/**
 * Publish `samples/d2-packs` to the asset repository.
 *
 * The baked atlas packs are ~66 MB of indexed PNG. PNG is already deflate
 * compressed, so git's delta compression buys almost nothing: every re-bake changes
 * nearly every file, and a normal commit would grow the repository by another ~60 MB
 * each time (measured: the code repository went 63 MB → 117 MB over two bakes).
 *
 * So the asset repository deliberately keeps **exactly one commit**: every publish
 * creates an orphan history (a brand new repository in a temp directory), commits the
 * current packs, and force-pushes it over the remote. The repository therefore stays
 * at "one snapshot" (~66 MB) no matter how often the packs are re-baked, and the code
 * repository — which no longer contains the packs — clones in a couple of megabytes.
 *
 * Usage:
 * ```
 * node scripts/publish-packs.ts                    # default remote
 * node scripts/publish-packs.ts <git-remote-url>   # explicit remote
 * ```
 *
 * The remote needs credentials; either pass a URL with them, or run
 * `git config --global credential.helper store` once so `git push` does not prompt.
 * Nothing here writes a password to disk.
 *
 * @module
 */

import { execFileSync } from 'node:child_process'
import {
  cpSync, existsSync, mkdtempSync, readdirSync, readFileSync, rmSync, statSync, writeFileSync,
} from 'node:fs'
import { createHash } from 'node:crypto'
import { tmpdir } from 'node:os'
import { join, resolve } from 'node:path'

/** Where the packs live inside the code repository. */
const PACKS_DIR = resolve(import.meta.dirname, '..', 'samples', 'd2-packs')

/** The asset repository, without credentials. */
const DEFAULT_REMOTE = 'https://git.projectdiablo2.cn/troytt/diablo2-web-assets.git'

/** The code repository, linked from the generated README. */
const CODE_REPO = 'https://git.projectdiablo2.cn/troytt/diablo2-web'

/** The archive mirror served next to the deployment. */
const ARCHIVE_BASE = 'https://www.laiseek.xyz/diablo2/assets'

/** Raised when the packs are missing or git fails. */
class PublishError extends Error {}

/**
 * Run one git command in `cwd`, inheriting stdio so progress is visible.
 *
 * @param args - git arguments.
 * @param cwd - directory to run in.
 */
function git(args: readonly string[], cwd: string): void {
  try {
    execFileSync('git', args, { cwd, stdio: ['ignore', 'inherit', 'inherit'] })
  } catch {
    throw new PublishError(`git ${args.join(' ')} failed`)
  }
}

/**
 * Collect the statistics that go into the generated README.
 *
 * @returns file count, total bytes, map-block count and the `index.json` hash.
 */
function measure(): { files: number; bytes: number; maps: number; indexSha: string } {
  const indexPath = join(PACKS_DIR, 'index.json')
  if (!existsSync(indexPath)) {
    throw new PublishError(`no packs at ${PACKS_DIR} — run: npm run pack:data`)
  }
  const index = JSON.parse(readFileSync(indexPath, 'utf8')) as { entries?: unknown[]; levels?: unknown[] }
  const indexSha = createHash('sha256').update(readFileSync(indexPath)).digest('hex')
  let files = 0
  let bytes = 0
  const walk = (dir: string): void => {
    for (const entry of readdirSync(dir, { withFileTypes: true })) {
      const path = join(dir, entry.name)
      if (entry.isDirectory()) walk(path)
      else {
        files += 1
        bytes += statSync(path).size
      }
    }
  }
  walk(PACKS_DIR)
  return { files, bytes, maps: index.levels?.length ?? index.entries?.length ?? 0, indexSha }
}

/**
 * Build the README that ships inside the asset repository.
 *
 * @param stats - output of {@link measure}.
 * @param stamp - `YYYY-MM-DD` bake date.
 * @returns the markdown text.
 */
function readme(stats: ReturnType<typeof measure>, stamp: string): string {
  const mb = (stats.bytes / 1048576).toFixed(1)
  return `# d2web 烘焙图集包（${stamp}）

这是 [\`troytt/diablo2-web\`](${CODE_REPO}) 的**烘焙产物**：把原版暗黑破坏神 II（1.13c）的地图
解包成 web 原生格式——索引色 PNG 图集页 + \`scene.json\`（画家序绘制列表、碰撞 RLE、出生点、
对象元数据）+ \`index.json\`（含各 act 调色板）。

