import type { ShellPhase } from "./types";

const HANDOFF_KEY = "healer-man.memory-reset.v1";

export interface MemoryResetHandoff {
  readonly ownerId: string;
  readonly characterId: string;
  readonly phase: Extract<ShellPhase, "characters" | "main-menu" | "class-hall">;
}

interface HandoffStorage {
  getItem(key: string): string | null;
  setItem(key: string, value: string): void;
  removeItem(key: string): void;
}

function browserStorage(): HandoffStorage | null {
  try {
    return typeof window === "undefined" ? null : window.sessionStorage;
  } catch {
    return null;
  }
}

/** A full page reload is the browser's boundary for releasing imported modules. */
export function requestMemoryReset(handoff: MemoryResetHandoff): boolean {
  if (import.meta.env.MODE === "test") return false;
  const storage = browserStorage();
  if (!storage) return false;
  try {
    storage.setItem(HANDOFF_KEY, JSON.stringify(handoff));
    window.location.reload();
    return true;
  } catch {
    try { storage.removeItem(HANDOFF_KEY); } catch { /* Storage may be disabled. */ }
    return false;
  }
}

/** Consume once so a later ordinary reload never replays an old navigation. */
export function consumeMemoryReset(
  ownerId: string,
  characterIds: readonly string[],
  storage: HandoffStorage | null = browserStorage(),
): MemoryResetHandoff | null {
  if (!storage) return null;
  let raw: string | null;
  try {
    raw = storage.getItem(HANDOFF_KEY);
    storage.removeItem(HANDOFF_KEY);
  } catch {
    return null;
  }
  if (!raw) return null;
  try {
    const value = JSON.parse(raw) as Partial<MemoryResetHandoff>;
    if (value.ownerId !== ownerId || !value.characterId || !characterIds.includes(value.characterId)) return null;
    if (value.phase !== "characters" && value.phase !== "main-menu" && value.phase !== "class-hall") return null;
    return value as MemoryResetHandoff;
  } catch {
    return null;
  }
}