from dataclasses import replace
from decimal import Decimal

import pytest

from fin_hub.accounting import (
    AccountingCapability,
    DatevDuoAdapter,
    SchemaMigrations,
    default_registry,
)
from fin_hub.services.billing import BillingBasisExport, BillingBasisRecord


def _export(schema_version: str = "0.1") -> BillingBasisExport:
    record = BillingBasisRecord(
        billing_basis_id="billing-basis:stable",
        cost_attribution_key="client:acme|app:portal|instance:prod-01",
        client_id="acme",
        application_id="portal",
        app_instance_id="prod-01",
        period_month="2026-07",
        currency="EUR",
        price_id="price:agreement-v1",
        price_revision_of=None,
        price_source="agreement-v1",
        revenue=Decimal("200.00"),
        direct_cost=Decimal("20.00"),
        allocated_cost=Decimal("80.00"),
        total_cost=Decimal("100.00"),
        margin=Decimal("100.00"),
        financial_fact_ids=("fact:1",),
        financial_fact_corrections=(),
        allocation_ids=("allocation:1",),
        allocation_revisions=(),
        provenance=("agreement-v1",),
    )
    return BillingBasisExport(
        schema_version=schema_version,
        artifact_type="billing_basis_report",
        records=(record,),
        exceptions=(),
        disclaimer="Reporting basis only; not an invoice.",
    )


def test_datev_duo_is_default_and_prepares_only_an_incomplete_draft():
    transfer = default_registry().prepare(_export())

    assert transfer.adapter_id == "datev-duo-v1"
    assert transfer.provider == "DATEV Unternehmen online"
    assert transfer.records[0]["external_reference"] == "billing-basis:stable"
    assert transfer.records[0]["net_billing_basis"] == Decimal("200.00")
    assert transfer.records[0]["requires_legal_and_tax_completion"] is True
    assert "Provider draft only" in transfer.disclaimer
    assert not any(
        key in transfer.records[0]
        for key in ("invoice_number", "issue_date", "payment_status")
    )


def test_qonto_requires_explicit_selection_and_keeps_datev_as_destination():
    transfer = default_registry().prepare(
        _export(),
        adapter_id="qonto-invoice-draft-v1",
        required_capabilities=frozenset(
            {AccountingCapability.INVOICE_DRAFT_WORKFLOW}
        ),
    )

    assert transfer.provider == "Qonto"
    assert transfer.records[0]["bookkeeping_destination"] == (
        "DATEV Unternehmen online"
    )


def test_capability_mismatch_never_silently_falls_back_to_qonto():
    with pytest.raises(ValueError, match="lacks capabilities: invoice_draft_workflow"):
        default_registry().prepare(
            _export(),
            required_capabilities=frozenset(
                {AccountingCapability.INVOICE_DRAFT_WORKFLOW}
            ),
        )


def test_breaking_schema_requires_an_explicit_migration():
    with pytest.raises(ValueError, match="no explicit billing-basis schema migration"):
        default_registry().prepare(_export("1.0"))


def test_registered_schema_migration_must_produce_declared_version():
    migrations = SchemaMigrations()
    migrations.register("1.0", "0.1", lambda export: replace(export, schema_version="0.1"))
    from fin_hub.accounting.adapters import AdapterRegistry

    registry = AdapterRegistry(
        (DatevDuoAdapter(),),
        default_adapter_id="datev-duo-v1",
        migrations=migrations,
    )

    assert registry.prepare(_export("1.0")).source_schema_version == "0.1"