#!/usr/bin/env node
import fs from "node:fs";
import { fileURLToPath } from "node:url";

export const BOOTSTRAP_LIMIT_BYTES = 2048;
export const READ_NODE_LIMIT_BYTES = 16384;

function fail(message) {
  throw new Error(message);
}
export function loadTree(file) {
  return JSON.parse(fs.readFileSync(file, "utf8"));
}

export function verifyTree(tree) {
  const errors = [];
  if (tree?.protocol !== "HLDP-v1.0") errors.push("protocol must be HLDP-v1.0");
  if (!tree?.root || typeof tree.root !== "string") errors.push("root must be a non-empty path");
  if (!tree?.nodes || typeof tree.nodes !== "object" || Array.isArray(tree.nodes)) errors.push("nodes must be an object");
  if (errors.length) return errors;

  if (!tree.nodes[tree.root]) errors.push(`root node not found: ${tree.root}`);
  const required = ["path", "summary", "trigger", "emergence", "lock", "why"];
  for (const [key, node] of Object.entries(tree.nodes)) {
    if (!node || typeof node !== "object") {
      errors.push(`${key}: node must be an object`);
      continue;
    }
    if (node.path !== key) errors.push(`${key}: node.path must equal its address`);
    for (const field of required) {
      if (typeof node[field] !== "string" || !node[field].trim()) errors.push(`${key}: missing ${field}`);
    }
    if (!Array.isArray(node.children)) errors.push(`${key}: children must be an array`);
    else {
      if (node.children.length > 10) errors.push(`${key}: more than 10 children`);
      if (new Set(node.children).size !== node.children.length) errors.push(`${key}: duplicate child path`);
      for (const child of node.children) if (!tree.nodes[child]) errors.push(`${key}: child not found: ${child}`);
    }
    if (!Array.isArray(node.sources) || node.sources.length === 0) errors.push(`${key}: sources must be a non-empty array`);
    if (!Array.isArray(node.rejected)) errors.push(`${key}: rejected must be an array`);
  }

  const visiting = new Set();
  const visited = new Set();
  function walk(key) {
    if (visiting.has(key)) return errors.push(`${key}: cycle detected`);
    if (visited.has(key) || !tree.nodes[key]) return;
    visiting.add(key);
    for (const child of tree.nodes[key].children ?? []) walk(child);
    visiting.delete(key);
    visited.add(key);
  }
  walk(tree.root);
  for (const key of Object.keys(tree.nodes)) if (!visited.has(key)) errors.push(`${key}: unreachable from root`);
  return errors;
}

function terms(query) {
  const raw = query.toLowerCase().match(/[\p{L}\p{N}_-]+/gu) ?? [];
  const expanded = [];
  for (const token of raw) {
    expanded.push(token);
    const characters = [...token];
    if (/\p{Script=Han}/u.test(token) && characters.length > 1) {
      for (let i = 0; i < characters.length - 1; i += 1) {
        expanded.push(characters.slice(i, i + 2).join(""));
      }
    }
  }
  return [...new Set(expanded)];
}

export function route(tree, query, max = 3, from = tree.root) {
  const current = tree.nodes[from];
  if (!current) fail(`node not found: ${from}`);
  const needles = terms(query);
  return current.children
    .map((childPath, index) => {
      const child = tree.nodes[childPath];
      const haystack = `${childPath} ${child?.summary ?? ""}`.toLowerCase();
      const score = needles.reduce((sum, term) => sum + (haystack.includes(term) ? 1 : 0), 0);
      return { path: childPath, summary: child?.summary ?? "", score, order: index };
    })
    .sort((a, b) => b.score - a.score || a.order - b.order)
    .slice(0, Math.max(1, Math.min(3, Number(max) || 3)))
    .map(({ order: _order, ...candidate }) => candidate);
}

export function readNode(tree, nodePath, limit = READ_NODE_LIMIT_BYTES) {
  const node = tree.nodes[nodePath];
  if (!node) fail(`node not found: ${nodePath}`);
  const encoded = JSON.stringify(node, null, 2);
  if (Buffer.byteLength(encoded) > limit) fail(`node exceeds ${limit} byte read limit`);
  return node;
}

export function bootstrap(protocolRoot) {
  const message = [
    "HLDP v1 单对话恢复：只把协议根页作为导航，不自动加载记忆正文。",
    `根页：${protocolRoot}`,
    "边界：人格主体 != Codex宿主 != 运行系统 != 任务角色 != 执行授权。",
    "方法：先看根节点摘要；按当前问题一次下钻一层；仅证据缺口时读原文。",
    "保留：trigger/emergence/lock/why、转折与否决原因、失效条件、sources。",
    "禁止：整读胶囊/日志；每消息或工具调用注入；恢复失败阻断用户输入。"
  ].join("\n");
  if (Buffer.byteLength(message) > BOOTSTRAP_LIMIT_BYTES) fail("bootstrap exceeds hard byte limit");
  return message;
}

function parseArgs(argv) {
  const [command, ...rest] = argv;
  const options = {};
  for (let i = 0; i < rest.length; i += 2) options[rest[i]?.replace(/^--/, "")] = rest[i + 1];
  return { command, options };
}

export function main(argv = process.argv.slice(2)) {
  const { command, options } = parseArgs(argv);
  if (command === "bootstrap") {
    console.log(bootstrap(options["protocol-root"] ?? "hldp/HLDP-RUNTIME-ROOT-v1.0.hdlp"));
    return;
  }
  if (!options.tree) fail("--tree is required");
  const tree = loadTree(options.tree);
  const errors = verifyTree(tree);
  if (errors.length) fail(errors.join("\n"));
  if (command === "verify") console.log(JSON.stringify({ ok: true, nodes: Object.keys(tree.nodes).length }));
  else if (command === "route") console.log(JSON.stringify(route(tree, options.query ?? "", options.max, options.from), null, 2));
  else if (command === "read-node") console.log(JSON.stringify(readNode(tree, options.path), null, 2));
  else fail("command must be bootstrap, verify, route, or read-node");
}

if (process.argv[1] === fileURLToPath(import.meta.url)) {
  try { main(); } catch (error) { console.error(error.message); process.exitCode = 1; }
}