diff --git a/app/Helpers/Report/ReportHelper.php b/app/Helpers/Report/ReportHelper.php
index 43349c78a1..22765419d5 100644
--- a/app/Helpers/Report/ReportHelper.php
+++ b/app/Helpers/Report/ReportHelper.php
@@ -61,9 +61,13 @@ class ReportHelper implements ReportHelperInterface
          */
         /** @var \FireflyIII\Repositories\Category\CategoryRepositoryInterface $repository */
         $repository = app('FireflyIII\Repositories\Category\CategoryRepositoryInterface');
+
+        /** @var \FireflyIII\Repositories\Category\SingleCategoryRepositoryInterface $singleRepository */
+        $singleRepository = app('FireflyIII\Repositories\Category\SingleCategoryRepositoryInterface');
+
         $set        = $repository->getCategories();
         foreach ($set as $category) {
-            $spent           = $repository->balanceInPeriod($category, $start, $end, $accounts);
+            $spent           = $singleRepository->balanceInPeriod($category, $start, $end, $accounts);
             $category->spent = $spent;
             $object->addCategory($category);
         }
diff --git a/app/Http/Controllers/CategoryController.php b/app/Http/Controllers/CategoryController.php
index 04ef878492..d878afa9aa 100644
--- a/app/Http/Controllers/CategoryController.php
+++ b/app/Http/Controllers/CategoryController.php
@@ -5,6 +5,7 @@ use Carbon\Carbon;
 use FireflyIII\Http\Requests\CategoryFormRequest;
 use FireflyIII\Models\Category;
 use FireflyIII\Repositories\Category\CategoryRepositoryInterface;
+use FireflyIII\Repositories\Category\SingleCategoryRepositoryInterface;
 use FireflyIII\Support\CacheProperties;
 use Illuminate\Pagination\LengthAwarePaginator;
 use Illuminate\Support\Collection;
@@ -68,12 +69,12 @@ class CategoryController extends Controller
     }
 
     /**
-     * @param CategoryRepositoryInterface $repository
-     * @param Category                    $category
+     * @param SingleCategoryRepositoryInterface $repository
+     * @param Category                          $category
      *
      * @return \Illuminate\Http\RedirectResponse
      */
-    public function destroy(CategoryRepositoryInterface $repository, Category $category)
+    public function destroy(SingleCategoryRepositoryInterface $repository, Category $category)
     {
 
         $name = $category->name;
@@ -107,17 +108,18 @@ class CategoryController extends Controller
     }
 
     /**
-     * @param CategoryRepositoryInterface $repository
+     * @param CategoryRepositoryInterface       $repository
+     * @param SingleCategoryRepositoryInterface $singleRepository
      *
      * @return \Illuminate\View\View
      */
-    public function index(CategoryRepositoryInterface $repository)
+    public function index(CategoryRepositoryInterface $repository, SingleCategoryRepositoryInterface $singleRepository)
     {
         $categories = $repository->getCategories();
 
         $categories->each(
-            function (Category $category) use ($repository) {
-                $category->lastActivity = $repository->getLatestActivity($category);
+            function (Category $category) use ($singleRepository) {
+                $category->lastActivity = $singleRepository->getLatestActivity($category);
             }
         );
 
@@ -143,14 +145,14 @@ class CategoryController extends Controller
     }
 
     /**
-     * @param CategoryRepositoryInterface $repository
+     * @param SingleCategoryRepositoryInterface $repository
      * @param Category                    $category
      *
      * @param                             $date
      *
      * @return \Illuminate\View\View
      */
-    public function showWithDate(CategoryRepositoryInterface $repository, Category $category, $date)
+    public function showWithDate(SingleCategoryRepositoryInterface $repository, Category $category, $date)
     {
         $carbon   = new Carbon($date);
         $range    = Preferences::get('viewRange', '1M')->data;
@@ -170,12 +172,12 @@ class CategoryController extends Controller
     }
 
     /**
-     * @param CategoryRepositoryInterface $repository
+     * @param SingleCategoryRepositoryInterface $repository
      * @param Category                    $category
      *
      * @return \Illuminate\View\View
      */
-    public function show(CategoryRepositoryInterface $repository, Category $category)
+    public function show(SingleCategoryRepositoryInterface $repository, Category $category)
     {
         $hideCategory = true; // used in list.
         $page         = intval(Input::get('page'));
@@ -226,11 +228,11 @@ class CategoryController extends Controller
 
     /**
      * @param CategoryFormRequest         $request
-     * @param CategoryRepositoryInterface $repository
+     * @param SingleCategoryRepositoryInterface $repository
      *
      * @return \Illuminate\Http\RedirectResponse
      */
-    public function store(CategoryFormRequest $request, CategoryRepositoryInterface $repository)
+    public function store(CategoryFormRequest $request, SingleCategoryRepositoryInterface $repository)
     {
         $categoryData = [
             'name' => $request->input('name'),
@@ -253,12 +255,12 @@ class CategoryController extends Controller
 
