"use client";

import { useSearchParams } from "next/navigation";
import { useRouter } from "next/navigation";
import { useEffect, useState } from "react";
import Header from "@/components/Header";
import DestructibleAlert from "@/components/DestructibleAlert";
import BackgroundWrapper from "@/components/BackgroundWrapper";
import { API_URL, getToken } from "@/lib/auth";
import { Loader, RefreshCw } from "lucide-react";
import { useAuth } from "@/context/AuthContext";
import { Question } from "@/types/exam";

type Subject = {
  subject_id: string;
  name: string;
  unit: string;
};

export default function PaperScreen() {
  const router = useRouter();
  const { user } = useAuth();

  const [subjects, setSubjects] = useState<Subject[]>([]);
  const [errorMsg, setErrorMsg] = useState<string | null>(null);
  const [refreshing, setRefreshing] = useState<boolean>(false);
  async function fetchSubjects() {
    setRefreshing(true);
    try {
      const token = await getToken();
      const response = await fetch(`${API_URL}/subjects/`, {
        method: "GET",
        headers: {
          Authorization: `Bearer ${token}`,
        },
      });

      if (!response.ok) {
        throw new Error("Failed to fetch subjects");
      }

      const fetchedSubjects: Subject[] = await response.json();
      setSubjects(fetchedSubjects);
    } catch (error) {
      setErrorMsg(
        "Error fetching subjects: " +
          (error instanceof Error ? error.message : "Unknown error")
      );
    } finally {
      setRefreshing(false);
    }
  }

  useEffect(() => {
    const fetchData = async () => {
      if (await getToken()) {
        fetchSubjects();
      }
    };
    fetchData();
  }, []);

  const onRefresh = async () => {
    fetchSubjects();
  };

  if (errorMsg) {
    return (
      <BackgroundWrapper>
        <Header displayTabTitle="Subjects" />
        <div className="overflow-y-auto">
          <div className="mt-5 px-5">
            <DestructibleAlert text={errorMsg} extraStyles="" />
          </div>
          <div className="flex justify-center mt-4">
            <button
              onClick={onRefresh}
              disabled={refreshing}
              className="px-4 py-2 bg-blue-500 text-white rounded hover:bg-blue-600 disabled:opacity-50"
            >
              {refreshing ? <Loader /> : <RefreshCw />}
            </button>
          </div>
        </div>
      </BackgroundWrapper>
    );
  }

  return (
    <BackgroundWrapper>
      <div>
        <Header displayTabTitle="Subjects" />
        <div className="mx-10 pt-10 overflow-y-auto">
          <h1 className="text-2xl font-semibold mb-5">
            {user?.preparation_unit}
          </h1>
          <div className="border border-[#c0dafc] flex flex-col gap-4 w-full rounded-[25px] p-4">
            {subjects.length > 0 ? (
              subjects
                .filter((subject) => subject.unit === user?.preparation_unit)
                .map((subject) => (
                  <div key={subject.subject_id}>
                    <button
                      onClick={() =>
                        router.push(
                          `/exam/pretest?test_id=${subject.subject_id}`
                        )
                      }
                      className="w-full border-2 border-[#B0C2DA] py-4 rounded-[10px] px-6 space-y-2 text-left hover:bg-gray-50 transition-colors"
                    >
                      <h3 className="text-xl font-medium">{subject.name}</h3>
                      <p className="text-md font-normal">Rating: 8/10</p>
                    </button>
                  </div>
                ))
            ) : (
              <div className="flex flex-col items-center justify-center">
                <div className="animate-spin rounded-full h-12 w-12 border-b-2 border-blue-500 mb-4"></div>
                <p className="text-xl font-medium text-center">Loading...</p>
              </div>
            )}
          </div>
          <div className="flex justify-center mt-4">
            <button
              onClick={onRefresh}
              disabled={refreshing}
              className="p-2 bg-blue-500 text-white hover:bg-blue-600 disabled:opacity-50 rounded-full"
            >
              {refreshing ? <Loader /> : <RefreshCw />}
            </button>
          </div>
        </div>
      </div>
      {/* <CustomBackHandler fallbackRoute="unit" useCustomHandler={false} /> */}
    </BackgroundWrapper>
  );
}
