# Gunbuilder Prototype — AI Coding Instructions

## Project Overview

**Gunbuilder** is a Next.js 14 (App Router) admin UI + consumer builder for a firearms parts marketplace. The system manages merchant feeds, normalizes product catalogs, powers a rifle builder interface, and backs a Spring Boot API.

### Key Architecture

- **Frontend**: Next.js 14 (App Router), TypeScript, TailwindCSS, React 18
- **Backend**: Spring Boot (proxied at `/api/*` via `next.config.mjs`)
- **Auth**: JWT tokens stored in cookies (`bb_access_token`, `bb_role`), validated in middleware
- **State**: React Context (AuthContext) for user/auth, client-side React hooks for UI state
- **Data**: Spring Boot REST API—responses paginated via Spring's `PageResponse<T>` structure with `content`, `totalElements`, `totalPages`, `number` (0-based), `size`

---

## File Structure & Naming Conventions

### App Router Layout

```
app/
├── layout.tsx                 # Root (AuthProvider, metadata, theme script)
├── (admin)/layout.tsx         # Admin area: auth gate + left nav sidebar
├── (app)/layout.tsx           # Consumer builder: TopNav + BuilderNav
├── (account)/                 # User account routes (protected)
├── login/page.tsx, register/page.tsx
├── api/                       # Server-side API route handlers
└── actions/                   # Server Actions (e.g., sendEmail.ts)
```

### Naming & Organization

- **Layout grouping**: Use `(admin)`, `(app)`, `(account)` route groups to scope nav & auth logic
- **Client vs Server**: Mark pages/components with `"use client"` if they use hooks, state, or browser APIs. Default is Server Component
- **Components**: Store in `/components` with category subdirectories: `builder/`, `parts/`, `ui/`
- **Utilities**: Place reusable logic in `/lib` (API calls, parsers, helpers)
- **Types**: Centralize in `/types` (e.g., `uiPart.ts`, `builderSlots.ts`, `user.ts`)
- **Data**: Non-fetched lookup tables in `/data` (e.g., `gunbuilderParts.ts` — builder slot definitions)

---

## Critical Patterns

### 1. **Authentication & Authorization**

- **Token storage**: Stored in HTTP-only cookies (`bb_access_token`, `bb_role`)
- **Client-side context**: `AuthContext` provides `token`, `user`, `login()`, `register()`, `logout()`, `refreshMeAndSession()`
- **Middleware gate** ([middleware.ts](middleware.ts#L24-L34)): Admin routes at `/admin/*` require `bb_access_token` + role check
  ```typescript
  if (pathname.startsWith("/admin")) {
    const token = req.cookies.get("bb_access_token")?.value;
    const role = req.cookies.get("bb_role")?.value;
    const ok = !!token && (!role || role === "ADMIN");
    if (!ok) redirect to /login
  }
  ```
- **Wrap pages**: Use `protectedPage()` HOC for client-side auth walls

### 2. **API Integration** ([lib/api.ts](lib/api.ts))

- **useApi() hook**: Returns `{ get(), post(), put() }` methods with auto-injected Bearer token
- **Response unwrapping** ([components/parts/PartsBrowseClient.tsx](components/parts/PartsBrowseClient.tsx#L36-L43)):
  ```typescript
  function unwrapContent<T>(json: any) {
    if (Array.isArray(json)) return { items: json };
    if (Array.isArray(json.content)) return { items: json.content, page: json }; // Spring PageResponse
    return { items: [] };
  }
  ```
- **Pagination**: API returns `{ content: T[], totalElements, totalPages, number, size }`—unwrap before rendering

### 3. **Builder State & Overlaps** ([lib/buildOverlaps.ts](lib/buildOverlaps.ts), [data/gunbuilderParts.ts](data/gunbuilderParts.ts))

- **Category slots**: Defined in `/data/gunbuilderParts.ts` (CATEGORIES array with id, name, group)
- **BuildState type**: `Partial<Record<CategoryId, string>>` (maps slot ID to selected product ID)
- **Overlap logic**: [getOverlapChipsForCategory()](lib/buildOverlaps.ts#L53) educates users when incompatible parts selected
  - E.g., selecting "complete-upper" + "barrel" → show warning chip
  - Used in [OverlapChip](components/builder/OverlapChip.tsx), [PartCard](components/PartCard.tsx)

