/**
 * Bundle every bare-module-manifest entry into IIFE scripts under bundles/ so the
 * system image can populate ctx.bare without relying on the Pear host node_modules.
 * Fail-fast: any esbuild error aborts the build (no stub placeholders).
 */
import {
  readFile,
  writeFile,
  mkdir,
  copyFile,
  readdir,
  unlink
} from 'node:fs/promises'
import { execSync } from 'node:child_process'
import { dirname, join } from 'node:path'
import { fileURLToPath, pathToFileURL } from 'node:url'
import * as esbuild from 'esbuild'

const __dirname = dirname(fileURLToPath(import.meta.url))
const repoRoot = join(__dirname, '..', '..')
const booterNodeModules = join(repoRoot, 'packages/bare-os-booter/node_modules')

/**
 * esbuild `platform: 'node'` marks builtins external; drive IIFEs run under `new Function`
 * on Pear with no `globalThis.require`. Map Node core modules to Bare shims so they bundle in.
 * Use package names (not absolute paths) so esbuild resolves them via `nodePaths`.
 */
function bareDriveBundleNodeBuiltinAliases() {
  return {
    assert: 'bare-assert',
    crypto: 'bare-crypto',
    events: 'bare-node-events',
    fs: 'bare-node-fs',
    net: 'bare-node-net',
    url: 'bare-url'
  }
}
const manifestPath = join(
  repoRoot,
  'packages/bare-os-booter/lib/bare-module-manifest.json'
)
const kernelLibBare = join(repoRoot, 'kernel/lib/bare')
const seederLibBare = join(repoRoot, 'packages/bare-os-seeder/kernel/lib/bare')
const bundlesKernel = join(kernelLibBare, 'bundles')
const bundlesSeeder = join(seederLibBare, 'bundles')

const STDLIB_GLOBAL = '__bare_os_stdlib__'
const IIFE_GLOBAL = '__bare_os_bundle_exports__'

const BUNDLE_CONCURRENCY = 6

/**
 * @param {{ optional?: unknown, nativeHint?: unknown }} ent
 */
function bundleTierForEntry(ent) {
  if (!ent || typeof ent !== 'object') return 'core'
  const optional = !!ent.optional
  const nativeHint = !!ent.nativeHint
  if (!optional) return 'core'
  return nativeHint ? 'optional_native' : 'optional_js'
}

const BUNDLE_TIER_THRESHOLDS = {
  core: { maxGrowthPct: 12, minPaddingBytes: 4096 },
  optional_js: { maxGrowthPct: 20, minPaddingBytes: 3072 },
  optional_native: { maxGrowthPct: 30, minPaddingBytes: 4096 }
}

function readGitHead(cwd) {
  try {
    return execSync('git rev-parse HEAD', {
      cwd,
      encoding: 'utf8',
      stdio: ['ignore', 'pipe', 'ignore']
    }).trim()
  } catch {
    return ''
  }
}

/** Resolve bare-native `imports` subpath specifiers (#web-view / #window) for the host OS. */
function bareNativeConditionalImportsPlugin() {
  const bareNativeRoot = join(repoRoot, 'node_modules/bare-native')
  function webViewAbs() {
    const p = process.platform
    if (p === 'darwin' || p === 'ios') return join(bareNativeRoot, 'lib/web-view/apple.js')
    if (p === 'win32') return join(bareNativeRoot, 'lib/web-view/win32.js')
    if (p === 'android') return join(bareNativeRoot, 'lib/web-view/android.js')
    return join(bareNativeRoot, 'lib/web-view/linux.js')
  }
  function windowAbs() {
    const p = process.platform
    if (p === 'darwin') return join(bareNativeRoot, 'lib/window/darwin.js')
    if (p === 'ios') return join(bareNativeRoot, 'lib/window/ios.js')
    if (p === 'win32') return join(bareNativeRoot, 'lib/window/win32.js')
    if (p === 'android') return join(bareNativeRoot, 'lib/window/android.js')
    return join(bareNativeRoot, 'lib/window/linux.js')
  }
  return {
    name: 'bare-native-subpath-imports',
    setup(build) {
      build.onResolve({ filter: /^#web-view$/ }, () => ({ path: webViewAbs() }))
      build.onResolve({ filter: /^#window$/ }, () => ({ path: windowAbs() }))
    }
  }
}