     /**
      * @param CategoryFormRequest         $request
-     * @param CategoryRepositoryInterface $repository
+     * @param SingleCategoryRepositoryInterface $repository
      * @param Category                    $category
      *
      * @return \Illuminate\Http\RedirectResponse
      */
-    public function update(CategoryFormRequest $request, CategoryRepositoryInterface $repository, Category $category)
+    public function update(CategoryFormRequest $request, SingleCategoryRepositoryInterface $repository, Category $category)
     {
         $categoryData = [
             'name' => $request->input('name'),
diff --git a/app/Http/Controllers/Chart/CategoryController.php b/app/Http/Controllers/Chart/CategoryController.php
index 7d6a97b24a..08f5116adb 100644
--- a/app/Http/Controllers/Chart/CategoryController.php
+++ b/app/Http/Controllers/Chart/CategoryController.php
@@ -7,6 +7,7 @@ use Carbon\Carbon;
 use FireflyIII\Http\Controllers\Controller;
 use FireflyIII\Models\Category;
 use FireflyIII\Repositories\Category\CategoryRepositoryInterface;
+use FireflyIII\Repositories\Category\SingleCategoryRepositoryInterface;
 use FireflyIII\Support\CacheProperties;
 use Illuminate\Support\Collection;
 use Navigation;
@@ -38,12 +39,12 @@ class CategoryController extends Controller
     /**
      * Show an overview for a category for all time, per month/week/year.
      *
-     * @param CategoryRepositoryInterface $repository
-     * @param Category                    $category
+     * @param SingleCategoryRepositoryInterface $repository
+     * @param Category                          $category
      *
      * @return \Symfony\Component\HttpFoundation\Response
      */
-    public function all(CategoryRepositoryInterface $repository, Category $category)
+    public function all(SingleCategoryRepositoryInterface $repository, Category $category)
     {
         // oldest transaction in category:
         $start   = $repository->getFirstActivityDate($category);
@@ -137,8 +138,13 @@ class CategoryController extends Controller
      *
      * @return \Illuminate\Http\JsonResponse
      */
-    public function multiYear(CategoryRepositoryInterface $repository, $reportType, Carbon $start, Carbon $end, Collection $accounts, Collection $categories)
+    public function multiYear($reportType, Carbon $start, Carbon $end, Collection $accounts, Collection $categories)
     {
+        /** @var CategoryRepositoryInterface $repository */
+        $repository = app('FireflyIII\Repositories\Category\CategoryRepositoryInterface');
+        /** @var SingleCategoryRepositoryInterface $singleRepository */
+        $singleRepository = app('FireflyIII\Repositories\Category\SingleCategoryRepositoryInterface');
+
         // chart properties for cache:
         $cache = new CacheProperties();
         $cache->addProperty($reportType);
@@ -180,8 +186,8 @@ class CategoryController extends Controller
                     $earned = $repository->earnedNoCategoryForAccounts($accounts, $currentStart, $currentEnd);
                 } else {
                     $name   = $category->name;
-                    $spent  = $repository->spentInPeriodForAccounts($category, $accounts, $currentStart, $currentEnd);
-                    $earned = $repository->earnedInPeriodForAccounts($category, $accounts, $currentStart, $currentEnd);
+                    $spent  = $singleRepository->spentInPeriodForAccounts($category, $accounts, $currentStart, $currentEnd);
+                    $earned = $singleRepository->earnedInPeriodForAccounts($category, $accounts, $currentStart, $currentEnd);
                 }
 
                 // save to array:
@@ -206,12 +212,12 @@ class CategoryController extends Controller
     }
 
     /**
-     * @param CategoryRepositoryInterface $repository
+     * @param SingleCategoryRepositoryInterface $repository
      * @param Category                    $category
      *
      * @return \Symfony\Component\HttpFoundation\Response
      */
-    public function currentPeriod(CategoryRepositoryInterface $repository, Category $category)
+    public function currentPeriod(SingleCategoryRepositoryInterface $repository, Category $category)
     {
         $start = clone Session::get('start', Carbon::now()->startOfMonth());
         $end   = Session::get('end', Carbon::now()->endOfMonth());
@@ -246,14 +252,14 @@ class CategoryController extends Controller
     }
 
