import type { CodeReaderRegistry } from '../registry'
import type { TreeSitterRuntime } from '../runtime'
import type { DocumentMessage } from './messages'
import { readBlockViews } from '../blockView'

/** 生成预览数据要读的那点文档信息（TextDocument 的子集）。 */
export interface DocumentSnapshot {
  languageId: string
  version: number
  getText: () => string
}

/** 当前文档 → 发给预览的 document 消息；语言不支持或解析失败时带 error，blocks 为空。 */
export async function documentMessage(
  document: DocumentSnapshot,
  registry: Pick<CodeReaderRegistry, 'languageFor' | 'translatorsFor' | 'selectedTranslator'>,
  runtime: Pick<TreeSitterRuntime, 'parse'>,
): Promise<DocumentMessage> {
  const { languageId, version } = document
  const source = document.getText()
  const translator = registry.selectedTranslator(languageId)
  const message: DocumentMessage = {
    type: 'document',
    version,
    languageId,
    blocks: [],
    translators: registry.translatorsFor(languageId).map(({ id, label }) => ({ id, label })),
    translatorId: translator?.id ?? '',
  }
  const adapter = registry.languageFor(languageId)
  if (!adapter)
    return { ...message, error: `代码阅读还不支持「${languageId}」这种语言` }
  try {
    return { ...message, blocks: await readBlockViews(runtime, adapter, translator, languageId, source) }
  }
  catch (err) {
    return { ...message, error: err instanceof Error ? err.message : String(err) }
  }
}