"use client";

/**
 * NotificationMatrix — the Settings grid controlling which events reach the
 * user over which channels (in-app, email, push). Account-wide preferences;
 * the device-level PushToggle above it governs whether *this* device can
 * receive push at all (two layers, like an OS permission vs. app settings).
 *
 * Cells write through to PUT /notifications/prefs one at a time and re-render
 * from the matrix the server returns, so the UI always shows resolved state.
 */

import { useEffect, useState } from "react";
import { toast } from "sonner";
import {
  notifications,
  type NotificationPrefs,
  type PrefChannel,
  type PrefEvent,
} from "@/lib/social";
import { ToggleSwitch } from "@/components/settings/setting-row";
import {
  enablePush,
  isPushEnabled,
  pushPermission,
  pushSupported,
} from "@/lib/push";

const EVENTS: {
  key: PrefEvent;
  label: string;
  description: string;
  /** Channels this event can actually be delivered on. Omit for all three.
   *  A cell outside this set renders as "—" rather than a live toggle, so we
   *  never show a switch that silently does nothing. */
  channels?: PrefChannel[];
}[] = [
  {
    key: "follows",
    label: "Follows",
    description: "Follow requests and accepted requests.",
  },
  {
    key: "post_interactions",
    label: "Post interactions",
    description: "Likes and mentions on your posts.",
  },
  {
    key: "sadhna_reminders",
    label: "Sādhana reminders",
    description: "Daily nudges to chant your rounds and share a verse.",
  },
  {
    key: "community",
    label: "Community",
    description:
      "Rare announcements — such as new feature, downtime etc.",
    // Announcements are in-app/push only; we deliberately don't email them.
    channels: ["in_app", "push"],
  },
];

const CHANNELS: { key: PrefChannel; label: string }[] = [
  { key: "in_app", label: "In-app" },
  { key: "email", label: "Email" },
  { key: "push", label: "Push" },
];

export function NotificationMatrix() {
  const [prefs, setPrefs] = useState<NotificationPrefs | null>(null);
  const [failed, setFailed] = useState(false);
  // The "event/channel" cell currently being written, so only it disables.
  const [busyCell, setBusyCell] = useState<string | null>(null);

  useEffect(() => {
    let cancelled = false;
    notifications
      .prefs()
      .then(({ prefs }) => {
        if (!cancelled) setPrefs(prefs);
      })
      .catch(() => {
        if (!cancelled) setFailed(true);
      });
    return () => {
      cancelled = true;
    };
  }, []);

  async function toggle(event: PrefEvent, channel: PrefChannel) {
    if (!prefs) return;
    // Default-on when the key is absent: prefs are stored as opt-outs, and a
    // BFF that predates this category simply omits it.
    const next = !(prefs[event]?.[channel] ?? true);
    setBusyCell(`${event}/${channel}`);
    try {
      // Turning a push cell ON only helps if this device can receive push —
      // offer the permission/subscription right at the gesture, best-effort
      // (the account-wide pref still saves if the user declines).
      if (
        channel === "push" &&
        next &&
        pushSupported() &&
        pushPermission() !== "denied" &&
        !(await isPushEnabled())
      ) {
        await enablePush().catch(() => {
          /* declined / unavailable — other subscribed devices still get it */
        });
      }
      const { prefs: updated } = await notifications.setPref(
        event,
        channel,
        next,
      );
      setPrefs(updated);
    } catch {
      toast.error("Could not update preference");
    } finally {
      setBusyCell(null);
    }
  }

  if (failed) {
    return (
      <p className="py-3 text-xs text-muted-foreground">
        Couldn&apos;t load your notification preferences. Reload to try again.
      </p>
    );
  }

  return (
    <div className="grid grid-cols-[1fr_auto_auto_auto] items-center gap-x-4 gap-y-0 sm:gap-x-6">
      {/* Header row */}
      <span aria-hidden />
      {CHANNELS.map((c) => (
        <span
          key={c.key}
          className="pb-2 text-center text-xs font-medium text-muted-foreground"
        >
          {c.label}
        </span>
      ))}

      {EVENTS.map((event) => (
        <div key={event.key} className="contents">
          <div className="min-w-0 border-t border-border py-3">
            <span className="text-sm text-foreground">{event.label}</span>
            <p className="text-xs text-muted-foreground mt-0.5">
              {event.description}
            </p>
          </div>
          {CHANNELS.map((channel) => {
            const deliverable =
              !event.channels || event.channels.includes(channel.key);
            return (
              <div
                key={channel.key}
                className="flex justify-center border-t border-border py-3"
              >
                {!deliverable ? (
                  <span
                    className="text-xs text-muted-foreground"
                    title={`${event.label} isn't delivered by ${channel.label.toLowerCase()}`}
                  >
                    &mdash;
                  </span>
                ) : prefs ? (
                  <ToggleSwitch
                    checked={prefs[event.key]?.[channel.key] ?? true}
                    disabled={busyCell === `${event.key}/${channel.key}`}
                    onToggle={() => toggle(event.key, channel.key)}
                    label={`${event.label} — ${channel.label}`}
                  />
                ) : (
                  <span className="text-xs text-muted-foreground">…</span>
                )}
              </div>
            );
          })}
        </div>
      ))}
    </div>
  );
}