<?php
/**
 * GroupCollector.php
 * Copyright (c) 2019 thegrumpydictator@gmail.com
 *
 * This file is part of Firefly III.
 *
 * Firefly III is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Firefly III is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Firefly III. If not, see <http://www.gnu.org/licenses/>.
 */

declare(strict_types=1);

namespace FireflyIII\Helpers\Collector;

use Carbon\Carbon;
use Carbon\Exceptions\InvalidDateException;
use Exception;
use FireflyIII\Models\Bill;
use FireflyIII\Models\Budget;
use FireflyIII\Models\Category;
use FireflyIII\Models\Tag;
use FireflyIII\Models\TransactionCurrency;
use FireflyIII\Models\TransactionGroup;
use FireflyIII\User;
use Illuminate\Database\Eloquent\Builder as EloquentBuilder;
use Illuminate\Database\Eloquent\Relations\HasMany;
use Illuminate\Database\Query\JoinClause;
use Illuminate\Pagination\LengthAwarePaginator;
use Illuminate\Support\Collection;
use Log;

/**
 * Class GroupCollector
 */
class GroupCollector implements GroupCollectorInterface
{
    /** @var array The accounts to filter on. Asset accounts or liabilities. */
    private $accountIds;
    /** @var array The standard fields to select. */
    private $fields;
    /** @var bool Will be set to true if query result contains account information. (see function withAccountInformation). */
    private $hasAccountInformation;
    /** @var bool Will be true if query result includes bill information. */
    private $hasBillInformation;
    /** @var bool Will be true if query result contains budget info. */
    private $hasBudgetInformation;
    /** @var bool Will be true if query result contains category info. */
    private $hasCatInformation;
    /** @var bool Will be true of the query has the tag info tables joined. */
    private $hasJoinedTagTables;
    /** @var int The maximum number of results. */
    private $limit;
    /** @var int The page to return. */
    private $page;
    /** @var HasMany The query object. */
    private $query;
    /** @var int Total number of results. */
    private $total;
    /** @var User The user object. */
    private $user;

    /**
     * Group collector constructor.
     */
    public function __construct()
    {
        if ('testing' === config('app.env')) {
            app('log')->warning(sprintf('%s should not be instantiated in the TEST environment!', get_class($this)));
        }
        $this->hasAccountInformation = false;
        $this->hasCatInformation     = false;
        $this->hasBudgetInformation  = false;
        $this->hasBillInformation    = false;
        $this->hasJoinedTagTables    = false;

        $this->total  = 0;
        $this->limit  = 50;
        $this->page   = 0;
        $this->fields = [
            # group
            'transaction_groups.id as transaction_group_id',
            'transaction_groups.user_id as user_id',
            'transaction_groups.created_at as created_at',
            'transaction_groups.updated_at as updated_at',
            'transaction_groups.title as transaction_group_title',

            # journal
            'transaction_journals.id as transaction_journal_id',
            'transaction_journals.transaction_type_id',
            'transaction_types.type as transaction_type_type',
            'transaction_journals.description',
            'transaction_journals.date',
            'transaction_journals.order',

            # source info (always present)
            'source.id as source_transaction_id',
            'source.account_id as source_account_id',
            'source.reconciled',

            # currency info:
            'source.amount as amount',
            'source.transaction_currency_id as currency_id',
            'currency.code as currency_code',
            'currency.name as currency_name',
            'currency.symbol as currency_symbol',
            'currency.decimal_places as currency_decimal_places',

            # foreign currency info
            'source.foreign_amount as foreign_amount',
            'source.foreign_currency_id as foreign_currency_id',
            'foreign_currency.code as foreign_currency_code',
            'foreign_currency.symbol as foreign_currency_symbol',
            'foreign_currency.decimal_places as foreign_currency_decimal_places',

            # destination account info (always present)
            #'destination.id as destination_transaction_id', // not interesting.
            'destination.account_id as destination_account_id',
        ];
    }

    /**
     * Same as getGroups but everything is in a paginator.
     *
     * @return LengthAwarePaginator
     */
    public function getPaginatedGroups(): LengthAwarePaginator
    {
        $set = $this->getGroups();

        return new LengthAwarePaginator($set, $this->total, $this->limit, $this->page);
    }