     /**
-     * @param CategoryRepositoryInterface $repository
+     * @param SingleCategoryRepositoryInterface $repository
      * @param Category                    $category
      *
      * @param                             $date
      *
      * @return \Symfony\Component\HttpFoundation\Response
      */
-    public function specificPeriod(CategoryRepositoryInterface $repository, Category $category, $date)
+    public function specificPeriod(SingleCategoryRepositoryInterface $repository, Category $category, $date)
     {
         $carbon = new Carbon($date);
         $range  = Preferences::get('viewRange', '1M')->data;
diff --git a/app/Repositories/Category/CategoryRepository.php b/app/Repositories/Category/CategoryRepository.php
index e97bcb2dff..8ccc840780 100644
--- a/app/Repositories/Category/CategoryRepository.php
+++ b/app/Repositories/Category/CategoryRepository.php
@@ -6,9 +6,7 @@ use Auth;
 use Carbon\Carbon;
 use DB;
 use FireflyIII\Models\Category;
-use FireflyIII\Models\TransactionJournal;
 use FireflyIII\Models\TransactionType;
-use FireflyIII\Repositories\Shared\ComponentRepository;
 use FireflyIII\Support\CacheProperties;
 use Illuminate\Database\Query\JoinClause;
 use Illuminate\Support\Collection;
@@ -18,32 +16,9 @@ use Illuminate\Support\Collection;
  *
  * @package FireflyIII\Repositories\Category
  */
-class CategoryRepository extends ComponentRepository implements CategoryRepositoryInterface
+class CategoryRepository implements CategoryRepositoryInterface
 {
 
-    /**
-     * @param Category $category
-     *
-     * @return int
-     */
-    public function countJournals(Category $category)
-    {
-        return $category->transactionJournals()->count();
-
-    }
-
-    /**
-     * @param Category $category
-     *
-     * @return boolean
-     */
-    public function destroy(Category $category)
-    {
-        $category->delete();
-
-        return true;
-    }
-
     /**
      * @return Collection
      */
@@ -194,62 +169,6 @@ class CategoryRepository extends ComponentRepository implements CategoryReposito
 
     }
 
-    /**
-     * @param Category $category
-     *
-     * @return Carbon
-     */
-    public function getFirstActivityDate(Category $category)
-    {
-        /** @var TransactionJournal $first */
-        $first = $category->transactionjournals()->orderBy('date', 'ASC')->first();
-        if ($first) {
-            return $first->date;
-        }
-
-        return new Carbon;
-
-    }
-
-    /**
-     * @param Category $category
-     * @param int      $page
-     *
-     * @return Collection
-     */
-    public function getJournals(Category $category, $page)
-    {
-        $offset = $page > 0 ? $page * 50 : 0;
-
-        return $category->transactionJournals()->withRelevantData()->take(50)->offset($offset)
-                        ->orderBy('transaction_journals.date', 'DESC')
-                        ->orderBy('transaction_journals.order', 'ASC')
-                        ->orderBy('transaction_journals.id', 'DESC')
-                        ->get(
-                            ['transaction_journals.*']
-                        );
-
-    }
-
-    /**
-     * @param Category $category
-     *
-     * @return Carbon|null
-     */
-    public function getLatestActivity(Category $category)
-    {
-        $latest = $category->transactionjournals()
-                           ->orderBy('transaction_journals.date', 'DESC')
-                           ->orderBy('transaction_journals.order', 'ASC')
-                           ->orderBy('transaction_journals.id', 'DESC')
-                           ->first();
-        if ($latest) {
-            return $latest->date;
-        }
-
-        return null;
-    }
-
     /**
      * @param Carbon $start
      * @param Carbon $end
@@ -270,266 +189,6 @@ class CategoryRepository extends ComponentRepository implements CategoryReposito
                    ->get(['transaction_journals.*']);
     }
 
