(C++) Shopify OAuth2 Authentication

Demonstrates obtaining an access token for a Shopify application using OAuth2 authentication. This example is for non-web-apps, and requires that a browser window be displayed to get authorization from the user.

A web-based application would not obtain an OAuth2 token in this way, because the redirect URL would route back to the web application.

Note: Once an access token is in hand, the remainder of the Chilkat examples, which use an already-obtained access token, apply to both web and non-web apps.

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#include <CkOAuth2.h>
#include <CkStringBuilder.h>

void ChilkatSample(void)
    {
    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkOAuth2 oauth2;
    bool success;

    // This should be the port in the localhost callback URL for your app.  
    // The callback URL would look like "http://localhost:3017/" if the port number is 3017.
    // Make sure that "http://localhost:3017/" is listed in your Whitelisted Redirection URLs for your Shopify app.
    oauth2.put_ListenPort(3017);

    // The full content of the Authorization Endpoin for Shopify looks like this:
    // https://{shop}.myshopify.com/admin/oauth/authorize?client_id={api_key}&scope={scopes}&redirect_uri={redirect_uri}&state={nonce}&grant_options[]={option}

    // Replace "chilkat" with your shop name.
    oauth2.put_AuthorizationEndpoint("https://chilkat.myshopify.com/admin/oauth/authorize");
    oauth2.put_TokenEndpoint("https://chilkat.myshopify.com/admin/oauth/access_token");

    // Replace these with actual values.
    oauth2.put_ClientId("SHOPIFY_API_KEY");
    oauth2.put_ClientSecret("SHOPIFY_API_SECRET_KEY");

    oauth2.put_CodeChallenge(true);
    oauth2.put_CodeChallengeMethod("S256");

    // Set requested scopes.  See https://help.shopify.com/api/getting-started/authentication/oauth
    oauth2.put_Scope("read_product_listings,read_customers,read_orders,read_draft_orders");

    // Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
    const char *url = oauth2.startAuth();
    if (oauth2.get_LastMethodSuccess() != true) {
        std::cout << oauth2.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "url: " << url << "\r\n";

    // At this point, your application should load the URL in a browser.
    // For example, 
    // in C#: System.Diagnostics.Process.Start(url);
    // in Java: Desktop.getDesktop().browse(new URI(url));
    // in VBScript: Set wsh=WScript.CreateObject("WScript.Shell")
    //              wsh.Run url
    // in Xojo: ShowURL(url)  (see http://docs.xojo.com/index.php/ShowURL)
    // in Dataflex: Runprogram Background "c:\Program Files\Internet Explorer\iexplore.exe" sUrl        
    // The Google account owner would interactively accept or deny the authorization request.

    // Add the code to load the url in a web browser here...
    // Add the code to load the url in a web browser here...
    // Add the code to load the url in a web browser here...
    // System.Diagnostics.Process.Start(url);

    // Now wait for the authorization.
    // We'll wait for a max of 30 seconds.
    int numMsWaited = 0;
    while ((numMsWaited < 30000) && (oauth2.get_AuthFlowState() < 3)) {
        oauth2.SleepMs(100);
        numMsWaited = numMsWaited + 100;
    }

    // If there was no response from the browser within 30 seconds, then 
    // the AuthFlowState will be equal to 1 or 2.
    // 1: Waiting for Redirect. The OAuth2 background thread is waiting to receive the redirect HTTP request from the browser.
    // 2: Waiting for Final Response. The OAuth2 background thread is waiting for the final access token response.
    // In that case, cancel the background task started in the call to StartAuth.
    if (oauth2.get_AuthFlowState() < 3) {
        oauth2.Cancel();
        std::cout << "No response from the browser!" << "\r\n";
        return;
    }

    // Check the AuthFlowState to see if authorization was granted, denied, or if some error occurred
    // The possible AuthFlowState values are:
    // 3: Completed with Success. The OAuth2 flow has completed, the background thread exited, and the successful JSON response is available in AccessTokenResponse property.
    // 4: Completed with Access Denied. The OAuth2 flow has completed, the background thread exited, and the error JSON is available in AccessTokenResponse property.
    // 5: Failed Prior to Completion. The OAuth2 flow failed to complete, the background thread exited, and the error information is available in the FailureInfo property.
    if (oauth2.get_AuthFlowState() == 5) {
        std::cout << "OAuth2 failed to complete." << "\r\n";
        std::cout << oauth2.failureInfo() << "\r\n";
        return;
    }

    if (oauth2.get_AuthFlowState() == 4) {
        std::cout << "OAuth2 authorization was denied." << "\r\n";
        std::cout << oauth2.accessTokenResponse() << "\r\n";
        return;
    }

    if (oauth2.get_AuthFlowState() != 3) {
        std::cout << "Unexpected AuthFlowState:" << oauth2.get_AuthFlowState() << "\r\n";
        return;
    }

    std::cout << "OAuth2 authorization granted!" << "\r\n";
    std::cout << "Access Token = " << oauth2.accessToken() << "\r\n";

    // Save the full JSON access token response to a file.
    CkStringBuilder sbJson;
    sbJson.Append(oauth2.accessTokenResponse());
    sbJson.WriteFile("qa_data/tokens/shopify-access-token.json","utf-8",false);

    // The saved JSON response looks like this:

    // {
    //   "access_token": "1364e43a5332583188cb27bc85469b1f",
    //   "scope": "read_product_listings,read_customers,read_orders,read_draft_orders"
    // }
    }