    /**
     * Return the groups.
     *
     * @return Collection
     */
    public function getGroups(): Collection
    {
        /** @var Collection $result */
        $result = $this->query->get($this->fields);

        // now to parse this into an array.
        $collection  = $this->parseArray($result);
        $this->total = $collection->count();

        // now filter the array according to the page and the
        $offset = $this->page * $this->limit;

        return $collection->slice($offset, $this->limit);

    }

    /**
     * Define which accounts can be part of the source and destination transactions.
     *
     * @param Collection $accounts
     *
     * @return GroupCollectorInterface
     */
    public function setAccounts(Collection $accounts): GroupCollectorInterface
    {
        if ($accounts->count() > 0) {
            $accountIds = $accounts->pluck('id')->toArray();
            $this->query->where(
                function (EloquentBuilder $query) use ($accountIds) {
                    $query->whereIn('source.account_id', $accountIds);
                    $query->orWhereIn('destination.account_id', $accountIds);
                }
            );
            app('log')->debug(sprintf('GroupCollector: setAccounts: %s', implode(', ', $accountIds)));
            $this->accountIds = $accountIds;
        }

        return $this;
    }

    /**
     * Limit the search to a specific bill.
     *
     * @param Bill $bill
     *
     * @return GroupCollectorInterface
     */
    public function setBill(Bill $bill): GroupCollectorInterface
    {
        $this->withBillInformation();
        $this->query->where('transaction_journals.bill_id', '=', $bill->id);

        return $this;
    }

    /**
     * Will include bill name + ID, if any.
     *
     * @return GroupCollectorInterface
     */
    public function withBillInformation(): GroupCollectorInterface
    {
        if (false === $this->hasBillInformation) {
            // join bill table
            $this->query->leftJoin('bills', 'bills.id', '=', 'transaction_journals.bill_id');
            // add fields
            $this->fields[]           = 'bills.id as bill_id';
            $this->fields[]           = 'bills.name as bill_name';
            $this->hasBillInformation = true;
        }

        return $this;
    }

    /**
     * Limit the search to a specific budget.
     *
     * @param Budget $budget
     *
     * @return GroupCollectorInterface
     */
    public function setBudget(Budget $budget): GroupCollectorInterface
    {
        $this->withBudgetInformation();
        $this->query->where('budgets.id', $budget->id);

        return $this;
    }

    /**
     * Will include budget ID + name, if any.
     *
     * @return GroupCollectorInterface
     */
    public function withBudgetInformation(): GroupCollectorInterface
    {
        if (false === $this->hasBudgetInformation) {
            // join link table
            $this->query->leftJoin('budget_transaction_journal', 'budget_transaction_journal.transaction_journal_id', '=', 'transaction_journals.id');
            // join cat table
            $this->query->leftJoin('budgets', 'budget_transaction_journal.budget_id', '=', 'budgets.id');
            // add fields
            $this->fields[]             = 'budgets.id as budget_id';
            $this->fields[]             = 'budgets.name as budget_name';
            $this->hasBudgetInformation = true;
        }

        return $this;
    }

    /**
     * Limit the search to a specific set of budgets.
     *
     * @param Collection $budgets
     *
     * @return GroupCollectorInterface
     */
    public function setBudgets(Collection $budgets): GroupCollectorInterface
    {
        if ($budgets->count() > 0) {
            $this->withBudgetInformation();
            $this->query->whereIn('budgets.id', $budgets->pluck('id')->toArray());
        }

        return $this;
    }

    /**
     * Limit the search to a specific category.
     *
     * @param Category $category
     *
     * @return GroupCollectorInterface
     */
    public function setCategory(Category $category): GroupCollectorInterface
    {
        $this->withCategoryInformation();
        $this->query->where('categories.id', $category->id);