-    /**
-     * @param Category   $category
-     * @param Carbon     $start
-     * @param Carbon     $end
-     * @param Collection $accounts
-     *
-     * @return string
-     */
-    public function balanceInPeriod(Category $category, Carbon $start, Carbon $end, Collection $accounts)
-    {
-        return $this->commonBalanceInPeriod($category, $start, $end, $accounts);
-    }
-
-    /**
-     * Corrected for tags
-     *
-     * @param Category $category
-     * @param Carbon   $date
-     *
-     * @return string
-     */
-    public function spentOnDaySum(Category $category, Carbon $date)
-    {
-        return $category->transactionjournals()->transactionTypes([TransactionType::WITHDRAWAL])->onDate($date)->get(['transaction_journals.*'])->sum('amount');
-    }
-
-    /**
-     * @param array $data
-     *
-     * @return Category
-     */
-    public function store(array $data)
-    {
-        $newCategory = new Category(
-            [
-                'user_id' => $data['user'],
-                'name'    => $data['name'],
-            ]
-        );
-        $newCategory->save();
-
-        return $newCategory;
-    }
-
-    /**
-     * @param Category $category
-     * @param array    $data
-     *
-     * @return Category
-     */
-    public function update(Category $category, array $data)
-    {
-        // update the account:
-        $category->name = $data['name'];
-        $category->save();
-
-        return $category;
-    }
-
-    /**
-     * @deprecated
-     * This method returns the sum of the journals in the category, optionally
-     * limited by a start or end date.
-     *
-     * @param Category $category
-     * @param Carbon   $start
-     * @param Carbon   $end
-     *
-     * @return string
-     */
-    public function journalsSum(Category $category, Carbon $start = null, Carbon $end = null)
-    {
-        $query = $category->transactionJournals()
-                          ->orderBy('transaction_journals.date', 'DESC')
-                          ->orderBy('transaction_journals.order', 'ASC')
-                          ->orderBy('transaction_journals.id', 'DESC');
-        if (!is_null($start)) {
-            $query->after($start);
-        }
-
-        if (!is_null($end)) {
-            $query->before($end);
-        }
-
-        return $query->get(['transaction_journals.*'])->sum('amount');
-
-    }
-
-    /**
-     * @param Category       $category
-     * @param \Carbon\Carbon $start
-     * @param \Carbon\Carbon $end
-     *
-     * @return string
-     */
-    public function spentInPeriod(Category $category, Carbon $start, Carbon $end)
-    {
-        $cache = new CacheProperties; // we must cache this.
-        $cache->addProperty($category->id);
-        $cache->addProperty($start);
-        $cache->addProperty($end);
-        $cache->addProperty('spentInPeriod');
-
-        if ($cache->has()) {
-            return $cache->get(); // @codeCoverageIgnore
-        }
-
-        $sum = $category->transactionjournals()->transactionTypes([TransactionType::WITHDRAWAL])->before($end)->after($start)->get(['transaction_journals.*'])
-                        ->sum(
-                            'amount'
-                        );
-
-        $cache->store($sum);
-
-        return $sum;
-    }
-
-    /**
-     * @param Category       $category
-     * @param \Carbon\Carbon $start
-     * @param \Carbon\Carbon $end
-     *
-     * @return string
-     */
-    public function earnedInPeriod(Category $category, Carbon $start, Carbon $end)
-    {
-        $cache = new CacheProperties; // we must cache this.
-        $cache->addProperty($category->id);
-        $cache->addProperty($start);
-        $cache->addProperty($end);
-        $cache->addProperty('earnedInPeriod');
-
-        if ($cache->has()) {
-            return $cache->get(); // @codeCoverageIgnore
-        }
-
-        $sum = $category->transactionjournals()->transactionTypes([TransactionType::DEPOSIT])->before($end)->after($start)->get(['transaction_journals.*'])
-                        ->sum(
-                            'amount'
-                        );
-
-        $cache->store($sum);
-
-        return $sum;
-    }
-
-
-    /**
-     * @param Category $category
-     * @param int      $page
-     * @param Carbon   $start
-     * @param Carbon   $end
-     *
-     * @return mixed
-     */
-    public function getJournalsInRange(Category $category, $page, Carbon $start, Carbon $end)
-    {
-        $offset = $page > 0 ? $page * 50 : 0;
-
-        return $category->transactionJournals()
-                        ->after($start)
-                        ->before($end)
-                        ->withRelevantData()->take(50)->offset($offset)
-                        ->orderBy('transaction_journals.date', 'DESC')
-                        ->orderBy('transaction_journals.order', 'ASC')
-                        ->orderBy('transaction_journals.id', 'DESC')
-                        ->get(
-                            ['transaction_journals.*']
-                        );
-    }
-
-    /**
-     * @param Category $category
-     *
-     * @param Carbon   $start
-     * @param Carbon   $end
-     *
-     * @return int
-     */
-    public function countJournalsInRange(Category $category, Carbon $start, Carbon $end)
-    {
-        return $category->transactionJournals()->before($end)->after($start)->count();
-    }
-
-    /**
-     *
-     * Corrected for tags.
-     *
-     * @param Category $category
-     * @param Carbon   $date
-     *
-     * @return float
-     */
-    public function earnedOnDaySum(Category $category, Carbon $date)
-    {
-        return $category->transactionjournals()->transactionTypes([TransactionType::DEPOSIT])->onDate($date)->get(['transaction_journals.*'])->sum('amount');
-    }
-
-    /**
-     * Calculates how much is spent in this period.
-     *
-     * @param Category   $category
-     * @param Collection $accounts
-     * @param Carbon     $start
-     * @param Carbon     $end
-     *
-     * @return string
-     */
-    public function spentInPeriodForAccounts(Category $category, Collection $accounts, Carbon $start, Carbon $end)
-    {
-        $accountIds = [];
-        foreach ($accounts as $account) {
-            $accountIds[] = $account->id;
-        }
-
-        $sum
-            = $category
-            ->transactionjournals()
-            ->leftJoin('transactions', 'transactions.transaction_journal_id', '=', 'transaction_journals.id')
-            ->after($start)
-            ->before($end)
-            ->whereIn('transactions.account_id', $accountIds)
-            ->transactionTypes([TransactionType::WITHDRAWAL])
-            ->get(['transaction_journals.*'])
-            ->sum('amount');
-
-        return $sum;
-
-    }
-
-    /**
-     * Calculate how much is earned in this period.
-     *
-     * @param Category   $category
-     * @param Collection $accounts
-     * @param Carbon     $start
-     * @param Carbon     $end
-     *
-     * @return string
-     */
-    public function earnedInPeriodForAccounts(Category $category, Collection $accounts, Carbon $start, Carbon $end)
-    {
-        $accountIds = [];
-        foreach ($accounts as $account) {
-            $accountIds[] = $account->id;
-        }
-        $sum
-            = $category
-            ->transactionjournals()
-            ->leftJoin('transactions', 'transactions.transaction_journal_id', '=', 'transaction_journals.id')
-            ->before($end)
-            ->whereIn('transactions.account_id', $accountIds)
-            ->transactionTypes([TransactionType::DEPOSIT])
-            ->after($start)
-            ->get(['transaction_journals.*'])
-            ->sum('amount');
-
-        return $sum;
-
-    }
 
