From f3bb61f3e413906fc79f22c6d87745783b1e88bd Mon Sep 17 00:00:00 2001
From: MarkBaker <mark@lange.demon.co.uk>
Date: Sun, 20 Mar 2022 14:03:36 +0100
Subject: [PATCH] Initial work implementing the FILTER() Lookup/Reference
 function

Tighten up on vector formats; and provide a couple of helper methods for testing row/column vectors
---
 CHANGELOG.md                                  |  2 +-
 .../Calculation/Calculation.php               |  2 +-
 .../Calculation/LookupRef/Filter.php          | 65 ++++++++++++++
 .../Calculation/LookupRef/Matrix.php          | 17 ++++
 .../Calculation/LookupRef/Unique.php          |  4 +-
 .../Functions/LookupRef/FilterTest.php        | 85 +++++++++++++++++++
 .../LookupRef/MatrixHelperFunctionsTest.php   | 77 +++++++++++++++++
 7 files changed, 248 insertions(+), 4 deletions(-)
 create mode 100644 src/PhpSpreadsheet/Calculation/LookupRef/Filter.php
 create mode 100644 tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/FilterTest.php
 create mode 100644 tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/MatrixHelperFunctionsTest.php

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 500d1ac4..3ac8c9a9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,7 +9,7 @@ and this project adheres to [Semantic Versioning](https://semver.org).
 
 ### Added
 
-- Implementation of the UNIQUE() Lookup/Reference (array) function
+- Implementation of the FILTER() and UNIQUE() Lookup/Reference (array) function
 - Implementation of the ISREF() Information function.
 - Added support for reading "formatted" numeric values from Csv files; although default behaviour of reading these values as strings is preserved.
 
diff --git a/src/PhpSpreadsheet/Calculation/Calculation.php b/src/PhpSpreadsheet/Calculation/Calculation.php
index b3988260..0f94a7e7 100644
--- a/src/PhpSpreadsheet/Calculation/Calculation.php
+++ b/src/PhpSpreadsheet/Calculation/Calculation.php
@@ -1040,7 +1040,7 @@ class Calculation
         ],
         'FILTER' => [
             'category' => Category::CATEGORY_LOOKUP_AND_REFERENCE,
-            'functionCall' => [Functions::class, 'DUMMY'],
+            'functionCall' => [LookupRef\Filter::class, 'filter'],
             'argumentCount' => '2-3',
         ],
         'FILTERXML' => [
diff --git a/src/PhpSpreadsheet/Calculation/LookupRef/Filter.php b/src/PhpSpreadsheet/Calculation/LookupRef/Filter.php
new file mode 100644
index 00000000..a5e7dc17
--- /dev/null
+++ b/src/PhpSpreadsheet/Calculation/LookupRef/Filter.php
@@ -0,0 +1,65 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheet\Calculation\LookupRef;
+
+use PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
+
+class Filter
+{
+    /**
+     * @param mixed $lookupArray
+     * @param mixed $matchArray
+     * @param mixed $ifEmpty
+     *
+     * @return mixed
+     */
+    public static function filter($lookupArray, $matchArray, $ifEmpty = null)
+    {
+        if (!is_array($matchArray)) {
+            return ExcelError::VALUE();
+        }
+
+        $result = (Matrix::isColumnVector($matchArray))
+            ? self::filterByRow($lookupArray, $matchArray)
+            : self::filterByColumn($lookupArray, $matchArray);
+
+        if (empty($result)) {
+            return $ifEmpty ?? ExcelError::CALC();
+        }
+
+        return array_values($result);
+    }
+
+    private static function filterByRow(array $lookupArray, array $matchArray): array
+    {
+        $matchArray = array_values(array_column($matchArray, 0));
+
+        return array_filter(
+            array_values($lookupArray),
+            function ($index) use ($matchArray): bool {
+                return (bool) $matchArray[$index];
+            },
+            ARRAY_FILTER_USE_KEY
+        );
+    }
+
+    private static function filterByColumn(array $lookupArray, array $matchArray): array
+    {
+        $lookupArray = Matrix::transpose($lookupArray);
+
+        if (count($matchArray) === 1) {
+            $matchArray = array_pop($matchArray);
+        }
+
+        array_walk(
+            $matchArray,
+            function (&$value): void {
+                $value = [$value];
+            }
+        );
+
+        $result = self::filterByRow($lookupArray, $matchArray);
+
+        return Matrix::transpose($result);
+    }
+}
diff --git a/src/PhpSpreadsheet/Calculation/LookupRef/Matrix.php b/src/PhpSpreadsheet/Calculation/LookupRef/Matrix.php
index 27e6f8eb..a447e203 100644
--- a/src/PhpSpreadsheet/Calculation/LookupRef/Matrix.php
+++ b/src/PhpSpreadsheet/Calculation/LookupRef/Matrix.php
@@ -10,6 +10,23 @@ class Matrix
 {
     use ArrayEnabled;
 
