import type {
  FinancialSurfaceKind,
  RatioRow,
  StandardizedFinancialRow,
  StructuredKpiRow,
  TrendSeries
} from '@/lib/types';
import { KPI_CATEGORY_ORDER } from '@/lib/server/financials/kpi-registry';
import { RATIO_CATEGORY_ORDER } from '@/lib/server/financials/ratios';

function toTrendSeriesRow(row: {
  key: string;
  label: string;
  category: string;
  unit: TrendSeries['unit'];
  values: Record<string, number | null>;
}) {
  return {
    key: row.key,
    label: row.label,
    category: row.category,
    unit: row.unit,
    values: row.values
  } satisfies TrendSeries;
}

export function buildFinancialCategories(rows: Array<{ category: string }>, surfaceKind: FinancialSurfaceKind) {
  const counts = new Map<string, number>();
  for (const row of rows) {
    counts.set(row.category, (counts.get(row.category) ?? 0) + 1);
  }

  const order = surfaceKind === 'ratios'
    ? [...RATIO_CATEGORY_ORDER]
    : surfaceKind === 'segments_kpis'
      ? [...KPI_CATEGORY_ORDER]
      : [...counts.keys()];

  return order
    .filter((key) => (counts.get(key) ?? 0) > 0)
    .map((key) => ({
      key,
      label: key.replace(/_/g, ' ').replace(/\b\w/g, (char) => char.toUpperCase()),
      count: counts.get(key) ?? 0
    }));
}

export function buildTrendSeries(input: {
  surfaceKind: FinancialSurfaceKind;
  statementRows?: StandardizedFinancialRow[];
  ratioRows?: RatioRow[];
  kpiRows?: StructuredKpiRow[];
}) {
  switch (input.surfaceKind) {
    case 'income_statement':
      return (input.statementRows ?? [])
        .filter((row) => row.key === 'revenue' || row.key === 'net_income')
        .map(toTrendSeriesRow);
    case 'balance_sheet':
      return (input.statementRows ?? [])
        .filter((row) => row.key === 'total_assets' || row.key === 'cash_and_equivalents' || row.key === 'total_debt')
        .map(toTrendSeriesRow);
    case 'cash_flow_statement':
      return (input.statementRows ?? [])
        .filter((row) => row.key === 'operating_cash_flow' || row.key === 'free_cash_flow' || row.key === 'capital_expenditures')
        .map(toTrendSeriesRow);
    case 'ratios':
      return (input.ratioRows ?? [])
        .filter((row) => row.category === 'margins')
        .map(toTrendSeriesRow);
    case 'segments_kpis': {
      const rows = input.kpiRows ?? [];
      const firstCategory = buildFinancialCategories(rows, 'segments_kpis')[0]?.key ?? null;
      return rows
        .filter((row) => row.category === firstCategory)
        .slice(0, 4)
        .map(toTrendSeriesRow);
    }
    default:
      return [];
  }
}