Improved organisation of Services

src/Services/Formatters/SIFormatter.php

@@ -0,0 +1,104 @@
+<?php
+/**
+ * This file is part of Part-DB (https://github.com/Part-DB/Part-DB-symfony).
+ *
+ * Copyright (C) 2019 - 2022 Jan Böhmer (https://github.com/jbtronics)
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published
+ * by the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+declare(strict_types=1);
+
+namespace App\Services\Formatters;
+
+/**
+ * A service that helps you to format values using the SI prefixes.
+ */
+class SIFormatter
+{
+    /**
+     * Returns the magnitude of a value (the count of decimal place of the highest decimal place).
+     * For example, for 100 (=10^2) this function returns 2. For -2500 (=-2.5*10^3) this function returns 3.
+     *
+     * @param float $value the value of which the magnitude should be determined
+     *
+     * @return int The magnitude of the value
+     */
+    public function getMagnitude(float $value): int
+    {
+        return (int) floor(log10(abs($value)));
+    }
+
+    /**
+     * Returns the best SI prefix (and its corresponding divisor) for the given magnitude.
+     *
+     * @param int $magnitude the magnitude for which the prefix should be determined
+     *
+     * @return array A array, containing the divisor in first element, and the prefix symbol in second. For example, [1000, "k"].
+     */
+    public function getPrefixByMagnitude(int $magnitude): array
+    {
+        $prefixes_pos = ['', 'k', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'];
+        $prefixes_neg = ['', 'm', 'μ', 'n', 'p', 'f', 'a', 'z', 'y'];
+
+        if ($magnitude >= 0) {
+            $nearest = (int) floor(abs($magnitude) / 3);
+            $symbol = $prefixes_pos[$nearest];
+        } else {
+            $nearest = (int) round(abs($magnitude) / 3);
+            $symbol = $prefixes_neg[$nearest];
+        }
+
+        if ($magnitude < 0) {
+            $nearest *= -1;
+        }
+
+        return [10 ** (3 * $nearest), $symbol];
+    }
+
+    public function convertValue(float $value): array
+    {
+        //Choose the prefix to use
+        $tmp = $this->getPrefixByMagnitude($this->getMagnitude($value));
+
+        return [
+            'value' => $value / $tmp[0],
+            'prefix_magnitude' => log10($tmp[0]),
+            'prefix' => $tmp[1],
+        ];
+    }
+
+    /**
+     * Formats the given value to a string, using the given options.
+     *
+     * @param float  $value    The value that should be converted
+     * @param string $unit     The unit that should be appended after the prefix
+     * @param int    $decimals the number of decimals (after decimal dot) that should be outputed
+     *
+     * @return string The formatted value
+     */
+    public function format(float $value, string $unit = '', int $decimals = 2): string
+    {
+        [$divisor, $symbol] = $this->getPrefixByMagnitude($this->getMagnitude($value));
+        $value /= $divisor;
+        //Build the format string, e.g.: %.2d km
+        if ('' !== $unit || '' !== $symbol) {
+            $format_string = '%.'.$decimals.'f '.$symbol.$unit;
+        } else {
+            $format_string = '%.'.$decimals.'f';
+        }
+
+        return sprintf($format_string, $value);
+    }
+}