Send SMS from ASP.NET Core with the SendiMessage API

var builder = WebApplication.CreateBuilder(args);

builder.Services.AddHttpClient("sendimessage", client =>
{
    client.BaseAddress = new Uri("https://api.sendimessage.com/v1/");
    client.DefaultRequestHeaders.Add("X-API-Key",
        builder.Configuration["SendiMessage:ApiKey"]); // from env / user-secrets
    client.DefaultRequestHeaders.Add("X-API-Secret",
        builder.Configuration["SendiMessage:ApiSecret"]);
});

var app = builder.Build();

app.MapPost("/notify", async (IHttpClientFactory factory, NotifyRequest body) =>
{
    var client = factory.CreateClient("sendimessage");
    var response = await client.PostAsJsonAsync("send-message", new
    {
        number = body.To, content = body.Text,
    });
    if (!response.IsSuccessStatusCode)
        return Results.StatusCode(502);

    var message = await response.Content.ReadFromJsonAsync<QueuedMessage>();
    return Results.Ok(message); // { message_handle, status: "QUEUED", … }
});

app.MapPost("/webhooks/sendimessage", (HttpRequest request) =>
{
    // Verify the SendiMessage-Signature header before trusting the event.
    return Results.Ok();
});

app.Run();

record NotifyRequest(string To, string Text);
record QueuedMessage(string Message_Handle, string Status);
record WebhookEvent(string Type);