import { useState, useEffect, useRef, useCallback } from "react";
import { useTranslation } from "react-i18next";
import { ExternalLink, Plug, Search, X } from "lucide-react";
import { getActiveSessions, deleteOpenTab, type ActiveSessionInfo, type OpenTabRecord } from "@/main-axios";
import { tabIcon } from "@/shell/tabUtils";
import type { Tab, TabType } from "@/types/ui-types";
import { Badge } from "@/components/badge";
import { Input } from "@/components/input";
import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/components/tooltip";

const CONNECTION_TAB_TYPES: TabType[] = [
  "terminal",
  "rdp",
  "vnc",
  "telnet",
  "files",
  "docker",
  "stats",
  "tunnel",
];

const TYPE_LABELS: Record<string, string> = {
  terminal: "SSH",
  rdp: "RDP",
  vnc: "VNC",
  telnet: "Telnet",
  files: "Files",
  docker: "Docker",
  stats: "Stats",
  tunnel: "Tunnel",
};

function formatDuration(ms: number): string {
  const s = Math.max(0, Math.floor(ms / 1000));
  if (s < 60) return `${s}s`;
  const m = Math.floor(s / 60);
  if (m < 60) return `${m}m ${s % 60}s`;
  const h = Math.floor(m / 60);
  return `${h}h ${m % 60}m`;
}

function formatExpiry(updatedAt: string): string {
  const TTL_MS = 30 * 60 * 1000;
  const elapsed = Date.now() - new Date(updatedAt).getTime();
  const remaining = TTL_MS - elapsed;
  if (remaining <= 0) return "expiring";
  return formatDuration(remaining);
}

function ConnectionRow({
  isActive,
  isLive,
  tabType,
  name,
  subLabel,
  icon,
  onSwitch,
  onClose,
  switchTitle,
  faded,
}: {
  isActive?: boolean;
  isLive: boolean;
  tabType: string;
  name: string;
  subLabel: string;
  icon: React.ReactNode;
  onSwitch?: () => void;
  onClose: () => void;
  switchTitle?: string;
  faded?: boolean;
}) {
  return (
    <div
      role={onSwitch ? "button" : undefined}
      tabIndex={onSwitch ? 0 : undefined}
      onClick={onSwitch}
      onKeyDown={(e) => e.key === "Enter" && onSwitch?.()}
      className={`group flex items-center gap-2.5 px-3 py-2.5 border-b border-border/40 transition-colors last:border-b-0 ${
        faded ? "opacity-60" : ""
      } ${
        isActive
          ? "bg-accent-brand/8 cursor-pointer border-l-2 border-l-accent-brand"
          : onSwitch
            ? "hover:bg-muted/40 cursor-pointer"
            : ""
      }`}
    >
      <div
        className={`shrink-0 flex items-center justify-center size-7 rounded ${
          isActive
            ? "bg-accent-brand/15 text-accent-brand"
            : "bg-muted/60 text-muted-foreground"
        }`}
      >
        {icon}
      </div>

      <div className="flex flex-col flex-1 min-w-0 gap-0.5">
        <div className="flex items-center gap-1.5 min-w-0">
          <span
            className={`shrink-0 size-1.5 rounded-full ${
              isLive ? "bg-green-500" : "bg-muted-foreground/30"
            }`}
          />
          <span
            className={`text-xs font-semibold truncate flex-1 ${
              isActive ? "text-accent-brand" : "text-foreground"
            }`}
          >
            {name}
          </span>
          <Badge
            variant="outline"
            className="text-[9px] px-1 py-0 h-4 font-mono shrink-0 text-muted-foreground/60 border-border/60"
          >
            {TYPE_LABELS[tabType] ?? tabType}
          </Badge>
        </div>
        <span className="text-[10px] text-muted-foreground/60 truncate pl-3">
          {subLabel}
        </span>
      </div>

