/**
 * Verdaccio 缓存目录扫描（§12.1）
 * - storage 目录解析优先级：VERDACCIO_STORAGE 环境变量 → UI 设置（settings.storage_dir）
 * - 递归扫描目录内所有 package.json，解析 versions/time，匹配 .tgz 计算占用，支持 scoped 包
 * - 未配置或无效时进入 demo 模式（VCM_DEMO=1 或首次无配置）
 */
import fs from 'node:fs'
import path from 'node:path'
import { getSetting } from './db.js'

// —— storage 目录解析 ——
export function resolveStorageDir() {
  return process.env.VERDACCIO_STORAGE || getSetting('storage_dir') || null
}

export function isValidStorage(dir) {
  if (!dir) return false
  try {
    const st = fs.statSync(dir)
    if (!st.isDirectory()) return false
    fs.accessSync(dir, fs.constants.R_OK)
    return true
  } catch {
    return false
  }
}

export function validateStorage(dir) {
  if (!isValidStorage(dir)) return { ok: false, message: '目录不存在或不可读' }
  // 至少包含 package.json 或 .tgz 之一，才算有效缓存目录
  const files = listFiles(dir, 1)
  const hasPkg = files.some(f => f.endsWith('package.json'))
  const hasTgz = files.some(f => f.endsWith('.tgz'))
  if (!hasPkg && !hasTgz) {
    return { ok: false, message: '目录中未找到 package.json / .tgz，不是有效的 Verdaccio 缓存目录' }
  }
  return { ok: true, message: 'ok' }
}

function listFiles(dir, depth = Infinity, out = []) {
  let entries
  try {
    entries = fs.readdirSync(dir, { withFileTypes: true })
  } catch {
    return out
  }
  for (const e of entries) {
    if (e.name === 'node_modules' || e.name.startsWith('.') || e.name === '.DS_Store') continue
    const full = path.join(dir, e.name)
    if (e.isDirectory()) {
      if (depth > 0) listFiles(full, depth - 1, out)
    } else {
      out.push(full)
    }
  }
  return out
}

function readJson(file) {
  try {
    return JSON.parse(fs.readFileSync(file, 'utf8'))
  } catch {
    return null
  }
}

function fmtMb(bytes) {
  return Number((bytes / 1024 / 1024).toFixed(1))
}

// 目录名 → 包名（支持 scoped：@scope/name）
function dirToPkgName(segments) {
  if (segments.length >= 2 && segments[0].startsWith('@')) {
    return `${segments[0]}/${segments[1]}`
  }
  return segments[segments.length - 1]
}

// 从 package.json 所在目录向上推导包名
function pkgNameFromDir(pkgDir, storageDir) {
  const rel = path.relative(storageDir, pkgDir).split(path.sep)
  return dirToPkgName(rel)
}

function parseVersion(v) {
  // 去前缀 v、prerelease 后缀仅比较主体
  return (String(v).replace(/^v/, '') || '').trim()
}

/**
 * 扫描 storage 目录
 * @returns {Array} 包列表（versionsDetail: [{version, size(MB), date}]）
 */
export function scanStorage(storageDir) {
  const packages = []
  if (!isValidStorage(storageDir)) return packages

  const pkgFiles = listFiles(storageDir).filter(f => f.endsWith('package.json'))
  const storageRoot = path.resolve(storageDir)

  for (const pkgFile of pkgFiles) {
    const pkgDir = path.dirname(pkgFile)
    const meta = readJson(pkgFile)
    if (!meta) {
      // 元数据损坏：标记异常包，不影响其他包
      packages.push({
        name: pkgNameFromDir(pkgDir, storageRoot),
        status: 'broken',
        versions: 0,
        size: 0,
        lastUpdated: null,
        versionsDetail: [],
      })
      continue
    }

    const versionsObj = meta.versions || {}
    const timeObj = meta.time || {}
    const distTags = meta['dist-tags'] || {}

    const versionsDetail = []
    let totalBytes = 0
    for (const [v, info] of Object.entries(versionsObj)) {
      // tgz 物理文件：Verdaccio 约定 {pkgDir}/{version}.tgz
      const tgz = path.join(pkgDir, `${v}.tgz`)
      let size = 0
      try {
        size = fs.statSync(tgz).size
      } catch {
        // 无物理文件：用元数据 dist.tarball 大小兜底（无则 0）
        size = (info && info.dist && typeof info.dist.unpackedSize === 'number') ? info.dist.unpackedSize : 0
      }
      totalBytes += size
      versionsDetail.push({
        version: parseVersion(v),
        size: fmtMb(size),
        date: timeObj[v] ? timeObj[v].slice(0, 10) : null,
      })
    }
    // 按 semver 数值排序（旧 → 新）
    versionsDetail.sort((a, b) => a.version.localeCompare(b.version, undefined, { numeric: true }))

