import type { CustomTextEditorProvider, Disposable, TextDocument, TextDocumentShowOptions, WebviewPanel } from 'vscode'
import type { ClaudeImage } from '../../cc/spawnClaude'
import type { CommentEdit, CommentJob, WriteResult } from '../commentRewrite'
import type { BlockKind, LocalSymbol, RuleLocation, RuleReference } from '../contract'
import type { OpenedFrom, PreviewDiffBases } from '../diff/diffBase'
import type { OldDocument, SentDocument } from '../diff/previewDiff'
import type { WorkspaceEntries } from '../entries/workspaceEntries'
import type { DefinitionStart, IndexedName, NameSources } from '../nameResolution'
import type { CodeQa, TopRequest } from '../qa/codeQa'
import type { CodeReaderRegistry } from '../registry'
import type { LookupSources } from '../ruleLookups'
import type { TreeSitterRuntime } from '../runtime'
import type { ImportedName, LinkTarget, SymbolNode } from '../symbolLinks'
import type { ThemeColors } from '../theme/codeColors'
import type { IndexFind } from '../workspaceIndex'
import type { BlockFilter } from './blockFilter'
import type { FoundLocation } from './definitions'
import type { ChatKind, DefinitionPeek, ExtensionToWebview, Occurrence, Reveal, SymbolReference, WebviewToExtension } from './messages'
import type { TargetSpot } from './openTarget'
import type { TopSubject } from './pathPreview'
import { realpath } from 'node:fs/promises'
import { commands, EndOfLine, Position, Range, Uri, window, workspace, WorkspaceEdit } from 'vscode'
import { logger } from '../../logging/logger'
import { webviewHtml, webviewUiRoot } from '../../webview/html'
import { DocumentCallees } from '../calleeKinds'
import { loadBlockCalls } from '../callTree/query'
import { CallTreeSession } from '../callTree/session'
import { commentFollowUp, commentJob, commentRewritePrompt, findBlock, writeCommentBody } from '../commentRewrite'
import { DefinitionKinds } from '../definitionKinds'
import { PreviewDiff } from '../diff/previewDiff'
import { blockReplacement } from '../editText'
import { locate, locateQa } from '../folderStore'
import { LanguageRequests } from '../languageRequests'
import { definitionFor, symbolAt, symbolOccurrences } from '../localSymbols'
import { DocumentNames, resolveNames } from '../nameResolution'
import { NOT_REWRITABLE } from '../qa/codeQa'
import { PATH_ASK_ANCHOR } from '../qa/pathQa'
import { askPrompt, followUpPrompt } from '../qa/prompt'
import { DocumentLookups } from '../ruleLookups'
import { referenceScope, resolveReference } from '../symbolLinks'
import { definitionAction } from './definitionAction'
import { definitionSiteNames, namesOnCard, pagePeekBlock, peekBlock } from './definitionPeek'
import { definitionKind, findDefinitions, languageDefinitions, pickDefinition, ruleDefinitions } from './definitions'
import { DefinitionSources } from './definitionSources'
import { documentMessage, pageDocument } from './documentMessage'
import { documentSymbolNodes } from './documentSymbols'
import { NavigationContext, OCCURRENCES_CONTEXT } from './occurrenceNavigation'
import { occurrencesOf } from './occurrences'
import { languageOf, openingFor } from './openTarget'
import { PATH_PREVIEW_SCHEME, topSubjectOf } from './pathPreview'
import { findRepoSymbol, isRepoImagePath, repoRootOf, resolveRepoEntry } from './repoPath'

export const PREVIEW_VIEW_TYPE = 'superpowers.codeReader.preview'

/** 连续输入时合并成一次重新解析。 */
const REFRESH_DELAY_MS = 150

/** 预览里各有一个 profile 下拉的两种对话 */
const CHAT_KINDS: readonly ChatKind[] = ['ask', 'rewrite']

/**
 * 一次打开预览带的话：这个标签页是从哪儿打开的（定对比什么）；要滚到哪（从文本编辑器切过来时它顶部那一行，或跳到的定义）；
 * 要不要把光标放进顶部「问 AI」输入框（侧栏「问 AI」打开的）。
 *
 * 只有侧栏各栏点开文件、「编辑」切回「预览」带 `from`；跳定义、点链接、问 AI 这些只是去看一眼，不带：新开的预览不比，已经开着的照旧。
 */
export interface OpenRequest {
  from?: OpenedFrom
  reveal?: Reveal
  focusPath?: boolean
}

/**
 * 「代码阅读预览」自定义编辑器。预览和普通编辑器共用同一个 TextDocument：
 * 块内修改走 WorkspaceEdit，未保存标记、⌘S、⌘Z 都是 VS Code 原生行为。
 */
export class PreviewEditorProvider implements CustomTextEditorProvider {
  private readonly previews = new Set<Preview>()
  /** 按文档 uri：等着交给马上要打开的新预览的打开请求（见 [open]） */
  private readonly requests = new Map<string, OpenRequest>()
  /** 哪个预览眼下能用键盘在高亮的各处出现之间跳，跟着它设快捷键 when 子句用的上下文键 */
  readonly navigation = new NavigationContext<Preview>(value => void commands.executeCommand('setContext', OCCURRENCES_CONTEXT, value))
  /** 调用的名字的定义是哪种块：各预览共用，定义所在的文件同一版只解析一次 */
  readonly definitionKinds: DefinitionKinds

  constructor(
    private readonly extensionUri: Uri,
    private readonly registry: CodeReaderRegistry,
    private readonly runtime: TreeSitterRuntime,
    private readonly filter: BlockFilter,
    /** 代码配色：各预览共用当前颜色主题的那一份，换了主题、改了代码配色的设置时发给订阅的 */
    readonly codeColors: Pick<ThemeColors, 'current' | 'subscribe'>,
    /** 库规则标的引用去哪儿查定义（交给标它的规则） */
    readonly resolveReference: (reference: RuleReference) => Promise<RuleLocation[]>,
    /** 问 AI：各预览共用，同一份文件开在几处时问答、正在答的问题都一样 */
    readonly qa: CodeQa,
    /** 工作区里别的文件定义的、原名叫 name 的中文名（languageId 是查的这份文档的语言） */
    readonly indexedNames: (languageId: string, name: string) => Promise<IndexedName[]>,
    /** 工作区索引里键是 key 的各项（规则查名字的定义时用，见 ruleLookups.ts；接口的调用树查契约和前端请求时用） */
    readonly indexed: IndexFind,
    /** 预览标差异时对比什么：看文件在哪、这个标签页是从哪儿打开的，基准变了发 onDidChange */
    readonly diffBases: PreviewDiffBases,
    /** 哪些文件是项目写明的入口、预览里哪些名字的块标成入口 */
    readonly entries: Pick<WorkspaceEntries, 'namesOf' | 'onDidChange'>,
    /** 在代码阅读侧栏的树上定位一个目录（仓库链接指到目录时）；树上没有它时返回 false */
    readonly revealInTree: (uri: Uri) => Promise<boolean>,
    /** 「了解一块代码」的对话页里接着说（subject 是那个功能，见 featureSubjectUri）；说不了时返回给人看的原因 */
    readonly askFeature: (subject: Uri, request: TopRequest) => Promise<string | undefined>,
  ) {
    this.definitionKinds = new DefinitionKinds(languageId => registry.languageFor(languageId), runtime)
  }

