/**
 * Host-resolved Bare / companion npm modules for in-image scripts (`ctx.bare`),
 * plus optional merge from trusted IIFE bundles on the system drive.
 */

import { readFileSync } from '#host-fs'
import { dirname, join } from '#host-path'
import { fileURLToPath } from 'url'
import bareModuleManifestEmbedded from './bare-module-manifest.data.mjs'
import { bareOsHostBooterWarn } from './bare-os-host-booter-log.js'

/**
 * `fileURLToPath` only accepts `file:` URLs. Pear uses `pear://dev/...` for `import.meta.url`,
 * so we must not call it at load time or when running under `pear run`.
 * @returns {string | null}
 */
function bareOsBooterPackageJsonPathForCreateRequire() {
  const href = String(import.meta.url)
  if (!href.startsWith('file:')) return null
  try {
    return fileURLToPath(new URL('../package.json', import.meta.url))
  } catch {
    return null
  }
}

/**
 * Drive IIFEs call `require("events")`, `require("bare-stream")`, …; `new Function` has no
 * lexical `require`, so they look at **`globalThis.require`**. On **`file:`** dev trees, install
 * Node's `createRequire` for the booter package for the duration of bundle eval. Under Pear
 * (`pear://`), skip — runtime `require` or `tryBareFetchImportWhenDriveMissing` covers fetch.
 * @param {() => void | Promise<void>} fn
 */
async function withDriveBundleGlobalRequire(fn) {
  if (typeof globalThis.require === 'function') return fn()
  const pkgJson = bareOsBooterPackageJsonPathForCreateRequire()
  let installed = false
  if (pkgJson) {
    try {
      const urlMod = await import('url')
      const bm = await import('bare-module')
      const createRequire = bm.createRequire || bm.default?.createRequire
      if (typeof createRequire === 'function') {
        const href = urlMod.pathToFileURL(pkgJson).href
        globalThis.require = createRequire(href)
        installed = true
      }
    } catch {
      /* bare-module createRequire unavailable (e.g. some pear:// trees) */
    }
  }
  try {
    return await fn()
  } finally {
    if (installed) {
      delete globalThis.require
    }
  }
}

export const BARE_OS_STDLIB_GLOBAL = '__bare_os_stdlib__'

const MANIFEST_NAME = 'bare-module-manifest.json'

/**
 * @param {unknown} m
 * @returns {typeof bareModuleManifestEmbedded}
 */
function cloneBareModuleManifest(m) {
  return /** @type {typeof bareModuleManifestEmbedded} */ (
    JSON.parse(JSON.stringify(m))
  )
}

/** @type {{ version: number, entries: Array<{ ctxKey: string, package: string, export?: string, bundle?: boolean, optional?: boolean, tier?: string }> } | null} */
let _cachedManifest = null

/**
 * Embedded copy of **`bare-module-manifest.json`** for Pear (`pear://` **import.meta.url**).
 * `bare-fs` coerces **`URL`** arguments through **`bare-url.fileURLToPath`**, which rejects
 * non-`file:` schemes, so **`readFileSync(new URL('pear:…'))`** cannot load the JSON from the
 * bundle. Static import of **`bare-module-manifest.data.mjs`** (regenerated by
 * **`npm run sync:bare-manifest`**) keeps the manifest in the Pear module graph.
 *
 * On **`file:`** trees, the JSON on disk is preferred so edits apply without regenerating `.data.mjs`.
 */
export function loadBareModuleManifest() {
  if (_cachedManifest) return _cachedManifest
  const href = String(import.meta.url)
  if (href.startsWith('pear:')) {
    _cachedManifest = cloneBareModuleManifest(bareModuleManifestEmbedded)
    return _cachedManifest
  }
  if (href.startsWith('file:')) {
    try {
      const libDir = dirname(fileURLToPath(href))
      const raw = readFileSync(join(libDir, MANIFEST_NAME), 'utf8')
      _cachedManifest = JSON.parse(raw)
    } catch {
      _cachedManifest = cloneBareModuleManifest(bareModuleManifestEmbedded)
    }
    return _cachedManifest
  }
  _cachedManifest = cloneBareModuleManifest(bareModuleManifestEmbedded)
  return _cachedManifest
}

/** Exported for tests: default export object from **`bare-module-manifest.data.mjs`**. */
export function bareOsBareModuleManifestEmbeddedRef() {
  return bareModuleManifestEmbedded
}

/**
 * @param {Record<string, string>} shellEnv
 */
export function bareOsBareModulesEnabled(shellEnv) {
  if (!shellEnv || typeof shellEnv !== 'object') return true
  const v = shellEnv.BARE_OS_BARE_MODULES
  return v !== '0' && v !== 'false'
}

/**
 * @param {Record<string, string>} shellEnv
 */
export function bareOsBareDriveBundlesEnabled(shellEnv) {
  if (!shellEnv || typeof shellEnv !== 'object') return true
  const v = shellEnv.BARE_OS_BARE_DRIVE_BUNDLES
  if (v === '0' || v === 'false') return false
  return bareOsBareModulesEnabled(shellEnv)
}

