<?php
require_once($path_to_root.'/'.'includes/date_functions.inc');
class Split {
	public $start_date;
	public $end_date;

	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 $quantity_max;

	public function __construct(array $data) {
		$this->details_id = array();
		foreach($data['detail'] as $detail_id => $detail) {
			array_push($this->details_id, $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');
	}

	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() {
		foreach($this->detail_ids as $detail_id) {
				$detail = $this->loadDetail($detail_id);
				$splits = $this->split($detail);
				$this->saveSplits($detail, $splits);
		}
	}

	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
 */
	protected function split($row) {
		$splits = array();
		$quantity = $row['quantity'];
		$quantity_sent = $row['qty_sent'];

		if($quantity >= $quantity_sent) return;
		if(($quantity-$quantity_sent) % $this->max_quantity < $this->max_quantity) return;
		
		// determine the number of split needed. This will give us the lenght of a split.
		$nsplit = ceiling($initial_quantity/$this->max_quantity);
		if($nsplit == 1) return;

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

		array_push($splits, $split = new Split($start_date, $period));
		$split_quantity = min($quantity, $this->max_quantity);
		while($split_quantity > 0) {
					$split->quantity += $split_quantity;
				// Check if the split has been entirely dispatch or not.
				if($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_dispatched = 0; // we don't need to check anymore.
					
				}
				$quantity -= $split_quantity;
				$split_quantity = min($quantity, $this->max_quantity);
		}

		return $splits;
	}

}
?>