"use client";

import Link from "next/link";
import { usePathname } from "next/navigation";
import { useState } from "react";
import { Menu, X } from "lucide-react";
import NumberFlow, { NumberFlowGroup } from "@number-flow/react";
import { AubadeDrawer, ResponsiveDialogTitle } from "@/components/shared/responsive-dialog";
import { useIsMobile } from "@/hooks/use-media-query";

interface Lesson {
  id: string;
  title: string;
}

interface Module {
  id: string;
  title: string;
  lessons: Lesson[];
}

interface Course {
  slug: string;
  title: string;
  modules: Module[];
}

function CourseNavBody({
  course,
  completedLessonIds,
  pathname,
  onNavigate,
}: {
  course: Course;
  completedLessonIds: Set<string>;
  pathname: string;
  onNavigate: () => void;
}) {
  const totalLessons = course.modules.reduce((s, m) => s + m.lessons.length, 0);
  const completedCount = course.modules
    .flatMap((m) => m.lessons)
    .filter((l) => completedLessonIds.has(l.id)).length;
  const progressPct = totalLessons > 0 ? Math.round((completedCount / totalLessons) * 100) : 0;

  return (
    <>
      {/* Course title + progress */}
      <div className="px-4 py-4" style={{ borderBottom: "2px solid var(--border)" }}>
        <Link
          href={`/courses/${course.slug}`}
          onClick={onNavigate}
          className="font-bold text-sm leading-snug block mb-1"
          style={{ color: "var(--foreground)" }}
        >
          {course.title}
        </Link>
        <Link
          href="/dashboard"
          onClick={onNavigate}
          className="text-xs block underline mb-3"
          style={{ color: "var(--muted-foreground)" }}
        >
          ← Все курсы
        </Link>

        {totalLessons > 0 && (
          <div>
            <div className="flex items-center justify-between mb-1">
              <NumberFlowGroup>
                <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
                  <NumberFlow value={completedCount} respectMotionPreference /> из {totalLessons} уроков
                </span>
                <span className="text-xs font-bold" style={{ color: "var(--foreground)" }}>
                  <NumberFlow value={progressPct} suffix="%" respectMotionPreference />
                </span>
              </NumberFlowGroup>
            </div>
            <div
              className="h-1.5 w-full"
              style={{ background: "var(--border)" }}
            >
              <div
                className="h-full transition-all duration-300 motion-reduce:transition-none"
                style={{
                  width: `${progressPct}%`,
                  background: progressPct === 100 ? "var(--foreground)" : "var(--accent)",
                  border: progressPct > 0 ? "1px solid var(--foreground)" : "none",
                }}
              />
            </div>
          </div>
        )}
      </div>

      {/* Modules and lessons */}
      <nav className="flex-1 py-2">
        {course.modules.map((mod) => {
          const modCompleted = mod.lessons.filter((l) => completedLessonIds.has(l.id)).length;
          return (
            <div key={mod.id}>
              <div className="flex items-center justify-between px-4 py-2">
                <p
                  className="text-xs font-bold uppercase tracking-widest"
                  style={{ color: "var(--muted-foreground)" }}
                >
                  {mod.title}
                </p>
                {mod.lessons.length > 0 && (
                  <span className="text-xs" style={{ color: "var(--muted-foreground)" }}>
                    {modCompleted}/{mod.lessons.length}
                  </span>
                )}
              </div>
              {mod.lessons.map((lesson) => {
                const active = pathname.includes(lesson.id);
                const done = completedLessonIds.has(lesson.id);
                return (
                  <Link
                    key={lesson.id}
                    href={`/courses/${course.slug}/lessons/${lesson.id}`}
                    onClick={() => onNavigate()}
                    className="flex items-center gap-2 px-4 py-2 text-sm leading-snug border-l-2 transition-colors"
                    style={{
                      borderLeftColor: active ? "var(--foreground)" : "transparent",
                      backgroundColor: active ? "var(--color-highlight)" : "transparent",
                      fontWeight: active ? 600 : 400,
                      color: done && !active ? "var(--muted-foreground)" : "var(--foreground)",
                    }}
                  >
                    <span
                      className="shrink-0 w-4 h-4 flex items-center justify-center text-xs"
                      style={{
                        border: `1.5px solid ${done ? "var(--foreground)" : "var(--border)"}`,
                        background: done ? "var(--foreground)" : "transparent",
                        color: "var(--background)",
                      }}
                    >
                      {done && "✓"}
                    </span>
                    <span className="flex-1 leading-snug">{lesson.title}</span>
                  </Link>
                );
              })}
            </div>
          );
        })}
      </nav>
    </>
  );
}

export function CourseSidebar({
  course,
  completedLessonIds = new Set(),
}: {
  course: Course;
  completedLessonIds?: Set<string>;
}) {
  const pathname = usePathname();
  // Tablet (768–1023px): the old off-canvas panel. Phone (<768px): bottom sheet.
  const [open, setOpen] = useState(false);
  const [sheetOpen, setSheetOpen] = useState(false);
  const isMobile = useIsMobile();
  const menuOpen = isMobile ? sheetOpen : open;

  return (
    <>
      {/* Mobile hamburger */}
      <button
        className="lg:hidden fixed top-3 left-3 z-50 p-2 rounded"
        style={{
          backgroundColor: "var(--background)",
          border: "1.5px solid var(--border)",
          color: "var(--foreground)",
        }}
        onClick={() => (isMobile ? setSheetOpen((v) => !v) : setOpen((v) => !v))}
        aria-label="Навигация по курсу"
        aria-expanded={menuOpen}
      >
        {menuOpen ? <X size={20} /> : <Menu size={20} />}
      </button>

      {/* Overlay */}
      {open && !isMobile && (
        <div
          className="lg:hidden fixed inset-0 bg-black/50 z-30"
          onClick={() => setOpen(false)}
        />
      )}

      <aside
        className={[
          "w-64 flex flex-col overflow-y-auto",
          "fixed top-[53px] left-0 bottom-0 z-40 transition-transform duration-200",
          "lg:sticky lg:shrink-0 lg:translate-x-0",
          open && !isMobile ? "translate-x-0" : "-translate-x-full lg:translate-x-0",
        ].join(" ")}
        style={{
          borderRight: "2px solid var(--border)",
          backgroundColor: "var(--background)",
          maxHeight: "calc(100vh - 53px)",
          top: "53px",
        }}
      >
        <CourseNavBody
          course={course}
          completedLessonIds={completedLessonIds}
          pathname={pathname}
          onNavigate={() => setOpen(false)}
        />
      </aside>

      {isMobile && (
        <AubadeDrawer open={sheetOpen} onOpenChange={setSheetOpen} className="px-0 pt-0">
          <ResponsiveDialogTitle className="sr-only">Навигация по курсу</ResponsiveDialogTitle>
          <CourseNavBody
            course={course}
            completedLessonIds={completedLessonIds}
            pathname={pathname}
            onNavigate={() => setSheetOpen(false)}
          />
        </AubadeDrawer>
      )}
    </>
  );
}