/**
 * When false, skip host `import(pkg)` for ctx.bare (use only `/lib/bare` IIFEs).
 * Set **`BARE_OS_BARE_HOST_IMPORTS=0`** for a fully image-local stdlib.
 */
export function bareOsBareHostImportsEnabled(shellEnv) {
  if (!shellEnv || typeof shellEnv !== 'object') return true
  const v = shellEnv.BARE_OS_BARE_HOST_IMPORTS
  if (v === '0' || v === 'false') return false
  return true
}

/**
 * Populate object with host `import()` results (per manifest). Mutates `target`.
 * @param {Record<string, string>} shellEnv
 * @param {Record<string, unknown>} target
 */
function bareHostRuntime() {
  if (typeof globalThis.Bare !== 'undefined') return true
  const v = globalThis.process?.versions
  return Boolean(v && typeof v.bare === 'string')
}

export async function buildBareCtxObjectFromHost(shellEnv, target) {
  if (!bareOsBareModulesEnabled(shellEnv)) return
  if (!bareOsBareHostImportsEnabled(shellEnv)) return
  const { entries } = loadBareModuleManifest()
  const onBare = bareHostRuntime()
  const tasks = entries.map(async (ent) => {
    if (!onBare && ent.nativeHint === true) return null
    const key = ent.ctxKey
    if (!key || target[key] !== undefined) return null
    try {
      const mod = await import(/* webpackIgnore: true */ ent.package)
      const val = ent.sideEffectImport
        ? mod?.default !== undefined
          ? mod.default
          : true
        : ent.export === '*'
          ? mod
          : mod?.default !== undefined
            ? mod.default
            : mod
      return { key, ent, val }
    } catch (err) {
      return { key, ent, err }
    }
  })
  const settled = await Promise.all(tasks)
  for (const r of settled) {
    if (!r) continue
    const { key, ent, val, err } = r
    if (err) {
      if (!ent.optional) {
        bareOsHostBooterWarn(
          'ctx_bare_module_load_failed',
          `ctx.bare.${key}: failed to load "${ent.package}"`,
          err?.message || String(err)
        )
      }
      continue
    }
    if (val !== undefined) target[key] = val
  }
}

/**
 * Execute trusted bundle sources that assign `globalThis.__bare_os_stdlib__[ctxKey]`.
 * Fills missing keys on `target` only.
 * @param {Record<string, string>} shellEnv
 * @param {{ readFile: (p: string, opts?: unknown) => Promise<Uint8Array | null> }} vfs
 * @param {Record<string, unknown>} target
 */
/**
 * Optional `/lib/bare/bare-module-lock.json` on the system image: `{ "pins": { "ctxKey": "semver" } }`.
 * Emits warnings for pins whose `ctxKey` is still missing after drive merge + host import.
 * @param {{ readFile: (p: string) => Promise<Uint8Array | null> }} vfs
 * @param {Record<string, unknown>} target
 * @returns {Promise<string[]>}
 */
export async function verifyBareModuleLockfile(vfs, target) {
  /** @type {string[]} */
  const warnings = []
  if (!vfs || typeof vfs.readFile !== 'function') return warnings
  let buf
  try {
    buf = await vfs.readFile('/lib/bare/bare-module-lock.json')
  } catch {
    return warnings
  }
  if (!buf || !buf.byteLength) return warnings
  let j
  try {
    j = JSON.parse(new TextDecoder().decode(buf))
  } catch {
    warnings.push('bare-module-lock.json: invalid JSON')
    return warnings
  }
  const pins = j && typeof j === 'object' ? j.pins : null
  if (!pins || typeof pins !== 'object') return warnings
  for (const [k, ver] of Object.entries(pins)) {
    if (target[k] === undefined) {
      warnings.push(
        `bare-module-lock: ctx.bare.${k} missing (pinned ${String(ver)})`
      )
    }
  }
  return warnings
}

/**
 * esbuild IIFE assigns `__bare_os_bundle_exports__` (CJS interop object), not the
 * default export itself. Entries use `export default <binding>` → `{ default: binding }`.
 * @param {unknown} val
 */
function unwrapDriveBundleExport(val) {
  if (val === null || val === undefined) return val
  if (typeof val !== 'object') return val
  if (Object.prototype.hasOwnProperty.call(val, 'default')) {
    const d = /** @type {{ default?: unknown }} */ (val).default
    if (d !== undefined) return d
  }
  return val
}

export async function maybeMergeBareFromDrive(shellEnv, vfs, target) {
  if (!bareOsBareModulesEnabled(shellEnv)) return
  if (!bareOsBareDriveBundlesEnabled(shellEnv)) return
  if (!vfs || typeof vfs.readFile !== 'function') return

