add download method for provider

src/provider/Provider.ts

@@ -1,7 +1,7 @@
 import Account from '../ocean/Account'
 import { noZeroX } from '../utils'
 import { Instantiable, InstantiableConfig } from '../Instantiable.abstract'
-import { DDO } from '../ddo/DDO'
+import { File } from '../ddo/interfaces/File'
 
 const apiPath = '/api/v1/services/'
 
@@ -102,6 +102,43 @@ export class Provider extends Instantiable {
         }
     }
 
+    public async download(
+        did: string,
+        txId: string,
+        tokenAddress: string,
+        serviceType: string,
+        serviceIndex: string,
+        destination: string,
+        account: Account,
+        files: File[],
+        index: number = -1
+    ): Promise<any> {
+        const signature = await this.createSignature(account, did)
+        const filesPromises = files
+            .filter((_, i) => index === -1 || i === index)
+            .map(async ({ index: i }) => {
+                let consumeUrl = this.getDownloadEndpoint()
+                consumeUrl += `?index=${i}`
+                consumeUrl += `&documentId=${did}`
+                consumeUrl += `&serviceId=${serviceIndex}`
+                consumeUrl += `&serviceType=${serviceType}`
+                consumeUrl += `tokenAddress=${tokenAddress}`
+                consumeUrl += `&transferTxId=${txId}`
+                consumeUrl += `&consumerAddress=${account.getId()}`
+                consumeUrl += `&signature=${signature}`
+
+                try {
+                    await this.ocean.utils.fetch.downloadFile(consumeUrl, destination, i)
+                } catch (e) {
+                    this.logger.error('Error consuming assets')
+                    this.logger.error(e)
+                    throw e
+                }
+            })
+        await Promise.all(filesPromises)
+        return destination
+    }
+
     public async getVersionInfo() {
         return (await this.ocean.utils.fetch.get(this.url)).json()
     }