    // 最近更新时间：取 time 字段最大
    const lastUpdated = Object.keys(timeObj).length
      ? Object.entries(timeObj).sort((a, b) => b[1].localeCompare(a[1]))[0][1].slice(0, 10)
      : null

    packages.push({
      name: pkgNameFromDir(pkgDir, storageRoot),
      versions: versionsDetail.length,
      size: fmtMb(totalBytes),
      lastUpdated,
      visits: 0, // 真实环境无访问统计，界面不依赖真实值
      distTags,
      versionsDetail,
    })
  }

  return packages
}

// —— demo 模式数据（无真实目录时的演示） ——
const DEMO_SEED = [
  ['lodash', 25, 4, 12456], ['@antv/g2', 32, 12, 7654], ['axios', 18, 1.2, 9832],
  ['react', 14, 10, 6543], ['vue', 12, 9, 5218], ['express', 16, 0.8, 4376],
  ['tensorflow', 24, 90, 2103], ['typescript', 20, 22, 3421], ['webpack', 19, 18, 2876],
  ['echarts', 15, 16, 1987], ['dayjs', 8, 0.6, 1789], ['uuid', 11, 0.4, 1654],
  ['vite', 9, 14, 1432], ['prisma', 7, 28, 1120], ['pg', 6, 5, 986],
  ['three', 10, 30, 876], ['sharp', 5, 24, 654], ['chalk', 6, 0.3, 743],
  ['semver', 4, 0.3, 532], ['zod', 5, 0.5, 421],
  ['prettier', 3, 1, 388], ['rollup', 8, 6, 356], ['eslint', 13, 8, 342],
  ['moment', 20, 2, 312], ['mocha', 7, 1.4, 301], ['cheerio', 9, 3, 287],
  ['@vue/compiler-sfc', 11, 5, 265], ['ioredis', 10, 4, 254], ['graphql', 12, 7, 243],
  ['socket.io', 6, 2, 231], ['xlsx', 14, 20, 218], ['d3', 9, 12, 205],
  ['puppeteer', 4, 15, 187], ['sharp', 5, 24, 176],
]

function pad(n) { return String(n).padStart(2, '0') }
function dateStr(offset) {
  const d = new Date(Date.now() - offset * 86400000)
  return `${d.getUTCFullYear()}-${pad(d.getUTCMonth() + 1)}-${pad(d.getUTCDate())}`
}
function rnd(min, max) { return Math.floor(Math.random() * (max - min + 1)) + min }

function genVersions(count) {
  const list = []
  for (let i = 0; i < count; i++) {
    list.push({
      version: `1.${rnd(0, 9)}.${rnd(0, 20)}`,
      size: Number((rnd(5, 400) / 10).toFixed(1)),
      date: dateStr((count - i) * rnd(3, 9)),
    })
  }
  list.sort((a, b) => a.version.localeCompare(b.version, undefined, { numeric: true }))
  return list
}

export function demoPackages() {
  const seen = new Set()
  return DEMO_SEED.filter(([n]) => !seen.has(n) && seen.add(n)).map(([name, verCount, sizeBase, visits]) => {
    const detail = genVersions(verCount)
    return {
      name,
      versions: detail.length,
      size: Number((detail.reduce((s, v) => s + v.size, 0)).toFixed(1)),
      lastUpdated: detail.length ? detail[detail.length - 1].date : null,
      visits,
      distTags: { latest: detail.length ? detail[detail.length - 1].version : '1.0.0' },
      versionsDetail: detail,
    }
  })
}

export function demoSummary() {
  return {
    demo: true,
    todayDownloads: 1234,
    todayTrend: '+18%',
    note: '演示模式：未配置 Verdaccio 缓存目录，展示内置演示数据。',
  }
}