import { useEffect, useState, useRef, useMemo, useCallback, useLayoutEffect } from "react";
import { useParams } from "react-router";
import { Download, Copy, Loader2 } from "lucide-react";
import { useTranslation } from "react-i18next";
import { App } from "antd";
import VirtualList from 'rc-virtual-list';
import { queryCleaningTaskLogByIdUsingGet, streamCleaningTaskLog, downloadCleaningTaskLog } from "../../cleansing.api";
import { TaskStatus } from "../../cleansing.model";

interface LogEntry { level: string; message: string; }
interface LogEntryWithIndex extends LogEntry { index: number; }

export default function LogsTable({
  retryCount,
  taskName,
  taskStatus
}: {
  retryCount: number;
  taskName: string;
  taskStatus?: TaskStatus;
}) {
  const { id = "" } = useParams();
  const { t } = useTranslation();
  const { message } = App.useApp();

  // 内部日志状态
  const [logs, setLogs] = useState<LogEntry[]>([]);
  const [selectedRun, setSelectedRun] = useState(retryCount + 1);
  
  const [isStreaming, setIsStreaming] = useState(false);
  const [isLoading, setIsLoading] = useState(false);
  
  const eventSourceRef = useRef<EventSource | null>(null);
  const prevRetryCountRef = useRef(retryCount);
  
  // 🔴 核心修复：用于测量容器高度的 Ref
  const listContainerRef = useRef<HTMLDivElement>(null);
  const [listHeight, setListHeight] = useState(500); // 默认高度，防止闪烁

  // 🔴 核心修复：动态测量可用高度
  useLayoutEffect(() => {
    const updateHeight = () => {
      if (listContainerRef.current) {
        setListHeight(listContainerRef.current.clientHeight);
      }
    };
    
    updateHeight();
    
    // 监听容器大小变化（例如窗口缩放或标签页切换）
    const resizeObserver = new ResizeObserver(updateHeight);
    if (listContainerRef.current) {
      resizeObserver.observe(listContainerRef.current);
    }
    
    return () => resizeObserver.disconnect();
  }, []);

  // 1. 停止流
  const stopStreaming = useCallback(() => {
    if (eventSourceRef.current) {
      eventSourceRef.current.close();
      eventSourceRef.current = null;
    }
    setIsStreaming(false);
  }, []);

  // 2. 开启流 (Tail 模式，仅追加)
  const startStreaming = useCallback(() => {
    const isLatest = selectedRun === retryCount + 1;
    if (!isLatest || isStreaming) return;

    setIsStreaming(true);
    const es = streamCleaningTaskLog(id, selectedRun - 1);
    eventSourceRef.current = es;

    es.onmessage = (event) => {
      try {
        const logEntry: LogEntry = JSON.parse(event.data);
        if (logEntry.message === "[END_OF_STREAM]" || logEntry.message === "[WAITING_TIMEOUT]") {
          if (logEntry.message === "[END_OF_STREAM]") stopStreaming();
          return;
        }
        setLogs(prev => [...prev, logEntry]);
      } catch (e) { console.error("SSE parse error", e); }
    };
    es.onerror = () => stopStreaming();
  }, [id, selectedRun, retryCount, isStreaming, stopStreaming]);

  // Effect A: 加载历史数据
  useEffect(() => {
    stopStreaming();
    setLogs([]);
    setIsLoading(true);

    const currentRetry = selectedRun - 1;
    queryCleaningTaskLogByIdUsingGet(id, currentRetry)
      .then(res => {
        setLogs(res.data || []);
        setIsLoading(false);
      })
      .catch(() => setIsLoading(false));
      
  }, [selectedRun, id, stopStreaming]);

  // Effect B: 管理实时流连接
  useEffect(() => {
    const isLatest = selectedRun === retryCount + 1;
    const shouldStream = isLatest && taskStatus === TaskStatus.RUNNING;

    if (shouldStream && !isStreaming && !isLoading) {
      startStreaming();
    } else if (!shouldStream) {
      stopStreaming();
    }
  }, [selectedRun, retryCount, taskStatus, isStreaming, isLoading, startStreaming, stopStreaming]);

  // Effect C: 智能同步 (只在用户查看最新轮次且任务重启时跟随)
  useEffect(() => {
    if (retryCount !== prevRetryCountRef.current) {
      const wasViewingLatest = (selectedRun - 1) === prevRetryCountRef.current;
      if (wasViewingLatest) {
        setSelectedRun(retryCount + 1);
      }
      prevRetryCountRef.current = retryCount;
    }
  }, [retryCount, selectedRun]);

  useEffect(() => {
    return () => stopStreaming();
  }, [stopStreaming]);

