how to display files with a download link from google drive - google-drive-api

Question

I've a requirement where I should display the list of all files from google drive (of course using oAuth for authorization and authentication)... displaying the list of files which has the extension (.mp3) along with the full path where the user can either copy the path of the file and paste it in a seperate url or can click on the file name to download the file. I'm not getting proper inputs of getting the full path of the file from google drive. I'm using asp.net application.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using Google.GData.Client;
using Google.GData.Documents;
using System.IO;
using Google.Apis.Drive.v2;
using Google.Apis.Drive;
using Google.Apis;
namespace AccessGoogleDriveData
{
public partial class GoogleOAuthCallback : System.Web.UI.Page
{
protected void Page_Load(object sender, EventArgs e)
{
string state = Request.QueryString["state"];
// creating oauthparameter with client id and secret key
OAuth2Parameters parameters = new OAuth2Parameters()
{
ClientId = "myclientid.apps.googleusercontent.com",
ClientSecret = "clientsecretid",
RedirectUri = "http://localhost:16615/GoogleOAuthCallback.aspx">,
Scope = "https://docs.google.com/feeds/ ",
State = "documents",
AccessType = "offline"
};
lstDocuments.Visible = false;
if (state != null)
{
parameters.AccessCode = Request.QueryString["code"];
// it gets accesstoken from google
Google.GData.Client.OAuthUtil.GetAccessToken(parameters);
GOAuth2RequestFactory requestFactory = new GOAuth2RequestFactory(null, "MyDocumentsListIntegration-v1", parameters);
DocumentsService service = new DocumentsService("MyDocumentsListIntegration-v1");
service.RequestFactory = requestFactory;
DocumentsListQuery query = new DocumentsListQuery();
// Make a request to the API and get all documents.
DocumentsFeed feed = service.Query(query);
lstDocuments.Visible = true;
if (feed.Entries.Count > 0)
{
// var documentsList = from entry in feed.Entries select entry.Title.Text;
var documentsList = from entry in feed.Entries where GetFileExtension(entry.Title.Text.ToString()) == "mp3" select entry.Title.Text;
lstDocuments.DataSource = documentsList;
lstDocuments.DataBind();
}
}
}
protected void btnGetDocuments_Click(object sender, EventArgs e)
{
OAuth2Parameters parameters = new OAuth2Parameters()
{
ClientId = "myclientid.apps.googleusercontent.com",
ClientSecret = "clientsecretid",
RedirectUri = "http://localhost:16615/GoogleOAuthCallback.aspx",
Scope = "https://docs.google.com/feeds/ ">,
State = "documents",
AccessType = "offline" // offline means it creats a refreshtoken
};
string url = Google.GData.Client.OAuthUtil.CreateOAuth2AuthorizationUrl(parameters);
Session["oauthDocumentsParameters"] = parameters;
// it redirct to google login page
Response.Redirect(url);
}
private string GetFileExtension(string sFileName)
{
sFileName = sFileName.Trim();
if (String.IsNullOrEmpty(sFileName))
{
return String.Empty;
}
string sExtension = String.Empty;
char[] cArr = sFileName.ToCharArray();
int iIndex = 0;
for (int i = cArr.Length - 1; i > -1; i--)
{
if (cArr[i].Equals('.'))
{
iIndex = i;
break;
}
}
if (iIndex > 0)
{
for (int i = iIndex + 1; i < cArr.Length; i++)
{
sExtension += cArr[i];
}
}
return sExtension.ToLower();
}
}
}