"use client";

import { useState, useEffect } from "react";
import { useQuery, useMutation } from "@tanstack/react-query";
import {
  Bell, Rss, CheckCircle, Copy, RefreshCw, XCircle,
  FlaskConical, Clock, Calendar, FileText, AlertTriangle,
} from "lucide-react";
import Link from "next/link";
import { notificationsAPI, type NotificationTestResult } from "@/lib/api";
import type { NotificationEvent } from "@/lib/types";

const AUTH_METHODS = [
  { value: "none", label: "No authentication", hint: "Public ntfy.sh topics or open self-hosted servers" },
  { value: "token", label: "Access token", hint: "ntfy token (tk_...)" },
  { value: "basic", label: "Username & password", hint: "For servers behind HTTP basic auth or nginx ACL" },
];

const HOURS = Array.from({ length: 24 }, (_, i) => {
  const period = i < 12 ? "AM" : "PM";
  const hour = i === 0 ? 12 : i > 12 ? i - 12 : i;
  return { value: i, label: `${hour}:00 ${period}` };
});

const EVENT_META: Record<string, { label: string; icon: typeof Bell; color: string }> = {
  new_document: { label: "New Bill Text", icon: FileText, color: "text-blue-500" },
  new_amendment: { label: "Amendment Filed", icon: FileText, color: "text-purple-500" },
  bill_updated: { label: "Bill Updated", icon: AlertTriangle, color: "text-orange-500" },
};

function timeAgo(iso: string) {
  const diff = Date.now() - new Date(iso).getTime();
  const m = Math.floor(diff / 60000);
  if (m < 1) return "just now";
  if (m < 60) return `${m}m ago`;
  const h = Math.floor(m / 60);
  if (h < 24) return `${h}h ago`;
  return `${Math.floor(h / 24)}d ago`;
}

export default function NotificationsPage() {
  const { data: settings, refetch } = useQuery({
    queryKey: ["notification-settings"],
    queryFn: () => notificationsAPI.getSettings(),
  });

  const { data: history = [], isLoading: historyLoading } = useQuery({
    queryKey: ["notification-history"],
    queryFn: () => notificationsAPI.getHistory(),
    staleTime: 60 * 1000,
  });

  const update = useMutation({
    mutationFn: (data: Parameters<typeof notificationsAPI.updateSettings>[0]) =>
      notificationsAPI.updateSettings(data),
    onSuccess: () => refetch(),
  });

  const resetRss = useMutation({
    mutationFn: () => notificationsAPI.resetRssToken(),
    onSuccess: () => refetch(),
  });

  // ntfy form state
  const [topicUrl, setTopicUrl] = useState("");
  const [authMethod, setAuthMethod] = useState("none");
  const [token, setToken] = useState("");
  const [username, setUsername] = useState("");
  const [password, setPassword] = useState("");
  const [ntfySaved, setNtfySaved] = useState(false);

  // Test state
  const [ntfyTesting, setNtfyTesting] = useState(false);
  const [ntfyTestResult, setNtfyTestResult] = useState<NotificationTestResult | null>(null);
  const [rssTesting, setRssTesting] = useState(false);
  const [rssTestResult, setRssTestResult] = useState<NotificationTestResult | null>(null);

  // RSS state
  const [rssSaved, setRssSaved] = useState(false);
  const [copied, setCopied] = useState(false);

  // Quiet hours state
  const [quietEnabled, setQuietEnabled] = useState(false);
  const [quietStart, setQuietStart] = useState(22);
  const [quietEnd, setQuietEnd] = useState(8);
  const [quietSaved, setQuietSaved] = useState(false);
  const [detectedTimezone, setDetectedTimezone] = useState<string>("");
  const [savedTimezone, setSavedTimezone] = useState<string | null>(null);

  // Digest state
  const [digestEnabled, setDigestEnabled] = useState(false);
  const [digestFrequency, setDigestFrequency] = useState<"daily" | "weekly">("daily");
  const [digestSaved, setDigestSaved] = useState(false);

