<?php
class DoubleEntry extends AppModel {

	var $name = 'DoubleEntry';
	var $validate = array(
		'id' => array('numeric'),
		'transaction_id' => array('numeric'),
		'amount' => array('money')
	);

	var $hasOne = array(
		'DebitEntry' => array(
			'className' => 'Entry',
			'conditions' => array('DebitEntry.crdr' => 'DEBIT'),
		),
		'CreditEntry' => array(
			'className' => 'Entry',
			'conditions' => array('CreditEntry.crdr' => 'CREDIT'),
		),
	);

	var $hasMany = array(
		'Entry',
	);


	var $belongsTo = array(
		'Transaction',
		'Invoice' => array(
			'className' => 'Transaction',
			'conditions' => array('Invoice.type' => 'INVOICE'),
		),
		'Receipt' => array(
			'className' => 'Transaction',
			'conditions' => array('Invoice.type' => 'RECEIPT'),
		),


		'Customer',
		'Lease',

		'DebitLedger' => array(
			'className' => 'Ledger',
			'foreignKey' => 'debit_ledger_id',
		),
		'CreditLedger' => array(
			'className' => 'Ledger',
			'foreignKey' => 'credit_ledger_id',
		),

		'Ledger' => array(
			'foreignKey' => false,
			// conditions will be used when JOINing tables
			// (such as find with LinkableBehavior)
			'conditions' => array('OR' =>
			    array('%{MODEL_ALIAS}.debit_ledger_id  = Ledger.id',
				  '%{MODEL_ALIAS}.credit_ledger_id = Ledger.id')),

			// finderQuery will be used when tables are put
			// together across several querys, not with JOIN.
			// (such as find with ContainableBehavior)
			'finderQuery' => 'NOT-IMPLEMENTED',

			'counterQuery' => ''
		),

	);


  /**************************************************************************
   **************************************************************************
   **************************************************************************
   * function: conditionEntryAsCreditOrDebit
   *  - returns the condition necessary to match a set of
   *    Ledgers to all related LedgerEntries
   */
  function conditionEntryAsCreditOrDebit($ledger_ids) {
    return array('OR' =>
		 array(array('debit_ledger_id'  => $ledger_ids),
		       array('credit_ledger_id' => $ledger_ids)));
  }

    
  function debitCreditFields($double_name = 'DoubleEntry', $ledger_name = 'Ledger', $sum = true) {
    $fields = array
      (
       ($sum ? 'SUM(' : '') .
       "IF({$double_name}.debit_ledger_id  = {$ledger_name}.id,
           {$double_name}.amount, NULL)" .
       ($sum ? ')' : '') . ' AS debit' . ($sum ? 's' : ''),

       ($sum ? 'SUM(' : '') .
       "IF({$double_name}.credit_ledger_id  = {$ledger_name}.id,
           {$double_name}.amount, NULL)" .
       ($sum ? ')' : '') . ' AS credit' . ($sum ? 's' : ''),

       ($sum ? 'SUM(' : '') .
       "IF(Account.type IN ('ASSET', 'EXPENSE'),
	   IF({$double_name}.debit_ledger_id = {$ledger_name}.id, 1, -1),
	   IF({$double_name}.credit_ledger_id = {$ledger_name}.id, 1, -1)
          ) * IF({$double_name}.amount, {$double_name}.amount, 0)" .
       ($sum ? ')' : '') . ' AS balance',
       );

    if ($sum)
      $fields[] = "COUNT({$double_name}.id) AS entries";

    return $fields;
  }

  /**************************************************************************
   **************************************************************************
   **************************************************************************
   * function: ledgerContext query helpers
   *  - Returns parameters necessary to generate a query which
   *    puts ledger entries into the context of a ledger.  Since
   *    debit/credit depends on the account type, it is required
   *    as an argument for each function to avoid having to
   *    query the ledger/account to find it out.
   */
  function ledgerContextFields($ledger_id = null, $account_type = null) {
    $fields = array('id', 'effective_date',
		    'lease_id', 'customer_id', 'comment', 'amount');

    if (isset($ledger_id)) {
      $fields[] = ("IF(DoubleEntry.debit_ledger_id = $ledger_id," .
		   "   DoubleEntry.amount, NULL) AS debit");
      $fields[] = ("IF(DoubleEntry.credit_ledger_id = $ledger_id," .
		   "   DoubleEntry.amount, NULL) AS credit");

      if (isset($account_type)) {
	if (in_array($account_type, array('ASSET', 'EXPENSE')))
	  $ledger_type = 'debit';
	else
	  $ledger_type = 'credit';

