add environment variables support (#255)

src/ZM/Config/Environment.php

@@ -0,0 +1,82 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ZM\Config;
+
+class Environment implements EnvironmentInterface
+{
+    private const VALUE_MAP = [
+        'true' => true,
+        '(true)' => true,
+        'false' => false,
+        '(false)' => false,
+        'null' => null,
+        '(null)' => null,
+        'empty' => '',
+    ];
+
+    private array $values;
+
+    /**
+     * @param array $values    额外的环境变量，优先级高于系统环境变量
+     * @param bool  $overwrite 是否允许后续 set() 覆盖已有的环境变量
+     */
+    public function __construct(
+        array $values = [],
+        private bool $overwrite = false
+    ) {
+        $this->values = $values + $_ENV + $_SERVER;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function set(string $name, mixed $value): self
+    {
+        if (array_key_exists($name, $this->values) && !$this->overwrite) {
+            // 如不允许覆盖已有的环境变量，则不做任何操作
+            return $this;
+        }
+
+        $this->values[$name] = $_ENV[$name] = $value;
+        putenv("{$name}={$value}");
+
+        return $this;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function get(string $name, mixed $default = null): mixed
+    {
+        if (isset($this->values[$name])) {
+            return $this->normalize($this->values[$name]);
+        }
+
+        return $default;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getAll(): array
+    {
+        $result = [];
+
+        foreach ($this->values as $key => $value) {
+            $result[$key] = $this->normalize($value);
+        }
+
+        return $result;
+    }
+
+    protected function normalize(mixed $value): mixed
+    {
+        if (!is_string($value)) {
+            return $value;
+        }
+
+        return self::VALUE_MAP[strtolower($value)] ?? $value;
+    }
+}

src/ZM/Config/EnvironmentInterface.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ZM\Config;
+
+interface EnvironmentInterface
+{
+    /**
+     * 设置环境变量
+     */
+    public function set(string $name, mixed $value): self;
+
+    /**
+     * 获取环境变量
+     */
+    public function get(string $name, mixed $default = null): mixed;
+
+    /**
+     * 获取所有环境变量
+     */
+    public function getAll(): array;
+}