  const perfBareStdlib =
    shellEnv?.BARE_OS_BOOT_PERF_DETAIL === '1' ||
    shellEnv?.BARE_OS_BOOT_PERF_DETAIL === 'true'
  const hrtBig =
    typeof globalThis.process?.hrtime?.bigint === 'function'
      ? () => globalThis.process.hrtime.bigint()
      : null
  const t0 = perfBareStdlib && hrtBig ? hrtBig() : null

  let metaBuf
  try {
    metaBuf = await vfs.readFile('/lib/bare/manifest.json')
  } catch {
    metaBuf = null
  }
  if (!metaBuf || metaBuf.byteLength === 0) return

  let meta
  try {
    const text = new TextDecoder().decode(metaBuf)
    meta = JSON.parse(text)
  } catch {
    return
  }
  const bundles = meta?.bundles
  if (!Array.isArray(bundles)) return

  const g = globalThis
  const sym = BARE_OS_STDLIB_GLOBAL
  g[sym] = g[sym] && typeof g[sym] === 'object' ? g[sym] : {}

  const concRaw = String(
    shellEnv?.BARE_OS_BARE_STDLIB_RESOLVE_CONCURRENCY ?? ''
  ).trim()
  const concParsed = Number.parseInt(concRaw, 10)
  const readConc =
    Number.isFinite(concParsed) && concParsed >= 1
      ? Math.min(concParsed, 32)
      : 4

  await withDriveBundleGlobalRequire(async () => {
    /** @type {{ path: string, keys: string[] }[]} */
    const work = []
    /** @type {Set<string>} */
    const seenPaths = new Set()
    let allKeysSatisfied = true
    for (const b of bundles) {
      const path = typeof b?.path === 'string' ? b.path : ''
      const keys = Array.isArray(b?.keys) ? b.keys : []
      if (!path.startsWith('/lib/bare/')) continue
      if (seenPaths.has(path)) continue
      seenPaths.add(path)
      for (const k of keys) {
        if (typeof k === 'string' && k && target[k] === undefined) {
          allKeysSatisfied = false
        }
      }
      work.push({ path, keys })
    }

    if (work.length > 0 && allKeysSatisfied) {
      await tryBareFetchImportWhenDriveMissing(target)
      return
    }

    /** @type {{ path: string, keys: string[], source: string | null }[]} */
    const prepared = []
    for (let i = 0; i < work.length; ) {
      const slice = work.slice(i, i + readConc)
      i += slice.length
      const chunk = await Promise.all(
        slice.map(async ({ path, keys }) => {
          let srcBuf
          try {
            srcBuf = await vfs.readFile(path)
          } catch {
            srcBuf = null
          }
          if (!srcBuf || srcBuf.byteLength === 0) {
            return { path, keys, source: null }
          }
          const source = new TextDecoder().decode(srcBuf)
          if (source.length > 12 * 1024 * 1024) {
            return { path, keys, source: null }
          }
          return { path, keys, source }
        })
      )
      prepared.push(...chunk)
    }

    for (const { path, keys, source } of prepared) {
      if (!source) continue

      try {
        const run = new Function(
          `"use strict"; ${source}\n//# sourceURL=bare-drive-bundle:${path}`
        )
        run()
      } catch (err) {
        bareOsHostBooterWarn(
          'drive_bundle_eval_failed',
          `drive bundle failed ${path}`,
          err?.message || String(err)
        )
        continue
      }

      const snap = g[sym]
      if (!snap || typeof snap !== 'object') continue

      for (const k of keys) {
        if (typeof k !== 'string' || !k) continue
        if (target[k] !== undefined) continue
        if (Object.prototype.hasOwnProperty.call(snap, k)) {
          target[k] = unwrapDriveBundleExport(snap[k])
        }
      }
    }
  })

  await tryBareFetchImportWhenDriveMissing(target)

  if (t0 && hrtBig) {
    const ns = Number(hrtBig() - t0)
    bareOsHostBooterWarn(
      'bare_stdlib_merge_ns',
      'maybeMergeBareFromDrive wall (hrtime bigint delta ns)',
      String(ns)
    )
  }
}

/**
 * When drive `fetch.js` eval fails (no `globalThis.require` or native addons), Bare can still
 * `import('bare-fetch')` from the booter — same as `buildBareCtxObjectFromHost`, but runs even
 * when the manifest marks the entry host-only.
 * @param {Record<string, unknown>} target
 */
async function tryBareFetchImportWhenDriveMissing(target) {
  if (target.fetch !== undefined) return
  if (!bareHostRuntime()) return
  try {
    let mod
    if (typeof import.meta.resolve === 'function') {
      try {
        mod = await import(import.meta.resolve('bare-fetch'))
      } catch {
        mod = await import('bare-fetch')
      }
    } else {
      mod = await import('bare-fetch')
    }
    const f = mod?.default
    if (typeof f === 'function') target.fetch = f
  } catch {
    /* optional */
  }
}