<?php
declare(strict_types = 1);
/**
 * TransactionMatcher.php
 * Copyright (C) 2016 Robert Horlings
 *
 * This software may be modified and distributed under the terms
 * of the MIT license.  See the LICENSE file for details.
 */

namespace FireflyIII\Rules;

use FireflyIII\Models\Rule;
use FireflyIII\Models\TransactionType;
use FireflyIII\Repositories\Journal\JournalRepositoryInterface;

/**
 * Class TransactionMatcher is used to find a list of
 * transaction matching a set of triggers
 *
 * @package FireflyIII\Rules
 */
class TransactionMatcher
{
    /** @var int Maximum number of transaction to search in (for performance reasons) * */
    private $range = 200;
    /** @var int */
    private $limit = 10;

    /** @var array */
    protected $transactionTypes = [TransactionType::DEPOSIT, TransactionType::WITHDRAWAL, TransactionType::TRANSFER];
    /** @var array List of triggers to match */
    protected $triggers = [];

    /**
     * Find matching transactions for the current set of triggers
     *
     * @param int $maxResults The maximum number of transactions returned
     *
     * @return array
     */
    public function findMatchingTransactions($maxResults = 50)
    {
        /** @var JournalRepositoryInterface $repository */
        $repository = app('FireflyIII\Repositories\Journal\JournalRepositoryInterface');

        // We don't know the number of transaction to fetch from the database, in
        // order to return the proper number of matching transactions. Since we don't want
        // to fetch all transactions (as the first transactions already match, or the last
        // transactions are irrelevant), we will fetch data in pages.

        // The optimal pagesize is somewhere between the maximum number of results to be returned
        // and the maximum number of transactions to consider.
        $pagesize = min($this->range / 2, $maxResults * 2);

        // Variables used within the loop
        $numTransactionsProcessed = 0;
        $page                     = 1;
        $matchingTransactions     = [];

        // Flags to indicate the end of the loop
        $reachedEndOfList           = false;
        $foundEnoughTransactions    = false;
        $searchedEnoughTransactions = false;

        // Start a loop to fetch batches of transactions. The loop will finish if:
        //   - all transactions have been fetched from the database
        //   - the maximum number of transactions to return has been found
        //   - the maximum number of transactions to search in have been searched 
        do {
            // Fetch a batch of transactions from the database
            $offset       = $page > 0 ? ($page - 1) * $pagesize : 0;
            $transactions = $repository->getJournalsOfTypes($this->transactionTypes, $offset, $page, $pagesize)->getCollection()->all();

            // Filter transactions that match the rule
            $matchingTransactions += array_filter(
                $transactions, function ($transaction) {
                $processor = new Processor(new Rule, $transaction);

                return $processor->isTriggeredBy($this->triggers);
            }
            );

            // Update counters
            $page++;
            $numTransactionsProcessed += count($transactions);

            // Check for conditions to finish the loop
            $reachedEndOfList           = (count($transactions) < $pagesize);
            $foundEnoughTransactions    = (count($matchingTransactions) >= $maxResults);
            $searchedEnoughTransactions = ($numTransactionsProcessed >= $this->range);
        } while (!$reachedEndOfList && !$foundEnoughTransactions && !$searchedEnoughTransactions);

        // If the list of matchingTransactions is larger than the maximum number of results
        // (e.g. if a large percentage of the transactions match), truncate the list
        $matchingTransactions = array_slice($matchingTransactions, 0, $maxResults);

        return $matchingTransactions;
    }

    /**
     * @return array
     */
    public function getTransactionLimit()
    {
        return $this->range;
    }

    /**
     * @return array
     */
    public function getTransactionTypes()
    {
        return $this->transactionTypes;
    }

    /**
     * @param array $transactionTypes
     *
     * @return $this
     */
    public function setTransactionTypes(array $transactionTypes)
    {
        $this->transactionTypes = $transactionTypes;

        return $this;
    }

    /**
     * @return array
     */
    public function getTriggers()
    {
        return $this->triggers;
    }

    /**
     * @param array $triggers
     *
     * @return $this
     */
    public function setTriggers($triggers)
    {
        $this->triggers = $triggers;

        return $this;
    }

    /**
     * @param int $limit
     *
     * @return $this
     */
    public function setTransactionLimit(int $limit)
    {
        $this->range = $limit;

        return $this;
    }

}