  /**
   * 注册成预览编辑器。标签页切走时页面留着（`retainContextWhenHidden`）：切回来不用重新生成、重发文档（切走期间改过的才补一次），页面也不用整份重画，
   * 代价是每个开着的预览切走后仍占着它那个页面的内存。
   */
  register(): Disposable {
    return window.registerCustomEditorProvider(PREVIEW_VIEW_TYPE, this, { webviewOptions: { retainContextWhenHidden: true } })
  }

  /**
   * 用 `show` 打开 `uri` 的预览，把 `request` 交给它：新建的预览解析时带走；`show` 只是切到了已经开着的预览（没有新建）时，交给切到的那个。
   *
   * `show` 默认按「预览标签」打开，同 `vscode.open`（用户关了 `workbench.editor.enablePreview` 时 VS Code 自会固定）。
   */
  async open(uri: Uri, request: OpenRequest, show: () => Thenable<unknown> = () => commands.executeCommand('vscode.openWith', uri, PREVIEW_VIEW_TYPE, { preview: true })): Promise<void> {
    const key = uri.toString()
    this.requests.set(key, request)
    let claimed: boolean
    try {
      await show()
      claimed = this.requests.get(key) !== request
    }
    finally {
      // 打开命令等新预览解析完才返回；没打开成时也不能把这次请求留给以后别处的打开
      if (this.requests.get(key) === request)
        this.requests.delete(key)
    }
    if (!claimed)
      [...this.previews].find(p => p.uri.toString() === key && p.active)?.reopen(request)
  }

  resolveCustomTextEditor(document: TextDocument, panel: WebviewPanel): void {
    // 问答带的图片（工作区文件夹的 .spx/code-qa/）也要能读，历史里才画得出缩略图
    const imageRoot = this.qa.imageRoot(topSubjectOf(document.uri).uri)
    panel.webview.options = { enableScripts: true, localResourceRoots: [webviewUiRoot(this.extensionUri), ...(imageRoot ? [imageRoot] : [])] }
    panel.webview.html = webviewHtml(panel.webview, this.extensionUri, 'code-reader.html')
    const key = document.uri.toString()
    const request = this.requests.get(key)
    this.requests.delete(key)
    const preview = new Preview(document, panel, this, this.registry, this.runtime, this.filter, request)
    this.previews.add(preview)
    panel.onDidDispose(() => {
      this.previews.delete(preview)
      this.navigation.update(preview, false)
      preview.dispose()
    })
  }

  /** 「跳到下一处 / 上一处高亮」：发给能跳的那个预览，从命令面板运行时发给活动的预览。 */
  moveOccurrence(step: 1 | -1): void {
    this.navigation.target(this.previews, preview => preview.active)?.moveOccurrence(step)
  }

  /** 让已打开的预览按当前注册表重发；给了 languageId 就只刷这种语言的。 */
  refresh(languageId?: string): void {
    for (const preview of this.previews) {
      if (languageId === undefined || preview.languageId === languageId)
        void preview.push()
    }
  }

  /** uri 的预览视口顶部那块的起始行；几个编辑器组里都开着这个文件的预览时取活动的那个。 */
  visibleLine(uri: Uri): number | undefined {
    return this.shown(uri)?.visibleLine
  }

  /** uri 的预览这个标签页是从哪儿打开的；几个编辑器组里都开着时取活动的那个，页面还没准备好、不知道的没有。 */
  openedFrom(uri: Uri): OpenedFrom | undefined {
    return this.shown(uri)?.openedFrom
  }

  /** uri 的预览：几个编辑器组里都开着时取活动的那个。 */
  private shown(uri: Uri): Preview | undefined {
    const key = uri.toString()
    const previews = [...this.previews].filter(p => p.uri.toString() === key)
    return previews.find(p => p.active) ?? previews[0]
  }
}

class Preview {
  /**
   * 页面发过 ready（装好了、能收消息）之后才发消息。标签页切走时页面留着，照常收消息；
   * 页面真的重新加载了（webview 进程崩了重建、开发者重载 webview）会再发 ready，那时整份重发
   */
  private ready = false
  /** 切走期间该重新生成的文档没生成（文件改了、规则变了）：重新看得见时补一次；没过期的切回来什么都不用做 */
  private outdated = false
  /** 页面上那份文档的版本：还不是眼下这一版时（正在生成、切走期间改过），要滚到的位置等新的那份一起带过去 */
  private shown: number | undefined
  /** 侧栏「问 AI」打开的：页面准备好后把光标放进顶部输入框 */
  private pendingPathFocus = false
  /** 解析是异步的：只发最后一次请求的结果，慢的旧结果不能盖掉新的 */
  private latest = 0
  private timer: NodeJS.Timeout | undefined
  private readonly disposables: Disposable[]
  /** 名字的定义去哪儿查：库规则标了引用的问规则，其余问语言扩展 */
  private readonly definitions: DefinitionSources<FoundLocation>
  /** webview 报来的视口顶部那块的起始行 */
  visibleLine: number | undefined
  /** 最近一次发出去的文档（版本、块树、源码）：问 AI 时按块的记号在里面找那块代码，对比基准变了时拿它重新比 */
  private sent: SentDocument | undefined
  /** 发文档后在后台问语言扩展的请求（中文名、库规则查的定义、调用的种类）排队发：在途的有上限，离视口近的先发，文档改了排着的作废 */
  private readonly requests = new LanguageRequests(() => this.document.version, () => this.visibleLine)
  /** 能看调用树的块（函数、类、接口卡片）落在几棵调用树里。文档发出去之后再数，不挡住第一次预览，离视口近的先数；同一版文档数过的页面重新加载后接着用 */
  private readonly callTrees = new CallTreeSession(
    message => this.post(message),
    () => {
      if (!this.sent || this.sent.version !== this.document.version)
        return undefined
      return {
        version: this.sent.version,
        blocks: this.sent.blocks,
        load: (block, cancelled) => loadBlockCalls(this.document, block, this.owner.indexed, cancelled),
      }
    },
    offset => this.requests.distance(this.document.positionAt(offset).line),
  )