  // 3. 复制逻辑
  const handleCopyLogs = () => {
    if (logs.length === 0) {
      message.warning("当前没有可复制的日志");
      return;
    }
    const text = logs.map(log => `[${log.level}] ${log.message}`).join('\n');
    if (navigator.clipboard && navigator.clipboard.writeText) {
      navigator.clipboard.writeText(text).then(() => message.success("日志已复制"));
    } else {
      fallbackCopy(text);
    }
  };

  const fallbackCopy = (text: string) => {
    const ta = document.createElement("textarea");
    ta.value = text;
    ta.style.position = "fixed";
    ta.style.left = "-9999px";
    document.body.appendChild(ta);
    ta.select();
    try {
      document.execCommand("copy");
      message.success("日志已复制");
    } catch (err) {
      message.error("复制失败");
    }
    document.body.removeChild(ta);
  };

  const handleDownload = async () => {
    try {
      const blob = await downloadCleaningTaskLog(id, selectedRun - 1);
      const url = window.URL.createObjectURL(blob);
      const a = document.createElement('a');
      a.href = url; a.download = `${taskName}_run_${selectedRun}.log`;
      document.body.appendChild(a); a.click(); a.remove();
      window.URL.revokeObjectURL(url);
    } catch (e) { console.error("Download failed", e); }
  };

  const hasContent = logs.length > 0;
  const logsWithIndex: LogEntryWithIndex[] = useMemo(() => 
    logs.map((log, index) => ({ ...log, index })), [logs]);

  const getLevelClass = (level: string) => {
    if (level.includes("ERROR") || level.includes("FATAL")) return "text-red-500";
    if (level.includes("WARN")) return "text-yellow-500";
    return "text-green-500";
  };

  const isWaitingForLogs = !hasContent && !isLoading && taskStatus === TaskStatus.RUNNING;

  return (
    // 🔴 核心修复：使用 Flex 布局 + 固定高度 + overflow-hidden 切断外部滚动
    <div className="relative flex flex-col h-[600px] w-full bg-gray-800 border border-gray-700 rounded-lg overflow-hidden text-gray-300">
      
      {/* 1. 头部区域 (绝对固定，不参与滚动) */}
      <div className="flex-none p-3 bg-gray-800 border-b border-gray-700 z-10 shadow-md">
        <div className="flex items-center justify-between">
          <div className="flex items-center gap-3">
            <label className="text-sm font-medium text-gray-500">{t("dataCleansing.detail.logTable.selectRun")}:</label>
            
            <select
              value={selectedRun}
              onChange={(e) => setSelectedRun(Number(e.target.value))}
              className="bg-gray-700 border border-gray-600 !text-white text-sm rounded-md px-2.5 py-1.5 min-w-[120px]"
            >
              {Array.from({ length: retryCount + 1 }, (_, i) => retryCount + 1 - i).map((num) => (
                <option key={num} value={num}>
                  {t("dataCleansing.detail.logTable.currentDisplay", { num }) || `第 ${num} 次运行`}
                </option>
              ))}
            </select>
            
            {isStreaming ? (
              <span className="text-xs text-blue-400 animate-pulse flex items-center gap-1">
                <span className="w-2 h-2 rounded-full bg-blue-400"></span>实时输出中...
              </span>
            ) : isWaitingForLogs ? (
              <span className="text-xs text-yellow-400 animate-pulse flex items-center gap-1">
                <span className="w-2 h-2 rounded-full bg-yellow-400"></span>正在连接...
              </span>
            ) : (
              <span className="text-xs text-gray-500">历史日志</span>
            )}
          </div>
          
          <div className="flex items-center gap-3">
            <button onClick={handleCopyLogs} disabled={!hasContent} className="flex items-center gap-2 px-3 py-1.5 text-sm text-white bg-gray-600 hover:bg-gray-700 border border-gray-500 rounded-md transition-colors disabled:opacity-50">
              <Copy className="w-4 h-4" />
              <span>复制</span>
            </button>
            <button onClick={handleDownload} className="flex items-center gap-2 px-3 py-1.5 text-sm text-white bg-blue-600 hover:bg-blue-700 border border-blue-500 rounded-md transition-colors">
              <Download className="w-4 h-4" />
              <span>下载</span>
            </button>
          </div>
        </div>
      </div>

      {/* 2. 内容区域 (自适应剩余高度，内部滚动) */}
      {/* 🔴 关键：ref 用于测量高度，overflow-hidden 确保内容不溢出 */}
      <div className="flex-1 relative overflow-hidden bg-gray-900/50" ref={listContainerRef}>
        {hasContent ? (
          // 🔴 VirtualList 使用动态计算的高度，确保滚动条只在这个区域内生成
          <VirtualList 
            key={selectedRun} 
            data={logsWithIndex} 
            height={listHeight} 
            itemHeight={22} 
            itemKey="index"
            // 确保滚动条样式正常（部分浏览器可能需要）
            className="scrollbar-thin scrollbar-thumb-gray-600 scrollbar-track-transparent"
          >
            {(log: LogEntryWithIndex) => (
              <div className="flex gap-3 py-0.5 whitespace-pre-wrap px-4">
                <span className={`min-w-20 ${getLevelClass(log.level)}`}>[{log.level}]</span>
                <span className="text-gray-100">{log.message}</span>
              </div>
            )}
          </VirtualList>
        ) : (
          <div className="h-full flex flex-col items-center justify-center text-gray-400">
            {isLoading ? (
              <>
                 <Loader2 className="w-8 h-8 animate-spin text-blue-500 mb-3" />
                 <p>正在加载日志...</p>
              </>
            ) : isWaitingForLogs ? (
              <>
                <Loader2 className="w-8 h-8 animate-spin text-blue-500 mb-3" />
                <p className="text-sm">等待任务产生日志...</p>
                <p className="text-xs text-gray-600 mt-1">Runtime 正在初始化。</p>
              </>
            ) : taskStatus === TaskStatus.PENDING ? (
              <p>任务排队中，等待执行...</p>
            ) : (
              <p className="text-center">当前任务无可用日志</p>
            )}
          </div>
        )}
      </div>
    </div>
  );
}