// replay.ts — Phase 7 distillation replay layer.
//
// Takes a task → retrieves matching playbooks/RAG records → builds a
// context bundle → calls a LOCAL model → validates → escalates if
// needed → logs the run as new evidence.
//
// This is NOT training. It's runtime behavior shaping via retrieval.
// A weak local model with the right prior context outperforms the
// same model with no context — proven by the local_only vs retrieval
// A/B in the report.
//
// Spec invariants:
//   - never bypass retrieval
//   - never discard provenance
//   - never allow free-form hallucinated output (validation gate)
//   - log every run as new evidence (data/_kb/replay_runs.jsonl)

import { existsSync, readFileSync, mkdirSync, appendFileSync } from "node:fs";
import { resolve, dirname } from "node:path";
import { canonicalSha256 } from "../../auditor/schemas/distillation/types";

const DEFAULT_ROOT = process.env.LH_DISTILL_ROOT ?? "/home/profit/lakehouse";
// Read env per-call so tests can override GATEWAY mid-process.
function gatewayUrl(): string { return process.env.LH_GATEWAY_URL ?? "http://localhost:3100"; }
const LOCAL_MODEL = process.env.LH_REPLAY_LOCAL_MODEL ?? "qwen3.5:latest";
const ESCALATION_MODEL = process.env.LH_REPLAY_ESCALATION_MODEL ?? "deepseek-v3.1:671b";

export interface ReplayRequest {
  task: string;
  local_only?: boolean;        // never escalate; just record validation result
  allow_escalation?: boolean;  // try the bigger model on local failure
  no_retrieval?: boolean;      // baseline mode: skip context bundle
  // Test-only: return a synthetic response without calling the gateway.
  // The synthetic response is deterministic (echoes context bundle
  // signals) so retrieval/bundle/log tests can run without an LLM.
  dry_run?: boolean;
}

export interface RetrievedArtifact {
  rag_id: string;
  source_run_id: string;
  title: string;
  content_preview: string;     // first 240 chars of content
  success_score: string;
  tags: string[];
  score: number;               // overlap score with task
}

export interface ContextBundle {
  retrieved_playbooks: RetrievedArtifact[];   // top accepted
  prior_successful_outputs: RetrievedArtifact[]; // accepted samples used as in-context exemplars
  failure_patterns: RetrievedArtifact[];      // partial/needs-review samples used as warnings
  validation_steps: string[];                 // extracted from accepted-content lines starting with "verify"/"check"/"assert"
  bundle_token_estimate: number;
}

export interface ValidationResult {
  passed: boolean;
  reasons: string[];           // explicit, every gate names itself
}

export interface ReplayResult {
  input_task: string;
  task_hash: string;            // sha256 of task — stable replay id
  retrieved_artifacts: { rag_ids: string[] };
  context_bundle: ContextBundle | null;   // null when --no-retrieval
  model_response: string;
  model_used: string;
  escalation_path: string[];    // models tried in order, e.g. ["qwen3.5:latest", "deepseek-v3.1:671b"]
  validation_result: ValidationResult;
  recorded_run_id: string;
  recorded_at: string;
  duration_ms: number;
}

interface RagSample {
  id: string;
  title: string;
  content: string;
  tags: string[];
  source_run_id: string;
  success_score: string;
  source_category: string;
}

// ─── Retrieval ────────────────────────────────────────────────────

function tokenize(text: string): Set<string> {
  // Lowercase + alphanumeric tokens of length ≥3. Keeps it simple and
  // deterministic; future tightening: add embedding similarity if the
  // RAG corpus grows past keyword scaling limits.
  return new Set(
    text.toLowerCase()
      .split(/[^a-z0-9_]+/)
      .filter(t => t.length >= 3),
  );
}

function jaccard(a: Set<string>, b: Set<string>): number {
  if (a.size === 0 || b.size === 0) return 0;
  let inter = 0;
  for (const t of a) if (b.has(t)) inter++;
  const union = a.size + b.size - inter;
  return union === 0 ? 0 : inter / union;
}

function loadRagCorpus(root: string): RagSample[] {
  const path = resolve(root, "exports/rag/playbooks.jsonl");
  if (!existsSync(path)) return [];
  const out: RagSample[] = [];
  for (const line of readFileSync(path, "utf8").split("\n")) {
    if (!line) continue;
    try { out.push(JSON.parse(line) as RagSample); } catch { /* skip */ }
  }
  return out;
}

