import type { AgentExecutionReceipt, PublicActivityPhase, WorkflowReceipt } from "./consultation-agent-events.ts";

export const ACTIVITY_ELAPSED_VISIBLE_AFTER_MS = 8_000;
export const ACTIVITY_COMPLETED_TRAIL_LIMIT = 3;

export type AgentActivityView = Readonly<{
  phase: PublicActivityPhase;
  label: string;
  startedAt?: number;
  completedTrail?: string;
}>;

export function activityCompletedTrail(steps: readonly string[]): string | undefined {
  if (steps.length === 0) return undefined;
  return `已完成：${steps.slice(-ACTIVITY_COMPLETED_TRAIL_LIMIT).join(" · ")}`;
}

export function nextActivityView(
  previous: AgentActivityView | undefined,
  next: Omit<AgentActivityView, "startedAt">,
  now = Date.now(),
): AgentActivityView {
  const startedAt = previous?.label === next.label && previous.startedAt ? previous.startedAt : now;
  const completedTrail = next.phase === "answer-composition"
    ? undefined
    : next.completedTrail !== undefined
      ? next.completedTrail || undefined
      : previous?.completedTrail;
  return {
    phase: next.phase,
    label: next.label,
    startedAt,
    ...(completedTrail ? { completedTrail } : {}),
  };
}

export function activityElapsedLabel(startedAt: number, now: number): string | null {
  const elapsedMs = now - startedAt;
  if (elapsedMs < ACTIVITY_ELAPSED_VISIBLE_AFTER_MS) return null;
  return `已用时 ${Math.floor(elapsedMs / 1000)} 秒`;
}

export type ChatMessage = {
  readonly role: "user" | "assistant";
  readonly text: string;
  readonly thinkingText?: string;
  readonly techniqueTruth?: string;
  readonly agentExecutionReceipt?: AgentExecutionReceipt;
  readonly workflowReceipt?: WorkflowReceipt;
};

export type ChatMessageView = ChatMessage & {
  readonly renderKey: string;
  readonly state: "settled" | "streaming" | "thinking";
  readonly activity?: AgentActivityView;
};

export function chatMessageViews(
  messages: readonly ChatMessage[],
  loading: boolean,
  streamingText: string,
  activity?: AgentActivityView,
  thinkingText?: string,
): readonly ChatMessageView[] {
  const settled = messages.map((message, index) => ({
    ...message,
    renderKey: `message-${index}`,
    state: "settled" as const,
  }));
  if (!loading || messages.at(-1)?.role === "assistant") return settled;

  return [
    ...settled,
    {
      role: "assistant",
      text: streamingText,
      thinkingText,
      renderKey: `message-${messages.length}`,
      state: streamingText ? "streaming" : "thinking",
      activity,
    },
  ];
}