src/lib/agent/debateProtocol.ts

/**
 * debateProtocol.ts — S219: Dual-Agent Debate Protocol
 *
 * Schema versionato (v:1) per massima forward-compatibility.
 * Gestisce:
 *  - Tipi strutturati per le proposte (programmaticamente diff-abili)
 *  - Divergence scoring (Jaccard pesato su plan/steps/risks)
 *  - Tiebreak deterministico (nessuna chiamata LLM extra)
 *  - JSON parsing robusto con 3 fallback + free-text finale
 *  - Formato output per la UI
 *
 * Design:
 *  - Zero LLM, zero React, zero side-effects — pure functions
 *  - Safari-safe: nessun Worker, nessun SharedArrayBuffer
 *  - DI-friendly: tutte le fn esportate per testing
 *
 * @module debateProtocol
 */

export const DEBATE_PROTOCOL_VERSION = 1 as const;

// import { safeJsonParse } from '../utils/safeJsonParse'; // removed: unused

export type DebateRole = "builder" | "critic";

// ── Tipi strutturati ────────────────────────────────────────────────────────

/** Proposta di un agente in un round del debate */
export interface DebateProposal {
  v: 1;
  role: DebateRole;
  taskId: string;
  round: number;
  /** Approccio generale alla soluzione (1–2 frasi) */
  plan: string;
  /** Passi concreti e ordinati */
  steps: string[];
  /** Rischi, edge case, regressioni identificati */
  risks: string[];
  /** Fiducia nella proposta: 0–100 */
  confidence: number;
  /** File/componenti da toccare */
  changes: string[];
  timestamp: number;
}

/** Risultato finale del debate (dopo N round o convergenza) */
export interface DebateConsensus {
  v: 1;
  taskId: string;
  rounds: number;
  /** true = convergenza organica, false = tiebreak applicato */
  agreed: boolean;
  /** Nome della regola di tiebreak se agreed=false */
  tiebreakRule?: string;
  /** Proposta finale da usare */
  final: DebateProposal;
  builderFinal: DebateProposal;
  criticFinal:  DebateProposal;
  /** 0 = proposte identiche, 1 = totalmente divergenti */
  divergenceScore: number;
  durationMs: number;
}

/** Evento emesso durante il debate per aggiornamenti UI */
export type DebateEvent =
  | { type: "round_start"; round: number; role: DebateRole }
  | { type: "proposal";   proposal: DebateProposal }
  | { type: "divergence"; score: number; round: number }
  | { type: "consensus";  consensus: DebateConsensus }
  | { type: "error";      error: string; round?: number };

export type DebateEventHandler = (event: DebateEvent) => void;

// ── Divergence scoring ──────────────────────────────────────────────────────

function tokenize(text: string): Set<string> {
  return new Set(
    text.toLowerCase().split(/\W+/).filter(t => t.length > 2)
  );
}

function jaccardSim(a: string, b: string): number {
  const sa = tokenize(a);
  const sb = tokenize(b);
  if (sa.size === 0 && sb.size === 0) return 1;
  let inter = 0;
  sa.forEach(t => { if (sb.has(t)) inter++; });
  const union = sa.size + sb.size - inter;
  return union === 0 ? 1 : inter / union;
}

/**
 * Quanto sono divergenti due proposte?
 * Peso: plan 30% · steps 40% · risks 30%.
 * Ritorna 0 (identiche) → 1 (totalmente diverse).
 */
export function scoreDivergence(a: DebateProposal, b: DebateProposal): number {
  const planSim  = jaccardSim(a.plan, b.plan);
  const stepsSim = jaccardSim(a.steps.join(" "), b.steps.join(" "));
  const risksSim = jaccardSim(a.risks.join(" "), b.risks.join(" "));
  const sim = 0.30 * planSim + 0.40 * stepsSim + 0.30 * risksSim;
  return Math.round((1 - sim) * 100) / 100;
}

// ── Tiebreak deterministico ─────────────────────────────────────────────────

export interface TiebreakResult {
  winner: "builder" | "critic" | "merge";
  rule: string;
  proposal: DebateProposal;
}

const CRITICAL_RISK_RE = /security|auth|data.?loss|crash|infinite.?loop|regression|breaking.?change|sql.?inject|xss|overflow/i;

/**
 * Tiebreak deterministico quando i due agenti non convergono.
 *
 * Regole (priorità decrescente):
 *  1. critic_security  — critico ha ≥2 rischi di sicurezza critici → merge con warning
 *  2. critic_confident — confidence critico > builder + 10 → vince critico
 *  3. builder_dominant — confidence builder > critico + 20 → vince builder
 *  4. merge_default    — merge steps builder + risks critico, confidence media
 */
export function applyTiebreak(
  builder: DebateProposal,
  critic:  DebateProposal,
): TiebreakResult {
  const criticalRisks = critic.risks.filter(r => CRITICAL_RISK_RE.test(r));

  // Regola 1: sicurezza
  if (criticalRisks.length >= 2) {
    const merged: DebateProposal = {
      ...builder,
      risks: [...new Set([...builder.risks, ...critic.risks])],
      steps: [
        ...builder.steps,
        `[CRITICO] Verificare prima di procedere: ${criticalRisks.slice(0, 2).join("; ")}`,
      ],
      confidence: Math.min(builder.confidence, critic.confidence),
      timestamp: Date.now(),
    };
    return { winner: "merge", rule: "critic_security", proposal: merged };
  }

