const fs = require('node:fs')
const path = require('node:path')

const { withXuqmConfig } = require('@xuqm/rn-common/metro')

const MODULE_RANGE_SIZE = 10_000_000

function readCache(file) {
  if (!fs.existsSync(file)) return {}
  try {
    return JSON.parse(fs.readFileSync(file, 'utf8'))
  } catch {
    return {}
  }
}

function writeCache(file, value) {
  fs.mkdirSync(path.dirname(file), { recursive: true })
  fs.writeFileSync(file, `${JSON.stringify(value, null, 2)}\n`)
}

function hasModule(cache, modulePath) {
  return Object.prototype.hasOwnProperty.call(cache, modulePath)
}

function isRuntimePrelude(modulePath) {
  return modulePath.includes('__prelude__') || modulePath.includes('polyfills')
}

function createModuleSerializer(environment = process.env) {
  const moduleId = environment.XUQM_MODULE_ID
  const moduleType = environment.XUQM_MODULE_TYPE
  if (!moduleId || !moduleType) return null

  const cacheFile = path.resolve(
    environment.XUQM_MODULE_CACHE_FILE ?? '.xuqm-cache/common-module-ids.json',
  )
  if (environment.XUQM_RESET_MODULE_CACHE === 'true') writeCache(cacheFile, {})

  const sharedCache = readCache(cacheFile)
  // processModuleFilter 会在 createModuleIdFactory 分配编号之后执行。必须冻结进入
  // 当前 bundle 之前已经存在的共享模块；否则 common 新分配的模块刚写入缓存，随即
  // 又会被当作 startup 已提供模块过滤，生成只含 require(entryId) 的无效空包。
  const inheritedSharedModules = new Set(Object.keys(sharedCache))
  const writesSharedCache = moduleType === 'startup' || moduleType === 'common'
  const moduleIndex = Number.parseInt(environment.XUQM_MODULE_INDEX ?? '0', 10)
  let nextId = writesSharedCache
    ? Object.values(sharedCache).reduce((maximum, value) => Math.max(maximum, Number(value)), -1) +
      1
    : (Number.isFinite(moduleIndex) && moduleIndex >= 0 ? moduleIndex + 1 : 1) * MODULE_RANGE_SIZE
  const localIds = new Map()

  return {
    createModuleIdFactory() {
      return modulePath => {
        if (hasModule(sharedCache, modulePath)) return sharedCache[modulePath]
        const existing = localIds.get(modulePath)
        if (existing !== undefined) return existing
        const id = nextId++
        localIds.set(modulePath, id)
        if (writesSharedCache) {
          sharedCache[modulePath] = id
          writeCache(cacheFile, sharedCache)
        }
        return id
      }
    },
    processModuleFilter(module) {
      if (moduleType === 'startup') return true
      if (isRuntimePrelude(module.path)) return false
      return !inheritedSharedModules.has(module.path)
    },
  }
}

/**
 * 同一份 Metro 配置同时服务日常开发和插件构建。CLI 构建插件时注入模块上下文；
 * 普通 `pnpm android/start` 没有这些变量，因此保持标准 React Native 行为。
 */
function withXuqmModuleConfig(metroConfig) {
  const configured = withXuqmConfig(metroConfig)
  const moduleSerializer = createModuleSerializer()
  if (!moduleSerializer) return configured
  const configuredFilter = configured.serializer?.processModuleFilter
  return {
    ...configured,
    serializer: {
      ...configured.serializer,
      ...moduleSerializer,
      processModuleFilter(module) {
        return (
          (configuredFilter ? configuredFilter(module) : true) &&
          moduleSerializer.processModuleFilter(module)
        )
      },
    },
  }
}

module.exports = {
  createModuleSerializer,
  withXuqmModuleConfig,
}