function retrieveRag(corpus: RagSample[], task: string, topK = 5): RetrievedArtifact[] {
  const taskTokens = tokenize(task);
  const scored = corpus.map(r => {
    const text = `${r.title} ${r.content} ${(r.tags ?? []).join(" ")}`;
    const score = jaccard(taskTokens, tokenize(text));
    return { record: r, score };
  });
  scored.sort((a, b) => b.score - a.score);
  return scored.slice(0, topK)
    .filter(s => s.score > 0)
    .map(s => ({
      rag_id: s.record.id,
      source_run_id: s.record.source_run_id,
      title: s.record.title,
      content_preview: s.record.content.slice(0, 240),
      success_score: s.record.success_score,
      tags: s.record.tags ?? [],
      score: s.score,
    }));
}

// Extract sentences that read like a check/verify/assert step from
// accepted samples — these are the validation_steps the local model
// should follow.
function extractValidationSteps(samples: RetrievedArtifact[], corpus: RagSample[]): string[] {
  const ids = new Set(samples.map(s => s.rag_id));
  const steps: string[] = [];
  for (const r of corpus) {
    if (!ids.has(r.id)) continue;
    for (const line of r.content.split("\n")) {
      const t = line.trim();
      if (/^[-*]\s*(verify|check|assert|confirm|ensure)\b/i.test(t) ||
          /^\s*(verify|check|assert|confirm|ensure)\s/i.test(t)) {
        steps.push(t.slice(0, 200));
        if (steps.length >= 6) return steps;
      }
    }
  }
  return steps;
}

function buildContextBundle(corpus: RagSample[], task: string): ContextBundle {
  const top = retrieveRag(corpus, task, 8);
  const accepted = top.filter(t => t.success_score === "accepted").slice(0, 3);
  const warnings = top.filter(t => t.success_score === "partially_accepted").slice(0, 2);
  const validation_steps = extractValidationSteps(accepted, corpus);

  // Token estimate (~4 chars/token rough)
  const totalChars = [...accepted, ...warnings].reduce(
    (a, x) => a + x.content_preview.length + x.title.length, 0,
  ) + validation_steps.reduce((a, s) => a + s.length, 0);
  const bundle_token_estimate = Math.ceil(totalChars / 4);

  return {
    retrieved_playbooks: top,
    prior_successful_outputs: accepted,
    failure_patterns: warnings,
    validation_steps,
    bundle_token_estimate,
  };
}

// ─── Prompt assembly ──────────────────────────────────────────────

function buildPrompt(task: string, bundle: ContextBundle | null): { system: string; user: string } {
  const system = [
    "You are a Lakehouse task executor. Stay grounded — only assert what you can derive from the prior successful patterns or the task itself.",
    "Do NOT hedge. Do NOT say 'as an AI'. Produce a concrete actionable answer.",
    "When prior successful outputs are provided, follow their style and format.",
  ].join(" ");

  if (!bundle) {
    return { system, user: `Task: ${task}\n\nProduce the answer.` };
  }

  const parts: string[] = [];
  if (bundle.prior_successful_outputs.length > 0) {
    parts.push("## Prior successful runs on similar tasks");
    parts.push("");
    for (const r of bundle.prior_successful_outputs) {
      parts.push(`### ${r.title} (score: ${r.success_score})`);
      parts.push(r.content_preview);
      parts.push("");
    }
  }
  if (bundle.failure_patterns.length > 0) {
    parts.push("## Patterns that produced PARTIAL results — avoid these failure modes");
    parts.push("");
    for (const r of bundle.failure_patterns) {
      parts.push(`- ${r.title}: ${r.content_preview.slice(0, 160)}`);
    }
    parts.push("");
  }
  if (bundle.validation_steps.length > 0) {
    parts.push("## Validation checklist (from accepted runs)");
    for (const s of bundle.validation_steps) parts.push(`- ${s}`);
    parts.push("");
  }
  parts.push("## Task");
  parts.push(task);
  parts.push("");
  parts.push("Produce the answer following the style of the prior successful runs above.");