     /**
      * Returns a collection of Categories appended with the amount of money that has been earned
diff --git a/app/Repositories/Category/CategoryRepositoryInterface.php b/app/Repositories/Category/CategoryRepositoryInterface.php
index a3d82b8db4..9878738d75 100644
--- a/app/Repositories/Category/CategoryRepositoryInterface.php
+++ b/app/Repositories/Category/CategoryRepositoryInterface.php
@@ -13,29 +13,6 @@ use Illuminate\Support\Collection;
  */
 interface CategoryRepositoryInterface
 {
-    /**
-     * @param Category $category
-     *
-     * @return int
-     */
-    public function countJournals(Category $category);
-
-    /**
-     * @param Category $category
-     *
-     * @param Carbon   $start
-     * @param Carbon   $end
-     *
-     * @return int
-     */
-    public function countJournalsInRange(Category $category, Carbon $start, Carbon $end);
-
-    /**
-     * @param Category $category
-     *
-     * @return boolean
-     */
-    public function destroy(Category $category);
 
     /**
      * Returns a collection of Categories appended with the amount of money that has been earned
@@ -94,31 +71,6 @@ interface CategoryRepositoryInterface
      */
     public function getCategories();
 
-
-    /**
-     * Calculates how much is spent in this period.
-     *
-     * @param Category   $category
-     * @param Collection $accounts
-     * @param Carbon     $start
-     * @param Carbon     $end
-     *
-     * @return string
-     */
-    public function spentInPeriodForAccounts(Category $category, Collection $accounts, Carbon $start, Carbon $end);
-
-    /**
-     * Calculate how much is earned in this period.
-     *
-     * @param Category   $category
-     * @param Collection $accounts
-     * @param Carbon     $start
-     * @param Carbon     $end
-     *
-     * @return string
-     */
-    public function earnedInPeriodForAccounts(Category $category, Collection $accounts, Carbon $start, Carbon $end);
-
     /**
      * Returns the amount spent without category by accounts in period.
      *
@@ -151,52 +103,6 @@ interface CategoryRepositoryInterface
      */
     public function getCategoriesAndExpenses(Carbon $start, Carbon $end);
 
-    /**
-     * @param Category $category
-     *
-     * @return Carbon
-     */
-    public function getFirstActivityDate(Category $category);
-
-    /**
-     * @param Category $category
-     * @param int      $page
-     *
-     * @return Collection
-     */
-    public function getJournals(Category $category, $page);
-
-    /**
-     * @param Category $category
-     * @param int      $page
-     *
-     * @param Carbon   $start
-     * @param Carbon   $end
-     *
-     * @return Collection
-     */
-    public function getJournalsInRange(Category $category, $page, Carbon $start, Carbon $end);
-
-    /**
-     * @deprecated
-     * This method returns the sum of the journals in the category, optionally
-     * limited by a start or end date.
-     *
-     * @param Category $category
-     * @param Carbon   $start
-     * @param Carbon   $end
-     *
-     * @return string
-     */
-    public function journalsSum(Category $category, Carbon $start = null, Carbon $end = null);
-
-    /**
-     * @param Category $category
-     *
-     * @return Carbon|null
-     */
-    public function getLatestActivity(Category $category);
-
     /**
      * @param Carbon $start
      * @param Carbon $end
@@ -205,71 +111,4 @@ interface CategoryRepositoryInterface
      */
     public function getWithoutCategory(Carbon $start, Carbon $end);
 
