/**
 * Pure state for the rectification chat surface: what the entry, the
 * transcript and the composer status show in each phase, and how a Case is
 * hydrated (turns + snapshot) before the surface is revealed.
 *
 * Nothing here touches React. The chat component and the surface hook call
 * these so the "is there anything to wait for, and what does the reader see
 * while waiting" decisions are testable without a DOM.
 */

import type { PersistedRectificationTurn } from "../components/conversational-birth-time-rectification.tsx";
import { BOOTSTRAP_PREPARE_TIMEOUT_MS } from "./home-bootstrap.ts";

/**
 * Upper bound on hydrating a Case (turns + snapshot) after `/cases/open`
 * returns and before the surface is revealed. Past it the surface opens with
 * whatever arrived and the composer status's retry path fills the rest. It is
 * the home reveal budget: one constant, not two.
 */
export const RECTIFICATION_OPEN_HYDRATE_TIMEOUT_MS = BOOTSTRAP_PREPARE_TIMEOUT_MS;

/** Static entry copy while `/cases/open` and hydration are in flight. No spinner. */
export const RECTIFICATION_OPENING_LABEL = "正在打开…";
export const RECTIFICATION_SIDEBAR_OPENING_NOTE = "打开中";

/** Question recovery: one immediate refetch after a turn, then this many timed retries. */
export const RECTIFICATION_QUESTION_RETRY_LIMIT = 2;
export const RECTIFICATION_QUESTION_RETRY_INTERVAL_MS = 2_000;

export const RECTIFICATION_QUESTION_PREPARING_LABEL = "正在准备下一个问题…";
export const RECTIFICATION_QUESTION_UNAVAILABLE_COPY = "没有拿到下一个问题。";
export const RECTIFICATION_QUESTION_RELOAD_LABEL = "重新加载";
export const RECTIFICATION_EMPTY_COPY = "这段校正还没有开始。";
export const RECTIFICATION_EMPTY_ACTION_LABEL = "开始提问";
export const RECTIFICATION_HYDRATION_INCOMPLETE_NOTICE = "校正记录没有完全加载，可以继续。";
export const RECTIFICATION_STOPPED_NOTICE = "已停止，已生成的内容保留；本次不会扣点。";

export function isAbortError(caught: unknown): boolean {
  return (caught instanceof DOMException || caught instanceof Error) && caught.name === "AbortError";
}
export const RECTIFICATION_INSUFFICIENT_CREDITS_NOTICE = "校正点数不足，正在前往兑换…";
export const RECTIFICATION_INSUFFICIENT_CREDITS_REDIRECT_MS = 600;

/** Live-row labels by the action that started the turn (task 1.4). */
export const RECTIFICATION_OPENING_LIVE_LABEL = "正在读取你的出生资料，准备第一个问题…";
export const RECTIFICATION_MESSAGE_LIVE_LABEL = "正在处理…";

export function rectificationInitialLiveLabel(
  action: "opening" | "message" | "read_only",
  continuationLabel?: string,
): string {
  if (action === "opening") return RECTIFICATION_OPENING_LIVE_LABEL;
  if (action === "read_only" && continuationLabel) return continuationLabel;
  return RECTIFICATION_MESSAGE_LIVE_LABEL;
}

export type RectificationCaseSnapshotPayload = Readonly<{
  latest_result?: unknown;
  current_question?: unknown;
  choice_card?: unknown;
  question_source?: unknown;
  next_user_action?: Readonly<{ id?: unknown }>;
  case?: Readonly<{
    status?: unknown;
    accepted_time?: unknown;
    confirmed_time?: unknown;
  }>;
  turns?: unknown;
}>;

export function isRectificationCaseSnapshotPayload(value: unknown): value is RectificationCaseSnapshotPayload {
  return Boolean(value) && typeof value === "object" && !Array.isArray(value);
}

type RawTurn = {
  id?: unknown;
  role?: unknown;
  text?: unknown;
  status?: unknown;
  question?: unknown;
  offer_result_id?: unknown;
  receipt?: unknown;
};

type RawToolActivity = {
  tool?: unknown;
  status?: unknown;
  methods?: unknown;
  started_at?: unknown;
  elapsed_ms?: unknown;
  detail?: unknown;
};

function stringList(value: unknown): string[] {
  return Array.isArray(value) ? value.map(String) : [];
}

