import type { CrawlTaskState } from '@/types';

// chrome.storage.local 中保存当前爬取任务状态的键名。
const CRAWL_TASK_STORAGE_KEY = 'crawlTaskState';

/**
 * 从 chrome.storage.local 读取当前爬取任务状态。
 */
export async function getCrawlTaskState(): Promise<CrawlTaskState | null> {
    const result = await chrome.storage.local.get(CRAWL_TASK_STORAGE_KEY);
    const state = result[CRAWL_TASK_STORAGE_KEY];
    return isCrawlTaskState(state) ? state : null;
}

/**
 * 将最新爬取任务状态写入 chrome.storage.local，供 popup 和 content script 同步读取。
 */
export async function setCrawlTaskState(state: CrawlTaskState): Promise<void> {
    await chrome.storage.local.set({ [CRAWL_TASK_STORAGE_KEY]: state });
}

/**
 * 读取任务状态后执行不可变更新，避免覆盖已取消或已替换的任务。
 */
export async function updateCrawlTaskState(
    taskId: string,
    updater: (state: CrawlTaskState) => CrawlTaskState,
): Promise<void> {
    const state = await getCrawlTaskState();

    if (!state || state.id !== taskId || state.status === 'canceled') {
        return;
    }

    await setCrawlTaskState(updater(state));
}

/**
 * 粗略判断 storage 中读取到的值是否像一个爬取任务状态对象。
 */
function isCrawlTaskState(value: unknown): value is CrawlTaskState {
    return typeof value === 'object' && value !== null && 'id' in value && 'steps' in value;
}