# File Uploads and Downloads

The SDK supports file uploads and downloads through the Marketplace API. The
upload flow is a three-step process: first register the file with the Marketplace
API, then request a presigned upload URL, and finally upload the file directly
to cloud storage. The SDK provides helper functions in `sharetribe-flex-sdk/file`
to make this easier.

## File helper functions

The `file` module exported from the SDK contains two helper functions.

```js
const sharetribeSdk = require('sharetribe-flex-sdk');
const { file } = sharetribeSdk;
```

### `file.metadata(file)`

Extracts the metadata needed for the first step of the upload flow,
`sdk.ownFiles.create()`, from a browser
[`File`](https://developer.mozilla.org/en-US/docs/Web/API/File) object.

**Parameters:**

| Name | Type | Description |
| --- | --- | --- |
| `file` | `File` | A browser `File` object, e.g. from an `<input type="file">` element |

**Returns:** An object with the following properties:

| Name | Type | Description |
| --- | --- | --- |
| `name` | `string` | The file name |
| `mimeType` | `string` | The MIME type of the file |
| `size` | `number` | The file size in bytes |

**Example:**

```js
const fileInput = document.querySelector('input[type="file"]');
const selectedFile = fileInput.files[0];

const metadata = file.metadata(selectedFile);
// { name: 'photo.jpg', mimeType: 'image/jpeg', size: 123456 }
```

### `file.upload({ method, url, headers, file, onUploadProgress })`

Uploads a file directly to cloud storage using a presigned URL obtained from
`sdk.fileUploads.create()`.

**Parameters:**

| Name | Type | Required | Description |
| --- | --- | --- | --- |
| `url` | `string` | Yes | The presigned upload URL — taken from `attributes.url` in the `sdk.fileUploads.create()` response |
| `file` | `File` | Yes | The file to upload |
| `method` | `string` | No | HTTP method — taken from `attributes.method` in the `sdk.fileUploads.create()` response, defaults to `'PUT'` |
| `headers` | `object` | No | Additional HTTP headers — taken from `attributes.headers` in the `sdk.fileUploads.create()` response |
| `onUploadProgress` | `function` | No | Callback called with a [ProgressEvent](https://developer.mozilla.org/en-US/docs/Web/API/ProgressEvent) as the file uploads |

**Returns:** A Promise that resolves when the upload is complete.

**Example:**

```js
file.upload({
  url: 'https://storage.example.com/presigned-upload-url',
  file: selectedFile,
  onUploadProgress: (progressEvent) => {
    const percent = Math.round((progressEvent.loaded * 100) / progressEvent.total);
    console.log(`${percent}% uploaded`);
  },
});
```

## Uploading a file

Uploading a file requires three steps:

1. Register the file with the Marketplace API with `sdk.ownFiles.create()`
2. Request a presigned upload URL with `sdk.fileUploads.create({ fileId })`
3. Upload the file directly to cloud storage with `file.upload()`

**Example:**

```js
const sharetribeSdk = require('sharetribe-flex-sdk');
const { file, types } = sharetribeSdk;
const { UUID } = types;

const sdk = sharetribeSdk.createInstance({
  clientId: 'your-client-id',
});

const fileInput = document.querySelector('input[type="file"]');
const selectedFile = fileInput.files[0];
const metadata = file.metadata(selectedFile);

// Step 1: Register the file with the Marketplace API
sdk.ownFiles.create({
  name: metadata.name,
  mimeType: metadata.mimeType,
  size: metadata.size,
})
  .then(ownFileResponse => {
    const fileId = ownFileResponse.data.data.id;

    // Step 2: Request a presigned upload URL for this file
    return sdk.fileUploads.create({ fileId })
      .then(uploadResponse => ({ fileId, uploadResponse }));
  })
  .then(({ uploadResponse }) => {
    const { method, url, headers } = uploadResponse.data.data.attributes;

    // Step 3: Upload the file directly to cloud storage
    return file.upload({ method, url, headers, file: selectedFile });
  })
  .then(() => {
    console.log('File uploaded successfully');
  })
  .catch(e => {
    console.error('Upload failed:', e);
  });
```

## Tracking upload progress

Pass `onUploadProgress` to `file.upload()` to track upload progress.

**Example:**

```js
const logProgress = (progressEvent) => {
  const percent = Math.round((progressEvent.loaded * 100) / progressEvent.total);
  console.log(`${percent}% uploaded`);
};

file.upload({ method, url, headers, file: selectedFile, onUploadProgress: logProgress });
```

## Downloading a file

To download a file, use `sdk.ownFileDownloads.create()` for files owned by the
current user, or `sdk.fileDownloads.create()` for other accessible files. Both
endpoints return a short-lived download URL that can be used to retrieve the
file content.

**Example:**

```js
const { UUID } = require('sharetribe-flex-sdk').types;

// Download a file owned by the current user
sdk.ownFileDownloads.create({ fileId: new UUID('a5d04285-07da-4fa0-b80b-ebabb8bac9e5') })
  .then(response => {
    const downloadUrl = response.data.data.attributes.url;
    window.location.href = downloadUrl;
  });

// Download a file accessible to the current user (e.g. from a transaction)
sdk.fileDownloads.create({ fileId: new UUID('a5d04285-07da-4fa0-b80b-ebabb8bac9e5') })
  .then(response => {
    const downloadUrl = response.data.data.attributes.url;
    window.location.href = downloadUrl;
  });
```