  /** 最近一次发出去的文档里语言插件自己认得出的名字（LanguageAdapter.symbols）：语言扩展查不到定义、各处出现时用 */
  private symbols: { version: number, list: LocalSymbol[] } | undefined
  /** 最近一次发出去的文档里各条导入引进来的名字：注释里不带路径的引用按它找导入的定义 */
  private imports: ImportedName[] = []
  /** 这份文档各版本显示成中文名的名字 */
  private readonly names: DocumentNames
  /** 库规则问的名字的定义查到了什么：查到的变了就重发文档 */
  private readonly lookups: DocumentLookups
  /** 调用的名字定义成哪种块（分新建还是调用）：查到的变了就重发文档 */
  private readonly callees: DocumentCallees
  /** 这份文件相比对比基准改了什么：发完文档再算、补发 */
  private readonly diff: PreviewDiff
  /**
   * 随下一份真正发出去的文档走、只走一次：新预览第一份文档要滚到的位置，或页面上还不是眼下这一版文档时来的 reveal。
   * 之后页面真的重新加载了，按 webview 自己记的位置恢复
   */
  private pendingReveal: Reveal | undefined
  /** 这个标签页是从哪儿打开的，定对比什么；打开请求没说的（跳定义新开的、VS Code 重启后恢复的）先空着，页面 ready 时按它记着的定 */
  private from: OpenedFrom | undefined

  constructor(
    private readonly document: TextDocument,
    private readonly panel: WebviewPanel,
    private readonly owner: PreviewEditorProvider,
    private readonly registry: CodeReaderRegistry,
    private readonly runtime: TreeSitterRuntime,
    private readonly filter: BlockFilter,
    /** 打开它的那次请求；VS Code 重启后恢复的、VS Code 自己换编辑器打开的没有 */
    request: OpenRequest | undefined,
  ) {
    this.from = request?.from
    this.pendingReveal = request?.reveal
    this.pendingPathFocus = request?.focusPath ?? false
    this.definitions = new DefinitionSources({
      rule: async reference => ruleDefinitions(await owner.resolveReference(reference)),
      language: async (offset) => {
        const found = await languageDefinitions(document.uri, document.positionAt(offset))
        return found.length > 0 ? found : this.localDefinitions(offset)
      },
    })
    this.names = new DocumentNames((version, names) => {
      if (version === document.version)
        this.post({ type: 'displayNames', version, names })
    })
    this.lookups = new DocumentLookups(() => this.schedulePush())
    this.callees = new DocumentCallees(() => this.schedulePush())
    this.diff = new PreviewDiff(
      () => this.from === undefined ? undefined : owner.diffBases.diffBase(document.uri, this.from),
      source => this.readOld(source),
      () => this.oldInputs(),
      diff => this.post({ type: 'diff', diff }),
      text => logger.add({ level: 'warn', source: 'codeReader', message: `${document.uri.fsPath}：${text}` }),
    )
    this.disposables = [
      owner.diffBases.onDidChange(() => {
        if (this.sent)
          void this.diff.update(this.sent)
      }),
      panel.webview.onDidReceiveMessage((msg: WebviewToExtension) => this.handleMessage(msg)),
      panel.onDidChangeViewState(() => {
        if (panel.visible && this.outdated)
          void this.push()
      }),
      workspace.onDidChangeTextDocument((e) => {
        if (e.document !== document || e.contentChanges.length === 0)
          return
        this.names.edited(document.version, e.contentChanges.map(change => ({ offset: change.rangeOffset, length: change.rangeLength, text: change.text })))
        this.schedulePush()
      }),
      workspace.onDidChangeConfiguration((e) => {
        if (this.ready && e.affectsConfiguration('editor.hover', document))
          this.postHoverDelay()
        if (this.ready && e.affectsConfiguration('editor.stickyScroll', document))
          this.postStickyScroll()
      }),
      // 页面没 ready 时收不到，等它 ready 再随第一份文档之前补发
      filter.subscribe((state) => {
        if (this.ready)
          this.post({ type: 'filter', ...state })
      }),
      // 同上：没 ready 的等 ready 时在第一份文档之前发眼下的
      owner.codeColors.subscribe((colors) => {
        if (this.ready)
          this.post({ type: 'codeColors', ...colors })
      }),
      // 项目的入口变了：重新发文档，卡片左边的入口图标跟着变
      owner.entries.onDidChange((uris) => {
        if (uris.some(uri => uri.toString() === document.uri.toString()))
          this.schedulePush()
      }),
      owner.qa.onDidChange((uris) => {
        if (uris.some(uri => uri.toString() === this.subject().uri.toString()))
          this.postQa()
      }),
      ...CHAT_KINDS.map(kind => owner.qa.profiles[kind].subscribe((choice) => {
        if (this.ready)
          this.post({ type: 'profiles', kind, ...choice })
      })),
      owner.qa.onDidAnswer((event) => {
        if (event.owner !== this.subject().uri.toString() || !this.ready)
          return
        if (event.kind === 'update') {
          const { askId, text, activity } = event.ask
          this.post({ type: 'answer', askId, text, ...(activity !== undefined && { activity }) })
          return
        }
        const { end, entryId } = event
        this.post({
          type: 'answerEnd',
          askId: event.ask.askId,
          status: end.status,
          ...(end.status === 'failed' && { error: end.error }),
          ...(end.status === 'done' && { text: end.answer.text, entryId }),
        })
        this.postQa()
      }),
      owner.qa.onDidRewrite((event) => {
        if (event.owner !== this.subject().uri.toString() || !this.ready)
          return
        if (event.kind === 'update') {
          const { askId, question, text, activity, queued } = event.ask
          this.post({ type: 'rewriteProgress', askId, question, text, ...(activity !== undefined && { activity }), ...(queued && { queued }) })
          return
        }
        const { end, entryId } = event
        this.post({
          type: 'rewriteEnd',
          askId: event.ask.askId,
          status: end.status,
          ...(end.status !== 'stopped' && end.error !== undefined && { error: end.error }),
          ...(end.status === 'done' && end.body !== undefined && { text: end.body }),
          ...(entryId !== undefined && { entryId }),
        })
        this.postQa()
      }),
    ]
  }

