Add API documentation and example

Api.md

@@ -0,0 +1,164 @@
+<!-- TOC -->
+
+- [OpenAPI specification](#openapi-specification)
+- [Example discord/gitter/api gateway](#example-discordgitterapi-gateway)
+    - [Configure matterbridge.toml](#configure-matterbridgetoml)
+    - [Get the messages from the buffer (GET /api/messages)](#get-the-messages-from-the-buffer-get-apimessages)
+    - [Stream messages (GET /api/stream)](#stream-messages-get-apistream)
+    - [Send message (POST /api/message)](#send-message-post-apimessage)
+- [Security](#security)
+- [Projects using the API](#projects-using-the-api)
+
+<!-- /TOC -->
+
+## OpenAPI specification
+
+Matterbridge API spec can be found on https://app.swaggerhub.com/apis-docs/matterbridge/matterbridge-api/0.1.0-oas3
+
+## Example discord/gitter/api gateway
+
+This example creates a gateway containing 3 bridges: discord,gitter and api.   
+The API will listen on localhost port 4242.
+
+### Configure matterbridge.toml
+
+This is based on the example in https://github.com/42wim/matterbridge/wiki/How-to-create-your-config
+
+We first add the API account configuration to this example, this makes the API listen on localhost port 4242 with a buffer of 1000 messages and the nicks we receive will look like "{nick}".
+
+```toml
+[api.myapi]
+BindAddress="127.0.0.1:4242"
+Buffer=1000
+RemoteNickFormat="{NICK}"
+```
+
+Next we add the API gateway configuration, this make sure that we receive the messages from the other bridges and we can sent them.
+
+```toml
+[[gateway.inout]]
+account="api.myapi"
+channel="api"
+```
+
+The full example
+
+```toml
+[discord.mydiscord]
+Token="MTk4NjIyNDgzNDcdOTI1MjQ4.Cl2FMZ.ZnCjm1XVW7vRze4b7Cq4se7kKWs-abD"
+Server="myserver"
+
+[gitter.mygitter]
+Token="319fda1761c6875739a489b6772daf2ace4b95d0"
+
+[api.myapi]
+BindAddress="127.0.0.1:4242"
+Buffer=1000
+RemoteNickFormat="{NICK}"
+
+[[gateway]]
+name="gateway1"
+enable=true
+
+[[gateway.inout]]
+account="discord.mydiscord"
+channel="general"
+
+[[gateway.inout]]
+account="gitter.mygitter"
+channel="42wim/mygreatproject"
+
+[[gateway.inout]]
+account="api.myapi"
+channel="api"
+```
+
+### Get the messages from the buffer (GET /api/messages)
+
+If we now type a "test" message in our "general" channel on discord, we get the following result
+
+```bash
+$ curl http://localhost:4242/api/messages
+```
+
+
+```json
+[
+ {
+  "text": "test",
+  "channel": "general",
+  "username": "wim",
+  "userid": "227183123686215680",
+  "avatar": "https://cdn.discordapp.com/avatars/227183947686215680/bd0e6c7fe63274597a4684884891b79d.jpg",
+  "account": "discord.mydiscord",
+  "event": "",
+  "protocol": "",
+  "gateway": "gateway1",
+  "parent_id": "",
+  "timestamp": "2019-01-09T22:37:18.647108348+01:00",
+  "id": "",
+  "Extra": null
+ }
+]
+```
+
+After we got this message (and we didn't type anything else), the buffer will be empty and doing a curl will now give an empty result
+
+```bash
+$ curl http://localhost:4242/api/messages
+```
+
+```json
+[]
+```
+
+### Stream messages (GET /api/stream)
+
+If we now type a "test" message in our "general" channel on discord, we get the following result
+
+```bash
+$ curl http://localhost:4242/api/stream
+```
+
+```json
+{"text":"","channel":"","username":"","userid":"","avatar":"","account":"","event":"api_connected","protocol":"","gateway":"","parent_id":"","timestamp":"2019-01-09T22:48:33.398737344+01:00","id":"","Extra":null}
+{"text":"test","channel":"general","username":"wim","userid":"227183123686215680","avatar":"https://cdn.discordapp.com/avatars/227183947686215680/bd0e6c7fe63274597a4684884891b79d.jpg","account":"discord.mydiscord","event":"","protocol":"","gateway":"gateway1","parent_id":"","timestamp":"2019-01-09T22:48:42.506629373+01:00","id":"","Extra":null}
+```
+
+At connect you first get a `api_connected` event, then you'll get a http stream of json messages
+
+### Send message (POST /api/message)
+
+We now post a `test` message from `randomuser` to the gateway `gateway1`
+
+Every bridge on the gateway (gitter and discord) will now receive this message.
+
+```bash
+curl -XPOST -H 'Content-Type: application/json'  -d '{"text":"test","username":"randomuser","gateway":"gateway1"}' http://localhost:4242/api/message
+```
+
+```json
+{"text":"test","channel":"api","username":"randomuser","userid":"","avatar":"","account":"api.local","event":"","protocol":"api","gateway":"gateway1","parent_id":"","timestamp":"2019-01-09T22:53:51.618575236+01:00","id":"","Extra":null}
+```
+
+## Security
+You can also protect the API with a token by adding a `token` option to your api account configuration.
+
+```toml
+[api.myapi]
+BindAddress="127.0.0.1:4242"
+Buffer=1000
+RemoteNickFormat="{NICK}"
+Token="verys3cret"
+```
+If you now want to sent a message with curl you'll have to add a `Authorization: Bearer <token>` header
+
+```bash
+curl -H "Authorization: Bearer verys3cret" http://localhost:4242/api/stream
+```
+
+## Projects using the API
+
+* [MatterLink](https://github.com/elytra/MatterLink) (Matterbridge link for Minecraft Server chat)
+* [pyCord](https://github.com/NikkyAI/pyCord) (crossplatform chatbot)
+* [Mattereddit](https://github.com/bonehurtingjuice/mattereddit) (Reddit chat support)

Features.md

@@ -61,5 +61,5 @@ See webhook in advanced for specific bridge information TODO
 Private groups are supported for Mattermost and Slack
 
 # API
-TODO
+See [[Api]]
 

Home.md

@@ -3,6 +3,9 @@ Welcome to the matterbridge wiki!
 ### FAQ
 The [[FAQ]]  
 
+### API
+See [[Api]]
+
 ### Features
 [[Features]]
 
@@ -11,4 +14,4 @@ Some simple steps to create your configuration: [[How-to-create-your-config]]
 
 ### Screenshots
 Screenshots matrix/gitter/slack/discord/mattermost/irc
-![](https://i.snag.gy/kKs309.jpg)
+![](https://i.snag.gy/kKs309.jpg)