+    /**
+     * Helper function; NOT an implementation of any Excel Function.
+     */
+    public static function isColumnVector(array $values): bool
+    {
+        return count($values, COUNT_RECURSIVE) === (count($values, COUNT_NORMAL) * 2);
+    }
+
+    /**
+     * Helper function; NOT an implementation of any Excel Function.
+     */
+    public static function isRowVector(array $values): bool
+    {
+        return count($values, COUNT_RECURSIVE) > 1 &&
+            (count($values, COUNT_NORMAL) === 1 || count($values, COUNT_RECURSIVE) === count($values, COUNT_NORMAL));
+    }
+
     /**
      * TRANSPOSE.
      *
diff --git a/src/PhpSpreadsheet/Calculation/LookupRef/Unique.php b/src/PhpSpreadsheet/Calculation/LookupRef/Unique.php
index 67b911aa..2ba51281 100644
--- a/src/PhpSpreadsheet/Calculation/LookupRef/Unique.php
+++ b/src/PhpSpreadsheet/Calculation/LookupRef/Unique.php
@@ -29,8 +29,8 @@ class Unique
         $exactlyOnce = (bool) $exactlyOnce;
 
         return ($byColumn === true)
-                ? self::uniqueByColumn($lookupVector, $exactlyOnce)
-                : self::uniqueByRow($lookupVector, $exactlyOnce);
+            ? self::uniqueByColumn($lookupVector, $exactlyOnce)
+            : self::uniqueByRow($lookupVector, $exactlyOnce);
     }
 
