Zig Requires Chilkat v10.1.2+

Schwab OAuth2 in a Desktop App

See more Schwab Examples

Demonstrates how to get a Charles Schwab OAuth2 access token from a desktop application or script. Zig

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // To further clarify, see OAuth 2.0 Authorization Flow

    // This is the way to initially obtain the OAuth2 access token.  Afterwards it can be
    // repeatedly refreshed without user interaction, as shown in this example: Refresh Schwab OAuth2 Access Token.

    const oauth2 = try chilkat.OAuth2.init();
    defer oauth2.deinit();

    // Your applicaton must use your own public web server as an intermediate
    // to receive and forward the redirect to localhost.
    // See Using Your Web Server as an Intermediary for OAuth2 Redirect to localhost

    oauth2.setAppCallbackUrl("https://yourwebserver.com/OAuth2.php");
    oauth2.setListenPort(3017);

    oauth2.setAuthorizationEndpoint("https://api.schwabapi.com/v1/oauth/authorize");
    oauth2.setTokenEndpoint("https://api.schwabapi.com/v1/oauth/token");

    // Replace these with actual values.
    oauth2.setClientId("APP_KEY");
    oauth2.setClientSecret("APP_SECRET");
    oauth2.setUseBasicAuth(true);
    oauth2.setCodeChallenge(false);

    oauth2.setScope("");

    // Begin the OAuth2 Authorization code flow.  This returns a URL that should be loaded in a browser.
    const url = oauth2.startAuth(alloc) catch {
        std.debug.print("{s}\n", .{try oauth2.getLastErrorText(alloc)});
        return;
    };

    std.debug.print("url = {s}\n", .{url});

    // Launch the default browser on the system and navigate to the url.
    // The LaunchBrowser method was added in Chilkat v10.1.2.
    oauth2.launchBrowser(url) catch {
        std.debug.print("{s}\n", .{try oauth2.getLastErrorText(alloc)});
        return;
    };

    // Wait for the user to approve or deny authorization in the browser.
    var num_ms_waited: i32 = 0;
    while ((num_ms_waited < 90000) and (oauth2.getAuthFlowState() < 3)) {
        oauth2.sleepMs(100);
        num_ms_waited = num_ms_waited + 100;
    }

    // If the browser does not respond within the specified time, AuthFlowState will be:
    //
    // 1: Waiting for Redirect – The OAuth2 background thread is waiting for the browser's redirect request.
    // 2: Waiting for Final Response – The thread is awaiting the final access token response.
    // In either case, cancel the background task initiated by StartAuth.

    if (oauth2.getAuthFlowState() < 3) {
        oauth2.cancel() catch {};
        std.debug.print("No response from the browser!\n", .{});
        return;
    }

    // Check AuthFlowState to determine if authorization was granted, denied, or failed:
    //
    // 3: Success – OAuth2 flow completed, the background thread exited, and the successful response is in AccessTokenResponse.
    // 4: Access Denied – OAuth2 flow completed, the background thread exited, and the error response is in AccessTokenResponse.
    // 5: Failure – OAuth2 flow failed before completion, the background thread exited, and error details are in FailureInfo.

    if (oauth2.getAuthFlowState() == 5) {
        std.debug.print("OAuth2 failed to complete.\n", .{});
        std.debug.print("{s}\n", .{try oauth2.getFailureInfo(alloc)});
        return;
    }

    if (oauth2.getAuthFlowState() == 4) {
        std.debug.print("OAuth2 authorization was denied.\n", .{});
        std.debug.print("{s}\n", .{try oauth2.getAccessTokenResponse(alloc)});
        return;
    }

    if (oauth2.getAuthFlowState() != 3) {
        std.debug.print("Unexpected AuthFlowState:{d}\n", .{oauth2.getAuthFlowState()});
        return;
    }

    // Save the full JSON access token response to a file.
    const sb_json = try chilkat.StringBuilder.init();
    defer sb_json.deinit();
    sb_json.append(try oauth2.getAccessTokenResponse(alloc)) catch {};
    sb_json.writeFile("qa_data/tokens/schwab-access-token.json", "utf-8", false) catch {};

    // The full JSON received looks like this:
    // {
    //   "expires_in": 3600,
    //   "x_refresh_token_expires_in": 8726400,
    //   "refresh_token": "L011546037639r ... 3vR2DrbOmg0Sdagw",
    //   "access_token": "eyJlbmMiOiJBMTI4Q0 ... oETJEMbeggg",
    //   "token_type": "bearer"
    // }

    std.debug.print("OAuth2 authorization granted!\n", .{});
    std.debug.print("Access Token = {s}\n", .{try oauth2.getAccessToken(alloc)});
}