"use client";

/**
 * /quizzes — every published quiz, with where you are in each.
 *
 * Reached from the Quizzes card on the search page. Quizzes are deliberately
 * not in search results: they're something to do, not something to look up.
 * Signed in only: visitors get the sign-in modal, and home if they dismiss it.
 *
 * The tab (?tab=todo) and, under All, the category you've drilled into
 * (?in=books&book=bg) both live in the URL, so a refresh keeps your place.
 */

import { useEffect, useMemo, useState } from "react";
import { usePathname, useRouter, useSearchParams } from "next/navigation";
import { useSignedInPage } from "@/components/auth/use-signed-in-page";
import { quiz, type QuizCard } from "@/lib/quiz";
import { QuizGrid } from "@/components/quiz/quiz-grid";
import { QuizBrowser } from "@/components/quiz/quiz-browser";
import { cn } from "@/lib/utils";

type Filter = "all" | "todo" | "done";
const FILTERS: readonly Filter[] = ["all", "todo", "done"];

export function QuizzesList() {
  const { user } = useSignedInPage();
  const userId = user?.id;
  const [list, setList] = useState<QuizCard[] | null>(null);
  const params = useSearchParams();
  const router = useRouter();
  const pathname = usePathname();
  const tabParam = params.get("tab") as Filter | null;
  const filter: Filter =
    tabParam && FILTERS.includes(tabParam) ? tabParam : "all";
  // Switching tab starts that tab at its top; All is the bare URL.
  const setFilter = (f: Filter) =>
    router.replace(f === "all" ? pathname : `${pathname}?tab=${f}`, {
      scroll: false,
    });

  useEffect(() => {
    if (!userId) return;
    let cancelled = false;
    quiz
      .list()
      .then((l) => !cancelled && setList(l))
      .catch(() => !cancelled && setList([]));
    return () => {
      cancelled = true;
    };
  }, [userId]);

  const shown = useMemo(
    () =>
      (list ?? []).filter((q) =>
        filter === "all"
          ? true
          : filter === "done"
            ? q.my.state === "completed"
            : q.my.state !== "completed",
      ),
    [list, filter],
  );

  return (
    <main className="mx-auto w-full max-w-3xl flex-1 px-4 py-6 sm:px-6 sm:py-10">
      <header className="mb-6">
        <h1 className="font-[family-name:var(--font-title)] text-2xl font-semibold text-foreground sm:text-3xl">
          Quizzes
        </h1>
        <p className="mt-1 text-sm text-muted-foreground">
          Test what you&apos;ve read and heard. Each quiz can be taken once, and
          only you can see your results.
        </p>
      </header>

      {user && (
        // Phones: three equal, thumb-sized tabs across the width. From sm up
        // they shrink back to compact pills.
        <div className="mb-4 grid grid-cols-3 gap-1.5 sm:flex sm:gap-1">
          {(
            [
              ["all", "All"],
              ["todo", "To do"],
              ["done", "Finished"],
            ] as const
          ).map(([k, label]) => (
            <button
              key={k}
              type="button"
              onClick={() => setFilter(k)}
              className={cn(
                "min-h-10 rounded-full px-4 py-2 text-[15px] font-medium transition-colors sm:min-h-0 sm:px-3 sm:py-1 sm:text-sm sm:font-normal",
                filter === k
                  ? "bg-primary text-primary-foreground dark:text-white"
                  : "bg-muted/60 text-muted-foreground hover:bg-muted hover:text-foreground sm:bg-transparent",
              )}
            >
              {label}
            </button>
          ))}
        </div>
      )}

      {!user ? null : list === null ? (
        <p className="text-sm text-muted-foreground">Loading…</p>
      ) : shown.length === 0 ? (
        <p className="text-sm text-muted-foreground">
          {list.length === 0
            ? "No quizzes yet — check back soon."
            : "Nothing here."}
        </p>
      ) : filter !== "all" ? (
        <QuizGrid quizzes={shown} />
      ) : (
        <QuizBrowser
          quizzes={shown}
          path={{
            in: params.get("in"),
            book: params.get("book"),
            year: params.get("year"),
          }}
        />
      )}
    </main>
  );
}