      <TooltipProvider>
        <div className="shrink-0 flex items-center gap-0.5 opacity-0 group-hover:opacity-100 transition-opacity">
          {switchTitle && onSwitch && (
            <Tooltip>
              <TooltipTrigger asChild>
                <button
                  onClick={(e) => { e.stopPropagation(); onSwitch(); }}
                  className="size-6 flex items-center justify-center text-muted-foreground/50 hover:text-foreground hover:bg-muted/60 rounded transition-colors"
                >
                  <ExternalLink className="size-3" />
                </button>
              </TooltipTrigger>
              <TooltipContent side="left">{switchTitle}</TooltipContent>
            </Tooltip>
          )}
          <button
            onClick={(e) => { e.stopPropagation(); onClose(); }}
            className="size-6 flex items-center justify-center text-muted-foreground/50 hover:text-destructive hover:bg-destructive/10 rounded transition-colors"
          >
            <X className="size-3" />
          </button>
        </div>
      </TooltipProvider>
    </div>
  );
}

function SectionHeader({ label, count }: { label: string; count: number }) {
  return (
    <div className="flex items-center gap-2 px-3 py-2 border-b border-border/60 bg-muted/20">
      <span className="text-[10px] font-bold uppercase tracking-widest text-muted-foreground/60 flex-1">
        {label}
      </span>
      <span className="text-[10px] font-semibold text-muted-foreground/40 bg-muted/60 rounded px-1.5 py-0.5">
        {count}
      </span>
    </div>
  );
}

export function ConnectionsPanel({
  tabs,
  activeTabId,
  allHosts,
  backgroundTabRecords,
  onSwitchToTab,
  onCloseTab,
  onReopenTab,
  onForgetBackground,
}: {
  tabs: Tab[];
  activeTabId: string;
  allHosts: { id: string; name: string }[];
  backgroundTabRecords: OpenTabRecord[];
  onSwitchToTab: (tabId: string) => void;
  onCloseTab: (tabId: string) => void;
  onReopenTab: (record: OpenTabRecord, restoredSessionId: string | null) => void;
  onForgetBackground: (recordId: string) => void;
}) {
  const { t } = useTranslation();
  const [now, setNow] = useState(Date.now());
  const [activeSessions, setActiveSessions] = useState<ActiveSessionInfo[]>([]);
  const [search, setSearch] = useState("");
  const pollTimerRef = useRef<ReturnType<typeof setInterval> | null>(null);

  const openTabs = tabs.filter((tab) => CONNECTION_TAB_TYPES.includes(tab.type));

  // Filter background records to only those not already open in the tab bar
  const openInstanceIds = new Set(tabs.map((t) => t.instanceId).filter(Boolean));
  const backgroundTabs = backgroundTabRecords.filter((r) => !openInstanceIds.has(r.id));

  const q = search.trim().toLowerCase();
  const filteredOpenTabs = q
    ? openTabs.filter((tab) => (tab.host?.name ?? tab.label).toLowerCase().includes(q))
    : openTabs;
  const filteredBackgroundTabs = q
    ? backgroundTabs.filter((r) => {
        const host = allHosts.find((h) => h.id === String(r.hostId));
        return (host?.name ?? r.label).toLowerCase().includes(q);
      })
    : backgroundTabs;

  useEffect(() => {
    const id = setInterval(() => setNow(Date.now()), 1000);
    return () => clearInterval(id);
  }, []);

  const refresh = useCallback(async () => {
    try {
      const sessions = await getActiveSessions();
      setActiveSessions((prev) => {
        const next = Array.isArray(sessions) ? sessions : [];
        if (JSON.stringify(prev) === JSON.stringify(next)) return prev;
        return next;
      });
    } catch {
      // silently ignore
    }
  }, []);

  useEffect(() => {
    refresh();
    pollTimerRef.current = setInterval(refresh, 5000);
    return () => { if (pollTimerRef.current) clearInterval(pollTimerRef.current); };
  }, [refresh]);

  const sessionByInstanceId = new Map(activeSessions.map((s) => [s.tabInstanceId, s]));