        return $this;
    }

    /**
     * Will include category ID + name, if any.
     *
     * @return GroupCollectorInterface
     */
    public function withCategoryInformation(): GroupCollectorInterface
    {
        if (false === $this->hasCatInformation) {
            // join link table
            $this->query->leftJoin('category_transaction_journal', 'category_transaction_journal.transaction_journal_id', '=', 'transaction_journals.id');
            // join cat table
            $this->query->leftJoin('categories', 'category_transaction_journal.category_id', '=', 'categories.id');
            // add fields
            $this->fields[]          = 'categories.id as category_id';
            $this->fields[]          = 'categories.name as category_name';
            $this->hasCatInformation = true;
        }

        return $this;
    }

    /**
     * Limit results to a specific currency, either foreign or normal one.
     *
     * @param TransactionCurrency $currency
     *
     * @return GroupCollectorInterface
     */
    public function setCurrency(TransactionCurrency $currency): GroupCollectorInterface
    {
        $this->query->where(
            function (EloquentBuilder $q) use ($currency) {
                $q->where('source.transaction_currency_id', $currency->id);
                $q->orWhere('source.foreign_currency_id', $currency->id);
            }
        );

        return $this;
    }

    /**
     * Limit the result to a set of specific journals.
     *
     * @param array $journalIds
     *
     * @return GroupCollectorInterface
     */
    public function setJournalIds(array $journalIds): GroupCollectorInterface
    {
        if (count($journalIds) > 0) {
            $this->query->whereIn('transaction_journals.id', $journalIds);
        }

        return $this;
    }

    /**
     * Limit the number of returned entries.
     *
     * @param int $limit
     *
     * @return GroupCollectorInterface
     */
    public function setLimit(int $limit): GroupCollectorInterface
    {
        $this->limit = $limit;
        app('log')->debug(sprintf('GroupCollector: The limit is now %d', $limit));

        return $this;
    }

    /**
     * Set the page to get.
     *
     * @param int $page
     *
     * @return GroupCollectorInterface
     */
    public function setPage(int $page): GroupCollectorInterface
    {
        $page       = 0 === $page ? 0 : $page - 1;
        $this->page = $page;
        app('log')->debug(sprintf('GroupCollector: page is now %d (is minus 1)', $page));

        return $this;
    }

    /**
     * Set the start and end time of the results to return.
     *
     * @param Carbon $start
     * @param Carbon $end
     *
     * @return GroupCollectorInterface
     */
    public function setRange(Carbon $start, Carbon $end): GroupCollectorInterface
    {
        if ($end < $start) {
            [$start, $end] = [$end, $start];
        }
        $startStr = $start->format('Y-m-d H:i:s');
        $endStr   = $end->format('Y-m-d H:i:s');

        $this->query->where('transaction_journals.date', '>=', $startStr);
        $this->query->where('transaction_journals.date', '<=', $endStr);
        app('log')->debug(sprintf('GroupCollector range is now %s - %s (inclusive)', $startStr, $endStr));

        return $this;
    }

    /**
     * Limit results to a specific tag.
     *
     * @param Tag $tag
     *
     * @return GroupCollectorInterface
     */
    public function setTag(Tag $tag): GroupCollectorInterface
    {
        $this->joinTagTables();
        $this->query->where('tag_transaction_journal.tag_id', $tag->id);

        return $this;
    }

    /**
     * Limit the search to one specific transaction group.
     *
     * @param TransactionGroup $transactionGroup
     *
     * @return GroupCollectorInterface
     */
    public function setTransactionGroup(TransactionGroup $transactionGroup): GroupCollectorInterface
    {
        $this->query->where('transaction_groups.id', $transactionGroup->id);

        return $this;
    }

    /**
     * Limit the included transaction types.
     *
     * @param array $types
     *
     * @return GroupCollectorInterface
     */
    public function setTypes(array $types): GroupCollectorInterface
    {
        $this->query->whereIn('transaction_types.type', $types);

        return $this;
    }

    /**
     * Set the user object and start the query.
     *
     * @param User $user
     *
     * @return GroupCollectorInterface
     */
    public function setUser(User $user): GroupCollectorInterface
    {
        $this->user = $user;
        $this->startQuery();

