From acd148b70b84ebe275e4b5631a9e5cc74025a0fc Mon Sep 17 00:00:00 2001
From: Dennis Eichhorn <spl1nes.com@googlemail.com>
Date: Sun, 15 Dec 2019 12:45:45 +0100
Subject: [PATCH] add maze generator

---
 Algorithm/Maze/MazeGenerator.php           | 158 +++++++++++++++++++++
 tests/Algorithm/Maze/MazeGeneratorTest.php | 101 +++++++++++++
 2 files changed, 259 insertions(+)
 create mode 100644 Algorithm/Maze/MazeGenerator.php
 create mode 100644 tests/Algorithm/Maze/MazeGeneratorTest.php

diff --git a/Algorithm/Maze/MazeGenerator.php b/Algorithm/Maze/MazeGenerator.php
new file mode 100644
index 000000000..84a846a2a
--- /dev/null
+++ b/Algorithm/Maze/MazeGenerator.php
@@ -0,0 +1,158 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.4
+ *
+ * @package   phpOMS\Algorithm\Maze
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+
+declare(strict_types=1);
+
+namespace phpOMS\Algorithm\Maze;
+
+/**
+ * Maze generator
+ *
+ * @package phpOMS\Algorithm\Maze
+ * @license OMS License 1.0
+ * @link    https://orange-management.org
+ * @since   1.0.0
+ */
+class MazeGenerator
+{
+    /**
+     * Constructor
+     * @codeCoverageIgnore
+     */
+    private function __construct()
+    {
+    }
+
+    /**
+     * Generate a random maze
+     *
+     * @param int $width  Width
+     * @param int $height Height
+     *
+     * @return array
+     *
+     * @since 1.0.0
+     */
+    public static function random(int $width, int $height) : array
+    {
+        $n          = $height * $width - 1;
+        $horizontal = \array_fill(0, $height, []);
+        $vertical   = \array_fill(0, $height, []);
+
+        $pos       = [\mt_rand(0, $height) - 1, \mt_rand(0, $width) - 1];
+        $path      = [$pos];
+        $unvisited = [];
+
+        for ($i = 0; $i < $height + 2; ++$i) {
+            $unvisited[] = [];
+
+            for ($j = 0; $j < $width + 1; ++$j) {
+                $unvisited[$i][] = $i > 0 && $i < $height + 1 && $j > 0 && ($i !== $pos[0] + 1 || $j != $pos[1] + 1);
+            }
+        }
+
+        while (0 < $n) {
+            $potential = [
+                [$pos[0] + 1, $pos[1]],
+                [$pos[0], $pos[1] + 1],
+                [$pos[0] - 1, $pos[1]],
+                [$pos[0], $pos[1] - 1],
+            ];
+
+            $neighbors = [];
+
+            for ($i = 0; $i < 4; ++$i) {
+                if ($unvisited[$potential[$i][0] + 1][$potential[$i][1] + 1] ?? false) {
+                    $neighbors[] = $potential[$i];
+                }
+            }
+
+            if (!empty($neighbors)) {
+                --$n;
+
+                $next                                  = $neighbors[\mt_rand(0, \count($neighbors) - 1)];
+                $unvisited[$next[0] + 1][$next[1] + 1] = false;
+
+                if ($next[0] === $pos[0]) {
+                    $horizontal[$next[0]][($next[1] + $pos[1] - 1) / 2] = true;
+                } else {
+                    $vertical[($next[0] + $pos[0] - 1) / 2][$next[1]] = true;
+                }
+
+                $path[] = $next;
+                $pos    = $next;
+            } else {
+                $pos = \array_pop($path);
+
+                if ($pos === null) {
+                    $n = 0;
+                }
+            }
+        }
+
+        $maze = [];
+        for ($i = 0; $i < $height * 2 + 1; ++$i) {
+            $line = [];
+
+            if ($i % 2 === 0) {
+                for ($j = 0; $j < $width * 4 + 1; ++$j) {
+                    if ($j % 4 === 0) {
+                        $line[$j] = '+';
+                    } else {
+                        $line[$j] = $i > 0 && ($vertical[$i / 2 - 1][(int) \floor($j / 4)] ?? false) ? ' ' : '-';
+                    }
+                }
+            } else {
+                for ($j = 0; $j < $width * 4 + 1; ++$j) {
+                    if ($j % 4 === 0) {
+                        $line[$j] = $j > 0 && ($horizontal[($i - 1) / 2][$j / 4 - 1] ?? false) ? ' ' : '|';
+                    } else {
+                        $line[$j] = ' ';
+                    }
+                }
+            }
+
+            if ($i === 0) {
+                $line[1] = $line[2] = $line[3] = ' ';
