<?php

    /**
     * Server OAuth Handler for iOS App
     *
     * iOS App launches Safari to this page on SecretHandshake server
     * This page sends the user to the Hacker School login page to get authorization code
     * It takes the auth code and sends it back to the server to get an access token
     * It redirects the user back to the app via a custom URL scheme
     * and sends the access and refresh tokens as query parameters to the app
     * which stores them for future use.
     */

    function getAuthenticationUrl($auth_endpoint, $client_id, $redirect_uri)
    {
        $parameters = array(
                                        'response_type' => 'code',
                                        'client_id'     => $client_id,
                                        'redirect_uri'  => $redirect_uri
                                        );
        return $auth_endpoint . '?' . http_build_query($parameters, null, '&');
    }

    function getAccessToken($token_endpoint, $grant_type, array $parameters, $client_id, $client_secret)
    {
        $parameters['grant_type'] = $grant_type;
        $parameters['client_id'] = $client_id;
        $parameters['client_secret'] = $client_secret;

        $http_headers = array();

        return executeRequest($token_endpoint, $parameters, 'POST', $http_headers, 0);
    }

    function executeRequest($url, $parameters = array(), $http_method = 'POST', array $http_headers = null, $form_content_type = 0)
    {

        $postBody = http_build_query($parameters);
        $requestHttpContext["content"] = $postBody;
        $requestHttpContext["method"] = 'POST';

        $options = array( 'http' => $requestHttpContext );
        $context = stream_context_create( $options );

        $response = file_get_contents($url, false, $context);

        return $response;

    }

    $client_id = 'my-client-id';
    $client_secret = 'my-client-secret';
    $authorization_endpoint = 'my-authorization-endpoint';
    $redirect_uri = 'my-redirect-uri';
    $token_endpoint = 'my-token-endpoint';


    if (!isset($_GET['code']))
    {
        $auth_url = getAuthenticationUrl($authorization_endpoint, $client_id, $redirect_uri);
        header('Location: ' . $auth_url);
        die('Redirect');
    } else {
        $params = array(
                        'code' => $_GET['code'],
                        'redirect_uri' => $redirect_uri
                        );

        $response = getAccessToken($token_endpoint, 'authorization_code', $params, $client_id, $client_secret);

        $info = json_decode($response, true);
        $querystring = http_build_query($info);
        $appurl = 'secrethandshake://oauth' . '?' . $querystring;
        header('Location: ' . $appurl);
        die('Redirect');

    }

?>

- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation
{
    // secrethandshake://oauth?access_token=324235253442

    if ([[url host] isEqualToString:@"oauth"]) {
        // parse the authentication code query
        [self authorizeFromExternalURL:url];
    }

    return YES;
}

- (void)authorizeFromExternalURL:(NSURL *)url
{
    [[OAuthHandler sharedHandler] handleAuthTokenURL:url];
}

-(void)handleAuthTokenURL:(NSURL *)url
{
    // handle query here
    NSDictionary *dict = [self parseQueryString:[url query]];

    if ([dict objectForKey:@"error"] != nil) {
        [self.delegate oauthHandlerDidFailWithError:[dict objectForKey:@"error"]];
    } else if ([dict objectForKey:@"access_token"] != nil && [dict objectForKey:@"refresh_token"] != nil) {
        // Save the access token and refresh token
        [[NSUserDefaults standardUserDefaults] setObject:[dict objectForKey:@"access_token"] forKey:kSHAccessTokenKey];
        [[NSUserDefaults standardUserDefaults] setObject:[dict objectForKey:@"refresh_token"] forKey:kSHRefreshTokenKey];

        [self.delegate oauthHandlerDidAuthorize];
    } else {
        [self.delegate oauthHandlerDidFailWithError:@"Access token not found. Failed to log in to Hacker School."];
    }

}

- (NSDictionary *)parseQueryString:(NSString *)query
{
    NSMutableDictionary *dict = [[NSMutableDictionary alloc] initWithCapacity:6];
    NSArray *pairs = [query componentsSeparatedByString:@"&"];

    for (NSString *pair in pairs) {
        NSArray *elements = [pair componentsSeparatedByString:@"="];
        NSString *key = [[elements objectAtIndex:0] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];
        NSString *val = [[elements objectAtIndex:1] stringByReplacingPercentEscapesUsingEncoding:NSUTF8StringEncoding];

        [dict setObject:val forKey:key];
        elements = nil;
        key = nil;
        val = nil;
    }
    pairs = nil;
    return dict;
}

-(void)refreshToken:(id)sender
{
    NSURL *tokenURL = [NSURL URLWithString:@"https://www.hackerschool.com/oauth/token"];
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:tokenURL];

    [request setHTTPMethod:@"POST"];
    NSString *postString = [NSString stringWithFormat:@"grant_type=refresh_token&client_id=%@&client_secret=%@&refresh_token=%@", kMyClientID, kMyClientSecret, [[NSUserDefaults standardUserDefaults] objectForKey:kSHRefreshTokenKey]];
    [request setHTTPBody:[postString dataUsingEncoding:NSUTF8StringEncoding]];

    [NSURLConnection sendAsynchronousRequest:request
                                       queue:[NSOperationQueue mainQueue]
                           completionHandler:^(NSURLResponse *response, NSData *data, NSError *error) {

                               NSString *responseBody = [ [NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];

                               NSLog(@"response: %@", responseBody);

                               NSData *jsonData = [responseBody dataUsingEncoding:NSUTF8StringEncoding];
                               NSError *e;
                               NSDictionary *jsonDict = [NSJSONSerialization JSONObjectWithData:jsonData options:NSJSONReadingAllowFragments error:&e];

                               if (e != nil) {
                                   NSLog(@"error: %@", e);
                                   [self launchExternalSignIn:nil];
                               } else if ([jsonDict objectForKey:@"error"] != nil){
                                   NSLog(@"error refreshing token: %@", [jsonDict objectForKey:@"error"]);
                                   [self launchExternalSignIn:nil];
                               } else {
                                   [[NSUserDefaults standardUserDefaults] setObject:[jsonDict objectForKey:@"access_token"] forKey:kSHAccessTokenKey];
                                   [[NSUserDefaults standardUserDefaults] setObject:[jsonDict objectForKey:@"refresh_token"] forKey:kSHRefreshTokenKey];
                                   [self.delegate oauthHandlerDidAuthorize];
                               }

                           }];

}