(Go) OAuth2 using an HTTP Proxy (for a Desktop Application)

Demonstrates how to send OAuth2 communications through an HTTP proxy for a desktop application. The technique is the same for all OAuth2 applications. This one happens to demonstrate for Microsoft Graph.

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

    // To use an HTTP proxy with OAuth2, create a Chilkat socket object and specify the details.
    socket := chilkat.NewSocket()
    // Use your HTTP proxy server domain or IP address.
    socket.SetHttpProxyHostname("myproxyserver.com")
    // Change this to the listening port of your HTTP proxy server (if necessary)
    socket.SetHttpProxyPort(808)
    // Specify login/password if needed.
    socket.SetHttpProxyUsername("myProxyLogin")
    socket.SetHttpProxyPassword("myProxyPassword")
    socket.SetHttpProxyForHttp(true)

    oauth2 := chilkat.NewOAuth2()
    var success bool

    // We don't need to connect the socket beforehand.
    // Just tell oauth2 to use the socket which has the HTTP proxy properties.
    success = oauth2.UseConnection(socket)

    // 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.
    oauth2.SetListenPort(3017)

    oauth2.SetAuthorizationEndpoint("https://login.microsoftonline.com/common/oauth2/v2.0/authorize")
    oauth2.SetTokenEndpoint("https://login.microsoftonline.com/common/oauth2/v2.0/token")

    // Replace these with actual values.
    oauth2.SetClientId("MICROSOFT-GRAPH-CLIENT-ID")
    // This is your app password:
    oauth2.SetClientSecret("MICROSOFT-GRAPH-CLIENT-SECRET")

    oauth2.SetCodeChallenge(false)
    // Provide a SPACE separated list of scopes.
    // See https://developer.microsoft.com/en-us/graph/docs/authorization/permission_scopes 

    // Important: To get a refresh token in the final response, you have to ask for "offline_access" scope
    oauth2.SetScope("openid profile offline_access user.readwrite mail.readwrite mail.send files.readwrite")

    // Begin the OAuth2 three-legged flow.  This returns a URL that should be loaded in a browser.
    url := oauth2.StartAuth()
    if oauth2.LastMethodSuccess() != true {
        fmt.Println(oauth2.LastErrorText())
        socket.DisposeSocket()
        oauth2.DisposeOAuth2()
        return
    }

    // 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 Microsoft 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...

    // Now wait for the authorization.
    // We'll wait for a max of 30 seconds.
    numMsWaited := 0
    for (numMsWaited < 30000) && (oauth2.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.AuthFlowState() < 3 {
        oauth2.Cancel()
        fmt.Println("No response from the browser!")
        socket.DisposeSocket()
        oauth2.DisposeOAuth2()
        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.AuthFlowState() == 5 {
        fmt.Println("OAuth2 failed to complete.")
        fmt.Println(oauth2.FailureInfo())
        socket.DisposeSocket()
        oauth2.DisposeOAuth2()
        return
    }

    if oauth2.AuthFlowState() == 4 {
        fmt.Println("OAuth2 authorization was denied.")
        fmt.Println(oauth2.AccessTokenResponse())
        socket.DisposeSocket()
        oauth2.DisposeOAuth2()
        return
    }

    if oauth2.AuthFlowState() != 3 {
        fmt.Println("Unexpected AuthFlowState:", oauth2.AuthFlowState())
        socket.DisposeSocket()
        oauth2.DisposeOAuth2()
        return
    }

    fmt.Println("OAuth2 authorization granted!")
    fmt.Println("Access Token = ", oauth2.AccessToken())

    // Get the full JSON response:
    json := chilkat.NewJsonObject()
    json.Load(oauth2.AccessTokenResponse())
    json.SetEmitCompact(false)

    // The JSON response looks like this:

    // {
    //   "token_type": "Bearer",
    //   "scope": "User.Read Mail.ReadWrite Mail.Send",
    //   "expires_in": 3600,
    //   "ext_expires_in": 0,
    //   "access_token": "EwBAA8l6B...",
    //   "refresh_token": "MCRMdbe...",
    //   "id_token": "eyJ0eXA..."
    // }

    // If an "expires_on" member does not exist, then add the JSON member by
    // getting the current system date/time and adding the "expires_in" seconds.
    // This way we'll know when the token expires.
    if json.HasMember("expires_on") != true {
        dtExpire := chilkat.NewCkDateTime()
        dtExpire.SetFromCurrentSystemTime()
        dtExpire.AddSeconds(*json.IntOf("expires_in"))
        json.AppendString("expires_on",*dtExpire.GetAsUnixTimeStr(false))
    }

    fmt.Println(*json.Emit())

    // Save the JSON to a file for future requests.
    fac := chilkat.NewFileAccess()
    fac.WriteEntireTextFile("qa_data/tokens/microsoftGraph.json",*json.Emit(),"utf-8",false)

    socket.DisposeSocket()
    oauth2.DisposeOAuth2()
    json.DisposeJsonObject()
    dtExpire.DisposeCkDateTime()
    fac.DisposeFileAccess()