Add a README.md with API documentation

Also fix some smaller issues found during writing the documentation

.idea/runConfigurations/All_in_briar_headless.xml

@@ -10,7 +10,7 @@
     <option name="TEST_OBJECT" value="package" />
     <option name="VM_PARAMETERS" value="" />
     <option name="PARAMETERS" value="" />
-    <option name="WORKING_DIRECTORY" value="file://$MODULE_DIR$" />
+    <option name="WORKING_DIRECTORY" value="file://$PROJECT_DIR$/briar-headless" />
     <option name="ENV_VARIABLES" />
     <option name="PASS_PARENT_ENVS" value="true" />
     <option name="TEST_SEARCH_SCOPE">

briar-headless/README.md

@@ -0,0 +1,180 @@
+# Briar REST API
+
+This is a headless Briar client that exposes a REST API
+with an integrated HTTP server instead of a traditional user interface.
+You can use this API to script the client behavior
+or to develop your own user interface for it.
+
+## How to use
+
+The REST API client comes as a `jar` file
+and needs a Java Runtime Environment (JRE).
+It currently works only on GNU/Linux operating systems.
+
+You can start the client (and its API server) like this:
+
+    $ java -jar briar-headless/build/libs/briar-headless.jar
+
+It is possible to put parameters at the end.
+Try `--help` for a list of options.
+
+On the first start, it will ask you to create a user account:
+
+    $ java -jar briar-headless.jar
+    No account found. Let's create one!
+
+    Nickname: testuser
+    Password:
+
+After entering a password, it will start up without further output.
+Use the `-v` option if you prefer more verbose logging.
+
+By default, Briar creates a folder `~/.briar` where it stores its database and other files.
+There you also find the authentication token which is required to interact with the API:
+
+    $ cat ~/.briar/auth_token
+    e175b010-e647-4440-ae8a-638d92ecfc8a
+
+You can test that things work as expected by running:
+
+    $ curl -H "Authorization: Bearer e175b010-e647-4440-ae8a-638d92ecfc8a" http://127.0.0.1:7000/v1/contacts
+    []
+
+The answer is an empty JSON array, because you don't have any contacts.
+Note you the HTTP request sets an `Authorization` header with the bearer token.
+A missing or wrong token will result in a `401` response.
+
+## REST API
+
+### Listing all contacts
+
+`GET /v1/contacts`
+
+Returns a JSON array of contacts:
+
+```json
+{
+    "author": {
+        "id": "y1wkIzAimAbYoCGgWxkWlr6vnq1F8t1QRA/UMPgI0E0=",
+        "name": "Test",
+        "publicKey": "BDu6h1S02bF4W6rgoZfZ6BMjTj/9S9hNN7EQoV05qUo="
+    },
+    "contactId": 1,
+    "verified": true
+}
+```
+
+### Adding a contact
+
+*Not yet implemented*
+
+The only workaround is to add a contact to the Briar app running on a rooted Android phone
+and then move its database (and key files) to the headless client.
+
+### Listing all private messages
+
+`GET /messages/{contactId}`
+
+The `{contactId}` is the `contactId` of the contact (`1` in the example above).
+It returns a JSON array of private messages:
+
+```json
+{
+    "body": "test",
+    "contactId": 1,
+    "groupId": "oRRvCri85UE2XGcSloAKt/u8JDcMkmDc26SOMouxr4U=",
+    "id": "ZGDrlpCxO9v7doO4Bmijh95QqQDykaS4Oji/mZVMIJ8=",
+    "local": true,
+    "read": true,
+    "seen": true,
+    "sent": true,
+    "timestamp": 1537376633850,
+    "type": "org.briarproject.briar.api.messaging.PrivateMessageHeader"
+}
+```
+
+If `local` is `true`, the message was sent by the Briar client instead of its remote contact.
+
+Attention: There can messages of other `type`s where the message `body` is `null`.
+
+### Writing a private message
+
+`POST /messages/{contactId}`
+
+The text of the message should be included in the form parameter `message`.
+
+### Listing blog posts
+
+`GET /v1/blogs/posts`
+
+Returns a JSON array of blog posts:
+
+```json
+{
+    "author": {
+        "id": "VNKXkaERPpXmZuFbHHwYT6Qc148D+KNNxQ4hwtx7Kq4=",
+        "name": "Test",
+        "publicKey": "NbwpQWjS3gHMjjDQIASIy/j+bU6NRZnSRT8X8FKDoN4="
+    },
+    "authorStatus": "ourselves",
+    "body": "Test Post Content",
+    "id": "X1jmHaYfrX47kT5OEd0OD+p/bptyR92IvuOBYSgxETM=",
+    "parentId": null,
+    "read": true,
+    "rssFeed": false,
+    "timestamp": 1535397886749,
+    "timestampReceived": 1535397886749,
+    "type": "post"
+}
+```
+
+### Writing a blog post
+
+`POST /v1/blogs/posts`
+
+The text of the blog post should be included in the form parameter `text`.
+
+## Websocket API
+
+The Briar client uses a websocket to notify a connected API client about new events.
+
+`WS /v1/ws`
+
+The authentication token needs to be provided with basic auth as the username
+while the password can be left empty.
+
+You can test connecting to the websocket with curl:
+
+    $ curl --no-buffer \
+           --header "Connection: Upgrade" \
+           --header "Upgrade: websocket" \
+           --header "Sec-WebSocket-Key: SGVsbG8sIHdvcmxkIQ==" \
+           --header "Sec-WebSocket-Version: 13" \
+           http://e175b010-e647-4440-ae8a-638d92ecfc8a@127.0.0.1:7000/v1/ws
+
+### Receiving new private messages
+
+When the Briar client receives a new private message,
+it will send a JSON object to connected websocket clients:
+
+```json
+{
+    "data": {
+        "body": "Test Message",
+        "contactId": 1,
+        "groupId": "oRRvCri85UE2XGcSloAKt/u8JDcMkmDc26SOMouxr4U=",
+        "id": "JBc+ogQIok/yr+7XtxN2iQgNfzw635mHikNaP5QOEVs=",
+        "local": false,
+        "read": false,
+        "seen": false,
+        "sent": false,
+        "timestamp": 1537389146088,
+        "type": "org.briarproject.briar.api.messaging.PrivateMessageHeader"
+    },
+    "name": "org.briarproject.briar.api.messaging.event.PrivateMessageReceivedEvent",
+    "type": "event"
+}
+```
+
+Note that the JSON object in `data` is exactly what the REST API returns
+when listing private messages.

