export interface TerminalToolBatch {
  declaredToolCalls: number;
  startedToolCalls: number;
  completedToolCalls: number;
  allTerminate: boolean;
  anyError: boolean;
}

export type RunOutcome =
  | { kind: "completed"; completionKind: "assistant-stop" | "terminating-tool" }
  | { kind: "failed"; detail: string }
  | { kind: "interrupted"; detail?: string };

export interface RunOutcomeInput {
  stopReason?: string;
  errorMessage?: string;
  providerErrors: number;
  lastToolError?: string;
  abortObserved: boolean;
  terminalToolBatch?: TerminalToolBatch;
}

/**
 * Classify the final settled state of a Pi run.
 *
 * An observed AbortSignal wins over tool/provider errors because Escape during
 * tool execution can leave the last assistant message at `toolUse`. A terminal
 * `toolUse` is successful only when the complete tool batch finished without
 * errors and every original result requested `terminate: true`.
 */
export function classifyRunOutcome(input: RunOutcomeInput): RunOutcome {
  const {
    stopReason,
    errorMessage,
    providerErrors,
    lastToolError,
    abortObserved,
    terminalToolBatch,
  } = input;

  if (abortObserved || stopReason === "aborted") {
    return { kind: "interrupted", detail: errorMessage };
  }

  if (errorMessage) return { kind: "failed", detail: errorMessage };
  if (stopReason === "length") {
    return { kind: "failed", detail: "模型输出达到长度限制，结果可能不完整。" };
  }
  if (stopReason === "error") {
    return { kind: "failed", detail: lastToolError || "模型请求以错误状态结束。" };
  }
  if (stopReason === "toolUse") {
    const completeTerminatingBatch = Boolean(
      terminalToolBatch
      && terminalToolBatch.declaredToolCalls > 0
      && terminalToolBatch.startedToolCalls === terminalToolBatch.declaredToolCalls
      && terminalToolBatch.completedToolCalls === terminalToolBatch.declaredToolCalls
      && terminalToolBatch.allTerminate
      && !terminalToolBatch.anyError,
    );
    return completeTerminatingBatch
      ? { kind: "completed", completionKind: "terminating-tool" }
      : { kind: "failed", detail: "Agent 在工具调用阶段停止，但没有形成完整、成功的终止工具批次。" };
  }
  if (stopReason && stopReason !== "stop") {
    return { kind: "failed", detail: `Agent 以非正常状态结束：${stopReason}。` };
  }
  if (!stopReason && providerErrors > 0) {
    return { kind: "failed", detail: `模型请求失败 ${providerErrors} 次。` };
  }

  return { kind: "completed", completionKind: "assistant-stop" };
}