  return { system, user: parts.join("\n") };
}

// ─── Model call ───────────────────────────────────────────────────

async function callModel(model: string, system: string, user: string): Promise<{ content: string; ok: boolean; error?: string }> {
  const provider = model.includes("/") ? "openrouter"
                : (model.startsWith("kimi-") || model.startsWith("qwen3-coder") || model.startsWith("deepseek-v") ||
                   model.startsWith("mistral-large") || model === "gpt-oss:120b" || model === "qwen3.5:397b")
                  ? "ollama_cloud" : "ollama";
  try {
    const r = await fetch(`${gatewayUrl()}/v1/chat`, {
      method: "POST",
      headers: { "content-type": "application/json" },
      body: JSON.stringify({
        provider, model,
        messages: [
          { role: "system", content: system },
          { role: "user", content: user },
        ],
        max_tokens: 1500,
        temperature: 0.1,
      }),
      signal: AbortSignal.timeout(180_000),
    });
    if (!r.ok) return { content: "", ok: false, error: `HTTP ${r.status}: ${(await r.text()).slice(0, 240)}` };
    const j: any = await r.json();
    const content = j?.choices?.[0]?.message?.content ?? "";
    return { content, ok: true };
  } catch (e) {
    return { content: "", ok: false, error: (e as Error).message.slice(0, 240) };
  }
}

// ─── Validation gate (deterministic; never an LLM) ───────────────

function validateResponse(response: string, bundle: ContextBundle | null): ValidationResult {
  const reasons: string[] = [];
  const trimmed = response.trim();

  if (trimmed.length === 0) {
    return { passed: false, reasons: ["empty response"] };
  }
  if (trimmed.length < 80) {
    reasons.push(`response too short (${trimmed.length} chars; min 80)`);
  }
  // Filler / hedge patterns the spec explicitly rejects.
  const fillers = [/as an ai/i, /i cannot/i, /i'm sorry, but/i, /i don'?t have access/i, /i am unable to/i];
  for (const re of fillers) {
    if (re.test(trimmed)) {
      reasons.push(`filler/hedge phrase detected: ${re}`);
    }
  }
  // If a validation checklist was supplied, expect the response to
  // touch at least one of the checklist topics. Soft check: presence of
  // any checklist token (≥3 chars) in the response.
  if (bundle && bundle.validation_steps.length > 0) {
    const checklistTokens = new Set<string>();
    for (const s of bundle.validation_steps) {
      for (const t of tokenize(s)) checklistTokens.add(t);
    }
    const respTokens = tokenize(trimmed);
    let overlap = 0;
    for (const t of checklistTokens) if (respTokens.has(t)) overlap++;
    if (checklistTokens.size > 0 && overlap === 0) {
      reasons.push("response shares no tokens with validation checklist (may not have followed prior patterns)");
    }
  }

  return { passed: reasons.length === 0, reasons };
}

// Test/dry-run synthesizer. Produces a deterministic response that
// echoes context-bundle signals so the retrieval+validation pipeline
// can be tested without an LLM. NOT used outside tests.
function dryRunSynthesize(task: string, bundle: ContextBundle | null): string {
  const parts: string[] = [
    "Synthetic dry-run response for task: " + task.slice(0, 120),
    "",
  ];
  if (bundle) {
    parts.push(`Retrieved ${bundle.retrieved_playbooks.length} playbooks; ${bundle.prior_successful_outputs.length} accepted, ${bundle.failure_patterns.length} partial.`);
    if (bundle.validation_steps.length > 0) {
      parts.push("Following validation checklist:");
      for (const s of bundle.validation_steps.slice(0, 3)) parts.push("- " + s);
    }
    if (bundle.prior_successful_outputs[0]) {
      parts.push("");
      parts.push("Anchored on prior accepted: " + bundle.prior_successful_outputs[0].title);
    }
  } else {
    parts.push("No retrieval context — answering from task alone. Verify and check produced output before approving.");
  }
  return parts.join("\n");
}

// ─── Evidence logging ────────────────────────────────────────────

async function logReplayEvidence(root: string, result: ReplayResult): Promise<void> {
  const path = resolve(root, "data/_kb/replay_runs.jsonl");
  mkdirSync(dirname(path), { recursive: true });
  const row = {
    schema: "replay_run.v1",
    ...result,
    // Truncate model_response in the persisted log to keep file lean;
    // full text lives in the in-memory ReplayResult and any caller
    // wanting the verbatim output can re-run with the same task.
    model_response: result.model_response.slice(0, 4000),
  };
  appendFileSync(path, JSON.stringify(row) + "\n");
}