  get languageId(): string {
    return this.document.languageId
  }

  get uri(): Uri {
    return this.document.uri
  }

  get active(): boolean {
    return this.panel.active
  }

  get openedFrom(): OpenedFrom | undefined {
    return this.from
  }

  async push(): Promise<void> {
    clearTimeout(this.timer)
    if (!this.ready)
      return
    // 切走的预览不在后台生成，后面跟着文档的查询也不起；分屏同时看得见的照常马上生成
    if (!this.panel.visible) {
      this.outdated = true
      return
    }
    this.outdated = false
    const request = ++this.latest
    // 路径页、功能对话页：文档是空的，只在顶部聊天
    if (this.document.uri.scheme === PATH_PREVIEW_SCHEME) {
      this.sent = undefined
      const reveal = this.pendingReveal
      this.pendingReveal = undefined
      this.shown = this.document.version
      this.post({
        type: 'document',
        version: this.document.version,
        languageId: '',
        blocks: [],
        source: '',
        colors: { roles: [], runs: [] },
        attributes: [],
        translators: [],
        translatorId: '',
        names: [],
        ...(reveal && { reveal }),
      })
      return
    }
    const { languageId, version } = this.document
    const source = this.document.getText()
    const session = this.lookups.session()
    const callees = this.callees.session()
    const { message, displayNames, symbols, imports, kinds, bindings } = await documentMessage({ languageId, version, getText: () => source, fileName: this.document.fileName, entryNames: this.owner.entries.namesOf(this.document.uri) }, this.registry, this.runtime, (text) => {
      logger.add({ level: 'warn', source: 'codeReader', message: `${this.document.uri.fsPath}：${text}` })
    }, session.lookup, callees.calleeKind)
    if (request !== this.latest)
      return
    this.definitions.remember(message.version, message.blocks)
    // 调用的定义就在这份文档里时，认种类直接用这一遍读出的，不再解析一遍
    this.owner.definitionKinds.remember(this.document.uri.toString(), version, kinds)
    // 解析失败的文档没有块：问 AI 找不到块，也不拿它比差异
    this.sent = message.error === undefined ? { version: message.version, blocks: message.blocks, source } : undefined
    this.symbols = { version, list: symbols }
    this.imports = imports
    const reveal = this.pendingReveal
    this.pendingReveal = undefined
    this.shown = version
    this.post({ ...pageDocument(message), names: this.names.known(version), ...(reveal && { reveal }) })
    if (this.sent)
      void this.diff.update(this.sent)
    // 文档在解析期间又改了的，等下一次发文档再查
    if (version === this.document.version) {
      this.names.resolve(version, report => resolveNames(displayNames, message.blocks, bindings, this.nameSources(version), report))
      this.lookups.resolve(version, session.requests(), this.lookupSources(version))
      this.callees.resolve(version, callees.requests(), offset => this.queued(version, offset, () => this.calleeKind(offset), undefined))
      this.callTrees.documentSent()
    }
  }

  /**
   * 对比基准里的旧版本排成视图数据：和这份文档同一种语言、同一个翻译插件和库规则；规则查定义、调用的种类用这份文档眼下查到的答案，
   * 两边同样的写法翻得一样，不会因为答案晚到被当成改了；项目入口也按眼下的标，两边的入口块一样。旧版本里规则出的错不记（记的是现在这份的）。
   */
  private async readOld(source: string): Promise<OldDocument | undefined> {
    const { message } = await documentMessage(
      { languageId: this.document.languageId, version: this.document.version, getText: () => source, fileName: this.document.fileName, entryNames: this.owner.entries.namesOf(this.document.uri) },
      this.registry,
      this.runtime,
      () => {},
      this.lookups.session().lookup,
      this.callees.session().calleeKind,
    )
    return message.error === undefined ? { blocks: message.blocks, attributes: message.attributes } : undefined
  }

  /** 排旧版本除了旧内容还看的（见 readOld）：选的翻译插件、项目入口、规则查到的定义和调用的种类变过几次。变了旧版本要重新解析 */
  private oldInputs(): string {
    return JSON.stringify([this.registry.selectedTranslator(this.document.languageId)?.id, this.owner.entries.namesOf(this.document.uri), this.lookups.revision, this.callees.revision])
  }

  /** 这份文档里 offset 处名字的定义是哪种块：语言扩展查到的几处定义里第一处认得出的；语言扩展没答是 undefined。 */
  private async calleeKind(offset: number): Promise<BlockKind | null | undefined> {
    const { document } = this
    const found = await languageDefinitions(document.uri, document.positionAt(offset))
    if (found.length === 0)
      return undefined
    for (const location of found) {
      const kind = await definitionKind(location, this.owner.definitionKinds)
      if (kind)
        return kind
    }
    return null
  }

  /** 这份文档里语言插件自己认得出、盖住 offset 的名字（只认最近一次发出去的那个版本）。 */
  private localSymbol(offset: number): LocalSymbol | undefined {
    return this.symbols?.version === this.document.version ? symbolAt(this.symbols.list, offset) : undefined
  }

  /** 语言扩展查不到定义时：语言插件自己认得出的名字的定义（见 definitionFor）。 */
  private localDefinitions(offset: number): FoundLocation[] {
    const symbol = this.localSymbol(offset)
    const target = symbol && definitionFor(symbol, offset)
    if (!target)
      return []
    const { document } = this
    return [{ uri: document.uri, range: new Range(document.positionAt(target.startIndex), document.positionAt(target.endIndex)) }]
  }

  /** offset 处名字的各处出现：先问语言扩展，它答不上来时用语言插件自己认得出的名字（见 symbolOccurrences）。 */
  private async occurrences(offset: number): Promise<Occurrence[]> {
    const found = await occurrencesOf(this.document, offset)
    const symbol = found.length > 0 ? undefined : this.localSymbol(offset)
    return symbol ? symbolOccurrences(symbol) : found
  }

  /** 这份文档里 offset 处名字的定义（语言扩展查的）落在哪儿。 */
  private async definitionStarts(offset: number): Promise<DefinitionStart[]> {
    const { document } = this
    return (await languageDefinitions(document.uri, document.positionAt(offset)))
      .map(({ uri, range }) => ({ uri: uri.toString(), line: range.start.line, character: range.start.character }))
  }

  /** 找 version 这一版的中文名落在哪些名字上时问的：这份文档的语言扩展（排队问）、工作区里的中文名索引、页面的视口。 */
  private nameSources(version: number): NameSources {
    const { document } = this
    return {
      uri: document.uri.toString(),
      occurrences: offset => this.queued(version, offset, async () => (await this.occurrences(offset)).map(({ start, end }) => ({ start, end })), []),
      definitions: offset => this.queued(version, offset, () => this.definitionStarts(offset), []),
      indexed: name => this.owner.indexedNames(document.languageId, name),
      visible: offset => this.requests.visible(document.positionAt(offset).line),
    }
  }

  /** 查 version 这一版库规则问的名字时问的：规则的工作区索引、这份文档的语言扩展（排队问）。 */
  private lookupSources(version: number): LookupSources {
    return {
      find: (index, key) => this.owner.indexed(index, key),
      definitions: offset => this.queued(version, offset, () => this.definitionStarts(offset), []),
    }
  }

  /** 排进后台请求的队（见 LanguageRequests）：version 这一版文档 offset 处要问的，没发就作废的交回 dropped（当语言扩展没答）。 */
  private queued<T>(version: number, offset: number, request: () => Promise<T>, dropped: T): Promise<T> {
    return this.requests.run(version, this.document.positionAt(offset).line, request, dropped)
  }

  /** 跳到高亮着的名字的下一处 / 上一处出现；页面还没 ready 就算了（还没有高亮）。 */
  moveOccurrence(step: 1 | -1): void {
    if (this.ready)
      this.post({ type: 'moveOccurrence', step })
  }

  /** 开着时又被点开（见 [PreviewEditorProvider.open]）：这次说了从哪儿打开的就按它重新比，没说的照旧；要滚到哪、要不要聚焦输入框照这次的。 */
  reopen(request: OpenRequest): void {
    if (request.from !== undefined) {
      this.from = request.from
      if (this.ready) {
        this.post({ type: 'openedFrom', from: request.from })
        if (this.sent)
          void this.diff.update(this.sent)
      }
    }
    if (request.reveal)
      this.reveal(request.reveal)
    if (request.focusPath)
      this.focusPathAsk()
  }

