jakub41/lunch-calculator-php

Lunch Calculator PHP

How It's Working

Class Calculator

Serves data, in which will be need in the class properties. We have 4 properties in class. In the 3 of them we keep our incoming data(as array of strings) in several structures before giving output.

Proprieties

• $bill: private array, where we keep incoming string as arrays of BillingItem Class:

    [0]=>{
  		object(BillItem) (3) {
    		["price"]=>
    			float
          	["paid_by"]=>
    			string
    		["attendees"]=> array{
    		[0] => 
    			string
    	}
    }
  

• $byLines: private array, where we keep data from $bills @prop as each line of incoming array as one array with counted debt of that line like:

    array(count of incoming lines) {
    	[first line]=>
    		array(1) {
    				[creditor]=>
    					array(1) {
  						[debtor]=>
  							float(debt to creditor)
    		   			    }
         				}
  

• $linedByBills: private array, where we keep data from @prop $byLines for printing it in the methods printBill and printOptimizedBill. In this @param we keep data structured like:

    array(1) {
    		[debtor]=>
    			array(1) {
    					[creditor]=>
    						float(debt)
    				    } 
    			}
  

• $calculate: method calculate must called just once. this @prop keeping (float) 1(calculate was called) or 0(calculate didn't called)

Methods

• __construct: constructor of class. Taking array of string and, and using BillItem Class serving data in @param $bills.

• calculate: private method. Main function for getting data from @prop $bills giving the output to methods printBill and printOptimizedBill. Useing @props $calculate, $bills, $byLines, Returning @props $linedByBills. Using helper methods calculateLines, createExcel, findCurrentDebt.

• calculateLines: private method. Getting from @prop $bills arrays one by one from loop of method calculate. Counting debt (how much must pay person to creditor) by everybody of one line(day), then deleting the debd of creditor from common price(creditor name is mentioned twice or more: as creditor and as debtor(s)). If person(not creditor) is in the array twice(was invited somebody) then his debt = debt * 2. return the counted array of that line (day).

• createExcel: calling from method calculate. Getting @param (array) $byLines, slicing from end of @param array by array and comparing sliced with first one using method compare_array_keys. If keys same, summing sliced array with first, if not, then adding sliced array as first array to local @var $end_result. Finish output is adding @var $end_result to @prop $byLines.

• compare_array_keys: used in loop. getting to array from method createExcel and returning (bool) true, if will be same keys in 2 array, and (bool) false, if there wouldn't same key.

• sum_array_values: used in loop. getting 2 arrays. checking if keys are same, then summing matched values. return one array summed from 2 ones.

• findCurrentDebt: calling from method calculate in the loop. taking last array from @prop $byLines and making its count smaller by finding repeating creditors as array key and summing its values(debtors, debt). using method sumDebt to make sum. At finish we get clear @prop $byLines with only one creditor with his debtors and them debt to creditor

• sumDebt : getting @params $mainCreditor, $increasedDebtors, $otherCreditors, subtract values(finding and decreasing debt of creditors) and giving them to method createAsNeed to make end array comparablele with the exist method printBill.

• createAsNeed: getting @params from and changing structure of @prop linedByBills for using it in the exist method printBill.

• printBill: public method. Print the each array which get from method calculate as string.

• printOptimizedBill: public method. Is using method checkSame. Print array, which was optimised(counted and deleted all debts, which may repeated like: debtor has debt to person1, debtor has debt to creditor, creditor has debt to person1) as string.

• checkSame: getting @params $mainDebtor, $debtor, $mainCreditors, $creditors from method printOptimizedBill. If finding two arrays(lines with debtors, creditors and debt) which can be optimised, then adding them as first array of @param linedByBills.