  // Detect the browser's local timezone once on mount
  useEffect(() => {
    try {
      setDetectedTimezone(Intl.DateTimeFormat().resolvedOptions().timeZone);
    } catch {
      // very old browser — leave empty, dispatcher will fall back to UTC
    }
  }, []);

  // Populate from loaded settings
  useEffect(() => {
    if (!settings) return;
    setTopicUrl(settings.ntfy_topic_url ?? "");
    setAuthMethod(settings.ntfy_auth_method ?? "none");
    setToken(settings.ntfy_token ?? "");
    setUsername(settings.ntfy_username ?? "");
    setPassword(settings.ntfy_password ?? "");
    setDigestEnabled(settings.digest_enabled ?? false);
    setDigestFrequency(settings.digest_frequency ?? "daily");
    setSavedTimezone(settings.timezone ?? null);
    if (settings.quiet_hours_start != null) {
      setQuietEnabled(true);
      setQuietStart(settings.quiet_hours_start);
      setQuietEnd(settings.quiet_hours_end ?? 8);
    } else {
      setQuietEnabled(false);
    }
  }, [settings]);

  const saveNtfy = (enabled: boolean) => {
    update.mutate(
      {
        ntfy_topic_url: topicUrl,
        ntfy_auth_method: authMethod,
        ntfy_token: authMethod === "token" ? token : "",
        ntfy_username: authMethod === "basic" ? username : "",
        ntfy_password: authMethod === "basic" ? password : "",
        ntfy_enabled: enabled,
      },
      { onSuccess: () => { setNtfySaved(true); setTimeout(() => setNtfySaved(false), 2000); } }
    );
  };

  const toggleRss = (enabled: boolean) => {
    update.mutate(
      { rss_enabled: enabled },
      { onSuccess: () => { setRssSaved(true); setTimeout(() => setRssSaved(false), 2000); } }
    );
  };

  const saveQuietHours = () => {
    const onSuccess = () => { setQuietSaved(true); setTimeout(() => setQuietSaved(false), 2000); };
    if (quietEnabled) {
      update.mutate(
        {
          quiet_hours_start: quietStart,
          quiet_hours_end: quietEnd,
          // Include the detected timezone so the dispatcher knows which local time to compare
          ...(detectedTimezone ? { timezone: detectedTimezone } : {}),
        },
        { onSuccess }
      );
    } else {
      // -1 signals the backend to clear quiet hours + timezone
      update.mutate({ quiet_hours_start: -1 }, { onSuccess });
    }
  };

  const saveDigest = () => {
    update.mutate(
      { digest_enabled: digestEnabled, digest_frequency: digestFrequency },
      { onSuccess: () => { setDigestSaved(true); setTimeout(() => setDigestSaved(false), 2000); } }
    );
  };

  const testNtfy = async () => {
    setNtfyTesting(true);
    setNtfyTestResult(null);
    try {
      const result = await notificationsAPI.testNtfy({
        ntfy_topic_url: topicUrl,
        ntfy_auth_method: authMethod,
        ntfy_token: authMethod === "token" ? token : "",
        ntfy_username: authMethod === "basic" ? username : "",
        ntfy_password: authMethod === "basic" ? password : "",
      });
      setNtfyTestResult(result);
    } catch (e: unknown) {
      const detail =
        (e as { response?: { data?: { detail?: string } } })?.response?.data?.detail
        ?? (e instanceof Error ? e.message : "Request failed");
      setNtfyTestResult({ status: "error", detail });
    } finally {
      setNtfyTesting(false);
    }
  };

  const testRss = async () => {
    setRssTesting(true);
    setRssTestResult(null);
    try {
      const result = await notificationsAPI.testRss();
      setRssTestResult(result);
    } catch (e: unknown) {
      const detail =
        (e as { response?: { data?: { detail?: string } } })?.response?.data?.detail
        ?? (e instanceof Error ? e.message : "Feed check failed");
      setRssTestResult({ status: "error", detail });
    } finally {
      setRssTesting(false);
    }
  };

  const rssUrl = settings?.rss_token
    ? `${typeof window !== "undefined" ? window.location.origin : ""}/api/notifications/feed/${settings.rss_token}.xml`
    : null;

