import { Link, useSearchParams } from 'react-router';
import { DEFAULT_SECTION, SECTIONS, isSectionKey, type SectionKey } from './sections';

/**
 * The left column: which part of the fofos site the detail panel is showing.
 *
 * ── Selection is in the URL ──
 *
 * `?section=…`, per `docs/navigation-audit.md`: what is on screen is addressable, so it survives a
 * reload, can be linked, and the detail panel reads it directly. The two panels are siblings in a
 * workspace and never speak to each other.
 *
 * ── Real links, not buttons ──
 *
 * `AGENTS.md`: "Rows and nav items are real links." `plugins/proxy-manager/web/NavPanel.tsx` uses
 * buttons calling `setParams`, which keeps the URL correct but gives up anchor semantics — no
 * cmd-click into a new tab, no middle-click, not link-focusable. That is the older pattern and the
 * file that documents it says not to copy it.
 *
 * `<Link>` rather than `<NavLink>` because active state here is a QUERY parameter and NavLink's
 * `isActive` compares paths — every section would light up at once. So the active class is computed
 * from the same value the detail panel reads, which is the one place it can come from.
 */

/**
 * The nav has a FOOT.
 *
 * Everything above it is a part of the client's site, in sitemap order. Below the divider is this
 * plugin's own machinery, which is not a page and does not belong in a list of them — the same split
 * the plugins nav makes with Update-all, and the reason it sits at the bottom of the panel rather than
 * at the bottom of the list. `mt-auto` pins it there whether there are ten sections or two.
 */

const rowClass = (active: boolean) =>
  `flex w-full items-start gap-2.5 border-b border-border px-3 py-2.5 text-left transition-colors ${
    active ? 'bg-muted' : 'hover:bg-muted/50'
  }`;

export const NavPanel = () => {
  const [params] = useSearchParams();
  const raw = params.get('section');
  const active: SectionKey = isSectionKey(raw) ? raw : DEFAULT_SECTION;

  const renderRow = (section: (typeof SECTIONS)[number]) => {
    const Icon = section.icon;

    // Everything else in the URL is preserved. This is one screen of a workspace, and the global
    // query string carries state that belongs to the shell rather than to this panel.
    const search = new URLSearchParams(params);
    search.set('section', section.key);

    return (
      <Link
        key={section.key}
        to={{ search: `?${search.toString()}` }}
        replace
        className={rowClass(active === section.key)}
      >
        <Icon className="mt-0.5 size-4 shrink-0 text-muted-foreground" />
        <span className="min-w-0 flex-1">
          <span className="flex items-baseline gap-2">
            <span className={`truncate text-sm ${section.built ? '' : 'text-muted-foreground'}`}>{section.label}</span>
            {/* Dimmed and labelled rather than hidden. A nav that shows only what is finished gives
                    no sense of what the thing is for — see sections.ts. */}
            {!section.built && (
              <span className="text-[10px] tracking-wide text-muted-foreground/70 uppercase">soon</span>
            )}
          </span>
          <span className="block truncate text-xs text-muted-foreground">{section.hint}</span>
        </span>
      </Link>
    );
  };

  return (
    <nav className="flex size-full flex-col overflow-auto">
      <div className="flex flex-col">{SECTIONS.filter((section) => !section.pinned).map(renderRow)}</div>

      {/* Separated by the same border the rows use, so it reads as the end of the panel rather than as
          one more page of the site. `border-t` and not `border-t-2`: it is a divider, not a heading. */}
      <div className="mt-auto flex flex-col border-t border-border">
        {SECTIONS.filter((section) => section.pinned).map(renderRow)}
      </div>
    </nav>
  );
};