<?php
require_once($path_to_root.'/'.'includes/date_functions.inc');
class SqlSet {
	protected $pairs;
	function __construct($set=null) {
		$this->pairs = $set ?  array_merge($set->pairs) : array();
	}

	function add($value, $field, $quote=true) {
		if($value !=null)  {
			array_push($this->pairs, $quote ? "$field = '$value'" : "$field = $value");
		}

		return $this;
	}

	function addDate($date, $field) {
		return $this->add(date2sql($date), $field);
	}

	function toString() {
		return implode(', ', $this->pairs);
	}
	
}
class Split {
	public $start_date;
	public $end_date;
	public $quantity=0;
	public $quantity_dispatched=0;
	

	function __construct($start_date, $period=null) {
			$this->start_date = $start_date;
			$this->end_date = $start_date;
			if($period) $this->extend($period);
	}

	function extend($days) {
			$this->end_date = add_days($this->end_date, $days);
	}
}

class Splitter {
	public $detail_ids = array() ;
	public $start_date;
	public $end_date;
	protected $days;
	public $max_quantity;

	public function __construct(array $data) {
		$this->detail_ids = array();
		foreach($data['detail'] as $detail_id => $detail) {
			array_push($this->detail_ids, $detail_id);
		}
		$this->start_date = $data['start_date'];
		$this->end_date = $data['end_date'];
		$this->days = date_diff2($this->end_date, $this->start_date, 'd');

		$this->max_quantity = $data['max_quantity'];
	}

	protected function loadDetail($detail_id) {
		$sql = "SELECT *
						FROM ".TB_PREF."sales_order_details
						WHERE id = $detail_id";
		$result = db_query($sql);
		return db_fetch($result);
	}

	public function splitAll() {
		$ok =  true;
		foreach($this->detail_ids as $detail_id) {
display_warning("processing $detail_id");
				$detail = $this->loadDetail($detail_id);
				$splits = $this->split($detail);
				$ok &= $this->saveSplits($detail, $splits);
		}

		return $ok; 
	}

	public function days() {
		return $this->days;
	}


	/* This function splits on order detail in bits of a specified size.
 * Each split  starting at the end time of the previous one.
 * the first split starts at the start_date and ends at the end_date.
 * The 'splitting' split the whole quantity not only the quantity left to dispatch
 * However, fully dispatched split won't be split in real, but merged with the next one
 */
	public function split($row) {
		$splits = array();
		$quantity = $row['quantity'];
		$quantity_sent = $row['qty_sent'];

		/* Check if the item has been fully dispatched.
		 * If so,  there is no need to do anything.
		 */
		if($quantity_sent >= $quantity) return $splits;
		
		// determine the number of split needed. This will give us the lenght of a split.
		$nsplit = ceil($quantity/$this->max_quantity);

		$period = $this->days/$nsplit;

		array_push($splits, $split = new Split($this->start_date, $period));
		$split->quantity_dispatched = $quantity_sent;
		$split_quantity = min($quantity, $this->max_quantity);
		while($split_quantity > 0) {
					$split->quantity += $split_quantity;
				// Check if the split has been entirely dispatch or not.
				if($split->quantity_dispatched > $split->quantity) {
					//extend the split
					$split->extend($period);
				}
				else {
					// create a new split
					array_push($splits, $split = new Split($split->end_date, $period));
					
				}
				$quantity -= $split_quantity;
				$split_quantity = min($quantity, $this->max_quantity);
		}

		// We need to remove the last split if it's empty
		if($split->quantity == 0) array_pop($splits);
		return $splits;
	}

	public function saveSplits($detail, $splits) {
		if(empty($splits)) return true;

		$detail_id = $detail['id'];
		$priority = $detail['priority'];
		$order_no = $detail['order_no'];
		$trans_type = $detail['trans_type'];

		/* We need to update the first one (as it exists already in the database)
		 * but insert the following one.
		 */
		$first = array_shift($splits);
		$set = new SqlSet();
		$set->addDate($first->start_date, 'hold_until_date')
				->addDate($first->end_date, 'expiry_date')
				->add($first->quantity, 'quantity', false)
				->add($priority, 'priority');
	display_warning($set->toString());
		db_query("UPDATE ".TB_PREF."sales_order_details
							SET {$set->toString()}
							WHERE id = $detail_id", "Problem splitting order details $detail_id");

		// Compute common field for each split
		$common_set  = new SqlSet();
		$common_set->add($order_no, 'order_no', false)
				->add($priority, 'priority')
				->add($trans_type, 'trans_type')
				->add($detail['required_date'], 'required_date')
				->add($detail['comment'], 'comment')
				->add($detail['stk_code'], 'stk_code')
				->add($detail['description'], 'description')
				->add($detail['unit_price'], 'unit_price', false)
				->add($detail['discount_percent'], 'discount_percent', false);

		foreach($splits as $split) {
			$set = new SqlSet($common_set);
			$set->addDate($split->start_date, 'hold_until_date')
				->addDate($split->end_date, 'expiry_date')
				->add($split->quantity, 'quantity', false);
	display_warning($set->toString());
		db_query("INSERT INTO ".TB_PREF."sales_order_details
							SET {$set->toString()}"
						 ,"Problem spliting order details $detail_id");
		}

		return true;
		

	}

}
?>