Agent-System/web/src/lib/blockSavePolicy.ts

import type { DocumentBlock } from '../types/block';

export const STALE_BLOCK_SAVE_MESSAGE =
  '保存失败：当前正文块身份已随后台刷新失效，编辑器仍保留你的修改。请勿关闭以免丢稿；刷新对照后重新打开该块再保存。';

export const HEAD_CONFLICT_SAVE_MESSAGE =
  '保存失败：文档已被他人更新。编辑器仍保留你的未保存修改，请刷新对照后重试。';

export const EDITOR_DOC_MISMATCH_MESSAGE =
  '保存失败：当前编辑会话不属于正在查看的文档。编辑器仍保留你的修改，请先回到原文档再保存。';

export const DOC_SWITCH_WHILE_EDITING_MESSAGE =
  '文档切换已取消：编辑器仍保留未保存修改。请先保存或关闭编辑器，再切换文档。';

export type BlockEditorSession = {
  docId: string;
  block: DocumentBlock;
};

export type SaveTargetDecision =
  | { ok: true; index: number }
  | { ok: false; keepEditor: true; reason: 'block_not_found'; message: string };

export type DocSwitchDecision =
  | { allow: true }
  | { allow: false; keepEditor: true; message: string };

/**
 * Resolve the PATCH target strictly by block id.
 * Matching another node by identical markdown would write the wrong slot.
 */
export function resolveSaveTargetBlock(
  children: ReadonlyArray<{ id: string; content?: string }>,
  updated: { id: string; content?: string },
): SaveTargetDecision {
  const index = children.findIndex((child) => child.id === updated.id);
  if (index === -1) {
    return {
      ok: false,
      keepEditor: true,
      reason: 'block_not_found',
      message: STALE_BLOCK_SAVE_MESSAGE,
    };
  }
  return { ok: true, index };
}

export function decideEditorDocBinding(input: {
  editorDocId?: string | null;
  activeDocId: string;
}): { ok: true } | { ok: false; keepEditor: true; reason: 'doc_mismatch'; message: string } {
  if (!input.editorDocId || input.editorDocId !== input.activeDocId) {
    return {
      ok: false,
      keepEditor: true,
      reason: 'doc_mismatch',
      message: EDITOR_DOC_MISMATCH_MESSAGE,
    };
  }
  return { ok: true };
}

/** SlimTabBar is usually under the modal, but handleSelectDoc also comes from chat/drawer/effects. */
export function decideActiveDocSwitch(input: {
  editorDocId?: string | null;
  nextDocId: string;
}): DocSwitchDecision {
  if (input.editorDocId && input.editorDocId !== input.nextDocId) {
    return { allow: false, keepEditor: true, message: DOC_SWITCH_WHILE_EDITING_MESSAGE };
  }
  return { allow: true };
}

export function interpretBlockSaveError(err: { code?: string; message?: string }): {
  keepEditor: true;
  conflict: string;
} {
  if (err.code === 'DOCUMENT_HEAD_CONFLICT') {
    return { keepEditor: true, conflict: HEAD_CONFLICT_SAVE_MESSAGE };
  }
  return {
    keepEditor: true,
    conflict: `保存失败：${err.message || '请求未成功'}。编辑器仍保留当前修改，请重试。`,
  };
}