-    /**
-     * Corrected for tags and list of accounts.
-     *
-     * @param Category       $category
-     * @param \Carbon\Carbon $start
-     * @param \Carbon\Carbon $end
-     * @param Collection     $accounts
-     *
-     * @return string
-     */
-    public function balanceInPeriod(Category $category, Carbon $start, Carbon $end, Collection $accounts);
-
-    /**
-     * @param Category       $category
-     * @param \Carbon\Carbon $start
-     * @param \Carbon\Carbon $end
-     *
-     * @return string
-     */
-    public function spentInPeriod(Category $category, Carbon $start, Carbon $end);
-
-    /**
-     * @param Category       $category
-     * @param \Carbon\Carbon $start
-     * @param \Carbon\Carbon $end
-     *
-     * @return string
-     */
-    public function earnedInPeriod(Category $category, Carbon $start, Carbon $end);
-
-    /**
-     *
-     * Corrected for tags.
-     *
-     * @param Category $category
-     * @param Carbon   $date
-     *
-     * @return float
-     */
-    public function spentOnDaySum(Category $category, Carbon $date);
-
-    /**
-     *
-     * Corrected for tags.
-     *
-     * @param Category $category
-     * @param Carbon   $date
-     *
-     * @return float
-     */
-    public function earnedOnDaySum(Category $category, Carbon $date);
-
-    /**
-     * @param array $data
-     *
-     * @return Category
-     */
-    public function store(array $data);
-
-    /**
-     * @param Category $category
-     * @param array    $data
-     *
-     * @return Category
-     */
-    public function update(Category $category, array $data);
-
 }
diff --git a/app/Repositories/Category/SingleCategoryRepository.php b/app/Repositories/Category/SingleCategoryRepository.php
new file mode 100644
index 0000000000..5c115c9ce1
--- /dev/null
+++ b/app/Repositories/Category/SingleCategoryRepository.php
@@ -0,0 +1,337 @@
+<?php
+
+namespace FireflyIII\Repositories\Category;
+
+use Carbon\Carbon;
+use FireflyIII\Models\Category;
+use FireflyIII\Models\TransactionJournal;
+use FireflyIII\Models\TransactionType;
+use FireflyIII\Repositories\Shared\ComponentRepository;
+use FireflyIII\Support\CacheProperties;
+use Illuminate\Support\Collection;
+
+/**
+ * Class SingleCategoryRepository
+ *
+ * @package FireflyIII\Repositories\Category
+ */
+class SingleCategoryRepository extends ComponentRepository implements SingleCategoryRepositoryInterface
+{
+
+    /**
+     * @param Category   $category
+     * @param Carbon     $start
+     * @param Carbon     $end
+     * @param Collection $accounts
+     *
+     * @return string
+     */
+    public function balanceInPeriod(Category $category, Carbon $start, Carbon $end, Collection $accounts)
+    {
+        return $this->commonBalanceInPeriod($category, $start, $end, $accounts);
+    }
+
+
+    /**
+     * @param Category $category
+     *
+     * @return int
+     */
+    public function countJournals(Category $category)
+    {
+        return $category->transactionJournals()->count();
+
+    }
+
+    /**
+     * @param Category $category
+     *
+     * @param Carbon   $start
+     * @param Carbon   $end
+     *
+     * @return int
+     */
+    public function countJournalsInRange(Category $category, Carbon $start, Carbon $end)
+    {
+        return $category->transactionJournals()->before($end)->after($start)->count();
+    }
+
+    /**
+     * @param Category $category
+     *
+     * @return boolean
+     */
+    public function destroy(Category $category)
+    {
+        $category->delete();
+
+        return true;
+    }
+
+    /**
+     * @param Category       $category
+     * @param \Carbon\Carbon $start
+     * @param \Carbon\Carbon $end
+     *
+     * @return string
+     */
+    public function earnedInPeriod(Category $category, Carbon $start, Carbon $end)
+    {
+        $cache = new CacheProperties; // we must cache this.
+        $cache->addProperty($category->id);
+        $cache->addProperty($start);
+        $cache->addProperty($end);
+        $cache->addProperty('earnedInPeriod');
+
+        if ($cache->has()) {
+            return $cache->get(); // @codeCoverageIgnore
+        }
+
+        $sum = $category->transactionjournals()->transactionTypes([TransactionType::DEPOSIT])->before($end)->after($start)->get(['transaction_journals.*'])
+                        ->sum(
+                            'amount'
+                        );
+
+        $cache->store($sum);
+
+        return $sum;
+    }
+
+
+    /**
+     * Calculate how much is earned in this period.
+     *
+     * @param Category   $category
+     * @param Collection $accounts
+     * @param Carbon     $start
+     * @param Carbon     $end
+     *
+     * @return string
+     */
+    public function earnedInPeriodForAccounts(Category $category, Collection $accounts, Carbon $start, Carbon $end)
+    {
+        $accountIds = [];
+        foreach ($accounts as $account) {
+            $accountIds[] = $account->id;
+        }
+        $sum
+            = $category
+            ->transactionjournals()
+            ->leftJoin('transactions', 'transactions.transaction_journal_id', '=', 'transaction_journals.id')
+            ->before($end)
