Struct BillingEngine 

pub struct BillingEngine { /* private fields */ }

The composition root for multi-product invoice generation.

Implementations

impl BillingEngine

pub fn new() -> Self

Create an empty engine. Register providers with add.

pub fn add<P: BillingProvider + 'static>(self, provider: P) -> Self

Register a BillingProvider. Returns self for method chaining.

Providers run in registration order. Register tax providers (e.g. MwStProvider) last — they will automatically run in a second pass.

pub fn validate( &self, ctx: &BillingContext, quantities: &Quantities, ) -> Vec<BillingWarning>

Run all registered providers and collect regulatory compliance warnings.

Does NOT generate positions or produce an invoice. Call this before bill() to check regulatory preconditions (e.g. §41a iMSys guard, missing tariff fields) without committing to billing.

An Error-severity warning indicates a definite regulatory violation. The operator should resolve the issue before calling bill().

pub fn bill_batch( &self, batch: Vec<(BillingContext, Quantities)>, ) -> Vec<Result<Invoice, EngineError>>

Bill multiple (context, quantities) pairs using this engine configuration.

Reuses the same provider set for every item in the batch. Fails fast per item (each error is independent). For large portfolios, collect all results and handle errors individually.

Example

let results = engine.bill_batch(batch);
let errors: Vec<_> = results.iter().filter_map(|r| r.as_ref().err()).collect();

pub fn bill( &self, ctx: BillingContext, quantities: &Quantities, ) -> Result<Invoice, EngineError>

Run all providers and assemble an Invoice.

Three-pass execution:

1. Commodity + levy providers (all is_tax_pass() == false)
2. Tax providers (all is_tax_pass() == true)
3. Abschlag deductions from ctx.abschlage (on every settling document — every InvoiceType except AdvancePayment)

Trait Implementations

impl Default for BillingEngine

fn default() -> BillingEngine

Returns the “default value” for a type.