## Get the redirect URL

This endpoint returns the URL where you should redirect your customer to complete their payment.
The URL is specific to the payment method that was selected.

You should only call this endpoint after `discover-next-action` returns `REDIRECT`. The URL may not
be ready immediately after creating the payment session - in this case you'll receive a `NOT_READY`
error and should try again in a few seconds.

After redirecting the customer, you should continue polling `discover-next-action` in the background
to know when they've completed the payment flow.

Note: Not all payment methods require redirection. For methods that don't support redirection,
you'll receive a `NOT_SUPPORTED` error.

## Endpoint signature

```http
POST https://api.reservepay.com/sdk/get-redirect-url HTTP/1.1
Content-Type: application/json
Accept: application/json

{
  merchant_id: string,
  installation_id: string,
  payment_session_id: string,
}
```

Returns: string

## Request arguments

### `merchant_id` (string)

**Required**. Your merchant ID that uniquely identifies your account.

### `installation_id` (string)

**Required**. The installation ID for this platform (e.g. your iOS app, Android app, website, or terminal).

### `payment_session_id` (string)

**Required**. The ID of the payment session returned from `select-payment-method`.

## Errors specific to this endpoint

### `NOT_FOUND`

This error occurs when we cannot find the merchant account, installation, or payment session with the IDs provided. Double check that you are using the correct IDs.

### `NOT_READY`

This error occurs when the redirect URL is not yet ready. Wait a few seconds and try again.

### `NOT_SUPPORTED`

This error occurs when trying to get a redirect URL for a payment method that doesn't support redirection (like QR codes).

## Errors common to all endpoints

### `UNHANDLED_ERROR`

This error occurs when the server encounters an unexpected internal error that it cannot handle gracefully. This typically happens due to bugs, infrastructure issues, or edge cases that weren't anticipated during development.

### `INVALID_ARGUMENTS`

This error occurs when the request contains invalid or missing parameters. Common cases include missing required fields, or values that don't match the expected format or type.

### `BAD_VERSION`

This error occurs when making requests to an API version that is either deprecated or not yet released. This commonly happens when using an outdated SDK or when the API version specified in the request URL is incorrect.