     /**
diff --git a/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/FilterTest.php b/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/FilterTest.php
new file mode 100644
index 00000000..710a42e0
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/FilterTest.php
@@ -0,0 +1,85 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Calculation\Functions\LookupRef;
+
+use PhpOffice\PhpSpreadsheet\Calculation\Information\ExcelError;
+use PhpOffice\PhpSpreadsheet\Calculation\LookupRef\Filter;
+use PHPUnit\Framework\TestCase;
+
+class FilterTest extends TestCase
+{
+    public function testFilterByRow(): void
+    {
+        $criteria = [[true], [false], [false], [false], [true], [false], [false], [false], [false], [false], [false], [true], [false], [false], [false], [true]];
+        $expectedResult = [
+            ['East', 'Tom', 'Apple', 6830],
+            ['East', 'Fritz', 'Apple', 4394],
+            ['South', 'Sal', 'Apple', 1310],
+            ['South', 'Hector', 'Apple', 98144],
+        ];
+        $result = Filter::filter($this->sampleDataForRow(), $criteria);
+        self::assertSame($expectedResult, $result);
+    }
+
+    public function testFilterByColumn(): void
+    {
+        $criteria = [[false, false, true, false, true, false, false, false, true, true]];
+        $expectedResult = [
+            ['Betty', 'Charlotte', 'Oliver', 'Zoe'],
+            ['B', 'B', 'B', 'B'],
+            [1, 2, 4, 8],
+        ];
+        $result = Filter::filter($this->sampleDataForColumn(), $criteria);
+        self::assertSame($expectedResult, $result);
+    }
+
+    public function testFilterException(): void
+    {
+        $criteria = 'INVALID';
+        $result = Filter::filter($this->sampleDataForColumn(), $criteria);
+        self::assertSame(ExcelError::VALUE(), $result);
+    }
+
+    public function testFilterEmpty(): void
+    {
+        $criteria = [[false], [false], [false]];
+        $expectedResult = ExcelError::CALC();
+        $result = Filter::filter([[1], [2], [3]], $criteria);
+        self::assertSame($expectedResult, $result);
+
+        $expectedResult = 'Invalid Data';
+        $result = Filter::filter([[1], [2], [3]], $criteria, $expectedResult);
+        self::assertSame($expectedResult, $result);
+    }
+
+    protected function sampleDataForRow(): array
+    {
+        return [
+            ['East', 'Tom', 'Apple', 6830],
+            ['West', 'Fred', 'Grape', 5619],
+            ['North', 'Amy', 'Pear', 4565],
+            ['South', 'Sal', 'Banana', 5323],
+            ['East', 'Fritz', 'Apple', 4394],
+            ['West', 'Sravan', 'Grape', 7195],
+            ['North', 'Xi', 'Pear', 5231],
+            ['South', 'Hector', 'Banana', 2427],
+            ['East', 'Tom', 'Banana', 4213],
+            ['West', 'Fred', 'Pear', 3239],
+            ['North', 'Amy', 'Grape', 6420],
+            ['South', 'Sal', 'Apple', 1310],
+            ['East', 'Fritz', 'Banana', 6274],
+            ['West', 'Sravan', 'Pear', 4894],
+            ['North', 'Xi', 'Grape', 7580],
+            ['South', 'Hector', 'Apple', 98144],
+        ];
+    }
+
+    protected function sampleDataForColumn(): array
+    {
+        return [
+            ['Aiden', 'Andrew', 'Betty', 'Caden', 'Charlotte', 'Emma', 'Isabella', 'Mason', 'Oliver', 'Zoe'],
+            ['A', 'C', 'B', 'A', 'B', 'C', 'A', 'A', 'B', 'B'],
+            [0, 4, 1, 2, 2, 0, 2, 4, 4, 8],
+        ];
+    }
+}
diff --git a/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/MatrixHelperFunctionsTest.php b/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/MatrixHelperFunctionsTest.php
new file mode 100644
index 00000000..e5b4cace
--- /dev/null
+++ b/tests/PhpSpreadsheetTests/Calculation/Functions/LookupRef/MatrixHelperFunctionsTest.php
@@ -0,0 +1,77 @@
+<?php
+
+namespace PhpOffice\PhpSpreadsheetTests\Calculation\Functions\LookupRef;
+
+use PhpOffice\PhpSpreadsheet\Calculation\LookupRef\Matrix;
+use PHPUnit\Framework\TestCase;
+
+class MatrixHelperFunctionsTest extends TestCase
+{
+    /**
+     * @dataProvider columnVectorProvider
+     */
+    public function testIsColumnVector(bool $expectedResult, array $array): void
+    {
+        $result = Matrix::isColumnVector($array);
+        self::assertSame($expectedResult, $result);
+    }
+
+    /**
+     * @dataProvider rowVectorProvider
+     */
+    public function testIsRowVector(bool $expectedResult, array $array): void
+    {
+        $result = Matrix::isRowVector($array);
+        self::assertSame($expectedResult, $result);
+    }
+
+    public function columnVectorProvider(): array
+    {
+        return [
+            [
+                true,
+                [
+                    [1], [2], [3],
+                ],
+            ],
+            [
+                false,
+                [1, 2, 3],
+            ],
+            [
+                false,
+                [
+                    [1, 2, 3],
+                    [4, 5, 6],
+                ],
+            ],
+        ];
+    }
+
+    public function rowVectorProvider(): array
+    {
+        return [
+            [
+                false,
+                [
+                    [1], [2], [3],
+                ],
+            ],
+            [
+                true,
+                [1, 2, 3],
+            ],
+            [
+                true,
+                [[1, 2, 3]],
+            ],
+            [
+                false,
+                [
+                    [1, 2, 3],
+                    [4, 5, 6],
+                ],
+            ],
+        ];
+    }
+}