<?php

/**
 * Patch testing component for the Joomla! CMS
 *
 * @copyright  Copyright (C) 2011 - 2012 Ian MacLennan, Copyright (C) 2013 - 2018 Open Source Matters, Inc. All rights reserved.
 * @license    GNU General Public License version 2 or later
 */

namespace Joomla\Component\Patchtester\Administrator\GitHub;

use Joomla\CMS\Http\Http;
use Joomla\CMS\Http\HttpFactory;
use Joomla\CMS\Http\Response;
use Joomla\CMS\Uri\Uri;
use Joomla\Component\Patchtester\Administrator\Github\Exception\UnexpectedResponse;
use Joomla\Registry\Registry;

/**
 * Helper class for interacting with the GitHub API.
 *
 * @since  3.0.0
 */
class GitHub
{
    /**
     * Options for the connector.
     *
     * @var    Registry
     * @since  3.0.0
     */
    protected $options;
/**
     * The HTTP client object to use in sending HTTP requests.
     *
     * @var    Http
     * @since  3.0.0
     */
    protected $client;
/**
     * Constructor.
     *
     * @param   Registry  $options  Connector options.
     * @param   Http      $client   The HTTP client object.
     *
     * @since   3.0.0
     */
    public function __construct(Registry $options = null, Http $client = null)
    {
        $this->options = $options ?: new Registry();
        $this->client  = $client ?: HttpFactory::getHttp($options);
    }

    /**
     * Get the HTTP client for this connector.
     *
     * @return  Http
     *
     * @since   3.0.0
     */
    public function getClient()
    {
        return $this->client;
    }

    /**
     * Get the diff for a pull request.
     *
     * @param   string   $user    The name of the owner of the GitHub repository.
     * @param   string   $repo    The name of the GitHub repository.
     * @param   integer  $pullId  The pull request number.
     *
     * @return  Response
     *
     * @since   3.0.0
     */
    public function getDiffForPullRequest($user, $repo, $pullId)
    {
        // Build the request path.
        $path = "/repos/$user/$repo/pulls/" . (int) $pullId;
// Build the request headers.
        $headers = array('Accept' => 'application/vnd.github.diff');
        $prepared = $this->prepareRequest($path, 0, 0, $headers);
        return $this->processResponse($this->client->get($prepared['url'], $prepared['headers']));
    }

    /**
     * Method to build and return a full request URL for the request.
     *
     * This method will add appropriate pagination details if necessary and also prepend the API url to have a complete URL for the request.
     *
     * @param   string   $path     Path to process
     * @param   integer  $page     Page to request
     * @param   integer  $limit    Number of results to return per page
     * @param   array    $headers  The headers to send with the request
     *
     * @return  array  Associative array containing the prepared URL and request headers
     *
     * @since   3.0.0
     */
    protected function prepareRequest(
        $path,
        $page = 0,
        $limit = 0,
        array $headers = array()
    ) {
        $url = $this->fetchUrl($path, $page, $limit);
        if ($token = $this->options->get('gh.token', false)) {
            $headers['Authorization'] = "token $token";
        }

        return array('url' => $url, 'headers' => $headers);
    }

    /**
     * Build and return a full request URL.
     *
     * This method will add appropriate pagination details and basic authentication credentials if necessary
     * and also prepend the API url to have a complete URL for the request.
     *
     * @param   string   $path   URL to inflect
     * @param   integer  $page   Page to request
     * @param   integer  $limit  Number of results to return per page
     *
     * @return  string   The request URL.
     *
     * @since   3.0.0
     */
    protected function fetchUrl($path, $page = 0, $limit = 0)
    {
        // Get a new Uri object using the API URL and given path.
        $uri = new Uri($this->options->get('api.url') . $path);
// If we have a defined page number add it to the JUri object.
        if ($page > 0) {
            $uri->setVar('page', (int) $page);
        }

