// extract_space_init.js - 把某个空间的 s2c 抓包抽成「结构化初始化模板」names/space-init-<spaceId>.json
//
// 用法: node extract_space_init.js --dir ../packets/plain/space-100073070 [--space 100073070] [--max 6]
//
// 模板不是原始帧字节：
//   · 容器记录 → 存「解出来的对象树」，发送时由 server/container.js 重新编码（可改、可换数据）
//   · 解不动的记录 → 存 hex（如实标注，不假装结构化）
//   · nullmap 原样保留（实测有 2 字节且带内容的 nullmap，含义是「哪些字段为空」，写 0 会错位）
//   · DelayMs 取自同目录 timeline_s2c.txt（相对首帧），保持原节奏
//
// 容器布局判定：三个布局都试，取「恰好吃到帧尾，或吃完后剩余字节里能认出下一条记录的 methodId」的那个。
'use strict';
const fs = require('fs');
const path = require('path');
const Link = require('./server/link');
const { LoadTables, MakeReader } = require('../tools/lib_space_codec');
const { MakeWriter } = require('./server/codec');
const { MakeContainerCodec } = require('./server/container');
const ModelService = require('./server/modelservice');

const Argv = process.argv.slice(2);
const Arg = (Name, Def) => {
  const I = Argv.indexOf('--' + Name);
  return I >= 0 && Argv[I + 1] ? Argv[I + 1] : Def;
};

const PROJECT = path.resolve(__dirname, '..');
const Dir = path.resolve(Arg('dir', ''));
const Max = Number(Arg('max', '8')) || 8;
if (!Dir || !fs.existsSync(Dir)) {
  console.error('用法: node extract_space_init.js --dir ../packets/plain/space-<id> [--space <id>] [--max N]');
  process.exit(1);
}

const Tables = LoadTables(path.join(PROJECT, 'names'));
const Reader = MakeReader(Tables, { EnumBytes: 4 });
const Writer = MakeWriter(Tables, { EnumBytes: 4 });
const Container = MakeContainerCodec(Tables, Reader, Writer);
const LAYOUTS = ['zt', 'pt', 'lt'];

// 8 字节处是不是一个「已知的 methodId」（method_table / codec_fields / 上行表任一）
function KnownMethodId(Buf, Off) {
  if (Off + 8 > Buf.length) return false;
  const V = Buf.readBigInt64BE(Off).toString();
  return Tables.CodecByMethod.has(V) || Tables.UplinkByMethod.has(V) || ModelService.Name(V) !== null;
}

function PickLayout(Buf, Off) {
  for (const L of LAYOUTS) {
    const R = Container.Read(L, Buf, Off);
    if (R.Bad) continue;
    if (R.Next === Buf.length || KnownMethodId(Buf, R.Next)) return { Layout: L, Result: R };
  }
  return null;
}

const Timeline = new Map();
const Tl = path.join(Dir, 'timeline_s2c.txt');
if (fs.existsSync(Tl)) {
  for (const Line of fs.readFileSync(Tl, 'utf8').split('\n')) {
    const M = /^(\S+)\t(\d+)$/.exec(Line.trim());
    if (M) Timeline.set(M[1], Number(M[2]));
  }
}

const Files = fs.readdirSync(Dir).filter((F) => /^s2c_\d+\.bin$/.test(F)).sort().slice(0, Max);
const SpaceArg = Arg('space', '');
const Out = { SpaceId: '', Note: '结构化初始化模板：容器存对象树（发送时重新编码），解不动的记录存 hex；nullmap 原样', Frames: [] };
let Base = null;
let Structured = 0;
let RawOnly = 0;

for (const File of Files) {
  const RawFile = fs.readFileSync(path.join(Dir, File));
  const Info = Link.PeekFrame(RawFile);
  const Body = Link.DecodeFrame(Link.ParseFrames(RawFile)[0]);
  const At = Link.NullmapSize(Body, 0);
  if (At + 8 > Body.length) continue; // 保活 ping 之类：帧体只有 nullmap，没有 spaceId
  const SpaceId = Body.readBigInt64BE(At).toString();
  Out.SpaceId = SpaceArg || SpaceId;
  const Nullmap = Body.slice(0, At).toString('hex');
  let Off = At + 8;
  const Records = [];
  while (Off + 8 <= Body.length) {
    const MethodId = Body.readBigInt64BE(Off).toString();
    const Start = Off;
    Off += 8;
    const Picked = PickLayout(Body, Off);
    if (Picked) {
      Records.push({ MethodId, Layout: Picked.Layout, Value: Picked.Result.Value });
      Off = Picked.Result.Next;
      Structured++;
    } else {
      Records.push({ MethodId, Hex: Body.slice(Off).toString('hex'), Note: '解不动，原样存' });
      Off = Body.length;
      RawOnly++;
    }
    if (Records[Records.length - 1].Layout === undefined) break;
    if (Off === Body.length) break;
  }
  const Ms = Timeline.has(File) ? Timeline.get(File) : null;
  if (Base === null) Base = Ms === null ? 0 : Ms;
  Out.Frames.push({
    File,
    SpaceId,
    NullmapHex: Nullmap,
    DelayMs: Ms === null ? 0 : Ms - Base,
    Compressed: Info.Compressed,
    Records,
  });
}

const OutFile = path.join(PROJECT, 'names', 'space-init-' + Out.SpaceId + '.json');
fs.writeFileSync(OutFile, JSON.stringify(Out, null, 1));
console.log('空间 ' + Out.SpaceId + '：' + Out.Frames.length + ' 帧，容器记录 ' + Structured + ' 个，原样存的记录 ' + RawOnly + ' 个');
for (const F of Out.Frames) {
  console.log('  ' + F.File.padEnd(14) + ' ' + F.Records.length + ' 条记录  @+' + F.DelayMs + 'ms  nullmap=' + F.NullmapHex +
    (F.Compressed ? '  (原压缩)' : '') + '  ' + F.Records.map((R) => (R.Layout ? R.Layout : 'hex') + ':' + (ModelService.Name(R.MethodId) || '#' + R.MethodId)).join(' '));
}
console.log('已写 ' + OutFile + '  ' + fs.statSync(OutFile).size + ' 字节');