<?php

namespace Aws\S3;

use Aws\Api\TimestampShape as TimestampShape;
use Aws\Credentials\CredentialsInterface;
use Aws\Signature\SignatureTrait;
use Aws\Signature\SignatureV4 as SignatureV4;
use GuzzleHttp\Psr7\Uri;

/**
 * Encapsulates the logic for getting the data for an S3 object POST upload form
 *
 * @link http://docs.aws.amazon.com/AmazonS3/latest/API/RESTObjectPOST.html
 * @link http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-post-example.html
 */
class PostObjectV4 {
	use SignatureTrait;

	private $client;
	private $bucket;
	private $formAttributes;
	private $formInputs;

	/**
	 * Constructs the PostObject.
	 *
	 * The options array accepts the following keys:
	 * @link http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-query-string-auth.html
	 *
	 * @param S3ClientInterface $client Client used with the POST object
	 * @param string $bucket Bucket to use
	 * @param array $formInputs Associative array of form input
	 *                                      fields.
	 * @param array $options Policy condition options
	 * @param mixed $expiration Upload expiration time value. By
	 *                                      default: 1 hour valid period.
	 */
	public function __construct(
		S3ClientInterface $client,
		$bucket,
		array $formInputs,
		array $options = [],
		$expiration = '+1 hours'
	) {
		$this->client = $client;
		$this->bucket = $bucket;

		// setup form attributes
		$this->formAttributes = [
			'action'  => $this->generateUri(),
			'method'  => 'POST',
			'enctype' => 'multipart/form-data'
		];

		$credentials = $this->client->getCredentials()->wait();

		if ( $securityToken = $credentials->getSecurityToken() ) {
			array_push( $options, [ 'x-amz-security-token' => $securityToken ] );
			$formInputs['X-Amz-Security-Token'] = $securityToken;
		}

		// setup basic policy
		$policy = [
			'expiration' => TimestampShape::format( $expiration, 'iso8601' ),
			'conditions' => $options,
		];

		// setup basic formInputs
		$this->formInputs = $formInputs + [ 'key' => '${filename}' ];

		// finalize policy and signature

		$this->formInputs += $this->getPolicyAndSignature(
			$credentials,
			$policy
		);
	}

	private function generateUri() {
		$uri = new Uri( $this->client->getEndpoint() );

		if ( $this->client->getConfig( 'use_path_style_endpoint' ) === true
		     || ( $uri->getScheme() === 'https'
		          && strpos( $this->bucket, '.' ) !== false )
		) {
			// Use path-style URLs
			$uri = $uri->withPath( "/{$this->bucket}" );
		} else {
			// Use virtual-style URLs if haven't been set up already
			if ( strpos( $uri->getHost(), $this->bucket . '.' ) !== 0 ) {
				$uri = $uri->withHost( $this->bucket . '.' . $uri->getHost() );
			}
		}

		return (string) $uri;
	}

	protected function getPolicyAndSignature(
		CredentialsInterface $credentials,
		array $policy
	) {
		$ldt                    = gmdate( SignatureV4::ISO8601_BASIC );
		$sdt                    = substr( $ldt, 0, 8 );
		$policy['conditions'][] = [ 'X-Amz-Date' => $ldt ];

		$region                 = $this->client->getRegion();
		$scope                  = $this->createScope( $sdt, $region, 's3' );
		$creds                  = "{$credentials->getAccessKeyId()}/$scope";
		$policy['conditions'][] = [ 'X-Amz-Credential' => $creds ];

		$policy['conditions'][] = [ 'X-Amz-Algorithm' => "AWS4-HMAC-SHA256" ];

		$jsonPolicy64 = base64_encode( json_encode( $policy ) );
		$key          = $this->getSigningKey(
			$sdt,
			$region,
			's3',
			$credentials->getSecretKey()
		);

		return [
			'X-Amz-Credential' => $creds,
			'X-Amz-Algorithm'  => "AWS4-HMAC-SHA256",
			'X-Amz-Date'       => $ldt,
			'Policy'           => $jsonPolicy64,
			'X-Amz-Signature'  => bin2hex(
				hash_hmac( 'sha256', $jsonPolicy64, $key, true )
			),
		];
	}

	/**
	 * Gets the S3 client.
	 *
	 * @return S3ClientInterface
	 */
	public function getClient() {
		return $this->client;
	}

	/**
	 * Gets the bucket name.
	 *
	 * @return string
	 */
	public function getBucket() {
		return $this->bucket;
	}

	/**
	 * Gets the form attributes as an array.
	 *
	 * @return array
	 */
	public function getFormAttributes() {
		return $this->formAttributes;
	}

	/**
	 * Set a form attribute.
	 *
	 * @param string $attribute Form attribute to set.
	 * @param string $value Value to set.
	 */
	public function setFormAttribute( $attribute, $value ) {
		$this->formAttributes[ $attribute ] = $value;
	}

	/**
	 * Gets the form inputs as an array.
	 *
	 * @return array
	 */
	public function getFormInputs() {
		return $this->formInputs;
	}

	/**
	 * Set a form input.
	 *
	 * @param string $field Field name to set
	 * @param string $value Value to set.
	 */
	public function setFormInput( $field, $value ) {
		$this->formInputs[ $field ] = $value;
	}
}