  const ResultBadge = ({ result }: { result: NotificationTestResult }) => (
    <div className={`flex items-start gap-2 text-xs rounded-md px-3 py-2 ${
      result.status === "ok"
        ? "bg-green-50 dark:bg-green-900/20 text-green-700 dark:text-green-400"
        : "bg-red-50 dark:bg-red-900/20 text-red-700 dark:text-red-400"
    }`}>
      {result.status === "ok"
        ? <CheckCircle className="w-3.5 h-3.5 mt-0.5 shrink-0" />
        : <XCircle className="w-3.5 h-3.5 mt-0.5 shrink-0" />}
      {result.detail}
    </div>
  );

  return (
    <div className="space-y-8 max-w-2xl">
      <div>
        <h1 className="text-2xl font-bold flex items-center gap-2">
          <Bell className="w-5 h-5" /> Notifications
        </h1>
        <p className="text-muted-foreground text-sm mt-1">
          Get alerted when bills you follow are updated, new text is published, or amendments are filed.
        </p>
      </div>

      {/* ntfy */}
      <section className="bg-card border border-border rounded-lg p-6 space-y-5">
        <div className="flex items-start justify-between gap-4">
          <div>
            <h2 className="font-semibold flex items-center gap-2">
              <Bell className="w-4 h-4" /> Push Notifications (ntfy)
            </h2>
            <p className="text-xs text-muted-foreground mt-1">
              Uses <a href="https://ntfy.sh" target="_blank" rel="noopener noreferrer" className="text-primary hover:underline">ntfy</a> — a free, open-source push notification service.
              Use the public <code className="bg-muted px-1 rounded">ntfy.sh</code> server or your own self-hosted instance.
            </p>
          </div>
          {settings?.ntfy_enabled && (
            <span className="flex items-center gap-1 text-xs text-green-600 dark:text-green-400 shrink-0">
              <CheckCircle className="w-3.5 h-3.5" /> Active
            </span>
          )}
        </div>

        <div className="space-y-1.5">
          <label className="text-sm font-medium">Topic URL</label>
          <p className="text-xs text-muted-foreground">
            The full URL to your ntfy topic, e.g.{" "}
            <code className="bg-muted px-1 rounded">https://ntfy.sh/my-pocketveto-alerts</code>
          </p>
          <input
            type="url"
            placeholder="https://ntfy.sh/your-topic"
            value={topicUrl}
            onChange={(e) => setTopicUrl(e.target.value)}
            className="w-full px-3 py-2 text-sm bg-background border border-border rounded-md focus:outline-none focus:ring-1 focus:ring-primary"
          />
        </div>

        <div className="space-y-2">
          <label className="text-sm font-medium">Authentication</label>
          <div className="space-y-2">
            {AUTH_METHODS.map(({ value, label, hint }) => (
              <label key={value} className="flex items-start gap-3 cursor-pointer">
                <input type="radio" name="ntfy-auth" value={value} checked={authMethod === value}
                  onChange={() => setAuthMethod(value)} className="mt-0.5" />
                <div>
                  <div className="text-sm font-medium">{label}</div>
                  <div className="text-xs text-muted-foreground">{hint}</div>
                </div>
              </label>
            ))}
          </div>
        </div>

        {authMethod === "token" && (
          <div className="space-y-1.5">
            <label className="text-sm font-medium">Access Token</label>
            <input type="password" placeholder="tk_..." value={token}
              onChange={(e) => setToken(e.target.value)}
              className="w-full px-3 py-2 text-sm bg-background border border-border rounded-md focus:outline-none focus:ring-1 focus:ring-primary" />
          </div>
        )}

