<?php

namespace UglyRobot\Infinite_Uploads\Aws\EndpointDiscovery;

use UglyRobot\Infinite_Uploads\Aws\AwsClient;
use UglyRobot\Infinite_Uploads\Aws\CacheInterface;
use UglyRobot\Infinite_Uploads\Aws\CommandInterface;
use UglyRobot\Infinite_Uploads\Aws\Credentials\CredentialsInterface;
use UglyRobot\Infinite_Uploads\Aws\Exception\AwsException;
use UglyRobot\Infinite_Uploads\Aws\Exception\UnresolvedEndpointException;
use UglyRobot\Infinite_Uploads\Aws\LruArrayCache;
use UglyRobot\Infinite_Uploads\Aws\Middleware;
use UglyRobot\Infinite_Uploads\Psr\Http\Message\RequestInterface;
use UglyRobot\Infinite_Uploads\Psr\Http\Message\UriInterface;
class EndpointDiscoveryMiddleware
{
    /**
     * @var CacheInterface
     */
    private static $cache;
    private static $discoveryCooldown = 60;
    private $args;
    private $client;
    private $config;
    private $discoveryTimes = [];
    private $nextHandler;
    private $service;
    public static function wrap($client, $args, $config)
    {
        return function (callable $handler) use($client, $args, $config) {
            return new static($handler, $client, $args, $config);
        };
    }
    public function __construct(callable $handler, \UglyRobot\Infinite_Uploads\Aws\AwsClient $client, array $args, $config)
    {
        $this->nextHandler = $handler;
        $this->client = $client;
        $this->args = $args;
        $this->service = $client->getApi();
        $this->config = $config;
    }
    public function __invoke(\UglyRobot\Infinite_Uploads\Aws\CommandInterface $cmd, \UglyRobot\Infinite_Uploads\Psr\Http\Message\RequestInterface $request)
    {
        $nextHandler = $this->nextHandler;
        $op = $this->service->getOperation($cmd->getName())->toArray();
        // Continue only if endpointdiscovery trait is set
        if (isset($op['endpointdiscovery'])) {
            $config = \UglyRobot\Infinite_Uploads\Aws\EndpointDiscovery\ConfigurationProvider::unwrap($this->config);
            $isRequired = !empty($op['endpointdiscovery']['required']);
            if ($isRequired && !$config->isEnabled()) {
                throw new \UglyRobot\Infinite_Uploads\Aws\Exception\UnresolvedEndpointException('This operation ' . 'requires the use of endpoint discovery, but this has ' . 'been disabled in the configuration. Enable endpoint ' . 'discovery or use a different operation.');
            }
            // Continue only if enabled by config
            if ($config->isEnabled()) {
                if (isset($op['endpointoperation'])) {
                    throw new \UglyRobot\Infinite_Uploads\Aws\Exception\UnresolvedEndpointException('This operation is ' . 'contradictorily marked both as using endpoint discovery ' . 'and being the endpoint discovery operation. Please ' . 'verify the accuracy of your model files.');
                }
                // Original endpoint may be used if discovery optional
                $originalUri = $request->getUri();
                $identifiers = $this->getIdentifiers($op);
                $cacheKey = $this->getCacheKey($this->client->getCredentials()->wait(), $cmd, $identifiers);
                // Check/create cache
                if (!isset(self::$cache)) {
                    self::$cache = new \UglyRobot\Infinite_Uploads\Aws\LruArrayCache($config->getCacheLimit());
                }
                if (empty($endpointList = self::$cache->get($cacheKey))) {
                    $endpointList = new \UglyRobot\Infinite_Uploads\Aws\EndpointDiscovery\EndpointList([]);
                }
                $endpoint = $endpointList->getActive();
                // Retrieve endpoints if there is no active endpoint
                if (empty($endpoint)) {
                    try {
                        $endpoint = $this->discoverEndpoint($cacheKey, $cmd, $identifiers);
                    } catch (\Exception $e) {
                        // Use cached endpoint, expired or active, if any remain
                        $endpoint = $endpointList->getEndpoint();
                        if (empty($endpoint)) {
                            return $this->handleDiscoveryException($isRequired, $originalUri, $e, $cmd, $request);
