/* ========================================
   TopNav Component — padhle (Refined Workspace)
   ======================================== */

import { useState, useRef, useEffect } from "react";
import "./TopNav.css";

const TopNav = ({ subjectItems, chapterData, activeGrade, onGradeChange, activeSubject, onSubjectChange, activeChapter, onChapterChange, user, onSignOut }) => {
  const [openDropdown, setOpenDropdown] = useState(null);
  const gradeRef = useRef(null);
  const subjectRef = useRef(null);
  const chapterRef = useRef(null);

  // Close dropdown when clicking outside
  useEffect(() => {
    const handleClickOutside = (e) => {
      const refs = [gradeRef, subjectRef, chapterRef];
      const isInside = refs.some((ref) => ref.current && ref.current.contains(e.target));
      if (!isInside) {
        setOpenDropdown(null);
      }
    };
    document.addEventListener("mousedown", handleClickOutside);
    return () => document.removeEventListener("mousedown", handleClickOutside);
  }, []);

  const toggleDropdown = (name) => {
    setOpenDropdown((prev) => (prev === name ? null : name));
  };

  const selectOption = (name, value) => {
    setOpenDropdown(null);
    switch (name) {
      case "grade":
        onGradeChange(value);
        break;
      case "subject":
        onSubjectChange(value);
        break;
      case "chapter":
        onChapterChange(value);
        break;
    }
  };

  const grades = [
    { id: "choose-standard", label: "Choose standard" },
    { id: "Grade 6", label: "Grade 6" },
    { id: "Grade 7", label: "Grade 7" },
    { id: "Grade 8", label: "Grade 8" },
    { id: "Grade 9", label: "Grade 9" },
    { id: "Grade 10", label: "Grade 10" },
    { id: "Grade 11", label: "Grade 11" },
    { id: "Grade 12", label: "Grade 12" },
  ];

  // Chapters are now generated dynamically from chapterData (see chapterOptions above)
  // Subjects now come from subjectItems prop
  // Static list removed — was not subject-aware.

  const subjectIcons = {
    math: "calculate",
    science: "science",
    history: "account_balance",
    language: "menu_book",
    english: "edit",
    geography: "public",
  };

  /* ─── Resolve subject display (ID → label) ─── */
  const resolvedSubjectLabel = activeSubject === "choose-subject"
    ? "Choose Subject"
    : subjectItems?.find((s) => s.id === activeSubject)?.label || activeSubject || "Choose Subject";

  /* ─── Resolve chapter pill label ─── */
  const resolvedChapterLabel = activeChapter === "choose-chapter" || !activeChapter
    ? "Choose Chapter"
    : activeChapter;

  /* ─── Subject-aware chapter options (from chapterData prop) ─── */
  const chapterOptions = (() => {
    const chapters = chapterData?.[activeSubject] || [];
    return [
      { id: "choose-chapter", label: "Choose Chapter" },
      ...chapters,
    ];
  })();

  return (
    <header className="topnav">
      <div className="topnav__selectors">
        {/* Grade Selector */}
        <div className="topnav__selector" ref={gradeRef}>
          <button
            className={`topnav__pill topnav__pill--dropdown ${openDropdown === "grade" ? "topnav__pill--open" : ""}`}
            onClick={() => toggleDropdown("grade")}
            aria-label="Select Grade"
            aria-expanded={openDropdown === "grade"}
          >
            <span className="material-symbols-outlined topnav__pill-icon">person_outline</span>
            <span className="topnav__pill-label">{activeGrade}</span>
            <span className="material-symbols-outlined topnav__pill-arrow">expand_more</span>
          </button>
          {openDropdown === "grade" && (
            <ul className="topnav__dropdown">
              {grades.map((grade) => (
                <li key={grade.id}>
                  <button
                    className={`topnav__dropdown-item ${activeGrade === grade.label ? "topnav__dropdown-item--active" : ""}`}
                    onClick={() => selectOption("grade", grade.label)}
                  >
                    {grade.label}
                  </button>
                </li>
              ))}
            </ul>
          )}
        </div>

        {/* Subject Selector */}
        <div className="topnav__selector" ref={subjectRef}>
          <button
            className={`topnav__pill topnav__pill--dropdown ${openDropdown === "subject" ? "topnav__pill--open" : ""}`}
            onClick={() => toggleDropdown("subject")}
            aria-label="Select Subject"
            aria-expanded={openDropdown === "subject"}
          >
            <span className={`material-symbols-outlined topnav__pill-icon`}>
              {activeSubject === "choose-subject" ? "science" : subjectIcons[activeSubject] || "science"}
            </span>
            <span className="topnav__pill-label">{resolvedSubjectLabel}</span>
            <span className="material-symbols-outlined topnav__pill-arrow">expand_more</span>
          </button>
          {openDropdown === "subject" && (
            <ul className="topnav__dropdown">
              {subjectItems?.map((subject) => (
                <li key={subject.id}>
                  <button
                    className={`topnav__dropdown-item ${activeSubject === subject.id ? "topnav__dropdown-item--active" : ""}`}
                    onClick={() => selectOption("subject", subject.id)}
                  >
                    <span className={`material-symbols-outlined topnav__dropdown-icon`}>
                      {subject.id === "choose-subject" ? "science" : subjectIcons[subject.id]}
                    </span>
                    {subject.label}
                  </button>
                </li>
              ))}
            </ul>
          )}
        </div>

        {/* Chapter Selector */}
        <div className="topnav__selector" ref={chapterRef}>
          <button
            className={`topnav__pill topnav__pill--dropdown ${openDropdown === "chapter" ? "topnav__pill--open" : ""}`}
            onClick={() => toggleDropdown("chapter")}
            aria-label="Select Chapter"
            aria-expanded={openDropdown === "chapter"}
          >
            <span className="material-symbols-outlined topnav__pill-icon">menu_book</span>
            <span className="topnav__pill-label">{resolvedChapterLabel}</span>
            <span className="material-symbols-outlined topnav__pill-arrow">expand_more</span>
          </button>
          {openDropdown === "chapter" && (
            <ul className="topnav__dropdown">
              {chapterOptions.map((chapter) => (
                <li key={chapter.id}>
                  <button
                    className={`topnav__dropdown-item ${(activeChapter === chapter.label || activeChapter === "choose-chapter") ? "topnav__dropdown-item--active" : ""}`}
                    onClick={() => selectOption("chapter", chapter.label)}
                  >
                    {chapter.label}
                  </button>
                </li>
              ))}
            </ul>
          )}
        </div>
      </div>

      <div className="topnav__actions">
        {/* Search */}
        <button className="topnav__action" aria-label="Search">
          <span className="material-symbols-outlined">search</span>
        </button>

        {/* Notifications */}
        <button className="topnav__action" aria-label="Notifications">
          <span className="material-symbols-outlined">notifications_none</span>
        </button>

        {/* User Avatar — Sign out on click */}
        <button
          className="topnav__avatar-btn"
          onClick={onSignOut}
          aria-label="Sign out"
          title="Sign out"
        >
          <span className="topnav__avatar-initial">
            {user?.email?.charAt(0).toUpperCase() || "U"}
          </span>
        </button>
      </div>
    </header>
  );
};

export default TopNav;