        {authMethod === "basic" && (
          <div className="space-y-3">
            <div className="space-y-1.5">
              <label className="text-sm font-medium">Username</label>
              <input type="text" placeholder="your-username" value={username}
                onChange={(e) => setUsername(e.target.value)}
                className="w-full px-3 py-2 text-sm bg-background border border-border rounded-md focus:outline-none focus:ring-1 focus:ring-primary" />
            </div>
            <div className="space-y-1.5">
              <label className="text-sm font-medium">Password</label>
              <input type="password" placeholder="your-password" value={password}
                onChange={(e) => setPassword(e.target.value)}
                className="w-full px-3 py-2 text-sm bg-background border border-border rounded-md focus:outline-none focus:ring-1 focus:ring-primary" />
            </div>
          </div>
        )}

        <div className="space-y-3 pt-1 border-t border-border">
          <div className="flex items-center gap-3">
            <button onClick={() => saveNtfy(true)} disabled={!topicUrl.trim() || update.isPending}
              className="flex items-center gap-2 px-4 py-2 text-sm bg-primary text-primary-foreground rounded-md hover:bg-primary/90 disabled:opacity-50 transition-colors">
              {ntfySaved ? <CheckCircle className="w-3.5 h-3.5" /> : <Bell className="w-3.5 h-3.5" />}
              {ntfySaved ? "Saved!" : "Save & Enable"}
            </button>
            <button onClick={testNtfy} disabled={!topicUrl.trim() || ntfyTesting}
              className="flex items-center gap-2 px-4 py-2 text-sm bg-muted hover:bg-accent rounded-md disabled:opacity-50 transition-colors">
              {ntfyTesting ? <RefreshCw className="w-3.5 h-3.5 animate-spin" /> : <FlaskConical className="w-3.5 h-3.5" />}
              {ntfyTesting ? "Sending…" : "Test"}
            </button>
            {settings?.ntfy_enabled && (
              <button onClick={() => saveNtfy(false)} disabled={update.isPending}
                className="text-xs text-muted-foreground hover:text-foreground transition-colors">
                Disable
              </button>
            )}
          </div>
          {ntfyTestResult && <ResultBadge result={ntfyTestResult} />}
        </div>
      </section>

      {/* Quiet Hours */}
      <section className="bg-card border border-border rounded-lg p-6 space-y-4">
        <div>
          <h2 className="font-semibold flex items-center gap-2">
            <Clock className="w-4 h-4" /> Quiet Hours
          </h2>
          <p className="text-xs text-muted-foreground mt-1">
            Pause ntfy push notifications during set hours. Events accumulate and fire as a batch when quiet hours end.
            RSS is unaffected.
          </p>
        </div>

        <label className="flex items-center gap-3 cursor-pointer">
          <input type="checkbox" checked={quietEnabled} onChange={(e) => setQuietEnabled(e.target.checked)}
            className="rounded" />
          <span className="text-sm font-medium">Enable quiet hours</span>
        </label>

        {quietEnabled && (
          <div className="space-y-3">
            <div className="flex items-center gap-3 flex-wrap">
              <div className="flex items-center gap-2">
                <label className="text-sm text-muted-foreground">From</label>
                <select value={quietStart} onChange={(e) => setQuietStart(Number(e.target.value))}
                  className="px-2 py-1.5 text-sm bg-background border border-border rounded-md">
                  {HOURS.map(({ value, label }) => <option key={value} value={value}>{label}</option>)}
                </select>
              </div>
              <div className="flex items-center gap-2">
                <label className="text-sm text-muted-foreground">To</label>
                <select value={quietEnd} onChange={(e) => setQuietEnd(Number(e.target.value))}
                  className="px-2 py-1.5 text-sm bg-background border border-border rounded-md">
                  {HOURS.map(({ value, label }) => <option key={value} value={value}>{label}</option>)}
                </select>
              </div>
              {quietStart > quietEnd && (
                <span className="text-xs text-muted-foreground">(overnight window)</span>
              )}
            </div>
            {detectedTimezone && (
              <p className="text-xs text-muted-foreground">
                Times are in your local timezone: <span className="font-medium text-foreground">{detectedTimezone}</span>
                {savedTimezone && savedTimezone !== detectedTimezone && (
                  <span className="text-amber-600 dark:text-amber-400"> · saved as {savedTimezone} — save to update</span>
                )}
              </p>
            )}
          </div>
        )}

