/** Pure helpers for the trial-intelligence pages (sorting whitelist, CSV cells). Shared by server components, route handlers and tests. */

export const INTEL_SORT_KEYS = ['active', 'total', 'recruiting', 'phase3Active', 'phase3Recruiting', 'growth', 'avgEnrollment', 'industryShare', 'sponsorHhi', 'distinctCountries', 'usShare', 'terminationShare', 'trialsPer1000Deaths', 'name'] as const;
export type IntelSortKey = (typeof INTEL_SORT_KEYS)[number];

/** Minimal shape the sorter needs (snake_case, as returned by the query layer). */
export interface IntelSortable {
  cancer_name: string;
  total_trials: number;
  active_trials: number;
  recruiting_trials: number;
  phase3_active: number;
  phase3_recruiting: number;
  trial_growth_yoy: number | null;
  avg_enrollment: number | null;
  industry_share: number | null;
  sponsor_hhi: number | null;
  distinct_countries: number;
  us_share: number | null;
  termination_share: number | null;
  trials_per_1000_deaths: number | null;
}

const FIELD: Record<IntelSortKey, keyof IntelSortable> = {
  active: 'active_trials',
  total: 'total_trials',
  recruiting: 'recruiting_trials',
  phase3Active: 'phase3_active',
  phase3Recruiting: 'phase3_recruiting',
  growth: 'trial_growth_yoy',
  avgEnrollment: 'avg_enrollment',
  industryShare: 'industry_share',
  sponsorHhi: 'sponsor_hhi',
  distinctCountries: 'distinct_countries',
  usShare: 'us_share',
  terminationShare: 'termination_share',
  trialsPer1000Deaths: 'trials_per_1000_deaths',
  name: 'cancer_name',
};

export function isIntelSortKey(v: string): v is IntelSortKey {
  return (INTEL_SORT_KEYS as readonly string[]).includes(v);
}

/**
 * Sort rows by a whitelisted key. Nulls always go last (whatever the direction) so "unknown" never
 * ranks above a real value; ties fall back to the cancer name for a deterministic order.
 */
export function sortIntel<T extends IntelSortable>(rows: readonly T[], key: IntelSortKey, order: 'asc' | 'desc'): T[] {
  const f = FIELD[key];
  const dir = order === 'asc' ? 1 : -1;
  return [...rows].sort((a, b) => {
    const va = a[f];
    const vb = b[f];
    if (va == null && vb == null) return a.cancer_name.localeCompare(b.cancer_name);
    if (va == null) return 1;
    if (vb == null) return -1;
    if (typeof va === 'string' || typeof vb === 'string') return dir * String(va).localeCompare(String(vb)) || a.cancer_name.localeCompare(b.cancer_name);
    return dir * ((va as number) - (vb as number)) || a.cancer_name.localeCompare(b.cancer_name);
  });
}

/** Column totals for the header strip (only meaningful for the mutually exclusive top-level set). */
export function intelTotals<T extends IntelSortable>(rows: readonly T[]): { entities: number; total: number; active: number; recruiting: number; phase3Active: number; phase3Recruiting: number } {
  return rows.reduce(
    (s, r) => ({ entities: s.entities + 1, total: s.total + r.total_trials, active: s.active + r.active_trials, recruiting: s.recruiting + r.recruiting_trials, phase3Active: s.phase3Active + r.phase3_active, phase3Recruiting: s.phase3Recruiting + r.phase3_recruiting }),
    { entities: 0, total: 0, active: 0, recruiting: 0, phase3Active: 0, phase3Recruiting: 0 },
  );
}

/** RFC 4180 cell: quote when the value contains a comma, quote or newline; null → empty. */
export function csvCell(v: unknown): string {
  const s = v == null ? '' : typeof v === 'object' ? JSON.stringify(v) : String(v);
  return /[",\n\r]/.test(s) ? `"${s.replace(/"/g, '""')}"` : s;
}

/** Signed percentage for growth values: "+21.5%", "−3.6%"; em dash when null. */
export function fmtGrowth(v: number | null | undefined, digits = 1): string {
  if (v == null || !Number.isFinite(v)) return '—';
  const pct = v * 100;
  const s = new Intl.NumberFormat('en-US', { maximumFractionDigits: digits, minimumFractionDigits: 0 }).format(Math.abs(pct));
  return `${pct > 0 ? '+' : pct < 0 ? '−' : ''}${s}%`;
}

/** Human label for a stop-reason category. */
export function reasonLabel(cat: string): string {
  const map: Record<string, string> = {
    enrollment: 'Enrollment / accrual',
    funding: 'Funding',
    sponsor_decision: 'Sponsor / business decision',
    safety: 'Safety / toxicity',
    efficacy: 'Efficacy / futility',
    drug_supply: 'Drug supply',
    investigator: 'Investigator',
    covid: 'COVID-19 / pandemic',
    other_stated: 'Other (stated, no rule matched)',
    not_stated: 'Not stated',
  };
  return map[cat] ?? cat.replace(/_/g, ' ');
}