src/shared/llm/grounding.ts

/**
 * Grounded Hallucination Detection
 * 
 * Google DeepMind approach: Every LLM claim must be traceable
 * to a piece of evidence. Claims without evidence are stripped.
 * 
 * This is NOT "ask LLM for confidence" — that's like asking
 * a cheater to grade their own exam.
 * 
 * This IS: cross-reference every output field against source data.
 */

import { logger } from "../utils/logger";

export interface GroundingResult {
  isGrounded: boolean;
  groundingScore: number;         // 0.0-1.0
  verifiedClaims: string[];       // claims that match evidence
  unverifiedClaims: string[];     // claims with no evidence
  strippedClaims: string[];       // claims removed from output
  corrections: Record<string, { claimed: unknown; actual: unknown }>;
}

export interface EvidenceSet {
  // Factual data we collected from providers/scrapers
  company_name: string;
  domain: string;
  employee_count: number | null;
  industry: string | null;
  tech_stack: string[];
  description: string | null;
  website_text: string;
  job_postings: string[];
  ai_job_count: number;
  linkedin_description: string | null;
  country: string | null;
  city: string | null;
  pain_signals_detected: string[];
}

/**
 * Validates LLM profile output against collected evidence.
 * Returns cleaned profile with unverifiable claims stripped.
 */
export function groundProfile(
  profile: Record<string, unknown>,
  evidence: EvidenceSet
): { cleaned: Record<string, unknown>; grounding: GroundingResult } {
  const verified: string[] = [];
  const unverified: string[] = [];
  const stripped: string[] = [];
  const corrections: Record<string, { claimed: unknown; actual: unknown }> = {};

  const cleaned = { ...profile };

  // ── Check profile_summary ──────────────────────────────────
  const summary = String(profile.profile_summary ?? "");
  
  // Does summary mention the right company?
  if (summary.length > 20 && !containsName(summary, evidence.company_name)) {
    stripped.push("summary_wrong_company");
    // Don't strip — just flag. LLM may paraphrase the name.
  }

  // Does summary claim employee count?
  const claimedEmpMatch = summary.match(/(\d[\d,]+)\s*(employees?|people|staff|team)/i);
  if (claimedEmpMatch && evidence.employee_count) {
    const claimed = parseInt(claimedEmpMatch[1].replace(/,/g, ""), 10);
    if (Math.abs(claimed - evidence.employee_count) > evidence.employee_count * 0.3) {
      corrections["employee_count"] = { claimed, actual: evidence.employee_count };
      // Fix the claim in the summary
      cleaned.profile_summary = summary.replace(
        claimedEmpMatch[0],
        `${evidence.employee_count} employees`
      );
      verified.push("employee_count_corrected");
    } else {
      verified.push("employee_count_accurate");
    }
  }

  // ── Check industry claim ───────────────────────────────────
  const claimedIndustry = summary.toLowerCase();
  if (evidence.industry) {
    const industryWords = evidence.industry.toLowerCase().split(/[\s_]+/);
    const hasIndustryMention = industryWords.some(w => claimedIndustry.includes(w));
    if (hasIndustryMention) {
      verified.push("industry_match");
    } else {
      unverified.push("industry_may_differ");
    }
  }

  // ── Check tech stack claims ─────────────────────────────────
  if (Array.isArray(profile.evidence_used)) {
    for (const claim of profile.evidence_used as string[]) {
      const claimLower = claim.toLowerCase();
      const isSupported =
        evidence.tech_stack.some(t => claimLower.includes(t.toLowerCase())) ||
        evidence.website_text.toLowerCase().includes(claimLower.slice(0, 20)) ||
        evidence.job_postings.some(j => claimLower.includes(j.toLowerCase().slice(0, 15))) ||
        evidence.pain_signals_detected.some(p => claimLower.includes(p.toLowerCase().slice(0, 15)));

      if (isSupported) {
        verified.push(`evidence: ${claim.slice(0, 40)}`);
      } else {
        unverified.push(`unverifiable: ${claim.slice(0, 40)}`);
      }
    }
  }

