v2: Updates

* Simplifies & beautifies everything
* Introduces a new Class system.
* Errors are defaulted to AWS's handler.
* New function names & more efficient handling.
* Should fix a majority of the errors.

Please read the README for more!

aws/Aws/S3/UseArnRegion/ConfigurationProvider.php

@@ -0,0 +1,175 @@
+<?php
+namespace Aws\S3\UseArnRegion;
+
+use Aws\AbstractConfigurationProvider;
+use Aws\CacheInterface;
+use Aws\ConfigurationProviderInterface;
+use Aws\S3\UseArnRegion\Exception\ConfigurationException;
+use GuzzleHttp\Promise;
+
+/**
+ * A configuration provider is a function that returns a promise that is
+ * fulfilled with a {@see \Aws\S3\UseArnRegion\ConfigurationInterface}
+ * or rejected with an {@see \Aws\S3\UseArnRegion\Exception\ConfigurationException}.
+ *
+ * <code>
+ * use Aws\S3\UseArnRegion\ConfigurationProvider;
+ * $provider = ConfigurationProvider::defaultProvider();
+ * // Returns a ConfigurationInterface or throws.
+ * $config = $provider()->wait();
+ * </code>
+ *
+ * Configuration providers can be composed to create configuration using
+ * conditional logic that can create different configurations in different
+ * environments. You can compose multiple providers into a single provider using
+ * {@see Aws\S3\UseArnRegion\ConfigurationProvider::chain}. This function
+ * accepts providers as variadic arguments and returns a new function that will
+ * invoke each provider until a successful configuration is returned.
+ *
+ * <code>
+ * // First try an INI file at this location.
+ * $a = ConfigurationProvider::ini(null, '/path/to/file.ini');
+ * // Then try an INI file at this location.
+ * $b = ConfigurationProvider::ini(null, '/path/to/other-file.ini');
+ * // Then try loading from environment variables.
+ * $c = ConfigurationProvider::env();
+ * // Combine the three providers together.
+ * $composed = ConfigurationProvider::chain($a, $b, $c);
+ * // Returns a promise that is fulfilled with a configuration or throws.
+ * $promise = $composed();
+ * // Wait on the configuration to resolve.
+ * $config = $promise->wait();
+ * </code>
+ */
+class ConfigurationProvider extends AbstractConfigurationProvider
+    implements ConfigurationProviderInterface
+{
+    const ENV_USE_ARN_REGION = 'AWS_S3_USE_ARN_REGION';
+    const INI_USE_ARN_REGION = 's3_use_arn_region';
+    const DEFAULT_USE_ARN_REGION = false;
+
+    public static $cacheKey = 'aws_s3_use_arn_region_config';
+
+    protected static $interfaceClass = ConfigurationInterface::class;
+    protected static $exceptionClass = ConfigurationException::class;
+
+    /**
+     * Create a default config provider that first checks for environment
+     * variables, then checks for a specified profile in the environment-defined
+     * config file location (env variable is 'AWS_CONFIG_FILE', file location
+     * defaults to ~/.aws/config), then checks for the "default" profile in the
+     * environment-defined config file location, and failing those uses a default
+     * fallback set of configuration options.
+     *
+     * This provider is automatically wrapped in a memoize function that caches
+     * previously provided config options.
+     *
+     * @param array $config
+     *
+     * @return callable
+     */
+    public static function defaultProvider(array $config = [])
+    {
+        $configProviders = [self::env()];
+        if (
+            !isset($config['use_aws_shared_config_files'])
+            || $config['use_aws_shared_config_files'] != false
+        ) {
+            $configProviders[] = self::ini();
+        }
+        $configProviders[] = self::fallback();
+
+        $memo = self::memoize(
+            call_user_func_array('self::chain', $configProviders)
+        );
+
+        if (isset($config['use_arn_region'])
+            && $config['use_arn_region'] instanceof CacheInterface
+        ) {
+            return self::cache($memo, $config['use_arn_region'], self::$cacheKey);
+        }
+
+        return $memo;
+    }
+
+    /**
+     * Provider that creates config from environment variables.
+     *
+     * @return callable
+     */
+    public static function env()
+    {
+        return function () {
+            // Use config from environment variables, if available
+            $useArnRegion = getenv(self::ENV_USE_ARN_REGION);
+            if (!empty($useArnRegion)) {
+                return Promise\promise_for(
+                    new Configuration($useArnRegion)
+                );
+            }
+
+            return self::reject('Could not find environment variable config'
+                . ' in ' . self::ENV_USE_ARN_REGION);
+        };
+    }
+
+    /**
+     * Config provider that creates config using a config file whose location
+     * is specified by an environment variable 'AWS_CONFIG_FILE', defaulting to
+     * ~/.aws/config if not specified
+     *
+     * @param string|null $profile  Profile to use. If not specified will use
+     *                              the "default" profile.
+     * @param string|null $filename If provided, uses a custom filename rather
+     *                              than looking in the default directory.
+     *
+     * @return callable
+     */
+    public static function ini($profile = null, $filename = null)
+    {
+        $filename = $filename ?: (self::getDefaultConfigFilename());
+        $profile = $profile ?: (getenv(self::ENV_PROFILE) ?: 'default');
+
+        return function () use ($profile, $filename) {
+            if (!is_readable($filename)) {
+                return self::reject("Cannot read configuration from $filename");
+            }
+
+            // Use INI_SCANNER_NORMAL instead of INI_SCANNER_TYPED for PHP 5.5 compatibility
+            $data = \Aws\parse_ini_file($filename, true, INI_SCANNER_NORMAL);
+            if ($data === false) {
+                return self::reject("Invalid config file: $filename");
+            }
+            if (!isset($data[$profile])) {
+                return self::reject("'$profile' not found in config file");
+            }
+            if (!isset($data[$profile][self::INI_USE_ARN_REGION])) {
+                return self::reject("Required S3 Use Arn Region config values 
+                    not present in INI profile '{$profile}' ({$filename})");
+            }
+
+            // INI_SCANNER_NORMAL parses false-y values as an empty string
+            if ($data[$profile][self::INI_USE_ARN_REGION] === "") {
+                $data[$profile][self::INI_USE_ARN_REGION] = false;
+            }
+
+            return Promise\promise_for(
+                new Configuration($data[$profile][self::INI_USE_ARN_REGION])
+            );
+        };
+    }
+
+    /**
+     * Fallback config options when other sources are not set.
+     *
+     * @return callable
+     */
+    public static function fallback()
+    {
+        return function () {
+            return Promise\promise_for(
+                new Configuration(self::DEFAULT_USE_ARN_REGION)
+            );
+        };
+    }
+}