        return $this;
    }

    /**
     * Automatically include all stuff required to make API calls work.
     *
     * @return GroupCollectorInterface
     */
    public function withAPIInformation(): GroupCollectorInterface
    {
        // include source + destination account name and type.
        $this->withAccountInformation()
            // include category ID + name (if any)
             ->withCategoryInformation()
            // include budget ID + name (if any)
             ->withBudgetInformation()
            // include bill ID + name (if any)
             ->withBillInformation();

        return $this;
    }

    /**
     * Will include the source and destination account names and types.
     *
     * @return GroupCollectorInterface
     */
    public function withAccountInformation(): GroupCollectorInterface
    {
        if (false === $this->hasAccountInformation) {
            // join source account table
            $this->query->leftJoin('accounts as source_account', 'source_account.id', '=', 'source.account_id');
            // join source account type table
            $this->query->leftJoin('account_types as source_account_type', 'source_account_type.id', '=', 'source_account.account_type_id');

            // add source account fields:
            $this->fields[] = 'source_account.name as source_account_name';
            $this->fields[] = 'source_account.iban as source_account_iban';
            $this->fields[] = 'source_account_type.type as source_account_type';

            // same for dest
            $this->query->leftJoin('accounts as dest_account', 'dest_account.id', '=', 'destination.account_id');
            $this->query->leftJoin('account_types as dest_account_type', 'dest_account_type.id', '=', 'dest_account.account_type_id');

            // and add fields:
            $this->fields[] = 'dest_account.name as destination_account_name';
            $this->fields[] = 'dest_account.iban as destination_account_iban';
            $this->fields[] = 'dest_account_type.type as destination_account_type';


            $this->hasAccountInformation = true;
        }

        return $this;
    }

    /**
     * Limit the search to a specific bunch of categories.
     *
     * @param Collection $categories
     *
     * @return GroupCollectorInterface
     */
    public function setCategories(Collection $categories): GroupCollectorInterface
    {
        if ($categories->count() > 0) {
            $this->withCategoryInformation();
            $this->query->whereIn('categories.id', $categories->pluck('id')->toArray());
        }

        return $this;
    }

    /**
     * Limit results to a specific set of tags.
     *
     * @param Collection $tags
     *
     * @return GroupCollectorInterface
     */
    public function setTags(Collection $tags): GroupCollectorInterface
    {
        $this->joinTagTables();
        $this->query->whereIn('tag_transaction_journal.tag_id', $tags->pluck('id')->toArray());

        return $this;
    }

    /**
     * Limit results to a transactions without a budget..
     *
     * @return GroupCollectorInterface
     */
    public function withoutBudget(): GroupCollectorInterface
    {
        $this->withBudgetInformation();
        $this->query->where(
            function (EloquentBuilder $q) {
                $q->whereNull('budget_transaction_journal.budget_id');
            }
        );

        return $this;
    }

    /**
     * Limit results to a transactions without a category.
     *
     * @return GroupCollectorInterface
     */
    public function withoutCategory(): GroupCollectorInterface
    {
        $this->withCategoryInformation();
        $this->query->where(
            function (EloquentBuilder $q) {
                $q->whereNull('category_transaction_journal.category_id');
            }
        );

        return $this;
    }

    /**
     *
     */
    public function dumpQuery(): void
    {

        echo $this->query->toSql();
        echo '<pre>';
        print_r($this->query->getBindings());
        echo '</pre>';
    }

    /**
     * Return the sum of all journals.
     *
     * @return string
     */
    public function getSum(): string
    {
        $journals = $this->getExtractedJournals();
        $sum      = '0';
        /** @var array $journal */
        foreach ($journals as $journal) {
            $amount = (string)$journal['amount'];
            $sum    = bcadd($sum, $amount);
        }

        return $sum;
    }

    /**
     * Return the transaction journals without group information. Is useful in some instances.
     *
     * @return array
     */
    public function getExtractedJournals(): array
    {
        $selection = $this->getGroups();
        $return    = [];
        /** @var array $group */
        foreach ($selection as $group) {
            foreach ($group['transactions'] as $journalId => $journal) {
                $journal['group_title'] = $group['title'];
                $return[$journalId]     = $journal;
            }
        }