  // Regola 2: critico molto più sicuro
  if (critic.confidence > builder.confidence + 10) {
    return { winner: "critic", rule: "critic_confident", proposal: critic };
  }

  // Regola 3: builder molto più sicuro
  if (builder.confidence > critic.confidence + 20) {
    return { winner: "builder", rule: "builder_dominant", proposal: builder };
  }

  // Regola 4: merge default
  const merged: DebateProposal = {
    ...builder,
    risks: [...new Set([...builder.risks, ...critic.risks])],
    confidence: Math.round((builder.confidence + critic.confidence) / 2),
    timestamp: Date.now(),
  };
  return { winner: "merge", rule: "merge_default", proposal: merged };
}

// ── JSON parsing robusto ────────────────────────────────────────────────────

const REQUIRED_FIELDS = ["plan", "steps", "risks", "confidence"] as const;

function extractJson(text: string): Record<string, unknown> | null {
  // Tentativo 1: testo diretto
  try { return JSON.parse(text.trim()) as Record<string, unknown>; } catch { /* */ }

  // Tentativo 2: blocco ```json ... ```
  const fenced = text.match(/```(?:json)?\s*([\s\S]*?)```/i);
  if (fenced?.[1]) {
    try { return JSON.parse(fenced[1].trim()) as Record<string, unknown>; } catch { /* */ }
  }

  // Tentativo 3: trova { ... } bilanciato
  const start = text.indexOf("{");
  if (start !== -1) {
    let depth = 0;
    for (let i = start; i < text.length; i++) {
      if (text[i] === "{") depth++;
      else if (text[i] === "}") {
        depth--;
        if (depth === 0) {
          try { return JSON.parse(text.slice(start, i + 1)) as Record<string, unknown>; } catch { break; }
        }
      }
    }
  }
  return null;
}

/**
 * Parsa il testo LLM in DebateProposal strutturata.
 * Ritorna null se il parsing fallisce completamente.
 */
export function parseProposal(
  rawText: string,
  role:    DebateRole,
  taskId:  string,
  round:   number,
): DebateProposal | null {
  const data = extractJson(rawText);
  if (!data) return null;
  for (const f of REQUIRED_FIELDS) {
    if (!(f in data)) return null;
  }
  return {
    v: 1, role, taskId, round,
    plan:       String(data.plan ?? "").slice(0, 500),
    steps:      Array.isArray(data.steps) ? data.steps.map(s => String(s).slice(0, 200)) : [],
    risks:      Array.isArray(data.risks) ? data.risks.map(r => String(r).slice(0, 200)) : [],
    confidence: Math.max(0, Math.min(100, Number(data.confidence ?? 50))),
    changes:    Array.isArray(data.changes) ? data.changes.map(c => String(c).slice(0, 200)) : [],  // S609: 100→200
    timestamp:  Date.now(),
  };
}

/** Fallback: costruisce proposta minimale da testo libero */
export function proposalFromFreeText(
  text:   string,
  role:   DebateRole,
  taskId: string,
  round:  number,
): DebateProposal {
  const lines = text.split("\n").map(l => l.trim()).filter(Boolean);
  return {
    v: 1, role, taskId, round,
    plan:       lines[0]?.slice(0, 400) ?? text.slice(0, 400),  // S610: 300→400
    steps:      lines.slice(1, 5).map(l => l.slice(0, 200)),  // S610: 150→200
    risks:      [],
    confidence: 35, // bassa: free-text non strutturato
    changes:    [],
    timestamp:  Date.now(),
  };
}

// ── Formatting ──────────────────────────────────────────────────────────────

/** Formatta il consenso finale in markdown leggibile per la UI */
export function formatConsensus(c: DebateConsensus): string {
  const icon = c.agreed ? "✅" : "⚖️";
  const how  = c.agreed
    ? "consenso raggiunto"
    : `tiebreak — regola: \`${c.tiebreakRule ?? "merge"}\``;
  const div  = Math.round(c.divergenceScore * 100);

  const parts = [
    `${icon} **Debate concluso** — ${c.rounds} round · ${how}`,
    `Divergenza finale: **${div}%** · Confidence: **${c.final.confidence}/100** · ${(c.durationMs/1000).toFixed(1)}s`,
    "",
    `### Piano approvato`,
    c.final.plan,
  ];

  if (c.final.steps.length) {
    parts.push("", "**Passi:**");
    c.final.steps.forEach((s, i) => parts.push(`${i + 1}. ${s}`));
  }

  if (c.final.risks.length) {
    parts.push("", "**Rischi identificati:**");
    c.final.risks.forEach(r => parts.push(`- ⚠️ ${r}`));
  }

  if (c.final.changes.length) {
    parts.push("", `**File da modificare:** ${c.final.changes.join(", ")}`);
  }

  if (!c.agreed) {
    parts.push(
      "",
      `> Builder confidence: ${c.builderFinal.confidence}/100 · Critic confidence: ${c.criticFinal.confidence}/100`,
    );
  }

  return parts.join("\n");
}