export type ResourceMonthReportExplainability = {
  entity: "resource_month";
  periodMonth: string | null;
  locationContextColumns: string[];
  holidayMetricColumns: string[];
  absenceMetricColumns: string[];
  capacityMetricColumns: string[];
  chargeabilityMetricColumns: string[];
  missingRecommendedColumns: string[];
  notes: string[];
};

export type ReportExplainability = ResourceMonthReportExplainability;

const RESOURCE_MONTH_LOCATION_COLUMNS = [
  "countryCode",
  "countryName",
  "federalState",
  "metroCityName",
] as const;

const RESOURCE_MONTH_HOLIDAY_COLUMNS = [
  "monthlyPublicHolidayCount",
  "monthlyPublicHolidayWorkdayCount",
  "monthlyPublicHolidayHoursDeduction",
] as const;

const RESOURCE_MONTH_ABSENCE_COLUMNS = [
  "monthlyAbsenceDayEquivalent",
  "monthlyAbsenceHoursDeduction",
] as const;

const RESOURCE_MONTH_CAPACITY_COLUMNS = [
  "monthlyBaseWorkingDays",
  "monthlyEffectiveWorkingDays",
  "monthlyBaseAvailableHours",
  "monthlySahHours",
  "monthlyChargeabilityTargetPct",
  "monthlyTargetHours",
] as const;

const RESOURCE_MONTH_CHARGEABILITY_COLUMNS = [
  "monthlyActualBookedHours",
  "monthlyExpectedBookedHours",
  "monthlyActualChargeabilityPct",
  "monthlyExpectedChargeabilityPct",
  "monthlyUnassignedHours",
] as const;

const RESOURCE_MONTH_RECOMMENDED_COLUMNS = [
  ...RESOURCE_MONTH_LOCATION_COLUMNS,
  ...RESOURCE_MONTH_HOLIDAY_COLUMNS,
  ...RESOURCE_MONTH_ABSENCE_COLUMNS,
  ...RESOURCE_MONTH_CAPACITY_COLUMNS,
] as const;

function pickIncludedColumns(
  requestedColumns: string[],
  columnGroup: readonly string[],
): string[] {
  return columnGroup.filter((column) => requestedColumns.includes(column));
}

export function buildResourceMonthReportExplainability(
  requestedColumns: string[],
  periodMonth?: string,
): ResourceMonthReportExplainability {
  const missingRecommendedColumns = RESOURCE_MONTH_RECOMMENDED_COLUMNS.filter(
    (column) => !requestedColumns.includes(column),
  );

  return {
    entity: "resource_month",
    periodMonth: periodMonth ?? null,
    locationContextColumns: pickIncludedColumns(requestedColumns, RESOURCE_MONTH_LOCATION_COLUMNS),
    holidayMetricColumns: pickIncludedColumns(requestedColumns, RESOURCE_MONTH_HOLIDAY_COLUMNS),
    absenceMetricColumns: pickIncludedColumns(requestedColumns, RESOURCE_MONTH_ABSENCE_COLUMNS),
    capacityMetricColumns: pickIncludedColumns(requestedColumns, RESOURCE_MONTH_CAPACITY_COLUMNS),
    chargeabilityMetricColumns: pickIncludedColumns(requestedColumns, RESOURCE_MONTH_CHARGEABILITY_COLUMNS),
    missingRecommendedColumns,
    notes: [
      "monthlySahHours already reflects region-specific public holidays from country, federal state, and city context when those attributes exist on the resource.",
      "monthlyAbsence* metrics only deduct workdays that are not already counted as public holidays.",
      "monthlyBaseAvailableHours shows pre-deduction capacity; compare it with holiday, absence, and SAH columns to explain the final monthly availability.",
    ],
  };
}