import NextImage from 'next/image'
import { Callout, Steps } from '@theguild/components'
import cdnTokenImage from '../../../../public/docs/pages/guides/cdn_token.png'
import historyImage from '../../../../public/docs/pages/guides/history.png'
import tokenImage from '../../../../public/docs/pages/guides/token.png'

# Single Schema Project

Once you've created a Hive project of type **Single Schema**, you can simply push your GraphQL
schema to the registry. This guide will guide you through the basics of schema pushing, checking and
fetching.

<Steps>

### Your GraphQL Schema

If you already have a GraphQL schema from your project, you can use it directly. The Hive CLI can
read GraphQL schemas from `.graphql` files in your local filesystem.

<Callout type="info">
  **Using code-first approach to write your GraphQL schema?**
  
  Please refer to the [Code-First Guide](/docs/other-integrations/code-first) to learn how to use the Hive with
code-first approach.

</Callout>

If you don't have a schema, you can use the following schema in this guide. Copy the contents into a
`schema.graphql` file and save it to your filesystem:

```graphql filename="schema.graphql" showLineNumbers
type Query {
  viewer: ViewerQuery!
  user(id: ID!): User!
}

type ViewerQuery {
  user: User!
  role: UserRole!
}

type User {
  id: ID!
  name: String!
  age: Int!
}

enum UserRole {
  USER
  ADMIN
}
```

### Hive CLI Access Token

As you may have noticed, Hive has created three targets under your project: `development`,
`staging`, and `production`. This guide will use the `development` target to explore the features
Hive offers.

To begin, select the `development` target under your Hive project and then choose the **Settings**
tab. On the Settings screen, you can manage your target's settings and access tokens.

Under the **Registry Access Tokens** section, click the **Generate new token** button. Give your
access token a name and select **Schema Check & Push** from the list of token presets:

<NextImage
  alt="Create Registry Token Form"
  src={tokenImage}
  className="mt-10 max-w-md rounded-lg drop-shadow-md"
/>

Click on **Generate Token** button and you should get your CLI token created, with permissions to
publish GraphQL schemas.

Make sure to copy your token and keep it safe. **You won't be able to see it again.**

<Callout type="info">
  **Note:** You can create multiple tokens with different permissions for different use cases.
</Callout>

### Publish your first schema

Now that you have your access token, you can publish your schema to the registry.

Run the following command in your terminal, to publish your `schema.graphql` to the registry
(replace `YOUR_TOKEN_HERE` with the token you have just created):

```bash
hive schema:publish \
  --registry.accessToken YOUR_TOKEN_HERE \
  schema.graphql
```

<Callout type="info">
  If you are running under a NodeJS project, make sure to include the `npx`, `yarn` or `pnpm` prefix
  to the command.
</Callout>

If everything goes well, you should see the following output:

```bash copy=false
✔ Published initial schema.
```

If you'll get to your target's page on Hive dashboard, you should see that it was updated with the
new schema you just published 🎉

<Callout type="info">
  You should also check out the **Explorer** tab: you can see the schema you just published, and
  explore the API types, fields, and arguments.
</Callout>

### Schema Checks

Hive can perform several checks on your schema before publishing it to the registry. You can use
Hive CLI to run these check and find potential breaking changes.

To see how schema checks works, let's make a small change to our schema.

Open the `schema.graphql` and make some breaking changes to your GraphQL schema.

First, we'll start with a non-breaking change - we'll add a new field to the `User` type:

```graphql {15} filename="schema.graphql" showLineNumbers
type Query {
  viewer: ViewerQuery!
  user(id: ID!): User!
}

type ViewerQuery {
  user: User!
  role: UserRole!
}

type User {
  id: ID!
  name: String!
  age: Int!
  location: String
}

enum UserRole {
  USER
  ADMIN
}
```

Now, run the Hive CLI with the `schema:check` command and your modified `schema.graphql` file:

```bash
hive schema:check \
  --registry.accessToken YOUR_TOKEN_HERE \
  schema.graphql
```

You should see that Hive successfully detect the change you made, and exists with a `0` exit code,
meaning that the schema is compatible, valid and has no breaking changes:

```bash copy=false
ℹ Detected 1 change

- Field location was added to object type User
```

Now, are going to introduce a breaking change. To do that, we'll change the type named `ViewerQuery`
to `Viewer`, and change the type of the `id` from `ID` to `String`:

```graphql {14,7,2} filename="schema.graphql" showLineNumbers
type Query {
  viewer: Viewer!
  user(id: ID!): User!
}

# We changed the name of the type from "ViewerQuery" to "Viewer"
type Viewer {
  user: User!
  role: UserRole!
}

type User {
  # We changed an existing field type from "ID" to "String"
  id: String!
  name: String!
  age: Int!
  location: String
}

enum UserRole {
  USER
  ADMIN
}
```