  /** 滚到 reveal：页面上已是眼下这一版文档就直接发；还不是（还没 ready、正在生成、切走期间改过）就随新的那份文档带过去。 */
  private reveal(reveal: Reveal): void {
    if (this.shown === this.document.version)
      this.post({ type: 'reveal', ...reveal })
    else
      this.pendingReveal = reveal
  }

  dispose(): void {
    this.callTrees.dispose()
    this.requests.dispose()
    clearTimeout(this.timer)
    this.names.dispose()
    this.lookups.dispose()
    this.callees.dispose()
    for (const disposable of this.disposables)
      disposable.dispose()
  }

  private post(message: ExtensionToWebview): void {
    void this.panel.webview.postMessage(message)
  }

  private postQa(): void {
    if (!this.ready)
      return
    const subject = this.subject()
    this.post(this.owner.qa.view(subject.uri, file => this.panel.webview.asWebviewUri(file).toString(), subject.kind))
  }

  /** 这一页顶部问的是什么（见 topSubjectOf）。 */
  private subject(): { uri: Uri, kind: TopSubject } {
    return topSubjectOf(this.document.uri)
  }

  /** 把光标放进顶部输入框；页面还没准备好就等 ready。 */
  private focusPathAsk(): void {
    if (!this.ready) {
      this.pendingPathFocus = true
      return
    }
    this.pendingPathFocus = false
    this.post({ type: 'focusPathAsk' })
  }

  /** kind 那种对话的 profile 列表每次现读（同看板）。 */
  private async postProfiles(kind: ChatKind): Promise<void> {
    const choice = await this.owner.qa.profiles[kind].choice()
    this.post({ type: 'profiles', kind, ...choice })
  }

  /**
   * 问 anchor 那块代码：按最近一次发出去的块树找到它，把完整问题和追问的话都交给 CodeQa，接不接着上次的会话由它定。
   * 找不到这块（代码刚改过、还没重新发）或问不了时，直接回一条失败。
   */
  private async ask(askId: string, anchor: string, question: string, images: ClaudeImage[]): Promise<void> {
    const subject = this.subject()
    if (anchor === PATH_ASK_ANCHOR) {
      const request = { askId, question, images }
      const refused = subject.kind === 'feature'
        ? await this.owner.askFeature(subject.uri, request)
        : await this.owner.qa.askPath(subject.uri, subject.kind, request)
      if (refused !== undefined)
        this.post({ type: 'answerEnd', askId, status: 'failed', error: refused })
      else
        this.postQa()
      return
    }
    const at = locateQa(subject.uri)
    const block = at && this.sent && { path: at.promptPath, languageId: this.document.languageId, blocks: this.sent.blocks, source: this.sent.source, anchor }
    const prompt = block && askPrompt(block, question)
    const followUp = block && followUpPrompt(block, question)
    const refused = prompt === undefined || followUp === undefined
      ? '这块代码刚改过，找不到了。等预览刷新后重新点「问 AI」再问。'
      : await this.owner.qa.ask(subject.uri, { askId, anchor, question, prompt, followUp, images })
    if (refused !== undefined) {
      this.post({ type: 'answerEnd', askId, status: 'failed', error: refused })
      return
    }
    this.postQa()
  }

  private schedulePush(): void {
    clearTimeout(this.timer)
    this.timer = setTimeout(() => void this.push(), REFRESH_DELAY_MS)
  }

  private async handleMessage(msg: WebviewToExtension): Promise<void> {
    switch (msg.type) {
      case 'ready':
        // 页面刚装好（新开的、VS Code 重启后恢复的、真的重新加载了的）：眼下的状态和文档整份发一遍
        this.ready = true
        // 打开请求说了从哪儿打开的就按它；没说的按页面记着的（VS Code 重启后恢复的），页面也没记过的（新开的）不比
        this.from ??= msg.openedFrom ?? 'other'
        this.post({ type: 'openedFrom', from: this.from })
        // 先于文档发：第一份文档按筛选画，不会先整份露出来再藏
        this.post({ type: 'filter', ...this.filter.current })
        this.postHoverDelay()
        this.postStickyScroll()
        this.postQa()
        for (const kind of CHAT_KINDS)
          void this.postProfiles(kind)
        // 也先于文档发：第一份文档一画出来就是主题的颜色，不会先没颜色再闪一下
        this.post({ type: 'codeColors', ...await this.owner.codeColors.current() })
        await this.push()
        if (this.pendingPathFocus)
          this.focusPathAsk()
        return
      case 'ask':
        await this.ask(msg.askId, msg.anchor, msg.question, msg.images)
        return
      case 'selectProfile':
        try {
          await this.owner.qa.profiles[msg.kind].select(msg.id)
        }
        catch (err) {
          void window.showErrorMessage(err instanceof Error ? err.message : String(err))
          await this.postProfiles(msg.kind)
        }
        return
      case 'stopAsk':
        this.owner.qa.stop(msg.askId)
        return
      case 'deleteQa':
        await this.owner.qa.delete(this.subject().uri, msg.anchor, msg.entryId)
        return
      case 'setFilter':
        await this.filter.set(msg.excluded)
        return
      case 'setOnlyChanges':
        await this.filter.setOnlyChanges(msg.on)
        return
      case 'edit':
        await replaceDocumentLines(this.document, msg.startLine, msg.endLine, msg.text)
        return
      case 'rewriteComment':
        await this.rewrite(msg.askId, msg.anchor, msg.request, msg.images)
        return
      case 'stopRewrite':
        this.owner.qa.stopRewrite(msg.askId)
        return
      case 'deleteRewrite':
        await this.owner.qa.deleteRewrite(this.subject().uri, msg.anchor, msg.entryId)
        return
      case 'forgetRound':
        if (msg.kind === 'ask')
          this.owner.qa.forgetAsk(this.subject().uri, msg.anchor)
        else
          this.owner.qa.forgetRewrite(this.subject().uri, msg.anchor)
        return
      case 'selectTranslator':
        await this.registry.selectTranslator(this.languageId, msg.id)
        this.owner.refresh(this.languageId)
        return
      case 'visibleLine':
        this.visibleLine = msg.line
        return
      case 'probeDefinition':
        await this.probeDefinition(msg.id, msg.version, msg.offset)
        return
      case 'goToDefinition':
        await this.goToDefinition(msg.version, msg.offset)
        return
      case 'peekDefinition':
        await this.peekDefinition(msg.id, msg.version, msg.offset)
        return
      case 'peekLink':
        await this.peekLink(msg.id, msg.path, msg.symbol, msg.block)
        return
      case 'findOccurrences':
        await this.findOccurrences(msg.id, msg.version, msg.offset)
        return
      case 'openRepoLink':
        await this.openRepoLink(msg.path, msg.symbol, msg.block)
        return
      case 'checkRepoLinks':
        await this.checkRepoLinks(msg.id, msg.paths, msg.references)
        return
      case 'checkRepoImages':
        await this.checkRepoImages(msg.id, msg.paths)
        return
      case 'openCallTree':
        this.callTrees.open(msg.version, msg.anchor)
        return
      case 'goToCallNode':
        await this.goToCallNode(Uri.parse(msg.uri), new Position(msg.line, msg.character))
        return
      case 'occurrenceNavigation':
        this.owner.navigation.update(this, msg.available)
    }
  }

