Zig

Refresh HMRC OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to refresh an HMRC access token. Zig

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

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

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

    // See Get HMRC Access Token
    // for sample code showing how to obtain a HMRC access token for desktop apps.

    // It is assumed we previously obtained an OAuth2 access token for HMRC.

    const json_token = try chilkat.JsonObject.init();
    defer json_token.deinit();
    json_token.loadFile("qa_data/tokens/hmrc.json") catch {
        std.debug.print("Failed to load hmrc.json\n", .{});
        return;
    };

    // The access token JSON looks something like this:

    // {
    //   "token_type": "Bearer",
    //   "scope": "user_impersonation",
    //   "expires_in": "3599",
    //   "ext_expires_in": "0",
    //   "expires_on": "1524783438",
    //   "not_before": "1524779538",
    //   "resource": "https://mydomain.api.crm.dynamics.com",
    //   "access_token": "...",
    //   "refresh_token": "...",
    //   "id_token": "..."
    // }

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

    oauth2.setTokenEndpoint("https://test-api.service.hmrc.gov.uk/oauth/token");

    // Replace these with actual values.
    oauth2.setClientId("HMRC-CLIENT-ID");
    oauth2.setClientSecret("HMRC-CLIENT-SECRET");

    // Get the "refresh_token"
    oauth2.setRefreshToken(try json_token.stringOf(alloc, "refresh_token"));

    // Send the HTTP POST to refresh the access token..
    oauth2.refreshAccessToken() catch {
        std.debug.print("{s}\n", .{try oauth2.getLastErrorText(alloc)});
        return;
    };

    // Load the access token response into the json object
    json_token.load(try oauth2.getAccessTokenResponse(alloc)) catch {};

    // 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_token.hasMember("expires_on")) {
        const dt_expire = try chilkat.DateTime.init();
        defer dt_expire.deinit();
        dt_expire.setFromCurrentSystemTime() catch {};
        dt_expire.addSeconds(json_token.intOf("expires_in")) catch {};
        json_token.appendString("expires_on", try dt_expire.getAsUnixTimeStr(alloc, false)) catch {};
    }

    // Save the new JSON access token response to a file.
    // The access + refresh tokens contained in this JSON will be needed for the next refresh.
    const sb_json = try chilkat.StringBuilder.init();
    defer sb_json.deinit();
    json_token.setEmitCompact(false);
    json_token.emitSb(sb_json) catch {};
    sb_json.writeFile("qa_data/tokens/hmrc.json", "utf-8", false) catch {};

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