"use client";

/**
 * SiteHeader — the single global navigation header.
 *
 * Sits at the top of every page (mounted in app/layout.tsx) so the page-specific
 * PageHeader can stay focused on titles and breadcrumbs.
 *
 * Layout:
 *
 *   ┌─────────────────────────────────────────────────────────────┐
 *   │  PRABHUPĀDA   Books · Letters · Lectures · Glossary  ⌕ ⚙ ◐ │
 *   │     SAYS                                                    │
 *   └─────────────────────────────────────────────────────────────┘
 *
 *   - Serif uppercase wordmark on the left (links home)
 *   - Section nav inline on md+; collapsed into the mobile drawer below
 *   - Right cluster: HeaderSearchButton, ReadingSettings, UserMenu
 *   - Sticky with a subtle border + backdrop blur when scrolled
 *
 * The HeaderSearchButton's expand-into-full-width behavior is preserved by
 * giving it the same conditional flex treatment that PageHeader used to do —
 * when expanded on mobile the wordmark + nav collapse out of the way.
 */

import { useState } from "react";
import Link from "next/link";
import { usePathname } from "next/navigation";
import { HeaderSearchButton } from "@/components/header-search";
import { ReadingSettings } from "@/components/reading-settings";
import { UserMenu } from "@/components/auth/user-menu";
import { MobileNavToggle } from "@/components/site-mobile-nav";
import { cn } from "@/lib/utils";

const PRIMARY_NAV = [
  { href: "/books", label: "Books" },
  { href: "/letters", label: "Letters" },
  { href: "/transcriptions", label: "Lectures" },
  { href: "/essays", label: "Essays" },
  { href: "/glossary", label: "Glossary" },
] as const;

export function SiteHeader() {
  const [searchExpanded, setSearchExpanded] = useState(false);
  const pathname = usePathname();

  function isActive(href: string): boolean {
    if (href === "/") return pathname === "/";
    return pathname.startsWith(href);
  }

  return (
    <header className="sticky top-0 z-30 border-b border-border bg-secondary text-secondary-foreground">
      <div className="max-w-5xl mx-auto px-3 sm:px-6 h-14 md:h-16 flex items-center gap-2 md:gap-6">
        {/* Mobile hamburger — visible below md, hidden when search is expanded */}
        <div className={cn("md:hidden", searchExpanded && "hidden")}>
          <MobileNavToggle items={PRIMARY_NAV} />
        </div>

        {/* Brand wordmark — two-line stacked "Prabhupāda / SAYS". Smaller
            type sizes on mobile so the row fits next to the hamburger and
            action icons on narrow phones (≤375px). */}
        <Link
          href="/"
          aria-label="Prabhupāda Says — home"
          className={cn(
            "shrink-0 leading-none text-foreground transition-opacity hover:opacity-80",
            "font-[family-name:var(--font-title)]",
            searchExpanded && "max-md:hidden",
          )}
        >
          <span className="block text-[0.78rem] md:text-lg font-semibold uppercase tracking-[0.08em] md:tracking-[0.12em]">
            Prabhupāda
          </span>
          <span className="block text-[0.55rem] md:text-[0.78rem] font-medium uppercase text-muted-foreground tracking-[0.18em] md:tracking-[0.22em] mt-0.5">
            Says
          </span>
        </Link>

        {/* Primary nav — desktop only; mobile uses the drawer.
            Stays visible even when search is expanded — on desktop the search
            input has a fixed max-width and fits alongside the nav, so there's
            no need to remove items (which would cause layout shift). */}
        <nav
          className="hidden md:flex items-center gap-5 flex-1 ml-2"
          aria-label="Primary"
        >
          {PRIMARY_NAV.map((item) => (
            <Link
              key={item.href}
              href={item.href}
              className={cn(
                "text-sm transition-colors relative",
                isActive(item.href)
                  ? "text-foreground after:absolute after:left-0 after:right-0 after:-bottom-1 after:h-px after:bg-primary"
                  : "text-muted-foreground hover:text-foreground",
              )}
            >
              {item.label}
            </Link>
          ))}
        </nav>

        {/* Spacer pushes the action cluster to the right on mobile */}
        <div
          className={cn("flex-1 md:hidden", searchExpanded && "hidden")}
          aria-hidden
        />

        {/* Action cluster — search, reading-settings, user menu.
            On mobile when search is expanded, the cluster fills the row so
            the input can grow. On desktop it always stays shrink-0 — the
            expanded search input has its own fixed max-width and doesn't
            need to steal space from the nav. */}
        <div
          className={cn(
            "flex items-center gap-1 shrink-0",
            searchExpanded && "max-md:flex-1 max-md:min-w-0 max-md:shrink",
          )}
        >
          <HeaderSearchButton
            expanded={searchExpanded}
            onExpandedChange={setSearchExpanded}
          />
          <div className={cn(searchExpanded && "max-md:hidden")}>
            <ReadingSettings />
          </div>
          <div className={cn(searchExpanded && "max-md:hidden")}>
            <UserMenu />
          </div>
        </div>
      </div>
    </header>
  );
}