"use client";

import { z } from "zod";

import { StorageKeys } from "@/data/storage/storage_keys";
import { Result, SessionAsyncUtil, type Result as ResultT } from "@/utils";

const ChatScrollSessionSchema = z.object({
  scrollTop: z.number(),
  scrollHeight: z.number(),
  clientHeight: z.number(),
  distanceFromBottom: z.number(),
  savedAt: z.number(),
});

export type ChatScrollSession = z.output<typeof ChatScrollSessionSchema>;

export class ChatScrollSessionStorage {
  private constructor() {}

  static setSnapshot(snapshot: ChatScrollSession): Promise<ResultT<void>> {
    return SessionAsyncUtil.setJson(
      StorageKeys.chatScrollSession,
      snapshot,
      ChatScrollSessionSchema,
    );
  }

  static getSnapshot(): Promise<ResultT<ChatScrollSession | null>> {
    return SessionAsyncUtil.getJson(
      StorageKeys.chatScrollSession,
      ChatScrollSessionSchema,
    );
  }

  static clearSnapshot(): Promise<ResultT<void>> {
    return SessionAsyncUtil.remove(StorageKeys.chatScrollSession);
  }

  static async consumeSnapshot(): Promise<ResultT<ChatScrollSession | null>> {
    const result = await ChatScrollSessionStorage.getSnapshot();
    const cleared = await ChatScrollSessionStorage.clearSnapshot();
    if (Result.isErr(result)) return result;
    if (Result.isErr(cleared)) return cleared;
    return result;
  }
}