<?php
class LedgerEntry extends AppModel {

	var $belongsTo = array(
		'Transaction',
		'Account',
		'Ledger',
	);

	var $hasOne = array(
		'Tender' => array(
			'dependent' => true,
		),
		'DebitDoubleEntry' => array(
			'className' => 'DoubleEntry',
		        'foreignKey' => 'debit_entry_id',
			'dependent' => true,
		),
		'CreditDoubleEntry' => array(
			'className' => 'DoubleEntry',
		        'foreignKey' => 'credit_entry_id',
			'dependent' => true,
		),
		'DoubleEntry' => array(
		        'foreignKey' => false,
		),
	);

	var $hasMany = array(
	);

	var $hasAndBelongsToMany = array(
		// The Debit half of the double entry matching THIS Credit (if it is one)
		'DebitEntry' => array(
			'className' => 'LedgerEntry',
			'joinTable' => 'double_entries',
			'linkalias' => 'DDE',
			'foreignKey' => 'credit_entry_id',
			'associationForeignKey' => 'debit_entry_id',
		),

		// The Credit half of the double entry matching THIS Debit (if it is one)
		'CreditEntry' => array(
			'className' => 'LedgerEntry',
			'joinTable' => 'double_entries',
			'linkalias' => 'CDE',
			'foreignKey' => 'debit_entry_id',
			'associationForeignKey' => 'credit_entry_id',
		),
	);


  /**************************************************************************
   **************************************************************************
   **************************************************************************
   * function: debitCreditFields
   *  - Returns the fields necessary to determine whether the queried
   *    entries are a debit, or a credit, and also the effect each have
   *    on the overall balance of the account/ledger.
   */

  function debitCreditFields($sum = false, $balance = true,
			     $entry_name = 'LedgerEntry', $account_name = 'Account') {
    $fields = array
      (
       ($sum ? 'SUM(' : '') .
       "IF({$entry_name}.crdr = 'DEBIT'," .
       "   {$entry_name}.amount, NULL)" .
       ($sum ? ')' : '') . ' AS debit' . ($sum ? 's' : ''),

       ($sum ? 'SUM(' : '') .
       "IF({$entry_name}.crdr = 'CREDIT'," .
       "   {$entry_name}.amount, NULL)" .
       ($sum ? ')' : '') . ' AS credit' . ($sum ? 's' : ''),
       );

    if ($balance)
      $fields[] = 
	($sum ? 'SUM(' : '') .
	"IF(${account_name}.type IN ('ASSET', 'EXPENSE')," .
	"   IF({$entry_name}.crdr = 'DEBIT',  1, -1)," .
	"   IF({$entry_name}.crdr = 'CREDIT', 1, -1))" .
	" * IF({$entry_name}.amount, {$entry_name}.amount, 0)" .
	($sum ? ')' : '') . ' AS balance';

    if ($sum)
      $fields[] = "COUNT({$entry_name}.id) AS entries";

    return $fields;
  }


  /**************************************************************************
   **************************************************************************
   **************************************************************************
   * function: verifyLedgerEntry
   *  - Verifies consistenty of new ledger entry data
   *    (not in a pre-existing ledger entry)
   */
  function verifyLedgerEntry($entry, $tender = null) {
/*     pr(array("LedgerEntry::verifyLedgerEntry()" */
/* 	     => compact('entry', 'tender'))); */

    if (empty($entry['account_id']) ||
	empty($entry['crdr']) ||
	empty($entry['amount'])
	) {
/*       pr(array("LedgerEntry::verifyLedgerEntry()" */
/* 	       => "Entry verification failed")); */
      return false;
    }

    if (isset($tender) && !$this->Tender->verifyTender($tender)) {
/*       pr(array("LedgerEntry::verifyLedgerEntry()" */
/* 	       => "Tender verification failed")); */
      return false;
    }

    return true;
  }


  /**************************************************************************
   **************************************************************************
   **************************************************************************
   * function: addLedgerEntry
   *  - Inserts new Ledger Entry into the database
   */
  function addLedgerEntry($entry, $tender = null) {
    //$this->prFunctionLevel(16);
    $this->prEnter(compact('entry', 'tender'));

    $ret = array('data' => $entry);
    if (!$this->verifyLedgerEntry($entry, $tender))
      return $this->prReturn(array('error' => true) + $ret);

    if (empty($entry['ledger_id']))
      $entry['ledger_id'] = 
	$this->Account->currentLedgerID($entry['account_id']);

    $this->create();
    if (!$this->save($entry))
      return $this->prReturn(array('error' => true) + $ret);

    $ret['ledger_entry_id'] = $this->id;

    if (isset($tender)) {
      $tender['account_id'] = $entry['account_id'];
      $tender['ledger_entry_id'] = $ret['ledger_entry_id'];
      $result = $this->Tender->addTender($tender);
      $ret['Tender'] = $result;
      if ($result['error'])
	return $this->prReturn(array('error' => true) + $ret);
    }

    return $this->prReturn($ret + array('error' => false));
  }


  /**************************************************************************
   **************************************************************************
   **************************************************************************
   * function: stats
   *  - Returns summary data from the requested ledger entry
   */
  function stats($id = null, $query = null, $set = null) {
    $this->queryInit($query);

    // REVISIT <AP>: 20090816
    //  This function appeared to be dramatically broken,
    //  a throwback to an earlier time.  I deleted its
    //  contents and added this error to ensure it does
    //  not get used.
    $this->INTERNAL_ERROR('This function should not be used');
  }

}