import { readdirSync, statSync, existsSync } from 'fs'
import { join, dirname } from 'path'
import { fileURLToPath } from 'url'
import type { ApiModule } from './types.js'
import type { ModuleDefinition } from '../../shared/modules/types.js'

const __filename = fileURLToPath(import.meta.url)
const __dirname = dirname(__filename)

function getSharedModulesPath(): string | null {
  const possiblePaths = [
    join(__dirname, '../../shared/modules'),
    join(__dirname, '../../../shared/modules'),
    join((process as unknown as { resourcesPath?: string })?.resourcesPath || '', 'shared/modules'),
  ]

  for (const p of possiblePaths) {
    if (existsSync(p)) {
      return p
    }
  }
  return null
}

export interface SharedModuleDefinition {
  id: string
  name: string
  backend?: {
    enabled?: boolean
  }
}

function needsBackendImplementation(moduleDef: SharedModuleDefinition): boolean {
  return moduleDef.backend?.enabled !== false
}

async function loadModuleDefinitions(): Promise<SharedModuleDefinition[]> {
  const modules: SharedModuleDefinition[] = []
  const sharedModulesPath = getSharedModulesPath()

  if (!sharedModulesPath) {
    return modules
  }

  const entries = readdirSync(sharedModulesPath)

  for (const entry of entries) {
    const entryPath = join(sharedModulesPath, entry)
    const stat = statSync(entryPath)

    if (!stat.isDirectory()) {
      continue
    }

    try {
      const moduleExports = await import(`../../shared/modules/${entry}/index.js`)

      for (const key of Object.keys(moduleExports)) {
        if (key.endsWith('_MODULE')) {
          const moduleDef = moduleExports[key] as ModuleDefinition
          if (moduleDef && moduleDef.id) {
            modules.push({
              id: moduleDef.id,
              name: moduleDef.name,
              backend: moduleDef.backend,
            })
          }
        }
      }
    } catch {
      // 模块加载失败，跳过
    }
  }

  return modules
}

export async function validateModuleConsistency(apiModules: ApiModule[]): Promise<void> {
  const sharedModules = await loadModuleDefinitions()

  if (sharedModules.length === 0) {
    console.log('[ModuleValidator] Skipping validation (shared modules not found, likely packaged mode)')
    return
  }

  const apiModuleIds = new Set(apiModules.map((m) => m.metadata.id))
  const errors: string[] = []

  for (const sharedModule of sharedModules) {
    const needsBackend = needsBackendImplementation(sharedModule)
    const hasApiModule = apiModuleIds.has(sharedModule.id)

    if (needsBackend && !hasApiModule) {
      errors.push(
        `Module '${sharedModule.id}' is defined in shared but not registered in API modules`
      )
    }

    if (!needsBackend && hasApiModule) {
      errors.push(
        `Module '${sharedModule.id}' has backend disabled but is registered in API modules`
      )
    }
  }

  if (errors.length > 0) {
    throw new Error(`Module consistency validation failed:\n  - ${errors.join('\n  - ')}`)
  }

  console.log(
    `[ModuleValidator] ✓ Module consistency validated: ${sharedModules.length} shared, ${apiModules.length} API`
  )
}