// ==================== 数据获取函数（带并发锁） ====================
let mexcFetching = false;
let binanceFetching = false;

async function fetchFromAPI(endpoint, source, cooldownSec, silentMode = false) {
    if ((source === 'mexc' && mexcFetching) || (source === 'binance' && binanceFetching)) {
        console.warn(`[自动获取] ${source.toUpperCase()} 上一次请求尚未完成，本次跳过`);
        return;
    }
    
    if (source === 'mexc') mexcFetching = true;
    else binanceFetching = true;
    
    if (infoCard && !silentMode) infoCard.classList.add('hide');
    const startTime = Date.now();
    
    if (!silentMode) {
        startCoolDown(source, cooldownSec);
    }
    
    if (!silentMode) {
        resultDiv.innerHTML = '<div class="no-data">⏳ 请求中，请稍候 (拉取K线数据)...</div>';
    }
    
    try {
        const controller = new AbortController();
        const timeoutId = setTimeout(() => controller.abort(), 45000);
        const response = await fetch(endpoint, {
            method: 'GET',
            headers: { 'Accept': 'application/json' },
            signal: controller.signal
        });
        clearTimeout(timeoutId);
        if (!response.ok) throw new Error(`HTTP ${response.status}`);
        const json = await response.json();
        if (!json || Object.keys(json).length === 0) throw new Error('后端返回空对象');
        const elapsed = ((Date.now() - startTime) / 1000).toFixed(1);
        const elapsedText = `✅ 加载完毕 ${elapsed}s`;
        
        if (source === 'mexc') {
            mexcElapsed = elapsedText;
            if (!silentMode) refreshCoolDownDisplay('mexc');
        } else {
            binanceElapsed = elapsedText;
            if (!silentMode) refreshCoolDownDisplay('binance');
        }
        
        cachedData = json;
        activeSource = source;
        cachedDynamicMap = null;  // 清除旧的动态指标缓存
        
        // 静默预加载动态指标（不阻塞界面）
        preloadDynamicIndicators();
        
        // 如果是自动获取（silentMode = true），则静默保存到服务器
        if (silentMode) {
            saveAllDataToServer();
        }
        
        if (silentMode) {
            console.log(`[自动获取] ${source.toUpperCase()} 数据已更新，共 ${Object.keys(json).length} 个币种，耗时 ${elapsed}s`);
            if (currentMode !== null && cachedData) {
                updateView();
            }
        } else {
            resultDiv.innerHTML = `<div class="no-data" style="background:#1a2a1a;">✅ ${source.toUpperCase()} 数据加载成功！共 ${Object.keys(json).length} 个币种<br>请点击上方标签查看数据</div>`;
            if (currentMode !== null && cachedData) {
                updateView();
            }
        }
    } catch (err) {
        console.error(err);
        const errMsg = `❌ 错误: ${err.message}`;
        if (!silentMode) {
            if (source === 'mexc') {
                if (timerMEXC) timerMEXC.textContent = errMsg;
                setTimeout(() => {
                    if (mexcCountdown > 0 && timerMEXC && timerMEXC.textContent === errMsg) refreshCoolDownDisplay('mexc');
                }, 3000);
            } else {
                if (timerBinance) timerBinance.textContent = errMsg;
                setTimeout(() => {
                    if (binanceCountdown > 0 && timerBinance && timerBinance.textContent === errMsg) refreshCoolDownDisplay('binance');
                }, 3000);
            }
            resultDiv.innerHTML = `<div class="no-data" style="background:#2a1a1f;">❌ 请求失败: ${err.message}<br>请检查后端 ${endpoint} 是否正常</div>`;
        } else {
            console.warn(`[自动获取] ${source.toUpperCase()} 获取失败: ${err.message}`);
        }
    } finally {
        if (source === 'mexc') mexcFetching = false;
        else binanceFetching = false;
    }
}