	$fields[] = ("(IF(DoubleEntry.{$ledger_type}_ledger_id = $ledger_id," .
		     "    1, -1) * DoubleEntry.amount) AS balance");
      }
    }

    return $fields;
  }

  function ledgerContextFields2($ledger_id = null, $account_id = null, $account_type = null) {
    $fields = array('id', 'effective_date', 'comment', 'amount');

    if (isset($ledger_id)) {
      $fields[] = ("IF(DoubleEntry.debit_ledger_id = $ledger_id," .
		   "   SUM(DoubleEntry.amount), NULL) AS debit");
      $fields[] = ("IF(DoubleEntry.credit_ledger_id = $ledger_id," .
		   "   SUM(DoubleEntry.amount), NULL) AS credit");

      if (isset($account_id) || isset($account_type)) {
	$Account = new Account();
	$account_ftype = $Account->fundamentalType($account_id ? $account_id : $account_type);
	$fields[] = ("(IF(DoubleEntry.{$account_ftype}_ledger_id = $ledger_id," .
		     "    1, -1) * SUM(DoubleEntry.amount)) AS balance");
      }
    }
    elseif (isset($account_id)) {
      $fields[] = ("IF(DebitLedger.account_id = $account_id," .
		   "   SUM(DoubleEntry.amount), NULL) AS debit");
      $fields[] = ("IF(CreditLedger.account_id = $account_id," .
		   "   SUM(DoubleEntry.amount), NULL) AS credit");

      $Account = new Account();
      $account_ftype = ucfirst($Account->fundamentalType($account_id));
      $fields[] = ("(IF({$account_ftype}Ledger.account_id = $account_id," .
		   "    1, -1) * SUM(DoubleEntry.amount)) AS balance");
    }

    return $fields;
  }


  function ledgerContextConditions($ledger_id, $account_type) {
    if (isset($ledger_id)) {
      return array
	('OR' =>
	 array(array('DoubleEntry.debit_ledger_id' => $ledger_id),
	       array('DoubleEntry.credit_ledger_id' => $ledger_id)),
	 );
    }

    return array();
  }      

  /**************************************************************************
   **************************************************************************
   **************************************************************************
   * function: findInLedgerContext
   *  - Returns an array of ledger entries that belong to a given ledger.
   *    There is extra logic to also figure out whether the double_entry
   *    amount is either a credit, or a debit, depending on how it was
   *    written into the ledger, as well as whether the amount increases or
   *    decreases the balance depending on the particular account type of
   *    the ledger.
   */
  function findInLedgerContext($ledger_id, $account_type, $cond = null, $link = null) {
    if (!isset($link))
      $link = array('Transaction');

    if (!isset($cond))
      $cond = array();

    $fields = $this->ledgerContextFields($ledger_id, $account_type);
    $cond[] = $this->ledgerContextConditions($ledger_id, $account_type);
    $order  = array('Transaction.stamp');

    $entries = $this->find
      ('all',
       array('link'       => $link,
	     'fields'     => $fields,
	     'conditions' => $cond,
	     'order'      => $order,
	     ));

    return $entries;
  }


  /**************************************************************************
   **************************************************************************
   **************************************************************************
   * function: stats
   *  - Returns summary data from the requested double entry
   */
  function stats($id) {

/*     $query = array */
/*       ( */
/*        'fields' => array("SUM(Reconciliation.amount) AS 'reconciled'"), */

/*        'conditions' => array(isset($cond) ? $cond : array(), */
/* 			     array('DoubleEntry.id' => $id)), */

/*        'group' => 'DoubleEntry.id', */
/*        ); */

/*     // Get the applied amounts on the debit side */
/*     $query['link'] = */
/*       array('DebitReconciliationDoubleEntry' => array('alias' => 'DRLE', 'DRLETransaction' => array('class' => 'Transaction'))); */
/*     $tmpstats = $this->find('first', $query); */
/*     $stats['debit_amount_reconciled'] = $tmpstats[0]['reconciled']; */

/*     // Get the applied amounts on the credit side */
/*     $query['link'] = */
/*       array('CreditReconciliationDoubleEntry' => array('alias' => 'CRLE', 'CRLETransaction' => array('class' => 'Transaction'))); */
/*     $tmpstats = $this->find('first', $query); */
/*     $stats['credit_amount_reconciled'] = $tmpstats[0]['reconciled']; */

    $stats['debit']['amount_reconciled'] = 0; 
    $stats['credit']['amount_reconciled'] = 0; 

    return $stats;
  }

}