        <button onClick={saveQuietHours} disabled={update.isPending}
          className="flex items-center gap-2 px-4 py-2 text-sm bg-primary text-primary-foreground rounded-md hover:bg-primary/90 disabled:opacity-50 transition-colors">
          {quietSaved ? <CheckCircle className="w-3.5 h-3.5" /> : null}
          {quietSaved ? "Saved!" : "Save Quiet Hours"}
        </button>
      </section>

      {/* Digest */}
      <section className="bg-card border border-border rounded-lg p-6 space-y-4">
        <div>
          <h2 className="font-semibold flex items-center gap-2">
            <Calendar className="w-4 h-4" /> Digest Mode
          </h2>
          <p className="text-xs text-muted-foreground mt-1">
            Instead of per-event push notifications, receive a single bundled ntfy summary on a schedule.
            RSS feed is always real-time regardless of this setting.
          </p>
        </div>

        <label className="flex items-center gap-3 cursor-pointer">
          <input type="checkbox" checked={digestEnabled} onChange={(e) => setDigestEnabled(e.target.checked)}
            className="rounded" />
          <span className="text-sm font-medium">Enable digest mode</span>
        </label>

        {digestEnabled && (
          <div className="flex items-center gap-3">
            <label className="text-sm text-muted-foreground">Frequency</label>
            <div className="flex gap-3">
              {(["daily", "weekly"] as const).map((freq) => (
                <label key={freq} className="flex items-center gap-2 cursor-pointer">
                  <input type="radio" name="digest-freq" value={freq} checked={digestFrequency === freq}
                    onChange={() => setDigestFrequency(freq)} />
                  <span className="text-sm capitalize">{freq}</span>
                  {freq === "weekly" && <span className="text-xs text-muted-foreground">(Mondays, 8 AM UTC)</span>}
                  {freq === "daily" && <span className="text-xs text-muted-foreground">(8 AM UTC)</span>}
                </label>
              ))}
            </div>
          </div>
        )}

        <button onClick={saveDigest} disabled={update.isPending}
          className="flex items-center gap-2 px-4 py-2 text-sm bg-primary text-primary-foreground rounded-md hover:bg-primary/90 disabled:opacity-50 transition-colors">
          {digestSaved ? <CheckCircle className="w-3.5 h-3.5" /> : null}
          {digestSaved ? "Saved!" : "Save Digest Settings"}
        </button>
      </section>

      {/* RSS */}
      <section className="bg-card border border-border rounded-lg p-6 space-y-4">
        <div className="flex items-start justify-between gap-4">
          <div>
            <h2 className="font-semibold flex items-center gap-2">
              <Rss className="w-4 h-4" /> RSS Feed
            </h2>
            <p className="text-xs text-muted-foreground mt-1">
              A private, tokenized RSS feed of your bill alerts — subscribe in any RSS reader.
              Independent of ntfy; enable either or both.
            </p>
          </div>
          {settings?.rss_enabled && (
            <span className="flex items-center gap-1 text-xs text-green-600 dark:text-green-400 shrink-0">
              <CheckCircle className="w-3.5 h-3.5" /> Active
            </span>
          )}
        </div>

        {rssUrl && (
          <div className="space-y-2">
            <label className="text-xs font-medium text-muted-foreground uppercase tracking-wide">Your feed URL</label>
            <div className="flex items-center gap-2">
              <code className="flex-1 text-xs bg-muted px-2 py-2 rounded truncate">{rssUrl}</code>
              <button onClick={() => { navigator.clipboard.writeText(rssUrl); setCopied(true); setTimeout(() => setCopied(false), 2000); }}
                className="shrink-0 p-1.5 rounded hover:bg-accent transition-colors" title="Copy RSS URL">
                {copied ? <CheckCircle className="w-4 h-4 text-green-500" /> : <Copy className="w-4 h-4 text-muted-foreground" />}
              </button>
            </div>
          </div>
        )}

