"""UN/CEFACT CII D16B, EN16931: positive, taxable service invoices."""
from pathlib import Path
from decimal import Decimal
import xml.etree.ElementTree as ET
from .calc import compute_totals, line_net
from .models import Invoice

NS = {k: f'urn:un:unece:uncefact:data:standard:{v}:100' for k, v in {
    'rsm': 'CrossIndustryInvoice', 'ram': 'ReusableAggregateBusinessInformationEntity',
    'udt': 'UnqualifiedDataType'}.items()}
for prefix, uri in NS.items():
    ET.register_namespace(prefix, uri)

def node(parent, name, value=None, **attrs):
    prefix, local = name.split(':')
    el = ET.SubElement(parent, f'{{{NS[prefix]}}}{local}', attrs)
    if value is not None:
        el.text = format(value, "f") if isinstance(value, Decimal) else str(value)
    return el

def ram(parent, name, value=None, **attrs):
    return node(parent, 'ram:' + name, value, **attrs)

def date_node(parent, name, value):
    node(ram(parent, name), 'udt:DateTimeString', value.strftime('%Y%m%d'), format='102')

def party(parent, name, data):
    p = ram(parent, name)
    ram(p, 'Name', data.name)
    address = ram(p, 'PostalTradeAddress')
    for key, value in [('PostcodeCode', data.address.postal_code), ('LineOne', data.address.street),
                       ('CityName', data.address.city), ('CountryID', data.address.country)]:
        ram(address, key, value)
    if data.email:
        ram(ram(p, 'URIUniversalCommunication'), 'URIID', data.email, schemeID='EM')
    for value, scheme in [(data.vat_id, 'VA'), (data.tax_number, 'FC')]:
        if value:
            ram(ram(p, 'SpecifiedTaxRegistration'), 'ID', value, schemeID=scheme)

def generate_facturx_xml(inv: Invoice, out_xml: Path, logger) -> Path:
    totals = compute_totals(inv)
    root = ET.Element(f'{{{NS["rsm"]}}}CrossIndustryInvoice')
    context = node(root, 'rsm:ExchangedDocumentContext')
    ram(ram(context, 'GuidelineSpecifiedDocumentContextParameter'), 'ID', 'urn:cen.eu:en16931:2017')
    doc = node(root, 'rsm:ExchangedDocument')
    ram(doc, 'ID', inv.meta.invoice_number)
    ram(doc, 'TypeCode', '380')
    date_node(doc, 'IssueDateTime', inv.meta.invoice_date)
    if inv.meta.notes:
        ram(ram(doc, 'IncludedNote'), 'Content', inv.meta.notes)
    transaction = node(root, 'rsm:SupplyChainTradeTransaction')
    for index, item in enumerate(inv.items, 1):
        line = ram(transaction, 'IncludedSupplyChainTradeLineItem')
        ram(ram(line, 'AssociatedDocumentLineDocument'), 'LineID', index)
        product = ram(line, 'SpecifiedTradeProduct')
        ram(product, 'Name', item.name)
        if item.description:
            ram(product, 'Description', item.description)
        agreement = ram(line, 'SpecifiedLineTradeAgreement')
        ram(ram(agreement, 'NetPriceProductTradePrice'), 'ChargeAmount', item.unit_price_net)
        ram(ram(line, 'SpecifiedLineTradeDelivery'), 'BilledQuantity', item.quantity, unitCode=item.unit)
        settlement = ram(line, 'SpecifiedLineTradeSettlement')
        tax = ram(settlement, 'ApplicableTradeTax')
        ram(tax, 'TypeCode', 'VAT')
        ram(tax, 'CategoryCode', 'S')
        ram(tax, 'RateApplicablePercent', item.tax_rate)
        ram(ram(settlement, 'SpecifiedTradeSettlementLineMonetarySummation'), 'LineTotalAmount', line_net(item))
    agreement = ram(transaction, 'ApplicableHeaderTradeAgreement')
    if inv.meta.buyer_reference:
        ram(agreement, 'BuyerReference', inv.meta.buyer_reference)
    party(agreement, 'SellerTradeParty', inv.seller)
    party(agreement, 'BuyerTradeParty', inv.buyer)
    if inv.meta.order_reference:
        ram(ram(agreement, 'BuyerOrderReferencedDocument'), 'IssuerAssignedID', inv.meta.order_reference)
    delivery = ram(transaction, 'ApplicableHeaderTradeDelivery')
    date_node(ram(delivery, 'ActualDeliverySupplyChainEvent'), 'OccurrenceDateTime', inv.meta.service_date)
    settlement = ram(transaction, 'ApplicableHeaderTradeSettlement')
    ram(settlement, 'PaymentReference', inv.payment.reference)
    ram(settlement, 'InvoiceCurrencyCode', inv.meta.currency)
    if inv.payment.iban:
        means = ram(settlement, 'SpecifiedTradeSettlementPaymentMeans')
        ram(means, 'TypeCode', '58')
        ram(ram(means, 'PayeePartyCreditorFinancialAccount'), 'IBANID', inv.payment.iban.replace(' ', ''))
        if inv.payment.bic:
            ram(ram(means, 'PayeeSpecifiedCreditorFinancialInstitution'), 'BICID', inv.payment.bic)
    for rate, base in totals.basis_by_rate.items():
        tax = ram(settlement, 'ApplicableTradeTax')
        ram(tax, 'CalculatedAmount', totals.tax_by_rate[rate])
        ram(tax, 'TypeCode', 'VAT')
        ram(tax, 'BasisAmount', base)
        ram(tax, 'CategoryCode', 'S')
        ram(tax, 'RateApplicablePercent', rate)
    if inv.meta.service_period_start:
        period = ram(settlement, 'BillingSpecifiedPeriod')
        date_node(period, 'StartDateTime', inv.meta.service_period_start)
        date_node(period, 'EndDateTime', inv.meta.service_period_end)
    terms = ram(settlement, 'SpecifiedTradePaymentTerms')
    date_node(terms, 'DueDateDateTime', inv.payment.due_date)
    summary = ram(settlement, 'SpecifiedTradeSettlementHeaderMonetarySummation')
    for name, amount in [('LineTotalAmount', totals.net_total), ('ChargeTotalAmount', '0.00'),
                         ('AllowanceTotalAmount', '0.00'), ('TaxBasisTotalAmount', totals.net_total)]:
        ram(summary, name, amount)
    ram(summary, 'TaxTotalAmount', totals.tax_total, currencyID=inv.meta.currency)
    ram(summary, 'GrandTotalAmount', totals.gross_total)
    ram(summary, 'DuePayableAmount', totals.gross_total)
    ET.indent(root)
    out_xml.parent.mkdir(parents=True, exist_ok=True)
    ET.ElementTree(root).write(out_xml, encoding='utf-8', xml_declaration=True)
    logger.info('Wrote EN16931 XML: %s', out_xml)
    return out_xml