        return $return;
    }

    /**
     * Search for words in descriptions.
     *
     * @param array $array
     *
     * @return GroupCollectorInterface
     */
    public function setSearchWords(array $array): GroupCollectorInterface
    {
        $this->query->where(
            function (EloquentBuilder $q) use ($array) {
                $q->where(
                    function (EloquentBuilder $q1) use ($array) {
                        foreach ($array as $word) {
                            $keyword = sprintf('%%%s%%', $word);
                            $q1->where('transaction_journals.description', 'LIKE', $keyword);
                        }
                    }
                );
                $q->orWhere(
                    function (EloquentBuilder $q2) use ($array) {
                        foreach ($array as $word) {
                            $keyword = sprintf('%%%s%%', $word);
                            $q2->where('transaction_groups.title', 'LIKE', $keyword);
                        }
                    }
                );
            }
        );

        return $this;
    }

    /**
     * Limit the result to a specific transaction group.
     *
     * @param TransactionGroup $transactionGroup
     *
     * @return GroupCollectorInterface
     */
    public function setGroup(TransactionGroup $transactionGroup): GroupCollectorInterface
    {
        $this->query->where('transaction_groups.id', $transactionGroup->id);

        return $this;
    }

    /**
     * Limit the search to a specific set of bills.
     *
     * @param Collection $bills
     *
     * @return GroupCollectorInterface
     */
    public function setBills(Collection $bills): GroupCollectorInterface
    {
        $this->withBillInformation();
        $this->query->whereIn('transaction_journals.bill_id', $bills->pluck('id')->toArray());

        return $this;
    }

    /**
     * Get transactions with a specific amount.
     *
     * @param string $amount
     *
     * @return GroupCollectorInterface
     */
    public function amountIs(string $amount): GroupCollectorInterface
    {
        $this->query->where(
            function (EloquentBuilder $q) use ($amount) {
                $q->where('source.amount', app('steam')->negative($amount));
            }
        );

        return $this;
    }

    /**
     * Get transactions where the amount is less than.
     *
     * @param string $amount
     *
     * @return GroupCollectorInterface
     */
    public function amountLess(string $amount): GroupCollectorInterface
    {
        $this->query->where(
            function (EloquentBuilder $q) use ($amount) {
                $q->where('destination.amount', '<', app('steam')->positive($amount));
            }
        );

        return $this;
    }

    /**
     * Get transactions where the amount is more than.
     *
     * @param string $amount
     *
     * @return GroupCollectorInterface
     */
    public function amountMore(string $amount): GroupCollectorInterface
    {
        $this->query->where(
            function (EloquentBuilder $q) use ($amount) {
                $q->where('destination.amount', '>', app('steam')->positive($amount));
            }
        );

        return $this;
    }

    /**
     * Collect transactions before a specific date.
     *
     * @param Carbon $date
     *
     * @return GroupCollectorInterface
     */
    public function setBefore(Carbon $date): GroupCollectorInterface
    {
        $beforeStr = $date->format('Y-m-d 00:00:00');
        $this->query->where('transaction_journals.date', '<=', $beforeStr);
        Log::debug(sprintf('GroupCollector range is now before %s (inclusive)', $beforeStr));

        return $this;
    }

    /**
     * Collect transactions after a specific date.
     *
     * @param Carbon $date
     *
     * @return GroupCollectorInterface
     */
    public function setAfter(Carbon $date): GroupCollectorInterface
    {
        $afterStr = $date->format('Y-m-d 00:00:00');
        $this->query->where('transaction_journals.date', '>=', $afterStr);
        Log::debug(sprintf('GroupCollector range is now after %s (inclusive)', $afterStr));

