import { createHash } from "node:crypto";

export const RESULT_V1_SCHEMA_VERSION = 1;
export const MAX_RESULT_MEMBERS = 32;
export const MAX_RESULT_MEMBER_BYTES = 2 * 1024 * 1024;
/** Soft cap for HTTP wire payloads; Go fail-closes at 8MB. */
export const MAX_RESULT_WIRE_BYTES = 6 * 1024 * 1024;
/** Tail window for execution.log patches; full log remains on shared volume. */
export const EXECUTION_LOG_PATCH_BYTES = 128 * 1024;

const RETRYABLE_CODES = new Set(["agent.timeout", "agent.canceled", "agent.transient"]);
const ALLOWED_CODES = new Set([
  "agent.prompt_empty",
  "agent.unauthorized",
  "agent.timeout",
  "agent.canceled",
  "agent.transient",
  "agent.missing_deliverable",
  "agent.run_failed",
]);

export function typedErrorCode(payload) {
  const raw = String(payload?.fallback_reason || payload?.error || "");
  const t = raw.toLowerCase();
  if (t.includes("prompt_empty")) return "agent.prompt_empty";
  if (t.includes("unauthorized")) return "agent.unauthorized";
  if (t.includes("timeout") || t.includes("timed out")) return "agent.timeout";
  if (t.includes("cancel")) return "agent.canceled";
  if (
    t.includes("connection") ||
    t.includes("terminated") ||
    t.includes("econnreset") ||
    t.includes("socket hang")
  ) {
    return "agent.transient";
  }
  if (t.includes("missing target")) return "agent.missing_deliverable";
  if (payload?.retryable) return "agent.transient";
  if (!payload?.ok) return "agent.run_failed";
  return "";
}

export function membersDigest(members) {
  const rows = (Array.isArray(members) ? members : []).map((m) => ({
    kind: m.kind,
    path: m.path,
    digest: m.digest,
    size: m.size,
  }));
  return createHash("sha256").update(JSON.stringify(rows)).digest("hex");
}

/** Keep only the trailing bytes of execution.log for the HTTP patch wire. */
export function truncateExecutionLogContent(content, maxBytes = EXECUTION_LOG_PATCH_BYTES) {
  const buf = Buffer.from(String(content || ""), "utf8");
  if (buf.length <= maxBytes) {
    return buf.toString("utf8");
  }
  const tail = buf.subarray(buf.length - maxBytes);
  return `[truncated ${buf.length - maxBytes} bytes]\n` + tail.toString("utf8");
}

/**
 * Cap patch bodies so members and patches stay aligned under wire limits.
 * Oversized / overflow members are dropped from both lists (fail closed on wire size).
 */
export function capPatches(patches, opts = {}) {
  const maxMember = opts.maxMemberBytes ?? MAX_RESULT_MEMBER_BYTES;
  const maxTotal = opts.maxTotalBytes ?? MAX_RESULT_WIRE_BYTES;
  const maxMembers = opts.maxMembers ?? MAX_RESULT_MEMBERS;
  const out = [];
  let total = 0;
  for (const p of Array.isArray(patches) ? patches : []) {
    const rel = String(p?.rel_path || "");
    if (!rel || rel.includes("..") || rel.startsWith("/")) continue;
    let content = String(p.content || "");
    if (rel === "execution.log" || rel.endsWith("/execution.log")) {
      content = truncateExecutionLogContent(content);
    }
    const buf = Buffer.from(content, "utf8");
    if (buf.length > maxMember) continue;
    if (out.length >= maxMembers) break;
    if (total + buf.length > maxTotal) continue;
    total += buf.length;
    out.push({ rel_path: rel, content });
  }
  return out;
}

export function estimateWireBytes(payload) {
  return Buffer.byteLength(JSON.stringify(payload), "utf8");
}

export function withResultV1(payload) {
  const out = { ...payload };
  delete out.stderr;
  const capped = capPatches(Array.isArray(out.patches) ? out.patches : []);
  out.patches = capped;
  const members = [];
  for (const p of capped) {
    const rel = String(p?.rel_path || "");
    const buf = Buffer.from(String(p.content || ""), "utf8");
    members.push({
      kind: "file",
      path: rel,
      digest: createHash("sha256").update(buf).digest("hex"),
      size: buf.length,
    });
  }
  const ok = !!out.ok;
  const errorCode = ok ? "" : typedErrorCode(out);
  const retryable = !ok && RETRYABLE_CODES.has(errorCode) && !!out.retryable;
  out.capabilities = { typed_result: true };
  out.runner_protocol = "typed-v1";
  out.result_v1 = {
    schema_version: RESULT_V1_SCHEMA_VERSION,
    run_id: String(out.run_id || "unknown").slice(0, 128),
    outcome: ok ? "success" : "error",
    retryable,
    error_code: ALLOWED_CODES.has(errorCode) ? errorCode : ok ? "" : "agent.run_failed",
    members,
    content_digest: membersDigest(members),
  };
  return out;
}