import type { ConfidenceLevel, SourceKind } from "./types.js";

export const CONFIDENCE_RANK: Record<ConfidenceLevel, number> = { verified: 5, high: 4, moderate: 3, estimated: 2, unverified: 1 };

/** Base confidence by source category (before adjustments). */
export const SOURCE_KIND_BASE: Record<SourceKind, ConfidenceLevel> = {
  operator: "high",
  government: "high",
  filing: "high",
  utility: "high",
  cloud_provider: "high",
  registry: "high",
  dataset: "moderate",
  community: "moderate",
  secondary: "moderate",
  news: "moderate",
};

export interface ConfidenceInput {
  sourceKind: SourceKind;
  sourcePriority?: number; // 1 (best) … 5
  extractionCertainty?: number; // 0..1 (structured field = 1, regex on prose = 0.6, llm = 0.4)
  ageDays?: number;
  corroborations?: number; // number of independent sources agreeing
  conflicts?: number; // independent sources disagreeing
  isEstimate?: boolean;
}

export function computeConfidence(i: ConfidenceInput): ConfidenceLevel {
  if (i.isEstimate) return "estimated";
  let score = CONFIDENCE_RANK[SOURCE_KIND_BASE[i.sourceKind]];
  const cert = i.extractionCertainty ?? 1;
  if (cert < 0.5) score -= 2;
  else if (cert < 0.8) score -= 1;
  if ((i.corroborations ?? 0) >= 2) score += 1;
  if ((i.conflicts ?? 0) >= 1) score -= 1;
  if ((i.ageDays ?? 0) > 730) score -= 1;
  if ((i.sourcePriority ?? 3) >= 5) score -= 1;
  score = Math.max(1, Math.min(5, score));
  // "verified" requires corroboration by ≥2 independent primary-grade sources
  if (score === 5 && !((i.corroborations ?? 0) >= 2 && cert >= 0.8)) score = 4;
  return (Object.keys(CONFIDENCE_RANK) as ConfidenceLevel[]).find((k) => CONFIDENCE_RANK[k] === score) ?? "unverified";
}

export function bestConfidence(levels: ConfidenceLevel[]): ConfidenceLevel {
  return levels.reduce<ConfidenceLevel>((best, l) => (CONFIDENCE_RANK[l] > CONFIDENCE_RANK[best] ? l : best), "unverified");
}

export const CONFIDENCE_LABEL: Record<ConfidenceLevel, string> = { verified: "Verified", high: "High confidence", moderate: "Moderate confidence", estimated: "Estimated", unverified: "Unverified" };