        // If we have a defined items per page add it to the JUri object.
        if ($limit > 0) {
            $uri->setVar('per_page', (int) $limit);
        }

        return (string) $uri;
    }

    /**
     * Process the response and return it.
     *
     * @param   Response  $response      The response.
     * @param   integer   $expectedCode  The expected response code.
     *
     * @return  Response
     *
     * @throws  UnexpectedResponse
     *@since   3.0.0
     */
    protected function processResponse(Response $response, $expectedCode = 200)
    {
        // Validate the response code.
        if ($response->code != $expectedCode) {
// Decode the error response and throw an exception.
            $body  = json_decode($response->body);
            $error = isset($body->error) ? $body->error
                : (isset($body->message) ? $body->message : 'Unknown Error');

            throw new UnexpectedResponse(
                $response,
                $error,
                $response->code
            );
        }

        return $response;
    }

    /**
     * Get a file's contents from a repository.
     *
     * @param   string  $user  The name of the owner of the GitHub repository.
     * @param   string  $repo  The name of the GitHub repository.
     * @param   string  $path  The content path.
     * @param   string  $ref   The name of the commit/branch/tag. Default: the repository’s default branch (usually master)
     *
     * @return  Response
     *
     * @since   3.0.0
     */
    public function getFileContents($user, $repo, $path, $ref = null)
    {
        $path = "/repos/$user/$repo/contents/$path";
        $prepared = $this->prepareRequest($path);
        if ($ref) {
            $url = new Uri($prepared['url']);
            $url->setVar('ref', $ref);
            $prepared['url'] = (string) $url;
        }

        return $this->processResponse($this->client->get($prepared['url'], $prepared['headers']));
    }

    /**
     * Get the list of modified files for a pull request.
     *
     * @param   string   $user    The name of the owner of the GitHub repository.
     * @param   string   $repo    The name of the GitHub repository.
     * @param   integer  $pullId  The pull request number.
     *
     * @return  Response
     *
     * @since   3.0.0
     */
    public function getFilesForPullRequest($user, $repo, $pullId, $page = 1)
    {
        // Build the request path.
        $path = "/repos/$user/$repo/pulls/" . (int) $pullId . '/files?page=' . $page;
        $prepared = $this->prepareRequest($path);
        return $this->processResponse($this->client->get($prepared['url'], $prepared['headers']));
    }

    /**
     * Get a list of the open issues for a repository.
     *
     * @param   string   $user   The name of the owner of the GitHub repository.
     * @param   string   $repo   The name of the GitHub repository.
     * @param   integer  $page   The page number from which to get items.
     * @param   integer  $limit  The number of items on a page.
     *
     * @return  Response
     *
     * @since   3.0.0
     */
    public function getOpenIssues($user, $repo, $page = 0, $limit = 0)
    {
        $prepared = $this->prepareRequest(
            "/repos/$user/$repo/issues",
            $page,
            $limit
        );
        return $this->processResponse($this->client->get($prepared['url'], $prepared['headers']));
    }

    /**
     * Get a list of the open pull requests for a repository.
     *
     * @param   string   $user   The name of the owner of the GitHub repository.
     * @param   string   $repo   The name of the GitHub repository.
     * @param   integer  $page   The page number from which to get items.
     * @param   integer  $limit  The number of items on a page.
     *
     * @return  Response
     *
     * @since   3.0.0
     */
    public function getOpenPulls($user, $repo, $page = 0, $limit = 0)
    {
        $prepared = $this->prepareRequest(
            "/repos/$user/$repo/pulls",
            $page,
            $limit
        );
        return $this->processResponse($this->client->get($prepared['url'], $prepared['headers']));
    }

    /**
     * Get an option from the connector.
     *
     * @param   string  $key      The name of the option to get.
     * @param   mixed   $default  The default value if the option is not set.
     *
     * @return  mixed  The option value.
     *
     * @since   3.0.0
     */
    public function getOption($key, $default = null)
    {
        return $this->options->get($key, $default);
    }

    /**
     * Get a single pull request.
     *
     * @param   string   $user    The name of the owner of the GitHub repository.
     * @param   string   $repo    The name of the GitHub repository.
     * @param   integer  $pullId  The pull request number.
     *
     * @return  Response
     *
     * @since   3.0.0
     */
    public function getPullRequest($user, $repo, $pullId)
    {
        // Build the request path.
        $path = "/repos/$user/$repo/pulls/" . (int) $pullId;
        $prepared = $this->prepareRequest($path);
        return $this->processResponse($this->client->get($prepared['url'], $prepared['headers']));
    }

    /**
     * Get the rate limit for the authenticated user.
     *
     * @return  Response
     *
     * @since   3.0.0
     */
    public function getRateLimit()
    {
        $prepared = $this->prepareRequest('/rate_limit');
        return $this->processResponse($this->client->get($prepared['url'], $prepared['headers']));
    }

    /**
     * Set an option for the connector.
     *
     * @param   string  $key    The name of the option to set.
     * @param   mixed   $value  The option value to set.
     *
     * @return  $this
     *
     * @since   3.0.0
     */
    public function setOption($key, $value)
    {
        $this->options->set($key, $value);
        return $this;
    }
}