<?php
namespace Aws;

use Aws\Endpoint\PartitionEndpointProvider;
use Aws\Endpoint\PartitionInterface;

class MultiRegionClient implements AwsClientInterface
{
    use AwsClientTrait;

    /** @var AwsClientInterface[] A pool of clients keyed by region. */
    private $clientPool = [];
    /** @var callable */
    private $factory;
    /** @var PartitionInterface */
    private $partition;
    /** @var array */
    private $args;
    /** @var array */
    private $config;
    /** @var HandlerList */
    private $handlerList;
    /** @var array */
    private $aliases;

    public static function getArguments()
    {
        $args = array_intersect_key(
            ClientResolver::getDefaultArguments(),
            ['service' => true, 'region' => true]
        );
        $args['region']['required'] = false;

        return $args + [
            'client_factory' => [
                'type' => 'config',
                'valid' => ['callable'],
                'doc' => 'A callable that takes an array of client'
                    . ' configuration arguments and returns a regionalized'
                    . ' client.',
                'required' => true,
                'internal' => true,
                'default' => function (array $args) {
                    $namespace = manifest($args['service'])['namespace'];
                    $klass = "Aws\\{$namespace}\\{$namespace}Client";
                    $region = isset($args['region']) ? $args['region'] : null;

                    return function (array $args) use ($klass, $region) {
                        if ($region && empty($args['region'])) {
                            $args['region'] = $region;
                        }

                        return new $klass($args);
                    };
                },
            ],
            'partition' => [
                'type'    => 'config',
                'valid'   => ['string', PartitionInterface::class],
                'doc'     => 'AWS partition to connect to. Valid partitions'
                    . ' include "aws," "aws-cn," and "aws-us-gov." Used to'
                    . ' restrict the scope of the mapRegions method.',
                'default' => function (array $args) {
                    $region = isset($args['region']) ? $args['region'] : '';
                    return PartitionEndpointProvider::defaultProvider()
                        ->getPartition($region, $args['service']);
                },
                'fn'      => function ($value, array &$args) {
                    if (is_string($value)) {
                        $value = PartitionEndpointProvider::defaultProvider()
                            ->getPartitionByName($value);
                    }

                    if (!$value instanceof PartitionInterface) {
                        throw new \InvalidArgumentException('No valid partition'
                            . ' was provided. Provide a concrete partition or'
                            . ' the name of a partition (e.g., "aws," "aws-cn,"'
                            . ' or "aws-us-gov").'
                        );
                    }

                    $args['partition'] = $value;
                    $args['endpoint_provider'] = $value;
                }
            ],
        ];
    }

    /**
     * The multi-region client constructor accepts the following options:
     *
     * - client_factory: (callable) An optional callable that takes an array of
     *   client configuration arguments and returns a regionalized client.
     * - partition: (Aws\Endpoint\Partition|string) AWS partition to connect to.
     *   Valid partitions include "aws," "aws-cn," and "aws-us-gov." Used to
     *   restrict the scope of the mapRegions method.
     * - region: (string) Region to connect to when no override is provided.
     *   Used to create the default client factory and determine the appropriate
     *   AWS partition when present.
     *
     * @param array $args Client configuration arguments.
     */
    public function __construct(array $args = [])
    {
        if (!isset($args['service'])) {
            $args['service'] = $this->parseClass();
        }

        $this->handlerList = new HandlerList(function (
            CommandInterface $command
        ) {
            list($region, $args) = $this->getRegionFromArgs($command->toArray());
            $command = $this->getClientFromPool($region)
                ->getCommand($command->getName(), $args);
            return $this->executeAsync($command);
        });

        $argDefinitions = static::getArguments();
        $resolver = new ClientResolver($argDefinitions);
        $args = $resolver->resolve($args, $this->handlerList);
        $this->config = $args['config'];
        $this->factory = $args['client_factory'];
        $this->partition = $args['partition'];
        $this->args = array_diff_key($args, $args['config']);
    }

    /**
     * Get the region to which the client is configured to send requests by
     * default.
     *
     * @return string
     */
    public function getRegion()
    {
        return $this->getClientFromPool()->getRegion();
    }

    /**
     * Create a command for an operation name.
     *
     * Special keys may be set on the command to control how it behaves,
     * including:
     *
     * - @http: Associative array of transfer specific options to apply to the
     *   request that is serialized for this command. Available keys include
     *   "proxy", "verify", "timeout", "connect_timeout", "debug", "delay", and
     *   "headers".
     * - @region: The region to which the command should be sent.
     *
     * @param string $name Name of the operation to use in the command
     * @param array  $args Arguments to pass to the command
     *
     * @return CommandInterface
     * @throws \InvalidArgumentException if no command can be found by name
     */
    public function getCommand($name, array $args = [])
    {
        return new Command($name, $args, clone $this->getHandlerList());
    }

    public function getConfig($option = null)
    {
        if (null === $option) {
            return $this->config;
        }

        if (isset($this->config[$option])) {
            return $this->config[$option];
        }

        return $this->getClientFromPool()->getConfig($option);
    }

    public function getCredentials()
    {
        return $this->getClientFromPool()->getCredentials();
    }

    public function getHandlerList()
    {
        return $this->handlerList;
    }

    public function getApi()
    {
        return $this->getClientFromPool()->getApi();
    }

    public function getEndpoint()
    {
        return $this->getClientFromPool()->getEndpoint();
    }

    /**
     * @param string $region    Omit this argument or pass in an empty string to
     *                          allow the configured client factory to apply the
     *                          region.
     *
     * @return AwsClientInterface
     */
    protected function getClientFromPool($region = '')
    {
        if (empty($this->clientPool[$region])) {
            $factory = $this->factory;
            $this->clientPool[$region] = $factory(
                array_replace($this->args, array_filter(['region' => $region]))
            );
        }

        return $this->clientPool[$region];
    }

    /**
     * Parse the class name and return the "service" name of the client.
     *
     * @return string
     */
    private function parseClass()
    {
        $klass = get_class($this);

        if ($klass === __CLASS__) {
            return '';
        }

        return strtolower(substr($klass, strrpos($klass, '\\') + 1, -17));
    }

    private function getRegionFromArgs(array $args)
    {
        $region = isset($args['@region'])
            ? $args['@region']
            : $this->getRegion();
        unset($args['@region']);

        return [$region, $args];
    }
}