relationships

import { DB } from 'ai-database'

const { db } = DB({
  Post: { title: 'string', author: 'Author.posts' },
  Author: { name: 'string' },
})

const { db } = DB({
  Post: {
    title: 'string',
    author: 'Author.posts',  // one-to-many
    tags: ['Tag.posts'],     // many-to-many
  },
  Author: {
    name: 'string',
    // posts: Post[] auto-created
  },
  Tag: {
    name: 'string',
    // posts: Post[] auto-created
  },
})

// Forward
const post = await db.Post.get('hello')
const author = await post.author  // Author

// Backward
const author = await db.Author.get('alice')
const posts = await author.posts  // Post[]

// Post has one author, Author has many posts
Post: {
  author: 'Author.posts',
}

// Post has many tags, Tag has many posts
Post: {
  tags: ['Tag.posts'],
}

// User has one profile, Profile has one user
User: {
  profile: 'Profile.user',
}

// Create author
const author = await db.Author.create({ name: 'Alice' })

// Create post with relationship
const post = await db.Post.create({
  title: 'Hello',
  content: '...',
  author: author.$id,  // relationship by ID
})

// Posts by verified authors
const posts = await db.Post.find({
  $rel: {
    type: 'authored',
    from: { type: 'Author', where: { verified: true } },
  },
})

// Edge: Post.author -> Author
{
  from: 'Post',
  name: 'author',
  to: 'Author',
  backref: 'posts',
  cardinality: 'many-to-one',
}

// Query edges for introspection
const edges = await db.Edge.find({ to: 'Author' })
// What types reference Author?