        return $this;
    }

    /**
     * @param Collection $collection
     *
     * @return Collection
     * @throws Exception
     */
    private function parseArray(Collection $collection): Collection
    {
        $groups = [];
        /** @var TransactionGroup $augmentedGroup */
        foreach ($collection as $augmentedGroup) {
            $groupId = $augmentedGroup->transaction_group_id;
            if (!isset($groups[$groupId])) {
                // make new array
                $groupArray                             = [
                    'id'           => $augmentedGroup->transaction_group_id,
                    'user_id'      => $augmentedGroup->user_id,
                    'title'        => $augmentedGroup->transaction_group_title,
                    'count'        => 1,
                    'sums'         => [],
                    'transactions' => [],
                ];
                $journalId                              = (int)$augmentedGroup->transaction_journal_id;
                $groupArray['transactions'][$journalId] = $this->parseAugmentedGroup($augmentedGroup);
                $groups[$groupId]                       = $groupArray;
                continue;
            }
            // or parse the rest.
            $journalId = (int)$augmentedGroup->transaction_journal_id;
            $groups[$groupId]['count']++;

            if (isset($groups[$groupId]['transactions'][$journalId])) {
                $groups[$groupId]['transactions'][$journalId] =
                    $this->mergeTags($groups[$groupId]['transactions'][$journalId], $augmentedGroup);
            }

            if (!isset($groups[$groupId]['transactions'][$journalId])) {
                $groups[$groupId]['transactions'][$journalId] = $this->parseAugmentedGroup($augmentedGroup);
            }

        }
        $groups = $this->parseSums($groups);

        return new Collection($groups);
    }

    /**
     * @param TransactionGroup $augmentedGroup
     *
     * @return array
     * @throws Exception
     */
    private function parseAugmentedGroup(TransactionGroup $augmentedGroup): array
    {
        $result               = $augmentedGroup->toArray();
        $result['tags']       = [];
        $result['date']       = new Carbon($result['date']);
        $result['created_at'] = new Carbon($result['created_at']);
        $result['updated_at'] = new Carbon($result['updated_at']);
        $result['reconciled'] = 1 === (int)$result['reconciled'];
        if (isset($augmentedGroup['tag_id'])) { // assume the other fields are present as well.
            $tagId   = (int)$augmentedGroup['tag_id'];
            $tagDate = null;
            try {
                $tagDate = Carbon::parse($augmentedGroup['tag_date']);
            } catch (InvalidDateException $e) {
                Log::debug(sprintf('Could not parse date: %s', $e->getMessage()));
            }

            $result['tags'][$tagId] = [
                'id'          => (int)$result['tag_id'],
                'name'        => $result['tag_name'],
                'date'        => $tagDate,
                'description' => $result['tag_description'],
                'latitude'    => $result['tag_latitude'],
                'longitude'   => $result['tag_longitude'],
                'zoom_level'  => $result['tag_zoom_level'],
            ];
        }

        return $result;
    }

    /**
     * @param array $existingJournal
     * @param TransactionGroup $newGroup
     * @return array
     */
    private function mergeTags(array $existingJournal, TransactionGroup $newGroup): array
    {
        $newArray = $newGroup->toArray();
        if (isset($newArray['tag_id'])) { // assume the other fields are present as well.
            $tagId = (int)$newGroup['tag_id'];

            $tagDate = null;
            try {
                $tagDate = Carbon::parse($newArray['tag_date']);
            } catch (InvalidDateException $e) {
                Log::debug(sprintf('Could not parse date: %s', $e->getMessage()));
            }

            $existingJournal['tags'][$tagId] = [
                'id'          => (int)$newArray['tag_id'],
                'name'        => $newArray['tag_name'],
                'date'        => $tagDate,
                'description' => $newArray['tag_description'],
                'latitude'    => $newArray['tag_latitude'],
                'longitude'   => $newArray['tag_longitude'],
                'zoom_level'  => $newArray['tag_zoom_level'],
            ];
        }

        return $existingJournal;
    }

    /**
     * @param array $groups
     *
     * @return array
     */
    private function parseSums(array $groups): array
    {
        /**
         * @var int $groudId
         * @var array $group
         */
        foreach ($groups as $groudId => $group) {
            /** @var array $transaction */
            foreach ($group['transactions'] as $transaction) {
                $currencyId = (int)$transaction['currency_id'];