/**
 * @template T
 * @param {T[]} items
 * @param {number} concurrency
 * @param {(item: T, index: number) => Promise<void>} fn
 */
async function runPool(items, concurrency, fn) {
  let i = 0
  async function worker() {
    while (i < items.length) {
      const idx = i++
      await fn(items[idx], idx)
    }
  }
  await Promise.all(Array.from({ length: concurrency }, () => worker()))
}

function stdinForEntry(ent) {
  const pkg = ent.package
  if (ent.sideEffectImport) {
    return `import ${JSON.stringify(pkg)};\nexport default true;\n`
  }
  if (ent.export === '*') {
    return `import * as _m from ${JSON.stringify(pkg)};\nexport default _m;\n`
  }
  return `import _m from ${JSON.stringify(pkg)};\nexport default _m;\n`
}

export async function buildBareLibs() {
  const manifest = JSON.parse(await readFile(manifestPath, 'utf8'))
  const entries = Array.isArray(manifest.entries) ? manifest.entries : []
  const entryByCtxKey = new Map(
    entries
      .filter((e) => e && typeof e === 'object' && e.ctxKey)
      .map((e) => [String(e.ctxKey), e])
  )
  const tierFilter = String(process.env.BARE_OS_BUNDLE_TIER || '')
    .trim()
    .toLowerCase()
  const toBundle = entries
    .filter((e) => e.ctxKey && e.package)
    .filter((e) => {
      if (!tierFilter || tierFilter === 'all') return true
      const t = (e.tier && String(e.tier).toLowerCase()) || 'core'
      return t === tierFilter
    })

  await mkdir(bundlesKernel, { recursive: true })
  await mkdir(bundlesSeeder, { recursive: true })

  /** @type {{ path: string, keys: string[] }[]} */
  const bundles = []
  /** @type {{ ctxKey: string, package: string, path: string, bytes: number }[]} */
  const bundleDiagnostics = []
  let ok = 0

  await runPool(toBundle, BUNDLE_CONCURRENCY, async (ent) => {
    const ctxKey = ent.ctxKey
    const pkg = ent.package
    const outfile = join(bundlesKernel, `${ctxKey}.js`)
    const outfileSeeder = join(bundlesSeeder, `${ctxKey}.js`)
    const footer = `;(function(){var g=globalThis;var s=${JSON.stringify(STDLIB_GLOBAL)};g[s]=g[s]||{};var e=typeof ${IIFE_GLOBAL}!=="undefined"?${IIFE_GLOBAL}:void 0;var v=e!=null&&typeof e==="object"&&Object.prototype.hasOwnProperty.call(e,"default")?e.default:e;g[s][${JSON.stringify(ctxKey)}]=v;})();`

    try {
      await esbuild.build({
        stdin: {
          contents: stdinForEntry(ent),
          resolveDir: repoRoot,
          sourcefile: `bare-lib-entry-${ctxKey}.js`,
          loader: 'js'
        },
        bundle: true,
        format: 'iife',
        globalName: IIFE_GLOBAL,
        platform: 'node',
        alias: bareDriveBundleNodeBuiltinAliases(),
        nodePaths: [booterNodeModules, join(repoRoot, 'node_modules')],
        plugins: [bareNativeConditionalImportsPlugin()],
        outfile,
        footer: { js: footer },
        logLevel: 'silent'
      })
    } catch (err) {
      const msg = err?.message || String(err)
      console.error(
        '[bare-os-bare-libs] bundle failed',
        ctxKey,
        '(' + pkg + '):',
        msg
      )
      throw new Error(
        `[bare-os-bare-libs] esbuild failed for ${ctxKey} (${pkg}): ${msg}`
      )
    }

    ok++
    bundles.push({
      path: `/lib/bare/bundles/${ctxKey}.js`,
      keys: [ctxKey]
    })

    const built = await readFile(outfile)
    await writeFile(outfileSeeder, built)
    bundleDiagnostics.push({
      ctxKey,
      package: pkg,
      path: `/lib/bare/bundles/${ctxKey}.js`,
      bytes: built.length,
      tier: bundleTierForEntry(ent)
    })
  })

  bundleDiagnostics.sort((a, b) => a.ctxKey.localeCompare(b.ctxKey))