        <div className="space-y-3 pt-1 border-t border-border">
          <div className="flex items-center gap-3">
            {!settings?.rss_enabled ? (
              <button onClick={() => toggleRss(true)} disabled={update.isPending}
                className="flex items-center gap-2 px-4 py-2 text-sm bg-primary text-primary-foreground rounded-md hover:bg-primary/90 disabled:opacity-50 transition-colors">
                {rssSaved ? <CheckCircle className="w-3.5 h-3.5" /> : <Rss className="w-3.5 h-3.5" />}
                {rssSaved ? "Enabled!" : "Enable RSS"}
              </button>
            ) : (
              <button onClick={() => toggleRss(false)} disabled={update.isPending}
                className="text-xs text-muted-foreground hover:text-foreground transition-colors">
                Disable RSS
              </button>
            )}
            {rssUrl && (
              <>
                <button onClick={testRss} disabled={rssTesting}
                  className="flex items-center gap-2 px-4 py-2 text-sm bg-muted hover:bg-accent rounded-md disabled:opacity-50 transition-colors">
                  {rssTesting ? <RefreshCw className="w-3.5 h-3.5 animate-spin" /> : <FlaskConical className="w-3.5 h-3.5" />}
                  {rssTesting ? "Checking…" : "Test"}
                </button>
                <button onClick={() => resetRss.mutate()} disabled={resetRss.isPending}
                  className="flex items-center gap-1.5 text-xs text-muted-foreground hover:text-foreground transition-colors"
                  title="Generate a new URL — old URL will stop working">
                  <RefreshCw className="w-3 h-3" /> Regenerate URL
                </button>
              </>
            )}
          </div>
          {rssTestResult && <ResultBadge result={rssTestResult} />}
        </div>
      </section>

      {/* Notification History */}
      <section className="bg-card border border-border rounded-lg p-6 space-y-4">
        <div className="flex items-center justify-between">
          <div>
            <h2 className="font-semibold flex items-center gap-2">
              <Bell className="w-4 h-4" /> Recent Alerts
            </h2>
            <p className="text-xs text-muted-foreground mt-1">Last 50 notification events for your account.</p>
          </div>
        </div>

        {historyLoading ? (
          <p className="text-sm text-muted-foreground">Loading history…</p>
        ) : history.length === 0 ? (
          <p className="text-sm text-muted-foreground">
            No events yet. Follow some bills and check back after the next poll.
          </p>
        ) : (
          <div className="divide-y divide-border">
            {history.map((event: NotificationEvent) => {
              const meta = EVENT_META[event.event_type] ?? { label: "Update", icon: Bell, color: "text-muted-foreground" };
              const Icon = meta.icon;
              const payload = event.payload ?? {};
              return (
                <div key={event.id} className="flex items-start gap-3 py-3">
                  <Icon className={`w-4 h-4 mt-0.5 shrink-0 ${meta.color}`} />
                  <div className="flex-1 min-w-0">
                    <div className="flex items-center gap-2 flex-wrap">
                      <span className="text-xs font-medium">{meta.label}</span>
                      {payload.bill_label && (
                        <Link href={`/bills/${event.bill_id}`}
                          className="text-xs font-mono bg-muted px-1.5 py-0.5 rounded hover:text-primary transition-colors">
                          {payload.bill_label}
                        </Link>
                      )}
                      <span className="text-xs text-muted-foreground ml-auto">{timeAgo(event.created_at)}</span>
                    </div>
                    {payload.bill_title && (
                      <p className="text-xs text-muted-foreground mt-0.5 line-clamp-1">{payload.bill_title}</p>
                    )}
                    {payload.brief_summary && (
                      <p className="text-xs text-muted-foreground mt-0.5 line-clamp-2">{payload.brief_summary}</p>
                    )}
                  </div>
                  <span className={`text-xs shrink-0 ${event.dispatched_at ? "text-green-500" : "text-amber-500"}`}
                    title={event.dispatched_at ? `Sent ${timeAgo(event.dispatched_at)}` : "Pending dispatch"}>
                    {event.dispatched_at ? "✓" : "⏳"}
                  </span>
                </div>
              );
            })}
          </div>
        )}
      </section>
    </div>
  );
}