+            }
+
+            if ($height * 2 - 1 === $i) {
+                $line[4 * $width] = ' ';
+            }
+
+            $maze[] = $line;
+        }
+
+        return $maze;
+    }
+
+    /**
+     * Render a maze
+     *
+     * @param array $maze Maze to render
+     *
+     * @return void
+     *
+     * @since 1.0.0
+     */
+    public static function render(array $maze) : void
+    {
+        foreach ($maze as $y => $row) {
+            foreach ($row as $x => $column) {
+                echo $column;
+            }
+
+            echo "\n";
+        }
+    }
+}
diff --git a/tests/Algorithm/Maze/MazeGeneratorTest.php b/tests/Algorithm/Maze/MazeGeneratorTest.php
new file mode 100644
index 000000000..0ecc58b93
--- /dev/null
+++ b/tests/Algorithm/Maze/MazeGeneratorTest.php
@@ -0,0 +1,101 @@
+<?php
+/**
+ * Orange Management
+ *
+ * PHP Version 7.4
+ *
+ * @package   tests
+ * @copyright Dennis Eichhorn
+ * @license   OMS License 1.0
+ * @version   1.0.0
+ * @link      https://orange-management.org
+ */
+declare(strict_types=1);
+
+namespace phpOMS\tests\Algorithm\PathFinding;
+
+use phpOMS\Algorithm\Maze\MazeGenerator;
+
+require_once __DIR__ . '/../../Autoloader.php';
+
+/**
+ * @testdox phpOMS\tests\Algorithm\Maze\MazeGeneratorTest: Maze generation
+ *
+ * @internal
+ */
+class MazeGeneratorTest extends \PHPUnit\Framework\TestCase
+{
+
+    /**
+     * @testdox A random maze can be generated
+     * @covers phpOMS\Algorithm\Maze\MazeGenerator
+     * @group framework
+     */
+    public function testMazeGeneration() : void
+    {
+        $maze = MazeGenerator::random(10, 7);
+
+        // correct top
+        self::assertEquals(
+            ['+', ' ', ' ', ' ', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+'],
+            $maze[0]
+        );
+
+        // correct bottom
+        self::assertEquals(
+            ['+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+', '-', '-', '-', '+'],
+            $maze[14]
+        );
+
+        // correct left
+        self::assertEquals(
+            ['+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+'],
+            [$maze[0][0], $maze[1][0], $maze[2][0], $maze[3][0], $maze[4][0], $maze[5][0], $maze[6][0], $maze[7][0], $maze[8][0], $maze[9][0], $maze[10][0], $maze[11][0], $maze[12][0], $maze[13][0], $maze[14][0]]
+        );
+
+        // correct right
+        self::assertEquals(
+            ['+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+', ' ', '+'],
+            [$maze[0][40], $maze[1][40], $maze[2][40], $maze[3][40], $maze[4][40], $maze[5][40], $maze[6][40], $maze[7][40], $maze[8][40], $maze[9][40], $maze[10][40], $maze[11][40], $maze[12][40], $maze[13][40], $maze[14][40]]
+        );
+    }
+
+    /**
+     * @testdox A random maze can be rendered
+     * @covers phpOMS\Algorithm\Maze\MazeGenerator
+     * @group framework
+     */
+    public function testMazeRender() : void
+    {
+        \ob_start();
+        MazeGenerator::render(MazeGenerator::random(10, 7));
+        $ob = \ob_get_clean();
+        \ob_clean();
+
+        $maze = \explode("\n", $ob);
+
+        // correct top
+        self::assertEquals(
+            '+   +---+---+---+---+---+---+---+---+---+',
+            $maze[0]
+        );
+
+        // correct bottom
+        self::assertEquals(
+            '+---+---+---+---+---+---+---+---+---+---+',
+            $maze[14]
+        );
+
+        // correct left
+        self::assertEquals(
+            ['+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+'],
+            [$maze[0][0], $maze[1][0], $maze[2][0], $maze[3][0], $maze[4][0], $maze[5][0], $maze[6][0], $maze[7][0], $maze[8][0], $maze[9][0], $maze[10][0], $maze[11][0], $maze[12][0], $maze[13][0], $maze[14][0]]
+        );
+
+        // correct right
+        self::assertEquals(
+            ['+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+', '|', '+', ' ', '+'],
+            [$maze[0][40], $maze[1][40], $maze[2][40], $maze[3][40], $maze[4][40], $maze[5][40], $maze[6][40], $maze[7][40], $maze[8][40], $maze[9][40], $maze[10][40], $maze[11][40], $maze[12][40], $maze[13][40], $maze[14][40]]
+        );
+    }
+}