  /** 回答 webview 第 id 次询问：offset 处的名字在这份文档里出现在哪几处。下标属于别的文档版本时不答，webview 换了文档版本会清掉高亮 */
  private async findOccurrences(id: number, version: number, offset: number): Promise<void> {
    const { document } = this
    if (version !== document.version)
      return
    const occurrences = await this.occurrences(offset)
    if (version === document.version)
      this.post({ type: 'occurrencesFound', id, occurrences })
  }

  /** 回答 webview 第 id 次询问：offset 处的名字有没有定义。下标属于别的文档版本时不答，webview 收到新文档后会重新问 */
  private async probeDefinition(id: number, version: number, offset: number): Promise<void> {
    const { document } = this
    if (version !== document.version)
      return
    const found = (await this.definitions.locate(version, offset)).length > 0
    if (version === document.version)
      this.post({ type: 'definitionProbed', id, found })
  }

  /** ⌘ / Ctrl + 点击：跳到 offset 处名字的定义，几处时先让用户挑。 */
  private async goToDefinition(version: number, offset: number): Promise<void> {
    const { document } = this
    if (version !== document.version)
      return
    const current = document.uri.toString()
    let action = definitionAction(await findDefinitions(await this.definitions.locate(version, offset)), current)
    if (action.kind === 'pick') {
      const picked = await pickDefinition(action.targets)
      action = definitionAction(picked ? [picked] : [], current)
    }
    if (action.kind === 'none' || action.kind === 'pick')
      return
    const { target } = action
    if (action.kind === 'here') {
      this.reveal({ line: target.line, definition: target.offset })
      return
    }
    try {
      await this.openElsewhere(target.location.uri, { range: target.location.range, offset: target.offset })
    }
    catch (err) {
      const message = err instanceof Error ? err.message : String(err)
      logger.add({ level: 'warn', source: 'codeReader', message: `没能打开定义 ${target.uri}：${message}` })
      void window.showErrorMessage(`代码阅读：没能打开定义所在的 ${workspace.asRelativePath(target.location.uri)}`)
    }
  }

  /** VS Code 的悬停延迟（按这份文件取，语言自己的设置优先）：页面按它弹、收定义卡片。 */
  private postHoverDelay(): void {
    const hover = workspace.getConfiguration('editor.hover', this.document)
    this.post({ type: 'hoverDelay', delay: hover.get<number>('delay', 300), hidingDelay: hover.get<number>('hidingDelay', 300) })
  }

  /** VS Code 的 Sticky Scroll 设置（按这份文件取，语言自己的设置优先）：页面按它把滚出去一半的卡片钉在顶上。 */
  private postStickyScroll(): void {
    const sticky = workspace.getConfiguration('editor.stickyScroll', this.document)
    this.post({ type: 'stickyScroll', enabled: sticky.get<boolean>('enabled', true), maxLineCount: sticky.get<number>('maxLineCount', 5) })
  }

  /**
   * 回答 webview 第 id 次要定义卡片：offset 处名字的第一处定义所在那块（见 peekAt）；指着的名字就是定义本身时没有。
   * 下标属于别的文档版本时不答，webview 换了文档版本会收起浮窗
   */
  private async peekDefinition(id: number, version: number, offset: number): Promise<void> {
    const { document } = this
    if (version !== document.version)
      return
    const [definition] = await findDefinitions(await this.definitions.locate(version, offset))
    const own = definition?.uri === document.uri.toString() && definition.offset === offset
    const peek = definition && !own ? await this.peekAt(definition.location.uri, definition.offset) : undefined
    if (version === document.version)
      this.post({ type: 'definitionPeeked', id, ...(peek && { peek }) })
  }

  /** 回答 webview 第 id 次要注释里的链接指的符号的卡片：符号同点这个链接时找的那个（symbolTarget），找不到没有。 */
  private async peekLink(id: number, rel: string | undefined, symbol: string, block: string | undefined): Promise<void> {
    let peek: DefinitionPeek | undefined
    try {
      const target = await this.symbolTarget(rel, symbol, block)
      peek = target && await this.peekAt(Uri.parse(target.uri), target.selection.startIndex)
    }
    catch (err) {
      const link = rel === undefined ? `[${symbol}]` : `${rel}#${symbol}`
      logger.add({ level: 'warn', source: 'codeReader', message: `没能找 ${link} 指的符号：${err instanceof Error ? err.message : String(err)}` })
    }
    this.post({ type: 'definitionPeeked', id, ...(peek && { peek }) })
  }

  /**
   * uri 里 offset 处的定义的卡片：盖住它的那块（peekBlock）。同一份文件用最近发出去的那份文档的块和中文名；
   * 别的文件打开它、按它的语言排视图数据（同它自己的预览：翻译插件、库规则、项目入口；规则查名字的定义、调用的种类不等），
   * 中文名只认起了中文名的定义本身。语言没有代码阅读、解析失败、没有块盖住定义处时没有。
   */
  private async peekAt(uri: Uri, offset: number): Promise<DefinitionPeek | undefined> {
    try {
      const target = await workspace.openTextDocument(uri)
      const line = target.positionAt(offset).line
      const path = workspace.asRelativePath(uri)
      if (uri.toString() === this.document.uri.toString()) {
        const { sent } = this
        if (sent?.version !== target.version)
          return undefined
        const block = peekBlock(sent.blocks, offset, line)
        return block && { path, line, block: pagePeekBlock(block, sent.source), names: namesOnCard(block, this.names.known(target.version)) }
      }
      const { message, displayNames } = await documentMessage(
        { languageId: target.languageId, version: target.version, getText: () => target.getText(), fileName: target.fileName, entryNames: this.owner.entries.namesOf(uri) },
        this.registry,
        this.runtime,
        // 那个文件里规则出的错由它自己的预览记
        () => {},
      )
      const block = message.error === undefined ? peekBlock(message.blocks, offset, line) : undefined
      return block && { path, line, block: pagePeekBlock(block, message.source), names: namesOnCard(block, definitionSiteNames(displayNames)) }
    }
    catch (err) {
      logger.add({ level: 'warn', source: 'codeReader', message: `没能读出 ${uri.toString()} 里定义的那块：${err instanceof Error ? err.message : String(err)}` })
      return undefined
    }
  }

