export type CanvasAgentOperationErrorCode =
  | "STALE_CANVAS_REVISION"
  | "CANVAS_AGENT_CONFIRMATION_REQUIRED"
  | "CANVAS_AGENT_CONFLICT"
  | "CANVAS_AGENT_WRITEBACK_DISABLED"
  | "CANVAS_AGENT_WRITEBACK_FAILED";

const CANVAS_AGENT_OPERATION_ERROR_CODES = new Set<string>([
  "STALE_CANVAS_REVISION",
  "CANVAS_AGENT_CONFIRMATION_REQUIRED",
  "CANVAS_AGENT_CONFLICT",
  "CANVAS_AGENT_WRITEBACK_DISABLED",
  "CANVAS_AGENT_WRITEBACK_FAILED",
]);

export function normalizeCanvasAgentOperationErrorCode(
  value: unknown
): CanvasAgentOperationErrorCode {
  const code = String(value || "").trim();
  return CANVAS_AGENT_OPERATION_ERROR_CODES.has(code)
    ? (code as CanvasAgentOperationErrorCode)
    : "CANVAS_AGENT_WRITEBACK_FAILED";
}

export function getCanvasAgentOperationErrorMessage(params: {
  code?: unknown;
  fallbackMessage?: string;
}) {
  const code = normalizeCanvasAgentOperationErrorCode(params.code);
  if (code === "STALE_CANVAS_REVISION") {
    return "画布已更新，生成结果已保留在对话中。请刷新画布后重新确认写回。";
  }
  if (code === "CANVAS_AGENT_CONFIRMATION_REQUIRED") {
    return "这个画布操作需要确认后再执行，生成结果已保留在对话中。";
  }
  if (code === "CANVAS_AGENT_CONFLICT") {
    return "画布目标状态有冲突，生成结果已保留在对话中。请检查槽位或刷新后重试。";
  }
  if (code === "CANVAS_AGENT_WRITEBACK_DISABLED") {
    return "当前画布 Agent 写回处于灰度保护，未修改画布。";
  }

  const fallback = String(params.fallbackMessage || "").trim();
  return fallback || "画布写回失败，生成结果已保留在对话中。";
}