### 4. **Parts Browsing & Filtering** ([components/parts/PartsBrowseClient.tsx](components/parts/PartsBrowseClient.tsx))

- **Page size**: Hardcoded to 24 items
- **Query params**: `platform`, `partRole`, `search`, `sort` (relevance | price-asc | price-desc | brand-asc), `page` (0-based)
- **View modes**: Card (grid) or list view via state hook
- **Product type**: `GunbuilderProductFromApi` with `id`, `name`, `brand`, `platform`, `partRole`, `price`, `imageUrl`, `buyUrl`, `inStock`

### 5. **Styling & Dark Mode**

- **TailwindCSS**: Configured for dark mode via `"class"` strategy ([tailwind.config.ts](tailwind.config.ts#L8))
- **Root script** ([app/layout.tsx](app/layout.tsx#L21-L31)): Inline JS checks localStorage for theme, applies `dark` class to `<html>`
- **Class pattern**: Use `dark:` prefix for dark-mode overrides (e.g., `dark:bg-black dark:text-zinc-50`)
- **Colors**: Zinc scale primary (white/950 light, black/50 dark); semantic grays for UI

### 6. **Form & Rich Text** ([components/ui/RichTextEditor.tsx](components/ui/RichTextEditor.tsx))

- **RichTextEditor**: Wraps Quill with image resize module for email/admin content
- **Email form**: [send_email_form.tsx](components/ui/send_email_form.tsx) uses form context + RichTextEditor combo

---

## Development Workflows

### Local Setup

```bash
npm install
npm run dev  # Starts Next.js at http://localhost:3000
```

### Environment Variables (.env.local)

```
NEXT_PUBLIC_API_BASE_URL=http://localhost:8080
NEXT_PUBLIC_ADMIN_BASE_PATH=/builder/admin
NEXT_PUBLIC_LAUNCH_ONLY_ROOT=false  # Set true to restrict non-launch content
```

### Building

```bash
npm run build
npm run start  # Production mode
npm run lint  # ESLint check
```

### Key Backend Endpoints (Spring Boot)

- `POST /api/auth/login` → returns `{ token, user }`
- `GET /api/gunbuilder/products?platform=...&partRole=...` → returns Spring PageResponse
- `POST /api/admin/...` → admin-only mutations (import, mapping, etc.)

---

## Common Tasks & Patterns

### Add a New Admin Page

1. Create `app/admin/[feature]/page.tsx` with `"use client"`
2. Add to [AdminLeftNavigation](components/AdminLeftNavigation.tsx) navGroups
3. Use `useAuth()` for permission checks; fallback `<protectedPage />` if needed
4. Fetch via `useApi()` hook

### Modify Parts Filtering

- Edit sort options in [SortBar](components/parts/SortBar.tsx) or query logic in [PartsBrowseClient](components/parts/PartsBrowseClient.tsx)
- Update `PAGE_SIZE` constant if needed
- Ensure query params flow through useRouter + useSearchParams

### Update Builder Slot Definitions

- Edit [data/gunbuilderParts.ts](data/gunbuilderParts.ts) CATEGORIES array
- Run [lib/buildOverlaps.ts](lib/buildOverlaps.ts) overlap checks if adding conflicting slots
- Update type in [types/builderSlots.ts](types/builderSlots.ts) to reflect new CategoryId union

### Add Server Action

- Create file in `app/actions/` (e.g., `sendEmail.ts`)
- Mark top with `"use server"`
- Import & call from client components; errors bubble naturally

---

## Known Constraints & Workarounds

- **No test suite**: Manual testing required; dev server hot-reload via `npm run dev`
- **Spring PageResponse unwrapping**: Always check for `.content` array when parsing API responses
- **Image URLs**: May be null; provide fallback in UI (e.g., placeholder image)
- **Mobile responsive**: TailwindCSS handles breakpoints; test with dark mode class toggle
- **Type safety**: Use strict TS config; leverage builder slot types to avoid string mismatches

---

## Integration Points & Gotchas

- **CORS**: Spring Boot backend must allow origin `http://localhost:3000` (or production domain)
- **API rewrites**: Next.js rewrites `/api/*` to backend at build time; ensure `NEXT_PUBLIC_API_BASE_URL` matches
- **Auth token refresh**: Handled in AuthContext `refreshMeAndSession()`—called on mount or nav
- **Dark mode class toggle**: Update `<html>` class, not just CSS var—required for TailwindCSS `dark:` selectors
- **Hydration**: Theme script runs inline before React hydration to avoid FOUC (flash of unstyled content)