Now, run the Hive CLI with the `schema:check` command and your modified `schema.graphql` file:

```bash
hive schema:check \
  --registry.accessToken YOUR_TOKEN_HERE \
  schema.graphql
```

Now, you should see that Hive detected a breaking change, and exists with a `1` exit code, meaning
that the schema check failed:

```bash copy=false
✖ Detected 3 errors

- Breaking Change: Type ViewerQuery was removed
- Breaking Change: Field Query.viewer changed type from ViewerQuery! to Viewer!
- Breaking Change: Field User.id changed type from ID! to String!

ℹ Detected 5 changes

- Type ViewerQuery was removed
- Field Query.viewer changed type from ViewerQuery! to Viewer!
- Field User.id changed type from ID! to String!
- Type Viewer was added
- Field location was added to object type User
```

### Evolve your schema

Now that you have your schema published, you can evolve it over time. You can add new types, fields,
and implement new capabilities for your consumers.

Ideally, you should avoid making breaking changes to your GraphQL schema, as they may affect and
break consumers who rely on its naming and structure.

However, sometimes breaking changes are necessary to evolve schema. If you decide that a breaking
change is valid and necessary, you can still publish a schema with those changes to Hive. Just be
aware of the changes and be capable of adjusting your application to them.

To publish your latest schema with breaking changes, use the `schema:publish` command.

Let's publish the schema we previously modified:

```bash
hive schema:publish \
  --registry.accessToken YOUR_TOKEN_HERE \
  schema.graphql
```

You should see now that Hive accepted your published schema and updated the registry:

```bash copy=false
✔ Schema published
```

It's a good timing to check the **History** tab of your Hive target. You should see that a new
schema is published now, and you can see the changes you made:

<NextImage
  alt="Schema History"
  src={historyImage}
  className="mt-10 max-w-2xl rounded-lg drop-shadow-md"
/>

### Fetch your schema

Now that your GraphQL schema is stored in the Hive registry, you can access and fetch it through
Hive's CDN (Content Delivery Network).

The Hive Cloud service leverages the
[CloudFlare Global Network](https://www.cloudflare.com/network/) to deliver your GraphQL schema and
schema metadata. This means that your schema will be available from the nearest location to your
GraphQL gateway, with 100% uptime, regardless of Hive's status. This ensures that everything
required for your GraphQL API is always available, and reduces the risk of depending on Hive as a
single point of failure. [You can read more about Hive's CDN here](/docs/high-availability-cdn).

To get started with Hive's CDN access, you'll need to create a CDN token from your target's
**Settings** page. You'll see a separate section for managing and creating CDN tokens, called **CDN
Access Token**.

Click on **Create new CDN Token** to create a new CDN token. Describe your token with an alias, and
click **Create**. Please store this access token securely. **You will not be able to see it again.**

<Callout type="info">
**Why are Registry and CDN tokens different?**

We use a separate, externally managed storage to manage CDN tokens to ensure high availability of
your schemas. This approach ensures that your GraphQL schemas are fully secured and highly
available. CDN tokens are read-only and can only fetch schemas from the CDN. They do not have
permissions to perform any other action on your Hive organization.

</Callout>

To use your access token, go to your target's page on Hive's dashboard and click on the **Connect to
CDN** button. You will see a screen with instructions on how to obtain different types of artifacts
from the CDN. For this guide, you can pick the **GraphQL SDL** artifact.

<NextImage
  alt="CDN Token Form"
  src={cdnTokenImage}
  className="mt-10 max-w-2xl rounded-lg drop-shadow-md"
/>

Copy the URL and let's try to fetch your schema using `curl` (replace `YOUR_HIVE_CDN_TOKEN` with
your CDN token, and `CDN_ENDPOINT_HERE` with the endpoint you copied from Hive's dashboard):

```bash
curl -L -H "X-Hive-CDN-Key: YOUR_HIVE_CDN_TOKEN" CDN_ENDPOINT_HERE
```

You should see that Hive CDN returns your full GraphQL schema as an output for that command.

### Next Steps

Now that you use the basic functionality of Hive as a schema registry, we recommend following other
powerful features of Hive:

- [CI/CD Integration](/docs/other-integrations/ci-cd)
- [Usage Reporting and Monitoring](/docs/schema-registry/usage-reporting)
- [Conditional Breaking Changes](/docs/management/targets#conditional-breaking-changes)
- [Alerts and Notifications](/docs/management/projects#alerts-and-notifications)
- [Schema Policies](/docs/schema-registry/schema-policy)

</Steps>
