Integra InvoCash con Rust

use reqwest::Client;
use serde_json::json;

const BASE_URL: &str = "https://{su-tenant}.invo.cash/api";

let client = Client::new();
let auth: serde_json::Value = client
    .post(format!("{}/auth/login", BASE_URL))
    .json(&json!({
        "email":    "usuario@empresa.com",
        "password": "tu_contraseña"
    }))
    .send().await?
    .json().await?;

let token = auth["access_token"].as_str().unwrap();

// Alternativa: API Key
// .header("X-API-Key", "tu_api_key")

let precio: f64 = 2000.0;
let tax_base    = precio;
let tax_amount  = (tax_base * 21.0 / 100.0 * 100.0).round() / 100.0;

let result: serde_json::Value = client
    .post(format!("{}/invoices", BASE_URL))
    .bearer_auth(token)
    .json(&json!({
        "customer_id":                123,
        "verifactu_issuer_territory": "MAINLAND",
        "simplified":                 false,
        "lines": [{
            "description":             "Servicio backend Rust",
            "quantity":                1,
            "unit_price":              precio,
            "tax_base":                tax_base,
            "tax_pctge":               21,
            "tax_amount":              tax_amount,
            "tax_withholding_pctge":   0,
            "tax_withholding_amount":  0,
            "tax_type":                "IVA",
            "clave_regimen":           "01",
            "qualification_operation": "S1",
            "exempt_operation":        null,
            "total":                   tax_base,
        }],
        "total": tax_base + tax_amount,
    }))
    .send().await?
    .json().await?;

// Estado VeriFactu
let vf: serde_json::Value = client
    .get(format!("{}/invoice/{}/verifactu", BASE_URL, invoice_id))
    .bearer_auth(token)
    .send().await?.json().await?;

// Descargar PDF
let pdf_bytes = client
    .get(format!("{}/invoice/{}/downloadPdf", BASE_URL, invoice_id))
    .bearer_auth(token)
    .send().await?
    .bytes().await?;
std::fs::write("factura.pdf", &pdf_bytes)?;