+            ->whereIn('transactions.account_id', $accountIds)
+            ->transactionTypes([TransactionType::DEPOSIT])
+            ->after($start)
+            ->get(['transaction_journals.*'])
+            ->sum('amount');
+
+        return $sum;
+
+    }
+
+    /**
+     *
+     * Corrected for tags.
+     *
+     * @param Category $category
+     * @param Carbon   $date
+     *
+     * @return float
+     */
+    public function earnedOnDaySum(Category $category, Carbon $date)
+    {
+        return $category->transactionjournals()->transactionTypes([TransactionType::DEPOSIT])->onDate($date)->get(['transaction_journals.*'])->sum('amount');
+    }
+
+    /**
+     * @param Category $category
+     *
+     * @return Carbon
+     */
+    public function getFirstActivityDate(Category $category)
+    {
+        /** @var TransactionJournal $first */
+        $first = $category->transactionjournals()->orderBy('date', 'ASC')->first();
+        if ($first) {
+            return $first->date;
+        }
+
+        return new Carbon;
+
+    }
+
+    /**
+     * @param Category $category
+     * @param int      $page
+     *
+     * @return Collection
+     */
+    public function getJournals(Category $category, $page)
+    {
+        $offset = $page > 0 ? $page * 50 : 0;
+
+        return $category->transactionJournals()->withRelevantData()->take(50)->offset($offset)
+                        ->orderBy('transaction_journals.date', 'DESC')
+                        ->orderBy('transaction_journals.order', 'ASC')
+                        ->orderBy('transaction_journals.id', 'DESC')
+                        ->get(
+                            ['transaction_journals.*']
+                        );
+
+    }
+
+    /**
+     * @param Category $category
+     * @param int      $page
+     * @param Carbon   $start
+     * @param Carbon   $end
+     *
+     * @return mixed
+     */
+    public function getJournalsInRange(Category $category, $page, Carbon $start, Carbon $end)
+    {
+        $offset = $page > 0 ? $page * 50 : 0;
+
+        return $category->transactionJournals()
+                        ->after($start)
+                        ->before($end)
+                        ->withRelevantData()->take(50)->offset($offset)
+                        ->orderBy('transaction_journals.date', 'DESC')
+                        ->orderBy('transaction_journals.order', 'ASC')
+                        ->orderBy('transaction_journals.id', 'DESC')
+                        ->get(
+                            ['transaction_journals.*']
+                        );
+    }
+
+
+    /**
+     * @param Category $category
+     *
+     * @return Carbon|null
+     */
+    public function getLatestActivity(Category $category)
+    {
+        $latest = $category->transactionjournals()
+                           ->orderBy('transaction_journals.date', 'DESC')
+                           ->orderBy('transaction_journals.order', 'ASC')
+                           ->orderBy('transaction_journals.id', 'DESC')
+                           ->first();
+        if ($latest) {
+            return $latest->date;
+        }
+
+        return null;
+    }
+
+
+    /**
+     * Calculates how much is spent in this period.
+     *
+     * @param Category   $category
+     * @param Collection $accounts
+     * @param Carbon     $start
+     * @param Carbon     $end
+     *
+     * @return string
+     */
+    public function spentInPeriodForAccounts(Category $category, Collection $accounts, Carbon $start, Carbon $end)
+    {
+        $accountIds = [];
+        foreach ($accounts as $account) {
+            $accountIds[] = $account->id;
+        }
+
+        $sum
+            = $category
+            ->transactionjournals()
+            ->leftJoin('transactions', 'transactions.transaction_journal_id', '=', 'transaction_journals.id')
+            ->after($start)
+            ->before($end)
+            ->whereIn('transactions.account_id', $accountIds)
+            ->transactionTypes([TransactionType::WITHDRAWAL])
+            ->get(['transaction_journals.*'])
+            ->sum('amount');
+
+        return $sum;
+
+    }
+
+    /**
+     * @param Category       $category
+     * @param \Carbon\Carbon $start
+     * @param \Carbon\Carbon $end
+     *
+     * @return string
+     */
+    public function spentInPeriod(Category $category, Carbon $start, Carbon $end)
+    {
+        $cache = new CacheProperties; // we must cache this.
+        $cache->addProperty($category->id);
+        $cache->addProperty($start);
+        $cache->addProperty($end);
+        $cache->addProperty('spentInPeriod');
+
+        if ($cache->has()) {
+            return $cache->get(); // @codeCoverageIgnore
+        }
+
+        $sum = $category->transactionjournals()->transactionTypes([TransactionType::WITHDRAWAL])->before($end)->after($start)->get(['transaction_journals.*'])
+                        ->sum(
+                            'amount'
+                        );
+
+        $cache->store($sum);
+
+        return $sum;
+    }
+
+
+    /**
+     * Corrected for tags
+     *
+     * @param Category $category
+     * @param Carbon   $date
+     *
+     * @return string
+     */