                // set default:
                if (!isset($groups[$groudId]['sums'][$currencyId])) {
                    $groups[$groudId]['sums'][$currencyId]['currency_id']             = $currencyId;
                    $groups[$groudId]['sums'][$currencyId]['currency_code']           = $transaction['currency_code'];
                    $groups[$groudId]['sums'][$currencyId]['currency_symbol']         = $transaction['currency_symbol'];
                    $groups[$groudId]['sums'][$currencyId]['currency_decimal_places'] = $transaction['currency_decimal_places'];
                    $groups[$groudId]['sums'][$currencyId]['amount']                  = '0';
                }
                $groups[$groudId]['sums'][$currencyId]['amount'] = bcadd($groups[$groudId]['sums'][$currencyId]['amount'], $transaction['amount']);

                if (null !== $transaction['foreign_amount'] && null !== $transaction['foreign_currency_id']) {
                    $currencyId = (int)$transaction['foreign_currency_id'];

                    // set default:
                    if (!isset($groups[$groudId]['sums'][$currencyId])) {
                        $groups[$groudId]['sums'][$currencyId]['currency_id']             = $currencyId;
                        $groups[$groudId]['sums'][$currencyId]['currency_code']           = $transaction['foreign_currency_code'];
                        $groups[$groudId]['sums'][$currencyId]['currency_symbol']         = $transaction['foreign_currency_symbol'];
                        $groups[$groudId]['sums'][$currencyId]['currency_decimal_places'] = $transaction['foreign_currency_decimal_places'];
                        $groups[$groudId]['sums'][$currencyId]['amount']                  = '0';
                    }
                    $groups[$groudId]['sums'][$currencyId]['amount'] = bcadd($groups[$groudId]['sums'][$currencyId]['amount'], $transaction['foreign_amount']);
                }
            }
        }

        return $groups;
    }

    /**
     * Join table to get tag information.
     */
    private function joinTagTables(): void
    {
        if (false === $this->hasJoinedTagTables) {
            // join some extra tables:
            $this->hasJoinedTagTables = true;
            $this->query->leftJoin('tag_transaction_journal', 'tag_transaction_journal.transaction_journal_id', '=', 'transaction_journals.id');
            $this->query->leftJoin('tags', 'tag_transaction_journal.tag_id', '=', 'tags.id');
            $this->fields[] = 'tags.id as tag_id';
            $this->fields[] = 'tags.tag as tag_name';
            $this->fields[] = 'tags.date as tag_date';
            $this->fields[] = 'tags.description as tag_description';
            $this->fields[] = 'tags.latitude as tag_latitude';
            $this->fields[] = 'tags.longitude as tag_longitude';
            $this->fields[] = 'tags.zoomLevel as tag_zoom_level';
        }
    }

    /**
     * Build the query.
     */
    private function startQuery(): void
    {
        app('log')->debug('GroupCollector::startQuery');
        $this->query = $this->user
            ->transactionGroups()
            ->leftJoin('transaction_journals', 'transaction_journals.transaction_group_id', 'transaction_groups.id')
            // join source transaction.
            ->leftJoin(
                'transactions as source', function (JoinClause $join) {
                $join->on('source.transaction_journal_id', '=', 'transaction_journals.id')
                     ->where('source.amount', '<', 0);
            }
            )
            // join destination transaction
            ->leftJoin(
                'transactions as destination', function (JoinClause $join) {
                $join->on('destination.transaction_journal_id', '=', 'transaction_journals.id')
                     ->where('destination.amount', '>', 0);
            }
            )
            // left join transaction type.
            ->leftJoin('transaction_types', 'transaction_types.id', '=', 'transaction_journals.transaction_type_id')
            ->leftJoin('transaction_currencies as currency', 'currency.id', '=', 'source.transaction_currency_id')
            ->leftJoin('transaction_currencies as foreign_currency', 'foreign_currency.id', '=', 'source.foreign_currency_id')
            ->whereNull('transaction_groups.deleted_at')
            ->whereNull('transaction_journals.deleted_at')
            ->whereNull('source.deleted_at')
            ->whereNull('destination.deleted_at')
            ->orderBy('transaction_journals.date', 'DESC')
            ->orderBy('transaction_journals.order', 'ASC')
            ->orderBy('transaction_journals.id', 'DESC')
            ->orderBy('transaction_journals.description', 'DESC')
            ->orderBy('source.amount', 'DESC');
    }
}