  // ── Check ai_readiness ─────────────────────────────────────
  const claimedReadiness = String(profile.ai_readiness ?? "");
  if (claimedReadiness === "high" && evidence.ai_job_count === 0 && evidence.tech_stack.length === 0) {
    corrections["ai_readiness"] = { claimed: "high", actual: "low" };
    cleaned.ai_readiness = "low";
    verified.push("ai_readiness_corrected");
  } else if (claimedReadiness === "low" && evidence.ai_job_count >= 3) {
    corrections["ai_readiness"] = { claimed: "low", actual: "high" };
    cleaned.ai_readiness = "high";
    verified.push("ai_readiness_corrected");
  } else {
    verified.push("ai_readiness_plausible");
  }

  // ── Check for PII leakage ──────────────────────────────────
  const outputStr = JSON.stringify(cleaned);
  const emailPattern = /[\w.+-]+@[\w-]+\.[a-z]{2,}/gi;
  const phonePattern = /\+?\d[\d\s\-().]{8,}/g;

  if (emailPattern.test(outputStr)) {
    stripped.push("pii_email_in_output");
    // Strip emails from all string fields
    for (const [key, val] of Object.entries(cleaned)) {
      if (typeof val === "string") {
        cleaned[key] = val.replace(emailPattern, "[EMAIL_REDACTED]");
      }
    }
  }

  if (phonePattern.test(outputStr)) {
    stripped.push("pii_phone_in_output");
    for (const [key, val] of Object.entries(cleaned)) {
      if (typeof val === "string") {
        cleaned[key] = val.replace(phonePattern, "[PHONE_REDACTED]");
      }
    }
  }

  // ── Compute grounding score ────────────────────────────────
  const totalChecks = verified.length + unverified.length + stripped.length;
  const groundingScore = totalChecks === 0 ? 0.5 : verified.length / totalChecks;

  const result: GroundingResult = {
    isGrounded: groundingScore >= 0.6 && stripped.length === 0,
    groundingScore,
    verifiedClaims: verified,
    unverifiedClaims: unverified,
    strippedClaims: stripped,
    corrections,
  };

  if (!result.isGrounded) {
    logger.warn(
      { groundingScore: groundingScore.toFixed(2), corrections: Object.keys(corrections).length },
      "Profile failed grounding — corrections applied"
    );
  }

  return { cleaned, grounding: result };
}

/**
 * Validates scoring signals against evidence.
 * Scores are computed DETERMINISTICALLY from signals — 
 * LLM only extracts signals, code computes score.
 */
export function groundSignals(
  signals: Record<string, unknown>,
  evidence: EvidenceSet
): { cleaned: Record<string, unknown>; grounding: GroundingResult } {
  const verified: string[] = [];
  const unverified: string[] = [];
  const corrections: Record<string, { claimed: unknown; actual: unknown }> = {};
  const cleaned = { ...signals };

  // Verify company_fit_signals
  const fitSignals = signals.company_fit_signals as Record<string, unknown> | undefined;
  if (fitSignals) {
    if (fitSignals.size_appropriate === true && evidence.employee_count !== null && evidence.employee_count < 3) {
      corrections["size_appropriate"] = { claimed: true, actual: false };
      verified.push("size_corrected");
    } else {
      verified.push("size_plausible");
    }
  }

  // Verify ai_readiness_signals
  const aiSignals = signals.ai_readiness_signals as Record<string, unknown> | undefined;
  if (aiSignals) {
    if (aiSignals.ai_jobs_present === true && evidence.ai_job_count === 0) {
      corrections["ai_jobs_present"] = { claimed: true, actual: false };
      verified.push("ai_jobs_corrected");
    } else {
      verified.push("ai_jobs_accurate");
    }

    if (aiSignals.tech_stack_relevant === true && evidence.tech_stack.length === 0) {
      corrections["tech_stack_relevant"] = { claimed: true, actual: false };
      verified.push("tech_stack_corrected");
    } else {
      verified.push("tech_stack_accurate");
    }
  }

  const totalChecks = verified.length + unverified.length;
  const groundingScore = totalChecks === 0 ? 0.5 : verified.length / totalChecks;

  return {
    cleaned,
    grounding: {
      isGrounded: groundingScore >= 0.6,
      groundingScore,
      verifiedClaims: verified,
      unverifiedClaims: unverified,
      strippedClaims: [],
      corrections,
    },
  };
}

// ─── Helpers ─────────────────────────────────────────────────

function containsName(text: string, name: string): boolean {
  const words = name.toLowerCase().split(/\s+/);
  const textLower = text.toLowerCase();
  // At least one significant word from company name should be present
  return words.some(w => w.length > 2 && textLower.includes(w));
}