function parseToolActivities(value: unknown): NonNullable<NonNullable<PersistedRectificationTurn["receipt"]>["tool_activities"]> | undefined {
  if (!Array.isArray(value)) return undefined;
  return value.flatMap((item: RawToolActivity) => {
    if (!item || typeof item !== "object" || typeof item.tool !== "string" || typeof item.status !== "string") return [];
    return [{
      tool: item.tool,
      status: item.status,
      methods: Array.isArray(item.methods) ? item.methods.map(String) : undefined,
      started_at: typeof item.started_at === "string" ? item.started_at : null,
      elapsed_ms: typeof item.elapsed_ms === "number" ? item.elapsed_ms : null,
      detail: item.detail && typeof item.detail === "object" ? item.detail as Record<string, unknown> : null,
    }];
  });
}

/** The Case API's `turns` rows, normalised to what the chat renders. */
export function parsePersistedRectificationTurns(value: unknown): PersistedRectificationTurn[] {
  if (!Array.isArray(value)) return [];
  return value.map((turn: RawTurn) => {
    const receipt = turn?.receipt && typeof turn.receipt === "object"
      ? turn.receipt as { status?: unknown; phases?: unknown; tools?: unknown; methods?: unknown; skill_name?: unknown; skill_version?: unknown; tool_activities?: unknown }
      : null;
    const toolActivities = parseToolActivities(receipt?.tool_activities);
    return {
      id: String(turn?.id ?? ""),
      role: turn?.role === "user" ? "user" as const : "assistant" as const,
      text: typeof turn?.text === "string" ? turn.text : null,
      status: String(turn?.status ?? "completed"),
      question: turn?.question ?? null,
      offer_result_id: typeof turn?.offer_result_id === "string" ? turn.offer_result_id : null,
      receipt: receipt ? {
        status: String(receipt.status ?? ""),
        phases: stringList(receipt.phases),
        tools: stringList(receipt.tools),
        methods: stringList(receipt.methods),
        skill_name: typeof receipt.skill_name === "string" ? receipt.skill_name : undefined,
        skill_version: typeof receipt.skill_version === "string" ? receipt.skill_version : undefined,
        ...(toolActivities ? { tool_activities: toolActivities } : {}),
      } : null,
    };
  });
}

export type RectificationCaseHydration = Readonly<{
  turns: PersistedRectificationTurn[];
  snapshot: RectificationCaseSnapshotPayload | null;
  /** False when the request failed or the deadline passed first. */
  complete: boolean;
}>;

export function rectificationCaseHref(caseId: string, sessionId: string): string {
  return `/api/rectification/cases/${encodeURIComponent(caseId)}?sessionId=${encodeURIComponent(sessionId)}`;
}

/**
 * Turns and snapshot come from one Case read, so hydration is a single request
 * raced against the reveal deadline. A late or failed read still resolves, with
 * empty turns and no snapshot, so the caller can reveal and let the surface's
 * own retry path fill in the rest.
 */
export async function hydrateRectificationCase(
  caseId: string,
  sessionId: string,
  options: Readonly<{
    timeoutMs?: number;
    fetchImpl?: typeof fetch;
    setTimeoutImpl?: (callback: () => void, delayMs: number) => unknown;
    clearTimeoutImpl?: (handle: unknown) => void;
  }> = {},
): Promise<RectificationCaseHydration> {
  const timeoutMs = options.timeoutMs ?? RECTIFICATION_OPEN_HYDRATE_TIMEOUT_MS;
  const fetchImpl = options.fetchImpl ?? fetch;
  const schedule = options.setTimeoutImpl ?? ((callback, delayMs) => setTimeout(callback, delayMs));
  const cancel = options.clearTimeoutImpl ?? ((handle) => clearTimeout(handle as ReturnType<typeof setTimeout>));
  const incomplete: RectificationCaseHydration = { turns: [], snapshot: null, complete: false };

  let deadline: unknown;
  const timeout = new Promise<RectificationCaseHydration>((resolve) => {
    deadline = schedule(() => resolve(incomplete), timeoutMs);
  });
  const read = (async (): Promise<RectificationCaseHydration> => {
    try {
      const response = await fetchImpl(rectificationCaseHref(caseId, sessionId), { cache: "no-store" });
      if (!response.ok) return incomplete;
      const payload: unknown = await response.json().catch(() => null);
      if (!isRectificationCaseSnapshotPayload(payload)) return incomplete;
      return {
        turns: parsePersistedRectificationTurns(payload.turns),
        snapshot: payload,
        complete: true,
      };
    } catch {
      return incomplete;
    }
  })();
  try {
    return await Promise.race([read, timeout]);
  } finally {
    cancel(deadline);
  }
}

export type RectificationConversationState =
  | "readonly"
  | "busy"
  | "opening"
  | "empty"
  | "conversation";