  /**
   * 在预览所在的编辑器组打开别的文件，和普通编辑器里 ⌘ + 点击一样：语言有代码阅读的用预览打开（新开的不比，已经开着的照旧），给了 spot 就滚过去、闪这处；
   * 其余用 VS Code 默认的打开方式，给了 spot 就选中它（见 openingFor）。目标是否按「预览标签」打开听 VS Code 的设置，
   * workbench.editor.enablePreviewFromCodeNavigation 为假时先把当前这个预览标签固定住，免得被目标替掉。
   */
  private async openElsewhere(uri: Uri, spot?: TargetSpot): Promise<void> {
    if (this.panel.active && !workspace.getConfiguration('workbench.editor').get<boolean>('enablePreviewFromCodeNavigation', false))
      await commands.executeCommand('workbench.action.keepEditor')
    const options: TextDocumentShowOptions = { viewColumn: this.panel.viewColumn }
    const opening = openingFor(await languageOf(uri), languageId => this.registry.languageFor(languageId) !== undefined, spot)
    if (opening.kind === 'default') {
      await commands.executeCommand('vscode.open', uri, { ...options, ...(opening.selection && { selection: opening.selection }) })
      return
    }
    await this.owner.open(uri, opening.reveal ? { reveal: opening.reveal } : {}, () => commands.executeCommand('vscode.openWith', uri, PREVIEW_VIEW_TYPE, options))
  }

  /** 点了调用树上的一个节点：打开它在的文件，滚到这一处（同 ⌘ + 点击跳到别的文件）。 */
  private async goToCallNode(uri: Uri, position: Position): Promise<void> {
    try {
      const target = await workspace.openTextDocument(uri)
      await this.openElsewhere(uri, { range: new Range(position, position), offset: target.offsetAt(position) })
    }
    catch (err) {
      logger.add({ level: 'warn', source: 'codeReader', message: `调用树里的 ${uri.toString()} 打不开：${err instanceof Error ? err.message : String(err)}` })
    }
  }

  /** 预览里这批仓库路径，哪些文件或目录不在；这批不带路径的引用，各按写在哪块找，哪些找不到。 */
  private async checkRepoLinks(id: number, paths: string[], references: SymbolReference[]): Promise<void> {
    const root = await repoRootOf(this.document.uri.fsPath)
    const asked = new Map<string, Promise<SymbolNode[]>>()
    const symbolsOf = (uri: string): Promise<SymbolNode[]> => {
      const known = asked.get(uri) ?? documentSymbolNodes(uri)
      asked.set(uri, known)
      return known
    }
    const [missing, unresolved] = await Promise.all([
      Promise.all(paths.map(async (rel) => {
        if (root === undefined || await resolveRepoEntry(root, rel) === undefined)
          return rel
        return undefined
      })),
      Promise.all(references.map(async reference => await this.resolveSymbolLink(reference, symbolsOf) ? undefined : reference)),
    ])
    this.post({ type: 'repoLinksChecked', id, missing: missing.filter(rel => rel !== undefined), unresolved: unresolved.filter(reference => reference !== undefined) })
  }

  /** 仓库根放进这个预览能读的本地目录，图片地址才能加载。真实位置和 git 给的路径不一样时两个都放。 */
  private addLocalRoot(fsPath: string): void {
    const uri = Uri.file(fsPath)
    const roots = this.panel.webview.options.localResourceRoots ?? []
    if (roots.some(root => root.fsPath === uri.fsPath))
      return
    this.panel.webview.options = { ...this.panel.webview.options, localResourceRoots: [...roots, uri] }
  }

  private async allowRepoRoot(root: string): Promise<void> {
    this.addLocalRoot(root)
    try {
      const real = await realpath(root)
      if (real !== root)
        this.addLocalRoot(real)
    }
    catch {
      // 仓库根这会儿读不到真实位置，就按 git 给的路径放行
    }
  }

  /** 这批仓库图片哪些在。在的带回预览里能直接用的地址；不在、不是图片、跑出仓库的没有地址。 */
  private async checkRepoImages(id: number, paths: string[]): Promise<void> {
    const root = await repoRootOf(this.document.uri.fsPath)
    if (root)
      await this.allowRepoRoot(root)
    const images = await Promise.all(paths.map(async (rel) => {
      if (root === undefined || !isRepoImagePath(rel))
        return { path: rel }
      const entry = await resolveRepoEntry(root, rel)
      if (!entry || entry.isDirectory)
        return { path: rel }
      const src = this.panel.webview.asWebviewUri(Uri.file(entry.fsPath)).toString()
      return { path: rel, src }
    }))
    this.post({ type: 'repoImagesChecked', id, images })
  }

  /**
   * 打开注释里的仓库链接：目录在代码阅读侧栏的树上定位，文件用编辑器打开。
   * 带了符号就按文档符号的名字跳过去；文件或符号没有就不打开。没有路径的是不带路径的引用，按这份文件、从它写在的那块（block）找（见 resolveSymbolLink）。
   */
  private async openRepoLink(rel: string | undefined, symbol?: string, block?: string): Promise<void> {
    const link = rel ?? `[${symbol}]`
    try {
      if (symbol !== undefined) {
        const target = await this.symbolTarget(rel, symbol, block)
        if (!target) {
          this.markRepoLinkBroken(rel, symbol, block)
          return
        }
        await this.showLinkTarget(target)
        this.markRepoLinkOpened(rel, symbol, block)
        return
      }
      if (rel === undefined)
        return
      const root = await repoRootOf(this.document.uri.fsPath)
      const entry = root === undefined ? undefined : await resolveRepoEntry(root, rel)
      if (!entry) {
        this.markRepoLinkBroken(rel)
        return
      }
      const uri = Uri.file(entry.fsPath)
      if (entry.isDirectory) {
        if (!await this.owner.revealInTree(uri))
          void window.showInformationMessage(`代码阅读：侧栏的树上没有 ${rel}`)
        this.markRepoLinkOpened(rel)
        return
      }
      await this.openElsewhere(uri)
      this.markRepoLinkOpened(rel)
    }
    catch (err) {
      const message = err instanceof Error ? err.message : String(err)
      logger.add({ level: 'warn', source: 'codeReader', message: `没能打开仓库链接 ${link}：${message}` })
      void window.showErrorMessage(`代码阅读：没能打开 ${link}`)
    }
  }

  /**
   * 链接指的符号在哪：没有 path 的是不带路径的引用，按这份文件、从它写在的那块（block）找（resolveSymbolLink）；
   * 有 path 的在那个文件的文档符号里找（locateRepoSymbol）。文件没有、是目录、符号没有时没有。点链接、悬停链接看定义卡片都按它找。
   */
  private async symbolTarget(rel: string | undefined, symbol: string, block: string | undefined): Promise<LinkTarget | undefined> {
    if (rel === undefined)
      return this.resolveSymbolLink({ symbol, block })
    const root = await repoRootOf(this.document.uri.fsPath)
    const entry = root === undefined ? undefined : await resolveRepoEntry(root, rel)
    return entry && !entry.isDirectory ? this.locateRepoSymbol(Uri.file(entry.fsPath), symbol) : undefined
  }

  /** 用文档符号按名字找（`Agent`、`Agent.owner_id`）；没有这个名字就没有，不打开到文件顶上。 */
  private async locateRepoSymbol(uri: Uri, symbol: string): Promise<LinkTarget | undefined> {
    const found = findRepoSymbol(await documentSymbolNodes(uri.toString()), symbol)
    return found && { uri: uri.toString(), selection: found.selection }
  }