// ─── Top-level replay function ───────────────────────────────────

export async function replay(opts: ReplayRequest, root = DEFAULT_ROOT): Promise<ReplayResult> {
  const t0 = Date.now();
  const recorded_at = new Date().toISOString();
  const task_hash = await canonicalSha256(opts.task);

  const corpus = loadRagCorpus(root);
  const bundle = opts.no_retrieval ? null : buildContextBundle(corpus, opts.task);
  const { system, user } = buildPrompt(opts.task, bundle);

  const escalation_path: string[] = [];
  let model_response = "";
  let model_used = "";
  let validation: ValidationResult = { passed: false, reasons: ["never executed"] };

  // Try local model first.
  escalation_path.push(LOCAL_MODEL);
  model_used = LOCAL_MODEL;
  const localCall = opts.dry_run
    ? { ok: true, content: dryRunSynthesize(opts.task, bundle) }
    : await callModel(LOCAL_MODEL, system, user);
  if (localCall.ok) {
    model_response = localCall.content;
    validation = validateResponse(model_response, bundle);
  } else {
    validation = { passed: false, reasons: [`local call failed: ${localCall.error}`] };
  }

  // Escalate if validation failed AND escalation allowed.
  if (!validation.passed && opts.allow_escalation && !opts.local_only) {
    escalation_path.push(ESCALATION_MODEL);
    const escalCall = opts.dry_run
      ? { ok: true, content: dryRunSynthesize(opts.task, bundle) + "\n\n[ESCALATED]" }
      : await callModel(ESCALATION_MODEL, system, user);
    if (escalCall.ok) {
      model_response = escalCall.content;
      model_used = ESCALATION_MODEL;
      validation = validateResponse(model_response, bundle);
      if (validation.passed) validation.reasons.unshift(`recovered via escalation to ${ESCALATION_MODEL}`);
    } else {
      validation.reasons.push(`escalation also failed: ${escalCall.error}`);
    }
  }

  // Stable derivation from task_hash + recorded_at (already an ISO
  // timestamp captured at start of the call). Avoids a second wall-clock
  // read and makes run_id reproducible given a fixed recorded_at — useful
  // for fixture-driven tests + acceptance gates. Replaces Date.now()-based
  // id post-Kimi-audit 2026-04-27.
  const recorded_run_id = `replay:${task_hash.slice(0, 16)}:${(await canonicalSha256(recorded_at)).slice(0, 12)}`;
  const result: ReplayResult = {
    input_task: opts.task,
    task_hash,
    retrieved_artifacts: { rag_ids: bundle?.retrieved_playbooks.map(p => p.rag_id) ?? [] },
    context_bundle: bundle,
    model_response,
    model_used,
    escalation_path,
    validation_result: validation,
    recorded_run_id,
    recorded_at,
    duration_ms: Date.now() - t0,
  };

  await logReplayEvidence(root, result);
  return result;
}

// ─── CLI ──────────────────────────────────────────────────────────

async function cli() {
  const taskIdx = process.argv.indexOf("--task");
  if (taskIdx < 0 || !process.argv[taskIdx + 1]) {
    console.error("usage: replay.ts --task \"<input>\" [--local-only] [--allow-escalation] [--no-retrieval]");
    process.exit(2);
  }
  const task = process.argv[taskIdx + 1];
  const local_only = process.argv.includes("--local-only");
  const allow_escalation = process.argv.includes("--allow-escalation");
  const no_retrieval = process.argv.includes("--no-retrieval");

  const r = await replay({ task, local_only, allow_escalation, no_retrieval });

  console.log(`[replay] run_id=${r.recorded_run_id}`);
  console.log(`[replay] retrieval: ${r.context_bundle ? r.context_bundle.retrieved_playbooks.length + " playbooks" : "DISABLED"}`);
  console.log(`[replay] escalation_path: ${r.escalation_path.join(" → ")}`);
  console.log(`[replay] model_used: ${r.model_used} · ${r.duration_ms}ms`);
  console.log(`[replay] validation: ${r.validation_result.passed ? "PASS" : "FAIL"}${r.validation_result.reasons.length ? " (" + r.validation_result.reasons.join("; ") + ")" : ""}`);
  console.log("");
  console.log("─── response ───");
  console.log(r.model_response.slice(0, 1500));
  if (r.model_response.length > 1500) console.log(`... [${r.model_response.length - 1500} more chars]`);
}

if (import.meta.main) cli().catch(e => { console.error(e); process.exit(1); });