  const hasAnything = openTabs.length > 0 || backgroundTabs.length > 0;
  const hasResults = filteredOpenTabs.length > 0 || filteredBackgroundTabs.length > 0;

  if (!hasAnything) {
    return (
      <div className="flex flex-col items-center justify-center flex-1 gap-3 p-6 text-center py-16">
        <div className="size-10 rounded-full bg-muted/40 flex items-center justify-center">
          <Plug className="size-5 text-muted-foreground/30" />
        </div>
        <div className="flex flex-col gap-1">
          <span className="text-sm font-semibold text-muted-foreground/60">
            {t("connections.noConnections")}
          </span>
          <span className="text-xs text-muted-foreground/40">
            {t("connections.noConnectionsDesc")}
          </span>
        </div>
      </div>
    );
  }

  return (
    <div className="flex flex-col">
      <div className="relative px-3 py-2 border-b border-border/60">
        <Search className="absolute left-5.5 top-1/2 -translate-y-1/2 size-3.5 text-muted-foreground/50 pointer-events-none" />
        <Input
          placeholder={t("connections.search")}
          value={search}
          onChange={(e) => setSearch(e.target.value)}
          className="pl-8 h-7 text-xs"
        />
      </div>

      {!hasResults && (
        <div className="flex flex-col items-center justify-center gap-2 py-10 text-center">
          <span className="text-xs text-muted-foreground/50">{t("connections.noSearchResults")}</span>
        </div>
      )}

      {filteredOpenTabs.length > 0 && (
        <div className="flex flex-col">
          <SectionHeader label={t("connections.sectionOpen")} count={filteredOpenTabs.length} />
          {filteredOpenTabs.map((tab) => {
            const isActive = tab.id === activeTabId;
            const liveSession = tab.instanceId ? sessionByInstanceId.get(tab.instanceId) : undefined;
            const isLive = tab.type === "terminal"
              ? (liveSession?.isConnected ?? false)
              : true;
            const duration = liveSession?.createdAt
              ? formatDuration(now - liveSession.createdAt)
              : formatDuration(now - tab.openedAt);

            return (
              <ConnectionRow
                key={tab.id}
                isActive={isActive}
                isLive={isLive}
                tabType={tab.type}
                name={tab.host?.name ?? tab.label}
                subLabel={
                  isLive && tab.type === "terminal"
                    ? t("connections.connectedFor", { duration })
                    : isLive
                      ? t("connections.connected")
                      : t("connections.disconnected")
                }
                icon={tabIcon(tab.type)}
                onSwitch={() => onSwitchToTab(tab.id)}
                onClose={() => onCloseTab(tab.id)}
              />
            );
          })}
        </div>
      )}

      {filteredBackgroundTabs.length > 0 && (
        <div className={`flex flex-col ${filteredOpenTabs.length > 0 ? "mt-2" : ""}`}>
          <SectionHeader label={t("connections.sectionBackground")} count={filteredBackgroundTabs.length} />
          <div className="px-3 py-1.5 border-b border-border/40">
            <span className="text-[10px] text-muted-foreground/50">
              {t("connections.backgroundDesc")}
            </span>
          </div>
          {filteredBackgroundTabs.map((record) => {
            const host = record.hostId
              ? allHosts.find((h) => h.id === String(record.hostId))
              : undefined;
            const expiresIn = formatExpiry(record.updatedAt);

            return (
              <ConnectionRow
                key={record.id}
                isLive={false}
                faded
                tabType={record.tabType}
                name={host?.name ?? record.label}
                subLabel={t("connections.expiresIn", { duration: expiresIn })}
                icon={tabIcon(record.tabType as TabType)}
                onSwitch={() => {
                  const liveSession = sessionByInstanceId.get(record.id);
                  onReopenTab(record, liveSession?.sessionId ?? null);
                }}
                onClose={async () => {
                  await deleteOpenTab(record.id).catch(() => {});
                  onForgetBackground(record.id);
                }}
                switchTitle={t("connections.reconnect")}
              />
            );
          })}
        </div>
      )}
    </div>
  );
}