+    public function spentOnDaySum(Category $category, Carbon $date)
+    {
+        return $category->transactionjournals()->transactionTypes([TransactionType::WITHDRAWAL])->onDate($date)->get(['transaction_journals.*'])->sum('amount');
+    }
+
+    /**
+     * @param array $data
+     *
+     * @return Category
+     */
+    public function store(array $data)
+    {
+        $newCategory = new Category(
+            [
+                'user_id' => $data['user'],
+                'name'    => $data['name'],
+            ]
+        );
+        $newCategory->save();
+
+        return $newCategory;
+    }
+
+    /**
+     * @param Category $category
+     * @param array    $data
+     *
+     * @return Category
+     */
+    public function update(Category $category, array $data)
+    {
+        // update the account:
+        $category->name = $data['name'];
+        $category->save();
+
+        return $category;
+    }
+
+
+}
\ No newline at end of file
diff --git a/app/Repositories/Category/SingleCategoryRepositoryInterface.php b/app/Repositories/Category/SingleCategoryRepositoryInterface.php
new file mode 100644
index 0000000000..c23784e51d
--- /dev/null
+++ b/app/Repositories/Category/SingleCategoryRepositoryInterface.php
@@ -0,0 +1,166 @@
+<?php
+
+namespace FireflyIII\Repositories\Category;
+
+use Carbon\Carbon;
+use FireflyIII\Models\Category;
+use Illuminate\Support\Collection;
+
+/**
+ * Interface SingleCategoryRepositoryInterface
+ *
+ * @package FireflyIII\Repositories\Category
+ */
+interface SingleCategoryRepositoryInterface
+{
+    /**
+     * Corrected for tags and list of accounts.
+     *
+     * @param Category       $category
+     * @param \Carbon\Carbon $start
+     * @param \Carbon\Carbon $end
+     * @param Collection     $accounts
+     *
+     * @return string
+     */
+    public function balanceInPeriod(Category $category, Carbon $start, Carbon $end, Collection $accounts);
+
+    /**
+     * @param Category $category
+     *
+     * @return int
+     */
+    public function countJournals(Category $category);
+
+    /**
+     * @param Category $category
+     *
+     * @param Carbon   $start
+     * @param Carbon   $end
+     *
+     * @return int
+     */
+    public function countJournalsInRange(Category $category, Carbon $start, Carbon $end);
+
+    /**
+     * @param Category $category
+     *
+     * @return boolean
+     */
+    public function destroy(Category $category);
+
+    /**
+     * @param Category       $category
+     * @param \Carbon\Carbon $start
+     * @param \Carbon\Carbon $end
+     *
+     * @return string
+     */
+    public function earnedInPeriod(Category $category, Carbon $start, Carbon $end);
+
+
+    /**
+     * Calculate how much is earned in this period.
+     *
+     * @param Category   $category
+     * @param Collection $accounts
+     * @param Carbon     $start
+     * @param Carbon     $end
+     *
+     * @return string
+     */
+    public function earnedInPeriodForAccounts(Category $category, Collection $accounts, Carbon $start, Carbon $end);
+
+    /**
+     *
+     * Corrected for tags.
+     *
+     * @param Category $category
+     * @param Carbon   $date
+     *
+     * @return float
+     */
+    public function earnedOnDaySum(Category $category, Carbon $date);
+
+    /**
+     * @param Category $category
+     *
+     * @return Carbon
+     */
+    public function getFirstActivityDate(Category $category);
+
+    /**
+     * @param Category $category
+     * @param int      $page
+     *
+     * @return Collection
+     */
+    public function getJournals(Category $category, $page);
+
+
+
+    /**
+     * @param Category $category
+     * @param int      $page
+     *
+     * @param Carbon   $start
+     * @param Carbon   $end
+     *
+     * @return Collection
+     */
+    public function getJournalsInRange(Category $category, $page, Carbon $start, Carbon $end);
+
+    /**
+     * @param Category $category
+     *
+     * @return Carbon|null
+     */
+    public function getLatestActivity(Category $category);
+
+    /**
+     * @param Category       $category
+     * @param \Carbon\Carbon $start
+     * @param \Carbon\Carbon $end
+     *
+     * @return string
+     */
+    public function spentInPeriod(Category $category, Carbon $start, Carbon $end);
+
+    /**
+     * Calculates how much is spent in this period.
+     *
+     * @param Category   $category
+     * @param Collection $accounts
+     * @param Carbon     $start
+     * @param Carbon     $end
+     *
+     * @return string
+     */
+    public function spentInPeriodForAccounts(Category $category, Collection $accounts, Carbon $start, Carbon $end);
+
+    /**
+     *
+     * Corrected for tags.
+     *
+     * @param Category $category
+     * @param Carbon   $date
+     *
+     * @return float
+     */
+    public function spentOnDaySum(Category $category, Carbon $date);
+
+    /**
+     * @param array $data
+     *
+     * @return Category
+     */
+    public function store(array $data);
+
+    /**
+     * @param Category $category
+     * @param array    $data
+     *
+     * @return Category
+     */
+    public function update(Category $category, array $data);
+}
\ No newline at end of file