                        }
                    }
                }
                $request = $this->modifyRequest($request, $endpoint);
                $g = function ($value) use($cacheKey, $cmd, $identifiers, $isRequired, $originalUri, $request, &$endpoint, &$g) {
                    if ($value instanceof AwsException && ($value->getAwsErrorCode() == 'InvalidEndpointException' || $value->getStatusCode() == 421)) {
                        return $this->handleInvalidEndpoint($cacheKey, $cmd, $identifiers, $isRequired, $originalUri, $request, $value, $endpoint, $g);
                    }
                    return $value;
                };
                return $nextHandler($cmd, $request)->otherwise($g);
            }
        }
        return $nextHandler($cmd, $request);
    }
    private function discoverEndpoint($cacheKey, \UglyRobot\Infinite_Uploads\Aws\CommandInterface $cmd, array $identifiers)
    {
        $discCmd = $this->getDiscoveryCommand($cmd, $identifiers);
        $this->discoveryTimes[$cacheKey] = time();
        $result = $this->client->execute($discCmd);
        if (isset($result['Endpoints'])) {
            $endpointData = [];
            foreach ($result['Endpoints'] as $datum) {
                $endpointData[$datum['Address']] = time() + $datum['CachePeriodInMinutes'] * 60;
            }
            $endpointList = new \UglyRobot\Infinite_Uploads\Aws\EndpointDiscovery\EndpointList($endpointData);
            self::$cache->set($cacheKey, $endpointList);
            return $endpointList->getEndpoint();
        }
        throw new \UglyRobot\Infinite_Uploads\Aws\Exception\UnresolvedEndpointException('The endpoint discovery operation ' . 'yielded a response that did not contain properly formatted ' . 'endpoint data.');
    }
    private function getCacheKey(\UglyRobot\Infinite_Uploads\Aws\Credentials\CredentialsInterface $creds, \UglyRobot\Infinite_Uploads\Aws\CommandInterface $cmd, array $identifiers)
    {
        $key = $this->service->getServiceName() . '_' . $creds->getAccessKeyId();
        if (!empty($identifiers)) {
            $key .= '_' . $cmd->getName();
            foreach ($identifiers as $identifier) {
                $key .= "_{$cmd[$identifier]}";
            }
        }
        return $key;
    }
    private function getDiscoveryCommand(\UglyRobot\Infinite_Uploads\Aws\CommandInterface $cmd, array $identifiers)
    {
        foreach ($this->service->getOperations() as $op) {
            if (isset($op['endpointoperation'])) {
                $endpointOperation = $op->toArray()['name'];
                break;
            }
        }
        if (!isset($endpointOperation)) {
            throw new \UglyRobot\Infinite_Uploads\Aws\Exception\UnresolvedEndpointException('This command is set to use ' . 'endpoint discovery, but no endpoint discovery operation was ' . 'found. Please verify the accuracy of your model files.');
        }
        $params = [];
        if (!empty($identifiers)) {
            $params['Operation'] = $cmd->getName();
            $params['Identifiers'] = [];
            foreach ($identifiers as $identifier) {
                $params['Identifiers'][$identifier] = $cmd[$identifier];
            }
        }
        $command = $this->client->getCommand($endpointOperation, $params);
        $command->getHandlerList()->appendBuild(\UglyRobot\Infinite_Uploads\Aws\Middleware::mapRequest(function (\UglyRobot\Infinite_Uploads\Psr\Http\Message\RequestInterface $r) {
            return $r->withHeader('x-amz-api-version', $this->service->getApiVersion());
        }), 'x-amz-api-version-header');
        return $command;
    }
    private function getIdentifiers(array $operation)
    {
        $inputShape = $this->service->getShapeMap()->resolve($operation['input'])->toArray();
        $identifiers = [];
        foreach ($inputShape['members'] as $key => $member) {
            if (!empty($member['endpointdiscoveryid'])) {
                $identifiers[] = $key;
            }
        }
        return $identifiers;
    }
    private function handleDiscoveryException($isRequired, $originalUri, \Exception $e, \UglyRobot\Infinite_Uploads\Aws\CommandInterface $cmd, \UglyRobot\Infinite_Uploads\Psr\Http\Message\RequestInterface $request)
