"use client";

import { useEffect, useState } from "react";
import { useRouter } from "next/navigation";
import { useAuth } from "@/components/AuthProvider";
import { c2api } from "@/lib/c2api";

interface LinkStatus {
  linked: boolean;
  discord_user_id?: string;
  discord_username?: string;
  linked_at?: string;
}

function fmtDate(iso: string) {
  return new Date(iso).toLocaleDateString("en-US", {
    month: "short", day: "numeric", year: "numeric",
  });
}

function Initials({ name }: { name: string }) {
  const parts = name.trim().split(/\s+/);
  const letters = parts.length >= 2
    ? parts[0][0] + parts[parts.length - 1][0]
    : name.slice(0, 2);
  return (
    <div className="w-16 h-16 rounded-full bg-indigo-700 flex items-center justify-center text-white text-xl font-bold select-none">
      {letters.toUpperCase()}
    </div>
  );
}

export default function ProfilePage() {
  const { user, isAdmin, signOut } = useAuth();
  const router = useRouter();

  const [linkStatus, setLinkStatus]   = useState<LinkStatus | null>(null);
  const [linkLoading, setLinkLoading] = useState(true);
  const [code, setCode]               = useState<string | null>(null);
  const [codeExpiry, setCodeExpiry]   = useState<number | null>(null);
  const [generating, setGenerating]   = useState(false);
  const [unlinking, setUnlinking]     = useState(false);

  useEffect(() => {
    if (!user) return;
    c2api.getLinkStatus()
      .then(setLinkStatus)
      .catch(() => setLinkStatus({ linked: false }))
      .finally(() => setLinkLoading(false));
  }, [user]);

  async function generateCode() {
    setGenerating(true);
    try {
      const res = await c2api.generateLinkCode();
      if (res.already_linked) {
        setLinkStatus((prev) => prev ? { ...prev, linked: true } : prev);
      } else if (res.code) {
        setCode(res.code);
        setCodeExpiry(res.expires_minutes ?? 15);
      }
    } finally {
      setGenerating(false);
    }
  }

  async function unlink() {
    setUnlinking(true);
    try {
      await c2api.unlinkDiscord();
      setLinkStatus({ linked: false });
      setCode(null);
    } finally {
      setUnlinking(false);
    }
  }

  async function handleSignOut() {
    await signOut();
    router.push("/login");
  }

  if (!user) return null;

  const displayName = user.displayName || user.email || "Account";

  return (
    <div className="max-w-lg space-y-6">
      {/* Header */}
      <div className="flex items-center gap-4">
        <Initials name={displayName} />
        <div>
          <h1 className="text-white text-xl font-bold">{displayName}</h1>
          {user.displayName && user.email && (
            <p className="text-gray-400 text-sm mt-0.5">{user.email}</p>
          )}
          {isAdmin && (
            <span className="inline-block mt-1 text-xs font-mono px-2 py-0.5 rounded-full bg-indigo-900 text-indigo-300">
              Admin
            </span>
          )}
        </div>
      </div>

      {/* Firebase account */}
      <section className="bg-gray-900 border border-gray-800 rounded-xl divide-y divide-gray-800">
        <div className="px-4 py-3">
          <p className="text-xs text-gray-500 uppercase tracking-wider font-mono mb-2">Account</p>
          <div className="space-y-2">
            <Row label="Email" value={user.email ?? "—"} />
            <Row label="UID" value={user.uid} mono truncate />
            <Row label="Role" value={isAdmin ? "Admin" : "Member"} />
            {user.metadata.creationTime && (
              <Row label="Joined" value={fmtDate(user.metadata.creationTime)} />
            )}
            {user.metadata.lastSignInTime && (
              <Row label="Last sign-in" value={fmtDate(user.metadata.lastSignInTime)} />
            )}
          </div>
        </div>
      </section>

      {/* Discord linking */}
      <section className="bg-gray-900 border border-gray-800 rounded-xl overflow-hidden">
        <div className="px-4 py-3">
          <p className="text-xs text-gray-500 uppercase tracking-wider font-mono mb-3">Discord</p>

          {linkLoading ? (
            <p className="text-gray-500 text-sm">Loading…</p>
          ) : linkStatus?.linked ? (
            <div className="space-y-3">
              <div className="space-y-2">
                {linkStatus.discord_username && (
                  <Row label="Username" value={`@${linkStatus.discord_username}`} />
                )}
                {linkStatus.discord_user_id && (
                  <Row label="User ID" value={linkStatus.discord_user_id} mono />
                )}
                {linkStatus.linked_at && (
                  <Row label="Linked" value={fmtDate(linkStatus.linked_at)} />
                )}
              </div>
              <div className="pt-1">
                <button
                  onClick={unlink}
                  disabled={unlinking}
                  className="text-xs text-red-500 hover:text-red-400 transition-colors disabled:opacity-50"
                >
                  {unlinking ? "Unlinking…" : "Unlink Discord account"}
                </button>
              </div>
            </div>
          ) : (
            <div className="space-y-3">
              <p className="text-sm text-gray-400">
                Link your Discord account to access private trips from both the web and Discord.
              </p>
              {code ? (
                <div className="space-y-2">
                  <div className="bg-gray-800 rounded-lg px-4 py-3 flex items-center gap-3">
                    <span className="font-mono text-2xl tracking-[0.4em] text-white select-all">{code}</span>
                  </div>
                  <p className="text-xs text-gray-400">
                    Run <span className="font-mono text-gray-200">/link {code}</span> in Discord. Code expires in {codeExpiry} minutes.
                  </p>
                  <button
                    onClick={generateCode}
                    disabled={generating}
                    className="text-xs text-gray-500 hover:text-gray-300 transition-colors disabled:opacity-50"
                  >
                    Generate new code
                  </button>
                </div>
              ) : (
                <button
                  onClick={generateCode}
                  disabled={generating}
                  className="bg-indigo-600 hover:bg-indigo-500 disabled:opacity-50 text-white text-sm rounded-lg px-4 py-2 transition-colors"
                >
                  {generating ? "Generating…" : "Get link code"}
                </button>
              )}
            </div>
          )}
        </div>
      </section>

      {/* Sign out */}
      <section className="bg-gray-900 border border-gray-800 rounded-xl">
        <div className="px-4 py-3 flex items-center justify-between">
          <p className="text-sm text-gray-400">Sign out of this device</p>
          <button
            onClick={handleSignOut}
            className="text-sm text-red-500 hover:text-red-400 transition-colors"
          >
            Sign out
          </button>
        </div>
      </section>
    </div>
  );
}

function Row({ label, value, mono = false, truncate = false }: {
  label: string;
  value: string;
  mono?: boolean;
  truncate?: boolean;
}) {
  return (
    <div className="flex items-start justify-between gap-4">
      <span className="text-xs text-gray-500 shrink-0">{label}</span>
      <span className={`text-sm text-gray-200 text-right ${mono ? "font-mono text-xs" : ""} ${truncate ? "truncate max-w-[200px]" : ""}`}>
        {value}
      </span>
    </div>
  );
}