from __future__ import annotations

import re
from decimal import Decimal

from .models import (
    FundPortfolioReport,
    Severity,
    ValidationFinding,
    ValidationResult,
)


ISIN_PATTERN = re.compile(r"^TR[A-Z0-9]{10}$")
CENT = Decimal("0.01")


def _difference_finding(
    *,
    code: str,
    message: str,
    expected: Decimal,
    actual: Decimal,
    tolerance: Decimal,
    sheet: str,
    severity: Severity = Severity.ERROR,
    record_key: str | None = None,
    page: int | None = None,
) -> ValidationFinding | None:
    if abs(expected - actual) <= tolerance:
        return None
    return ValidationFinding(
        severity=severity,
        code=code,
        message=message,
        sheet=sheet,
        record_key=record_key,
        page=page,
        expected=str(expected),
        actual=str(actual),
    )


def validate_report(report: FundPortfolioReport) -> ValidationResult:
    findings: list[ValidationFinding] = []

    for row in report.equities:
        if not ISIN_PATTERN.match(row.isin):
            findings.append(
                ValidationFinding(
                    severity=Severity.ERROR,
                    code="INVALID_ISIN",
                    message="ISIN biçimi geçersiz.",
                    sheet="Hisse Senetleri",
                    record_key=row.code,
                    page=row.source.page,
                    actual=row.isin,
                )
            )

        calculated = row.nominal * row.current_price
        tolerance = max(Decimal("1.00"), abs(row.total_value) * Decimal("0.000001"))
        finding = _difference_finding(
            code="POSITION_VALUE_MISMATCH",
            message="Nominal değer × güncel fiyat, toplam değerle uzlaşmıyor.",
            expected=row.total_value,
            actual=calculated,
            tolerance=tolerance,
            sheet="Hisse Senetleri",
            record_key=row.code,
            page=row.source.page,
        )
        if finding:
            findings.append(finding)

    totals = report.declared_totals
    calculated_equity_nominal = sum(
        (row.nominal for row in report.equities), start=Decimal("0")
    )
    calculated_equity_value = sum(
        (row.total_value for row in report.equities), start=Decimal("0")
    )
    calculated_repo_value = sum(
        (row.total_value for row in report.repos), start=Decimal("0")
    )
    calculated_derivative = sum(
        (row.total_value for row in report.derivatives), start=Decimal("0")
    )
    calculated_collateral = sum(
        (row.total_value for row in report.cash_collaterals), start=Decimal("0")
    )

    aggregate_checks = [
        _difference_finding(
            code="EQUITY_NOMINAL_ROUNDING",
            message=(
                "Detay nominal toplamı ile PDF beyan toplamı arasında fark var. "
                "Bu fark, kaynakta satırların iki ondalıkla gösterilmesinden kaynaklanabilir."
            ),
            expected=totals.equity_nominal,
            actual=calculated_equity_nominal,
            tolerance=Decimal("0.00"),
            sheet="Hisse Senetleri",
            severity=Severity.WARNING,
        ),
        _difference_finding(
            code="EQUITY_TOTAL_MISMATCH",
            message="Hisse detay toplamı PDF grup toplamıyla uzlaşmıyor.",
            expected=totals.equity_value,
            actual=calculated_equity_value,
            tolerance=CENT,
            sheet="Hisse Senetleri",
        ),
        _difference_finding(
            code="REPO_TOTAL_MISMATCH",
            message="Repo detay toplamı PDF grup toplamıyla uzlaşmıyor.",
            expected=totals.repo_value,
            actual=calculated_repo_value,
            tolerance=CENT,
            sheet="T. Repo",
        ),
        _difference_finding(
            code="DERIVATIVE_TOTAL_MISMATCH",
            message="Türev detay toplamı PDF grup toplamıyla uzlaşmıyor.",
            expected=totals.derivative_exposure,
            actual=calculated_derivative,
            tolerance=CENT,
            sheet="Türev",
        ),
        _difference_finding(
            code="COLLATERAL_TOTAL_MISMATCH",
            message="Nakit teminat toplamı PDF grup toplamıyla uzlaşmıyor.",
            expected=totals.cash_collateral_value,
            actual=calculated_collateral,
            tolerance=CENT,
            sheet="Türev",
        ),
    ]
    findings.extend(finding for finding in aggregate_checks if finding)

    calculated_portfolio = (
        totals.equity_value + totals.repo_value + totals.cash_collateral_value
    )
    portfolio_finding = _difference_finding(
        code="PORTFOLIO_RECONCILIATION_FAILED",
        message=(
            "Hisse + repo + VİOP nakit teminatı, fon portföy değeriyle uzlaşmıyor."
        ),
        expected=totals.fund_portfolio_value,
        actual=calculated_portfolio,
        tolerance=CENT,
        sheet="Özet",
    )
    if portfolio_finding:
        findings.append(portfolio_finding)

    fpd_sum = (
        totals.equity_fpd_pct
        + totals.repo_fpd_pct
        + totals.cash_collateral_fpd_pct
    )
    fpd_finding = _difference_finding(
        code="FPD_PERCENT_MISMATCH",
        message="FPD yüzdeleri %100'e ulaşmıyor.",
        expected=Decimal("1"),
        actual=fpd_sum,
        tolerance=Decimal("0.0001"),
        sheet="Özet",
    )
    if fpd_finding:
        findings.append(fpd_finding)

    findings.append(
        ValidationFinding(
            severity=Severity.INFO,
            code="DERIVATIVE_EXPOSURE_DISCLOSURE",
            message=(
                "Futures değeri maruziyet olarak raporlandı; fon portföy değeri "
                "uzlaştırmasına dahil edilmedi."
            ),
            sheet="Özet",
            expected=str(totals.derivative_exposure),
        )
    )

    error_count = sum(item.severity == Severity.ERROR for item in findings)
    warning_count = sum(item.severity == Severity.WARNING for item in findings)
    info_count = sum(item.severity == Severity.INFO for item in findings)
    status = "Başarısız" if error_count else "Uyarılı" if warning_count else "Doğrulandı"
    return ValidationResult(
        status=status,
        findings=findings,
        error_count=error_count,
        warning_count=warning_count,
        info_count=info_count,
    )