- 地图块 **${stats.maps} 个**（覆盖全 5 幕 136 个关卡预置与随机变体），文件 **${stats.files} 个**，合计 **${mb} MB**
- \`index.json\` sha256：\`${stats.indexSha}\`
- 生成时间：${stamp}

## 本仓库为什么只有一个提交

图集页是索引色 PNG（deflate 已压缩），git 的 delta 压缩对它几乎无收益：每次重烘几乎全部文件
都会变。若按普通方式提交，每烘焙一次仓库就再长 ~60 MB（实测代码仓库因此从 63 MB 涨到 117 MB）。
所以这里刻意**只保留一个提交**：每次重烘用 orphan 提交 + force push 覆盖，仓库体积恒定在
「一份快照」≈${Math.round(stats.bytes / 1048576)} MB。历史没有价值——需要旧版请从代码仓库
对应提交重新烘焙。

## 怎么用

\`\`\`bash
# 放进代码仓库的 samples/d2-packs/，页面默认就吃这个目录
git clone ${DEFAULT_REMOTE} samples/d2-packs
\`\`\`

只要一份压缩包（不需要 git）：

\`\`\`bash
curl -O ${ARCHIVE_BASE}/d2-packs-${stamp}.tar.xz
tar xJf d2-packs-${stamp}.tar.xz
\`\`\`

## 怎么重新生成并发布

在代码仓库里（需要自备原版 MPQ，放在 \`samples/d2/\`）：

\`\`\`bash
npm run pack:data        # scripts/pack-act-assets.ts → samples/d2-packs（约 2 分钟）
npm run verify:packs     # 与"现读现解"逐项比对：绘制序、碰撞栅格逐字节、每帧像素哈希
npm run publish:packs    # orphan 提交 + force push 覆盖本仓库
\`\`\`

## 许可

内容为原版游戏美术的解码产物，仅供**持有正版游戏数据**的人在本项目内使用；请勿再分发。
原版 MPQ 与第三方参考源码都不在本仓库内。
`
}

const remote = process.argv[2] ?? process.env['D2_ASSETS_REMOTE'] ?? DEFAULT_REMOTE
const stats = measure()
const stamp = new Date().toISOString().slice(0, 10)
const work = mkdtempSync(join(tmpdir(), 'd2-assets-'))

try {
  console.log(`图集包：${String(stats.maps)} 块地图 / ${String(stats.files)} 个文件 / ${(stats.bytes / 1048576).toFixed(1)} MB`)
  console.log(`index.json sha256：${stats.indexSha}`)
  console.log(`临时仓库：${work}`)

  git(['init', '-q', '-b', 'main'], work)
  cpSync(PACKS_DIR, work, { recursive: true })
  writeFileSync(join(work, 'README.md'), readme(stats, stamp))
  writeFileSync(join(work, '.gitattributes'), '*.png binary -diff\n*.json text eol=lf\n')
  git(['add', '-A'], work)
  git([
    '-c', `user.name=${process.env['GIT_AUTHOR_NAME'] ?? 'Dao Tao'}`,
    '-c', `user.email=${process.env['GIT_AUTHOR_EMAIL'] ?? 'taodao@google.com'}`,
    'commit', '-q', '-m',
    `烘焙图集包 ${stamp}：${String(stats.maps)} 个地图块（${(stats.bytes / 1048576).toFixed(1)} MB）

本仓库刻意只保留一个提交：图集页是索引色 PNG，git 的 delta 压缩对它几乎无收益，
每次重烘几乎全部文件都变；普通提交会让仓库每烘焙一次再长 ~60 MB。所以每次重烘都
用 orphan 提交 + force push 覆盖（见 README）。

index.json sha256: ${stats.indexSha}

由 troytt/diablo2-web 的 npm run pack:data 生成。`,
  ], work)
  console.log(`推送到 ${remote}（force，覆盖历史）…`)
  git(['push', '--force', remote, 'main'], work)
  console.log('完成。使用方：git clone ' + remote + ' samples/d2-packs')
} finally {
  rmSync(work, { recursive: true, force: true })
}