $invoices .= $row['record_num'];
  }

  // Get current outstanding balance
  $current_balance_owing = db_getVal("select sum(total - amount_paid) from invoice_header where school_num = $school_num and record_num in ($invoices)");

  // Check the order total
  if (!isset($P_mc_gross) || $P_mc_gross != $current_balance_owing) {
    $x = number_format($current_balance_owing, 2);
    echo("Invalid payment amount - expected {$x}");
    exit();
  }

  // Check the payment was sent to the correct account
  if ($P_receiver_email != 'mark@hotlunches.net' && $P_receiver_email != 'paypal@hotlunches.net') {
    echo("Payment was sent to an unexpected account.\n");
    echo("$P_receiver_email => 'mark@hotlunches.net'\n");
    exit();
  }

  // check for non-completed orders (ie. pending for some reason)
  if ($P_payment_status != 'Completed') {
    echo("Payment was not completed.");
    exit();
  }

  echo("Payment validated ok - updating database\n\n");

  // Update invoice header
  $today = date("Y-m-d",time());
  $query = "UPDATE invoice_header " .
           "SET amount_paid = total, status = 'Paid', reference = '{$P_txn_id}', payment_date = '$today', payment_method = 'PayPal' " .
           "WHERE school_num = $school_num " .
           "AND record_num in ($invoices)";
  db_query($query);
  echo("{$query}\n");

  // Update expiry date
  $renewal_date = db_getVal("SELECT max(renewal_date) FROM invoice_header WHERE school_num = $school_num");
  $edate = date("Y-m-d",strtotime($renewal_date) - 60 * 60 * 12);
  $query = "UPDATE schools SET expiry_date = '$edate' WHERE record_num = $school_num";
  db_query($query);
  echo("{$query}\n");


  echo("Payment processed ok\n\n\n");
?>