feat: updates from PR feedback

README.md

@@ -190,7 +190,12 @@ Print a new key pair. Does not change your current signing key
 
 Generate tokens that can be used as the `X-Auth-Secret` and `Authorization` headers required to use the UCAN-HTTP bridge.
 
-TODO: link to UCAN-HTTP bridge specification once it lands
+See the [UCAN Bridge specification](https://github.com/web3-storage/specs/blob/main/w3-ucan-bridge.md) for more information
+on how these are expected to be used.
+
+- `--can` One or more abilities to delegate.
+- `--expiration` Unix timestamp (in seconds) when the delegation is no longer valid. Zero indicates no expiration.
+- `--json` If set, output JSON suitable to splat into the `headers` field of a `fetch` request.
 
 ### `w3 can space info <did>`
 

bin.js

@@ -185,12 +185,12 @@ cli
   .option('-c, --can', 'One or more abilities to delegate.')
   .option(
     '-e, --expiration',
-    'Unix timestamp when the delegation is no longer valid. Zero indicates no expiration.',
+    'Unix timestamp (in seconds) when the delegation is no longer valid. Zero indicates no expiration.',
     0
   )
   .option(
-    '-o, --output',
-    'Path of file to write the exported delegation data to.'
+    '-j, --json',
+    'If set, output JSON suitable to spread into the `headers` field of a `fetch` request.'
   )
   .action(Bridge.generateTokens)
 

bridge.js

@@ -13,13 +13,14 @@ export { Account, Space }
  * @property {string} resource
  * @property {string[]|string} [can]
  * @property {number} [expiration]
+ * @property {boolean} [json]
  *
  * @param {string} resource
  * @param {BridgeGenerateTokensOptions} options
  */
 export const generateTokens = async (
   resource,
-  { can = ['store/add', 'upload/add'], expiration }
+  { can = ['store/add', 'upload/add'], expiration, json }
 ) => {
   const client = await getClient()
 
@@ -47,10 +48,19 @@ export const generateTokens = async (
     console.error(error)
     return process.exit(1)
   }
+  const xAuthSecret = base64url.encode(new TextEncoder().encode(password))
+  const authorization = base64url.encode(bytes)
 
-  console.log(`
-X-Auth-Secret header: ${base64url.encode(new TextEncoder().encode(password))}  
+  if (json) {
+    console.log(JSON.stringify({
+      "X-Auth-Secret": xAuthSecret,
+      "Authorization": authorization
+    }))
+  } else {
+    console.log(`
+X-Auth-Secret header: ${xAuthSecret}  
 
-Authorization header: ${base64url.encode(bytes)}
-`)
+Authorization header: ${authorization}
+    `)
+  }
 }