  /**
   * 注释里不带路径的引用（`[Name]`、`[Class.member]`）指到哪：从它写在的那块（block，在眼下这份块树里找）的声明起一层层往外找本文件定义的，
   * 再是导入进来的（见 symbolLinks.ts）。检查坏链接、点击、悬停看定义卡片都走这里。
   * 文档符号同仓库链接找符号那一套（symbols，一批引用一起问时共用一份），导入的名字问语言扩展它的定义（同跳到定义），定义几处取第一处。
   */
  private async resolveSymbolLink({ symbol, block }: SymbolReference, symbols: (uri: string) => Promise<SymbolNode[]> = documentSymbolNodes): Promise<LinkTarget | undefined> {
    const { document, sent } = this
    const at = block === undefined || !sent ? undefined : referenceScope(sent.blocks, block)
    try {
      return await resolveReference(symbol, at, this.imports, {
        uri: document.uri.toString(),
        symbols,
        definition: async (offset) => {
          const [found] = await languageDefinitions(document.uri, document.positionAt(offset))
          if (!found)
            return undefined
          const doc = await workspace.openTextDocument(found.uri)
          return { uri: found.uri.toString(), selection: { startIndex: doc.offsetAt(found.range.start), endIndex: doc.offsetAt(found.range.end) } }
        },
      })
    }
    catch (err) {
      logger.add({ level: 'warn', source: 'codeReader', message: `没能找注释里的引用 [${symbol}]：${err instanceof Error ? err.message : String(err)}` })
      return undefined
    }
  }

  /** 跳到链接指的符号：在这份文件里就在本预览里滚过去、闪一下；别的文件同 ⌘ + 点击跳到定义（见 openElsewhere）。 */
  private async showLinkTarget({ uri, selection }: LinkTarget): Promise<void> {
    if (uri === this.document.uri.toString()) {
      this.reveal({ line: this.document.positionAt(selection.startIndex).line, definition: selection.startIndex })
      return
    }
    const doc = await workspace.openTextDocument(Uri.parse(uri))
    await this.openElsewhere(doc.uri, { range: new Range(doc.positionAt(selection.startIndex), doc.positionAt(selection.endIndex)), offset: selection.startIndex })
  }

  private markRepoLinkBroken(path: string | undefined, symbol?: string, block?: string): void {
    this.post({ type: 'repoLinkBroken', ...(path !== undefined && { path }), ...(symbol !== undefined && { symbol }), ...(block !== undefined && { block }) })
  }

  private markRepoLinkOpened(path: string | undefined, symbol?: string, block?: string): void {
    this.post({ type: 'repoLinkOpened', ...(path !== undefined && { path }), ...(symbol !== undefined && { symbol }), ...(block !== undefined && { block }) })
  }

  /**
   * 重写 anchor 那块的注释：按最近一次发出去的块树找到它，记下它现在的样子（写回前比对），把发给模型的话和写回的办法交给 CodeQa。
   * 点按钮（没有 request）发技能命令、开新会话；输入框里说的话接着这块最近一次重写的会话说，带上块现在在哪。
   * 找不到这块、文件有没保存的修改（模型读的是磁盘上的文件）、开不了时，直接回一条失败。
   */
  private async rewrite(askId: string, anchor: string, request: string | undefined, images: ClaudeImage[]): Promise<void> {
    const fail = (error: string): void => this.post({ type: 'rewriteEnd', askId, status: 'failed', error })
    const { document } = this
    const block = this.sent && findBlock(this.sent.blocks, anchor)
    const job = block?.commentTarget && commentJob(block.commentTarget, block.startLine, block.endLine, line => document.lineAt(line).text, () => document.lineCount)
    if (!block || !job) {
      fail(block && !block.commentTarget ? '这块不能写注释。' : '这块代码刚改过，找不到了。等预览刷新后再重写。')
      return
    }
    const at = locate(document.uri)
    if (!at) {
      fail(NOT_REWRITABLE)
      return
    }
    if (document.isDirty) {
      fail('文件还有没保存的修改，模型读的是磁盘上的文件：先保存再重写注释。')
      return
    }
    const prompt = commentRewritePrompt(at.key, block.startLine, block.endLine, request)
    const question = request ?? prompt
    const refused = await this.owner.qa.rewrite(document.uri, {
      askId,
      anchor,
      question,
      prompt,
      ...(request !== undefined && { followUp: commentFollowUp(at.key, block.startLine, block.endLine, request) }),
      images,
      writeBack: body => this.writeBack(job, body),
    })
    if (refused !== undefined) {
      fail(refused)
      return
    }
    this.postQa()
  }

  /** 把交回的正文写回这份文件；预览关了也照样按 uri 打开文档来写。 */
  private async writeBack(job: CommentJob, body: string | undefined): Promise<string | undefined> {
    const document = await workspace.openTextDocument(this.document.uri)
    return writeCommentBody(job, body, {
      lineAt: line => document.lineAt(line).text,
      lineCount: () => document.lineCount,
      write: edit => writeCommentEdit(document, edit),
    })
  }
}

/** 写回重写好的注释：换掉原来那几行（同块编辑），或在块上面插进新写的几行。 */
async function writeCommentEdit(document: TextDocument, edit: CommentEdit): Promise<WriteResult> {
  if (edit.kind === 'replace')
    return replaceDocumentLines(document, edit.startLine, edit.endLine, edit.text)
  if (edit.line >= document.lineCount)
    return 'missing'
  const eol = document.eol === EndOfLine.CRLF ? '\r\n' : '\n'
  const change = new WorkspaceEdit()
  change.insert(document.uri, new Position(edit.line, 0), edit.text.split('\n').join(eol) + eol)
  if (!await workspace.applyEdit(change)) {
    void window.showErrorMessage(`代码阅读：没能把修改写回 ${workspace.asRelativePath(document.uri)}`)
    return 'rejected'
  }
  return 'written'
}

/** 把这几行换成 [text]（见 WriteResult）：块编辑和重写注释都走这条。 */
async function replaceDocumentLines(document: TextDocument, startLine: number, endLine: number, text: string): Promise<WriteResult> {
  const replacement = blockReplacement(line => document.lineAt(line).text, document.lineCount, startLine, endLine, text)
  if (!replacement) {
    logger.add({ level: 'warn', source: 'codeReader', message: `块内修改的行号 ${startLine}-${endLine} 已不在 ${document.uri.fsPath} 里，没有写回` })
    return 'missing'
  }
  if (replacement.unchanged)
    return 'unchanged'
  const edit = new WorkspaceEdit()
  edit.replace(document.uri, new Range(replacement.startLine, 0, replacement.endLine, replacement.endCharacter), replacement.text)
  if (!await workspace.applyEdit(edit)) {
    void window.showErrorMessage(`代码阅读：没能把修改写回 ${workspace.asRelativePath(document.uri)}`)
    return 'rejected'
  }
  return 'written'
}