/**
 * What the transcript area is doing when there are no rendered turns. `opening`
 * means the first turn is about to be requested (server said so); `empty` means
 * the Case has nothing to show and no automatic first turn — the reader needs a
 * way to start.
 */
export function rectificationConversationState(input: Readonly<{
  messageCount: number;
  busy: boolean;
  readonly: boolean;
  shouldStartOpening: boolean;
  openingStarted: boolean;
}>): RectificationConversationState {
  if (input.readonly) return "readonly";
  if (input.busy) return "busy";
  if (input.messageCount > 0) return "conversation";
  if (input.shouldStartOpening || input.openingStarted) return "opening";
  return "empty";
}

export type RectificationQuestionGapState = "idle" | "preparing" | "unavailable" | "verified_idle";

export type RectificationQuestionGapInput = Readonly<{
  /** The current question is rendered live inside an assistant message. */
  liveQuestionVisible: boolean;
  /** The snapshot names no current question at all. */
  questionMissing: boolean;
  /** The server said the question could not be loaded (`question_source: "unavailable"`). */
  questionLoadFailed: boolean;
  /** Candidate cards are offered and not yet adopted: the reader, not the server, holds the next move. */
  offerAwaitingReader?: boolean;
  /** GET / structured-choice `next_user_action.id`; `start_consultation` means post-adopt verify is done. */
  nextUserActionId?: string | null;
  busy: boolean;
  readonly: boolean;
  regenerating: boolean;
  snapshotLoaded: boolean;
  resumableCase: boolean;
  retryAttempts: number;
  retryLimit?: number;
}>;

/**
 * The gap between a settled turn and its next question. While retries remain
 * it is `preparing` (one live row, timed refetches); once they run out, or the
 * server itself reports the question unavailable, it is `unavailable` with a
 * manual reload. A snapshot that never arrived (hydration timed out) is a gap
 * too: the same retries fill it. Questions themselves live inside assistant
 * messages, so a visible live question means there is no gap.
 */
export function rectificationQuestionGapState(input: RectificationQuestionGapInput): RectificationQuestionGapState {
  const limit = input.retryLimit ?? RECTIFICATION_QUESTION_RETRY_LIMIT;
  if (input.readonly || input.busy || input.regenerating) return "idle";
  const retryGate = input.retryAttempts < limit ? "preparing" : "unavailable";
  if (!input.snapshotLoaded) return retryGate;
  if (!input.resumableCase) return "idle";
  if (input.liveQuestionVisible || input.offerAwaitingReader) return "idle";
  if (input.nextUserActionId === "start_consultation") return "verified_idle";
  if (input.questionLoadFailed) return "unavailable";
  // Either the snapshot names no question, or it names one that no settled
  // message carries live yet: both are a gap the next read may close.
  return retryGate;
}

/** Whether the gap should run another timed snapshot refetch. */
export function rectificationQuestionRetryActive(state: RectificationQuestionGapState): boolean {
  return state === "preparing";
}

/** Adoption live-row copy: the minute is shown so the reader knows what is being applied. */
export function rectificationAdoptingLabel(time: string): string {
  return `正在采用 ${time}…`;
}

/** Board copy when no candidate result exists yet (task 1.3). */
export function rectificationBoardEmptyCopy(declaredTime: string | null): Readonly<{
  clock: string | null;
  lines: readonly string[];
}> {
  if (!declaredTime) {
    return { clock: null, lines: ["补充经历后，这里会显示当前本命宫位和换升时刻。"] };
  }
  return {
    clock: declaredTime,
    lines: [`填报出生时间 ${declaredTime}`, "回答几个问题后，这里会显示宫位随时间的变化。"],
  };
}

/** The declared birth minute from the profile, or null when only a period was given. */
export function declaredBirthTime(profile: Readonly<{ time?: string; reportedTime?: string }>): string | null {
  const candidate = (profile.reportedTime || profile.time || "").trim();
  return /^\d{1,2}:\d{2}$/.test(candidate) ? candidate : null;
}