import {
    subtractFractions,
    decimalFraction,
    type FiscalFraction,
} from './fiscal-rational.ts';
import {
    validateProofParcel,
    requireProofParcel,
    type FiscalProofParcel,
} from './fiscal-proof-parcel.ts';

export const pecVersion = 'IRPC-PEC/1';
export const pecSource =
    'CIRPC, art. 66(1–2), Lei 34/2007, exemplar BR52, p. 768-(72): dedução após créditos anteriores, até à colecta, sem reembolso do PEC. Recorte demonstrado: pagamento efectivo do próprio exercício 2026, residente geral, ano civil, MZN. Não calcula a obrigação PEC, transporte, caducidade ou consumo de saldos oficiais.';
export type PecPayment = FiscalProofParcel & {
    id: string;
    document: string;
    issuer: string;
    date: string;
    subjectNuit: string;
    year: string;
    currency: string;
    proofAmount: string;
    amount: string;
    effective: '' | 'yes' | 'no';
    reference: string;
    previouslyUsed: string;
    priorUseReference: string;
};
export type PecPayments = {
    version: 1;
    state: '' | 'known' | 'absent';
    reference: string;
    rows: PecPayment[];
};
export const newPecPayment = (id: string): PecPayment => ({
    id,
    document: '',
    issuer: '',
    date: '',
    subjectNuit: '',
    year: '',
    currency: 'MZN',
    proofAmount: '',
    amount: '',
    effective: '',
    reference: '',
    previouslyUsed: '',
    priorUseReference: '',
});
export function validatePec(p: PecPayments) {
    const keys = Object.keys(newPecPayment(''));
    if (
        !p ||
        p.version !== 1 ||
        !['', 'known', 'absent'].includes(p.state) ||
        typeof p.reference !== 'string' ||
        !Array.isArray(p.rows) ||
        new Set(p.rows.map((r) => r?.id)).size !== p.rows.length ||
        p.rows.some(
            (r) =>
                !r ||
                keys.some(
                    (k) =>
                        typeof (r as unknown as Record<string, unknown>)[k] !==
                        'string',
                ) ||
                !['', 'yes', 'no'].includes(r.effective),
        )
    ) {
        throw Error(
            'Comprovativos PEC não recuperáveis; originais conservados.',
        );
    }
    for (const r of p.rows) validateProofParcel(r);
}
export const pecCompare = (a: FiscalFraction, b: FiscalFraction) =>
    BigInt(a.numerator) * BigInt(b.denominator) -
    BigInt(b.numerator) * BigInt(a.denominator);
const money = (s: string) => {
    if (!/^\d{1,18}(\.\d{1,2})?$/.test(s))
        throw Error(
            'Montante PEC em falta/inválido; declare zero explicitamente quando conhecido.',
        );
    return decimalFraction(s);
};
export function pecPaymentValue(
    r: PecPayment,
    subjectNuit: string,
    year: string,
) {
    requireProofParcel(r);
    if (
        !r.id.trim() ||
        !r.document.trim() ||
        !r.issuer.trim() ||
        !r.reference.trim() ||
        !r.priorUseReference.trim() ||
        r.effective !== 'yes' ||
        r.currency !== 'MZN' ||
        !/^20\d{2}-\d{2}-\d{2}$/.test(r.date) ||
        !Number.isFinite(Date.parse(r.date)) ||
        new Date(r.date).toISOString().slice(0, 10) !== r.date ||
        !r.date.startsWith(year + '-') ||
        r.subjectNuit !== subjectNuit ||
        r.year !== year ||
        year !== '2026'
    ) {
        throw Error(
            'PEC: exige prova efectiva, natureza PEC, titular, exercício 2026, data válida e MZN; saldos anteriores e previsões ficam separados.',
        );
    }
    const proofAmount = money(r.proofAmount),
        value = money(r.amount),
        previouslyUsed = money(r.previouslyUsed);
    if (
        pecCompare(previouslyUsed, proofAmount) > 0n ||
        pecCompare(value, subtractFractions(proofAmount, previouslyUsed)) > 0n
    )
        throw Error(
            'PEC: parcela e utilizações anteriores excedem o comprovativo disponível.',
        );
    return { proofAmount, value, previouslyUsed };
}
export function pecDeduction(
    available: FiscalFraction,
    colecta: FiscalFraction | null,
    ready: boolean,
    selected?: FiscalFraction | null,
) {
    const deducted =
        ready && colecta
            ? (selected ??
              (pecCompare(available, colecta) > 0n ? colecta : available))
            : null;
    return {
        version: pecVersion,
        available,
        deducted,
        remaining: deducted ? subtractFractions(available, deducted) : null,
        afterPec:
            deducted && colecta ? subtractFractions(colecta, deducted) : null,
        source: pecSource,
        officialBalancesConsumed: false,
        carryCreated: false,
    };
}