  const builtNames = new Set(bundleDiagnostics.map((d) => `${d.ctxKey}.js`))
  async function pruneStaleBundles(dir) {
    let names
    try {
      names = await readdir(dir)
    } catch {
      return
    }
    for (const name of names) {
      if (!name.endsWith('.js')) continue
      if (builtNames.has(name)) continue
      await unlink(join(dir, name))
      console.warn('[bare-os-bare-libs] removed stale bundle', name)
    }
  }
  await pruneStaleBundles(bundlesKernel)
  await pruneStaleBundles(bundlesSeeder)

  const { sanitizeBareBundlesInDir } = await import(
    pathToFileURL(join(repoRoot, 'scripts/sanitize-bare-bundles.mjs')).href
  )
  sanitizeBareBundlesInDir(bundlesKernel)
  sanitizeBareBundlesInDir(bundlesSeeder)

  for (const row of bundleDiagnostics) {
    const rel = join(bundlesKernel, `${row.ctxKey}.js`)
    try {
      const buf = await readFile(rel)
      row.bytes = buf.length
    } catch {
      /* keep prior */
    }
  }

  const driveManifest = {
    version: 1,
    bundles,
    bundleStats: { ok, failed: 0, attempted: toBundle.length },
    bundleDiagnostics,
    bundleProvenance: {
      schemaVersion: 1,
      generatedAt: new Date().toISOString(),
      gitCommit: readGitHead(repoRoot),
      nodeVersion: process.version,
      bundleTier: tierFilter && tierFilter !== 'all' ? tierFilter : 'all',
      normativeManifest: 'packages/bare-os-booter/lib/bare-module-manifest.json',
      buildScript: 'packages/bare-os-bare-libs/build.mjs'
    }
  }
  const json = JSON.stringify(driveManifest, null, 2) + '\n'
  await writeFile(join(kernelLibBare, 'manifest.json'), json)
  await writeFile(join(seederLibBare, 'manifest.json'), json)

  const bundleHealthPath = join(repoRoot, 'docs/audit/bundle-health.json')
  const bundleRegressionThresholds = {
    schemaVersion: 1,
    note:
      'Generated thresholds by package tier. verify-bundle-health fails when disk bytes exceed maxBytes for a ctxKey.',
    tierPolicies: BUNDLE_TIER_THRESHOLDS,
    byCtxKey: bundleDiagnostics.map((row) => {
      const ent = entryByCtxKey.get(row.ctxKey)
      const tier = row.tier || bundleTierForEntry(ent)
      const pol =
        BUNDLE_TIER_THRESHOLDS[tier] || BUNDLE_TIER_THRESHOLDS.optional_native
      const pct = Number(pol.maxGrowthPct) || 20
      const pad = Number(pol.minPaddingBytes) || 4096
      const growth = Math.ceil((Number(row.bytes) * pct) / 100)
      return {
        ctxKey: row.ctxKey,
        tier,
        baselineBytes: row.bytes,
        maxBytes: row.bytes + Math.max(growth, pad)
      }
    })
  }
  const bundleHealth = {
    schemaVersion: 1,
    generatedAt: new Date().toISOString(),
    normativeManifest: 'packages/bare-os-booter/lib/bare-module-manifest.json',
    buildTool: 'packages/bare-os-bare-libs/build.mjs',
    bundles: bundleDiagnostics,
    bundleStats: { ok, failed: 0, attempted: toBundle.length },
    bundleRegressionThresholds
  }
  await writeFile(
    bundleHealthPath,
    JSON.stringify(bundleHealth, null, 2) + '\n'
  )

  await copyFile(
    manifestPath,
    join(kernelLibBare, 'bare-module-manifest.json')
  )
  await copyFile(
    manifestPath,
    join(seederLibBare, 'bare-module-manifest.json')
  )

  const readmeSrc = join(__dirname, 'README.kernel-lib-bare.md')
  const readmeDstKernel = join(kernelLibBare, 'README.md')
  const readmeDstSeeder = join(seederLibBare, 'README.md')
  try {
    await copyFile(readmeSrc, readmeDstKernel)
    await copyFile(readmeSrc, readmeDstSeeder)
  } catch {
    /* optional */
  }

  console.log(
    '[bare-os-bare-libs] bundles:',
    ok,
    'ok,',
    toBundle.length,
    'attempted →',
    kernelLibBare
  )
}

if (
  process.argv[1] &&
  import.meta.url === pathToFileURL(process.argv[1]).href
) {
  await buildBareLibs()
}