    {
        // If no cached endpoints and discovery required,
        // throw exception
        if ($isRequired) {
            $message = 'The endpoint required for this service is currently ' . 'unable to be retrieved, and your request can not be fulfilled ' . 'unless you manually specify an endpoint.';
            throw new \UglyRobot\Infinite_Uploads\Aws\Exception\AwsException($message, $cmd, ['code' => 'EndpointDiscoveryException', 'message' => $message], $e);
        }
        // If discovery isn't required, use original endpoint
        return $this->useOriginalUri($originalUri, $cmd, $request);
    }
    private function handleInvalidEndpoint($cacheKey, $cmd, $identifiers, $isRequired, $originalUri, $request, $value, &$endpoint, &$g)
    {
        $nextHandler = $this->nextHandler;
        $endpointList = self::$cache->get($cacheKey);
        if ($endpointList instanceof EndpointList) {
            // Remove invalid endpoint from cached list
            $endpointList->remove($endpoint);
            // If possible, get another cached endpoint
            $newEndpoint = $endpointList->getEndpoint();
        }
        if (empty($newEndpoint)) {
            // If no more cached endpoints, make discovery call
            // if none made within cooldown for given key
            if (time() - $this->discoveryTimes[$cacheKey] < self::$discoveryCooldown) {
                // If no more cached endpoints and it's required,
                // fail with original exception
                if ($isRequired) {
                    return $value;
                }
                // Use original endpoint if not required
                return $this->useOriginalUri($originalUri, $cmd, $request);
            }
            $newEndpoint = $this->discoverEndpoint($cacheKey, $cmd, $identifiers);
        }
        $endpoint = $newEndpoint;
        $request = $this->modifyRequest($request, $endpoint);
        return $nextHandler($cmd, $request)->otherwise($g);
    }
    private function modifyRequest(\UglyRobot\Infinite_Uploads\Psr\Http\Message\RequestInterface $request, $endpoint)
    {
        $parsed = $this->parseEndpoint($endpoint);
        if (!empty($request->getHeader('User-Agent'))) {
            $userAgent = $request->getHeader('User-Agent')[0];
            if (strpos($userAgent, 'endpoint-discovery') === false) {
                $userAgent = $userAgent . ' endpoint-discovery';
            }
        } else {
            $userAgent = 'endpoint-discovery';
        }
        return $request->withUri($request->getUri()->withHost($parsed['host'])->withPath($parsed['path']))->withHeader('User-Agent', $userAgent);
    }
    /**
     * Parses an endpoint returned from the discovery API into an array with
     * 'host' and 'path' keys.
     *
     * @param $endpoint
     * @return array
     */
    private function parseEndpoint($endpoint)
    {
        $parsed = parse_url($endpoint);
        // parse_url() will correctly parse full URIs with schemes
        if (isset($parsed['host'])) {
            return $parsed;
        }
        // parse_url() will put host & path in 'path' if scheme is not provided
        if (isset($parsed['path'])) {
            $split = explode('/', $parsed['path'], 2);
            $parsed['host'] = $split[0];
            if (isset($split[1])) {
                $parsed['path'] = $split[1];
            } else {
                $parsed['path'] = '';
            }
            return $parsed;
        }
        throw new \UglyRobot\Infinite_Uploads\Aws\Exception\UnresolvedEndpointException("The supplied endpoint '" . "{$endpoint}' is invalid.");
    }
    private function useOriginalUri(\UglyRobot\Infinite_Uploads\Psr\Http\Message\UriInterface $uri, \UglyRobot\Infinite_Uploads\Aws\CommandInterface $cmd, \UglyRobot\Infinite_Uploads\Psr\Http\Message\RequestInterface $request)
    {
        $nextHandler = $this->nextHandler;
        $endpoint = $uri->getHost() . $uri->getPath();
        $request = $this->modifyRequest($request, $endpoint);
        return $nextHandler($cmd, $request);
    }
}