Jyotisha/frontend/src/lib/rectification-snapshot-messages.ts

import { parseTurnQuestion, persistedOfferFromTurn, type TurnQuestion } from "./rectification-agentic/v9/turn-question.ts";

export type SnapshotTurnMessage = {
  role: "assistant" | "user";
  turnId?: string;
  text: string;
  renderKey: string;
  question?: TurnQuestion;
  candidateOffer?: { resultId: string };
};

export function mergeTurnQuestions<T extends SnapshotTurnMessage>(
  current: T[],
  turns: readonly unknown[],
): T[] {
  const byId = new Map<string, { question: TurnQuestion | null; offerResultId: string | null }>();
  for (const item of turns) {
    if (!item || typeof item !== "object") continue;
    const turn = item as { id?: unknown; question?: unknown; offer_result_id?: unknown };
    if (typeof turn.id !== "string") continue;
    byId.set(turn.id, {
      question: parseTurnQuestion(turn.question),
      offerResultId: typeof turn.offer_result_id === "string" ? turn.offer_result_id : null,
    });
  }
  return current.map((message) => {
    if (!message.turnId || !byId.has(message.turnId)) return message;
    const next = byId.get(message.turnId);
    const question = next?.question ?? undefined;
    return {
      ...message,
      question: question ?? undefined,
      candidateOffer: persistedOfferFromTurn(
        next?.offerResultId,
        message.candidateOffer,
        true,
      ),
    };
  });
}

export function appendUnseenAssistantTurns<T extends SnapshotTurnMessage>(
  current: T[],
  extras: readonly T[],
): T[] {
  const known = new Set(current.flatMap((message) => message.turnId ? [message.turnId] : []));
  const incoming = extras.filter((message) => (
    message.role === "assistant"
    && message.turnId
    && !known.has(message.turnId)
  ));
  return incoming.length ? [...current, ...incoming] : current;
}

export function applySnapshotTurnsToMessages<T extends SnapshotTurnMessage>(
  current: T[],
  turns: readonly unknown[],
  extrasFromTurns: (turns: readonly unknown[]) => T[],
): T[] {
  return mergeTurnQuestions(
    appendUnseenAssistantTurns(current, extrasFromTurns(turns)),
    turns,
  );
}