# Spine — Add Book Form

Adds a form to create new books in `spine.org`, plus the write function
to persist them.

## Architecture

```
"Add book" link (index page)
        │
    GET /add
        │
templates/add.mustache ←── [spine-index-model] for datalist values
        │
    POST /add (form submission)
        │
    [spine-add-book] ──→ writes to spine.org
        │
    redirect to /index
```

## Template: `templates/add.mustache`

A new Mustache template with the Pico CSS + Tabler Icons shell (matching the
index page) and a `<form method="post" action="/add">`.

**View model:**

```json
{
  "app_title": "spine",
  "existing_authors": ["Ursula K. Le Guin", "Frank Herbert", ...],
  "existing_categories": ["scifi", "literary", ...]
}
```

`existing_authors` and `existing_categories` are extracted from the current
`spine-books` results. Empty lists are fine — the `<datalist>` just has no
options.

**Form fields:**

| Field | Input type | Required | Notes |
|---|---|---|---|
| date_added | `<input type="date">` | no | defaults to today |
| title | `<input type="text">` | **yes** | |
| author | `<input type="text" list="authors">` | no | datalist from existing |
| category | `<input type="text" list="categories">` | no | datalist from existing tags |
| format | `<select>` | no | hardcover / ebook / audiobook / — |
| isbn | `<input type="text">` | no | |
| cover | `<input type="text">` | no | path relative to spine.org |
| rec_by | `<input type="text">` | no | recommender name |
| rec_note | `<input type="text">` | no | why it's on your radar |
| initial_note | `<textarea>` | no | becomes first reading note |

**Datalists** for author and category:

```html
<input type="text" name="author" list="authors-list" />
<datalist id="authors-list">
  {{#existing_authors}}<option value="{{.}}">{{/existing_authors}}
</datalist>
```

"Add book" link on the index page (in `templates/index.mustache`) — placed in
the `<header>` alongside the title:

```html
<a role="button" href="/add">Add book</a>
```

## Write function: `spine-add-book`

```elisp
(spine-add-book &key title author category format isbn cover
                 rec_by rec_note date_added initial_note)
→ t on success, signals error on failure
```

**Behavior:**
1. Visits `spine-org-file` in a temporary buffer
2. Inserts a new top-level headline with TODO keyword `WANT`
3. Sets properties: `:AUTHOR:`, `:FORMAT:`, `:ISBN:`, `:COVER:`, `:REC_BY:`, `:REC_NOTE:`, `:ADDED:`, `:ID:`
4. Sets tags if category provided
5. Appends initial note as `- [DATE] note text` if provided
6. Saves the buffer
7. Returns `t`

**`:ID:` generation:** short random alphanumeric, e.g. `(format "%04x-%04x" (random 65535) (random 65535))`.

**`:ADDED:` date:** if `date_added` is provided, format as `[YYYY-MM-DD]`. If nil, omit the property.

**Properties with nil/empty values are omitted** — only set properties that have non-empty values. This keeps the Org file clean.

## Handler: `/add`

```elisp
(defservlet add text/html (path query request)
  (let ((method (car (car request))))
    (if (equal method "POST")
        ;; Process form submission
        (progn
          (spine-add-book
           :title (cdr (assoc "title" query))
           :author (cdr (assoc "author" query))
           :category (cdr (assoc "category" query))
           :format (cdr (assoc "format" query))
           :isbn (cdr (assoc "isbn" query))
           :cover (cdr (assoc "cover" query))
           :rec_by (cdr (assoc "rec_by" query))
           :rec_note (cdr (assoc "rec_note" query))
           :date_added (cdr (assoc "date_added" query))
           :initial_note (cdr (assoc "initial_note" query)))
          (httpd-redirect t "/index" 303))
      ;; GET: show the form
      (let ((model (spine-add-form-model (spine-books))))
        (insert (spine-render "add.mustache" model))))))
```

`spine-add-form-model` builds the view model from `spine-books` — extracts
unique authors and tags into flat lists.

**Form GET access:** `http://localhost:8080/add`

**Empty-books case:** if `spine-books` returns nil, the datalists are empty —
the form still works, you just get no suggestions.

## Error handling

| Case | Behavior |
|---|---|
| Title missing | redirect to `/add` with error message (query param) |
| Write fails | `spine-add-book` signals error, handler catches and shows error page |
| `spine.org` missing | `spine-add-book` creates a new file with the `#+TODO` header and first entry |

## Files changed

| File | Change |
|---|---|
| `templates/add.mustache` | New — add-book form template |
| `templates/index.mustache` | Modified — add "Add book" link in header |
| `spine.el` | New functions: `spine-add-book`, `spine-add-form-model`. New handler: `/add`. |

## Out of scope

- Validation beyond title required
- Edit existing book
- Delete book
- Cover image upload (text path only)
- Multi-category input (single category string → single tag for now)
- Error display on the form page (redirect on error, no inline messages)

## Styling

Uses Pico CSS form styles (`<input>`, `<select>`, `<textarea>`) which are
styled automatically by the Pico framework. No additional custom CSS needed
for the form — Pico handles layout, spacing, and theme.

## Acceptance

- [ ] "Add book" link visible on index page
- [ ] `GET /add` shows form with Pico styling
- [ ] Author and category fields have datalist suggestions from existing data
- [ ] Submitting the form creates a new `* WANT Title` headline in `spine.org`
- [ ] Properties are set correctly (title, author, format, ISBN, etc.)
- [ ] Initial note appears as `- [YYYY-MM-DD] text` in the body
- [ ] Empty optional fields are omitted (no empty properties)
- [ ] After submission, redirect to `/index` and new book is visible
- [ ] ERT tests still pass (model layer unchanged)