<?PHP

 // Description prefixes used to indicate types
 // e.g. 'DD -' => 'Direct Debit'
 $types = array();

 // Types where the real description should be discarded in favour
 // of the type name
 // e.g. 'Cash Withdrawal'
 $genericTypes = array();

 // Custom user rules for grouping different descriptions
 // e.g. '(?i)^(company|service123)' => 'Company'
 $rules = array();

 // Categories
 // e.g. 'Groceries' => array('Shop1', 'Shop2', '(?i)regex')
 $categories = array();

 @include('data.local.php');

 if (!function_exists('parseStatementPart')) {
  // Formats part (one field) of a transaction
  function parseStatementPart($key, $value) {
   if ($key == 'Date') {
    $format = 'd/m/' . (strlen($value) == 8 ? 'y' : 'Y');
    return DateTime::createFromFormat($format, $value)->setTime(0, 0, 0);
   } else if ($key == 'Amount') {
    return (double) $value;
   }

   return $value;
  }
 }

 if (!function_exists('parseStatementLine')) {
  // Formats an entire transaction from a statement
  function parseStatementLine($line) {
   global $categories, $genericTypes, $types, $rules;

   if (!isset($line['Exchange']) || empty($line['Exchange'])) {
    if (preg_match('/^(.*?)\s*\((.*? @ RATE .*?)\)$/', $line['Description'], $m)) {
     $line['Description'] = $m[1];
     $line['Exchange'] = $m[2];
    }
   }

   if (!isset($line['Type']) || empty($line['Type'])) {
    foreach ($types as $prefix => $type) {
     if (strpos($line['Description'], $prefix) === 0) {
      $line['Type'] = $type;

      if (array_search($type, $genericTypes) === false) {
       $line['Description'] = substr($line['Description'], strlen($prefix));
      } else {
       $line['RawDescription'] = $line['Description'];
       $line['Description'] = $type;
      }

      break;
     }
    }
   }

   foreach ($rules as $regex => $replacement) {
    if (preg_match('(' . $regex . ')', $line['Description'])) {
     $line['RawDescription'] = $line['Description'];
     $line['Description'] = $replacement;
    }
   }

   if (!isset($line['Category']) || empty($line['Category'])) {
    foreach ($categories as $cat => $entries) {
     foreach ($entries as $regex) {
      if (preg_match('(' . $regex . ')', $line['Description'])) {
       $line['Category'] = $cat;
       break;
      }
     }
    }
   }

   return $line;
  }
 }

 if (!function_exists('loadStatements')) {
  // Loads statements from the specified directory
  function loadStatements($dir = 'Statements') {
   $results = array();

   foreach (glob($dir . '/*.csv') as $statement) {
    $fh = fopen($statement, 'r');
    $data = array();

    $headers = array_map('trim', fgetcsv($fh));

    while (!feof($fh)) {
     $line = parseStatementLine(array_combine($headers, array_map('parseStatementPart', $headers, array_map('trim', fgetcsv($fh)))));
     $data[] = $line;
    }
    fclose($fh);

    $results[basename($statement)] = $data;
   }

   return $results;
  }
 }

 $entries = array_reduce(loadStatements(), 'array_merge', array());

 usort($entries, function($a, $b) { return $a['Date']->getTimestamp() - $b['Date']->getTimestamp(); });

 $descs = array_unique(array_map(function($t) { return $t['Description']; }, $entries));
 sort($descs);

 $amounts = array();
 $rawmonths = array();
 $months = array();
 $bydesc = array();
 array_walk($entries, function($entry) use(&$months, &$bydesc, &$amounts, &$rawmonths) {
  $rawmonths[$entry['Date']->format('Y-m')][] = $entry;

  if (!isset($entry['Category']) || $entry['Category'] != '(Ignored)') {
   $amounts[$entry['Date']->format('Y-m')][$entry['Amount'] < 0 ? 'out' : 'in'] += $entry['Amount'];
   $months[$entry['Date']->format('Y-m')][$entry['Description']]['Count']++; 
   $months[$entry['Date']->format('Y-m')][$entry['Description']]['Amount'] += $entry['Amount'];
   $bydesc[$entry['Description']]['Count']++;
   $bydesc[$entry['Description']]['Amount'] += $entry['Amount'];
  }
 });

 ksort($months);
 ksort($amounts);

 $monthsbydesc = array();

 array_walk(array_slice(array_reverse($months), 0, 6, true), function($monthentries, $month) use(&$monthsbydesc) {
  array_walk($monthentries, function($entry, $desc) use(&$monthsbydesc, $month) {
   $monthsbydesc[$desc][$month]['Count'] += $entry['Count'];
   $monthsbydesc[$desc][$month]['Amount'] += $entry['Amount'];
  });
 });

 $total = 0;
 array_walk($monthsbydesc, function($data, $desc) use(&$total) {
  $prob = count($data) / 6;
  $count = array_sum(array_map(function($x) { return $x['Count']; }, $data));
  $amount = array_sum(array_map(function($x) { return $x['Amount']; }, $data)); 
  $avgcount = $count / count($data);
  $avgamount = $amount / $count;
  $total += $prob * $avgcount * $avgamount;
  //echo "P($desc) = $prob, with avg of $avgcount trans/month, averaging $avgamount\n";
 });

 $transData = array(array(), array());
 array_walk($months, function($entries, $month) use(&$transData) {
  $ins = array_filter($entries, function($x) { return $x['Amount'] > 0; });
  $outs = array_filter($entries, function($x) { return $x['Amount'] < 0; });

  $totalin = array_sum(array_map(function($x) { return $x['Amount']; }, $ins));
  $totalout = array_sum(array_map(function($x) { return -1 * $x['Amount']; }, $outs));
  $time = strtotime($month . '-01') * 1000;

  $transData[0][] = array($time, $totalin);
  $transData[1][] = array($time, $totalout);
 });

?>
var data = <?PHP echo json_encode($rawmonths); ?>;