# Art Gallery — database structure

PostgreSQL schema for the virtual gallery. Canonical DDL is intended to live in `db/schema.sql` when checked in; this document describes the logical model either way.

Connection settings come from `.env` (see [setup.md](setup.md)).

## Overview

| Item | Typical value |
|------|----------------|
| Engine | PostgreSQL 14+ |
| Database | `Gallery` |
| App user | `gallery` |
| Time fields | Integer years (negative = BCE) |

## Entity relationship

```mermaid
erDiagram
  historical_eras ||--o{ art_movements : contains
  art_movements ||--o{ artists : groups
  artists ||--o{ artist_periods : has
  artists ||--o{ paintings : created
  artist_periods ||--o{ paintings : groups
  paintings ||--o{ painting_influences : influenced_by
  paintings ||--o{ painting_influences : influences
```

## Tables

### `historical_eras`

Broad chronological buckets (Ancient, Medieval, Renaissance, …).

| Column | Type | Notes |
|--------|------|-------|
| `id` | SERIAL PK | |
| `name` | VARCHAR(100) | Display label |
| `start_year`, `end_year` | INTEGER | Inclusive range |
| `start_definite`, `end_definite` | BOOLEAN | `false` → render as gradient edge on timeline |
| `description` | TEXT | Tooltip / sidebar copy |
| `sort_order` | INTEGER | Display order |

### `art_movements`

Finer-grained styles (Impressionism, Cubism, Suprematism, …).

| Column | Type | Notes |
|--------|------|-------|
| `id` | SERIAL PK | |
| `name` | VARCHAR(150) | |
| `start_year`, `end_year` | INTEGER | |
| `start_definite`, `end_definite` | BOOLEAN | Same visual semantics as eras |
| `era_id` | FK → `historical_eras` | Optional parent era |
| `description` | TEXT | |
| `color` | VARCHAR(20) | Hex colour for movement band |

### `artists`

| Column | Type | Notes |
|--------|------|-------|
| `id` | SERIAL PK | |
| `name` | VARCHAR(200) | |
| `birth_year`, `death_year` | INTEGER | Nullable; used for timeline portrait placement |
| `movement_id` | FK → `art_movements` | Primary movement |
| `portrait_path` | VARCHAR(500) | Relative to `data/images/` |
| `bio_short`, `bio_full` | TEXT | Wikipedia lead section (`npm run fetch-artist-bios`) |
| `wikipedia_title` | VARCHAR(300) | Source page title |
| `century` | INTEGER | Rounded century bucket for seeding limits |

### `artist_periods`

Phases within an artist’s career (e.g. “Blue Period”, “Roman Period”).

| Column | Type | Notes |
|--------|------|-------|
| `id` | SERIAL PK | |
| `artist_id` | FK → `artists` | ON DELETE CASCADE |
| `name` | VARCHAR(200) | |
| `start_year`, `end_year` | INTEGER | |
| `description` | TEXT | |
| `sort_order` | INTEGER | Wall order in 3D gallery |

### `paintings`

| Column | Type | Notes |
|--------|------|-------|
| `id` | SERIAL PK | |
| `artist_id` | FK → `artists` | ON DELETE CASCADE |
| `period_id` | FK → `artist_periods` | Optional grouping |
| `title` | VARCHAR(300) | |
| `year`, `year_end` | INTEGER | Creation date(s) |
| `description` | TEXT | |
| `image_path` | VARCHAR(500) | Full-size local file |
| `thumbnail_path` | VARCHAR(500) | Smaller variant for lists / 3D |
| `wikipedia_title` | VARCHAR(300) | Used by image fetcher |
| `sort_order` | INTEGER | |

### `painting_influences`

Directed edges: *this painting* was influenced by *that painting*.

| Column | Type | Notes |
|--------|------|-------|
| `id` | SERIAL PK | |
| `painting_id` | FK → `paintings` | The work being explained |
| `influenced_by_painting_id` | FK → `paintings` | The earlier / source work |
| `notes` | TEXT | Curator summary |
| `source` | VARCHAR(500) | General attribution |
| `aspects` | TEXT | What was borrowed (composition, colour, …) |
| `quote` | TEXT | Short citation |
| `source_author` | VARCHAR(200) | e.g. Gombrich, Janson |
| `source_url` | VARCHAR(500) | Reference link |

Unique constraint on `(painting_id, influenced_by_painting_id)`.

Used by the 3D gallery exit panel: predecessors are artists of `influenced_by_painting_id` works; successors are artists of paintings influenced by this artist’s works (see [API.md](API.md#get-apiartistsidnavigation)).

## Indexes

- `artists(movement_id)`, `artists(century)`
- `paintings(artist_id)`, `paintings(period_id)`
- `art_movements(era_id)`, `art_movements(start_year, end_year)`
- `painting_influences(painting_id)`, `painting_influences(influenced_by_painting_id)`

## First-time setup

The `gallery` database user needs `CREATE` on schema `public` for migrations. If tables cannot be created, run admin grants as PostgreSQL superuser before `npm run migrate`:

```sql
GRANT CREATE ON SCHEMA public TO gallery;
GRANT ALL PRIVILEGES ON ALL TABLES IN SCHEMA public TO gallery;
GRANT ALL PRIVILEGES ON ALL SEQUENCES IN SCHEMA public TO gallery;
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT ALL ON TABLES TO gallery;
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT ALL ON SEQUENCES TO gallery;
```

Then:

```bash
npm run migrate
npm run seed
npm run fetch-artist-bios
npm run expand-catalog
```

## Data conventions

- **Year zero** is not used; BCE years are negative integers.
- **Image paths** are relative to `IMAGE_DIR` (default `./data/images`), e.g. `portraits/Claude_Monet.jpg`, `paintings/thumbs/Raphael_The_School_of_Athens_thumb.jpg`.
- **Seeding cap**: curated ingest targets at most ~100 artists per century to keep the catalog manageable.
- **Catalog expansion**: `scripts/famous-paintings-data.js` plus `npm run expand-catalog` raises thin artist catalogs to at least six notable paintings (`MIN_PAINTINGS`, default 6).
- **Biographies**: `bio_short` and `bio_full` are populated by `npm run fetch-artist-bios` from English Wikipedia lead sections; `wikipedia_title` on the artist row is the source article.