briar-headless/src/main/java/org/briarproject/briar/headless/Router.kt

@@ -7,6 +7,7 @@ import io.javalin.apibuilder.ApiBuilder.*
 import io.javalin.core.util.ContextUtil
 import io.javalin.core.util.Header
 import org.briarproject.briar.headless.blogs.BlogController
+import org.briarproject.briar.headless.contact.ContactController
 import org.briarproject.briar.headless.forums.ForumController
 import org.briarproject.briar.headless.messaging.MessagingController
 import java.lang.Runtime.getRuntime
@@ -22,7 +23,7 @@ class Router @Inject
 constructor(
     private val briarService: BriarService,
     private val webSocketController: WebSocketController,
-    private val contactController: MessagingController,
+    private val contactController: ContactController,
     private val messagingController: MessagingController,
     private val forumController: ForumController,
     private val blogController: BlogController

briar-headless/src/main/java/org/briarproject/briar/headless/blogs/BlogController.kt

@@ -28,7 +28,7 @@ constructor(
                 val body = blogManager.getPostBody(header.id)
                 header.output(body)
             }
-        }
+        }.sortedBy { it.timestampReceived }
         return ctx.json(posts)
     }
 

briar-headless/src/main/java/org/briarproject/briar/headless/contact/OutputContact.kt

@@ -7,12 +7,12 @@ import javax.annotation.concurrent.Immutable
 
 @Immutable
 internal data class OutputContact(
-    val id: Int,
+    val contactId: Int,
     val author: OutputAuthor,
     val verified: Boolean
 ) {
     internal constructor(c: Contact) : this(
-        id = c.id.int,
+        contactId = c.id.int,
         author = c.author.output(),
         verified = c.isVerified
     )

briar-headless/src/main/java/org/briarproject/briar/headless/messaging/MessagingControllerImpl.kt

@@ -47,7 +47,7 @@ constructor(
                     header.output(contact.id, body)
                 }
             }
-        }
+        }.sortedBy { it.timestamp }
         return ctx.json(messages)
     }
 

briar-headless/src/test/java/org/briarproject/briar/headless/contact/ContactControllerTest.kt

@@ -29,7 +29,7 @@ internal class ContactControllerTest : ControllerTest() {
     fun testOutputContact() {
         val json = """
             {
-                "id": ${contact.id.int},
+                "contactId": ${contact.id.int},
                 "author": ${toJson(author.output())},
                 "verified": ${contact.isVerified}
             }