# i18n README

| Language     | File                               |
|--------------|------------------------------------|
| English (US) | [README.md](README.md)             |
| 简体中文         | [README_zh_CN.md](README_zh_CN.md) |


# 1. CrossLink: rule-based intercommunicating framework for BungeeCord and Velocity

CrossLink aims at bridging Minecraft chats and instant messaging platforms together.
CrossLink is a refactor of the legacy [BungeeCross](https://github.com/hit-mc/BungeeCross).
Heavy rewrite has been made to improve the software quality.

CrossLink treats all chat areas in sub-servers of a Minecraft server group as separate *endpoint*s. Different instant
messaging software are also different endpoints. Server operator creates configuration files, which describes how the
messages should be *routed* among distinct endpoints. This enables people from different Minecraft sub-server chats
and even different instant messaging platforms, chat together, in a tidy way.

Message forwarding is very configurable. CrossLink does not concern about where the messages come from,
or where they will ultimately go. The forwarding process is entirely controlled by the server operator.
Server operator combines **actions** like `filter by source`, `filter by content`, `replace by regexp`, `discard`
and `forward` into **rules**. Some sequential rules line up a routing table. CrossLink forward messages according to
the routing table. The combinations of **actions** are versatile to help build a highly configurable 
message forwarding system among grouped Minecraft servers and instant messaging platforms.

Currently, only Telegram is supported as an instant messaging platform.
If you wish to link to other instant messaging platforms, implementing that protocol in a *standalone* program
is encouraged, which could be linked to CrossLink with `psmb` protocol.


# 2. Environment Requirement

- Minecraft reverse proxy server：
    - BungeeCord (not tested, compatible in theory)
    - Waterfall (tested in `waterfall-1.18-470`)
    - Velocity (tested in `velocity-3.1.1-98`)

- Java Runtime：
    - OpenJDK 17 (tested in `OpenJDK 64-Bit Server VM (build 17.0.1+12-LTS, mixed mode, sharing)`)


# 3. Configuration

1. Copy plugin's `.jar` file to `plugins` folder.
2. Create subdirectory `crosslink` in that folder.
3. Create `messaging.json` and `api.json` in the folder created in previous step.
4. Copy and edit configuration like the examples below.

## 3.1 Example `messaging.json`

```json5
{
  "local": {
    // when a player joins the game,
    // show him recent messages sent before he has joined the server,
    // which live no longer than this time.
    // set a non-positive value to disable this feature
    "message_playback_seconds": 600
  },
  "remotes": [
    {
      "type": "telegram",
      // this endpoint is identified with "remote:Telegram"
      "id": "Telegram",
      // default: true, if set to false, this remote will be ignored
      "enabled": true,
      // Telegram Bot token
      "token": "======SECRET======",
      // repeat to and from this chat
      "chat_id": 123456789,
      // connect to Telegram API using this proxy
      "proxy": "socks://127.0.0.1:10809",
      // url to custom Telegram API
      "api": "https://my-telegram-api.com"
    },
    {
      "type": "psmb",
      // this endpoint is identified as "remote:mypsmb"
      "id": "mypsmb",
      // but it creates zero or one or more than one sub "virtual" endpoints
      "enabled": true,
      "host": "1.onesmp.org",
      "port": 3456,
      // messages sent to this endpoint will be published to the psmb topic whose id is 'subscribe_to'
      "publish_to": "chat_mc",
      // messages from topics matched by this pattern will be present on this endpoint
      "subscribe_from": "chat_im*",
      // the unique subscription client id required by psmb protocol
      "subscriber_id": 1314,
      // send keep alive packet in every 20 seconds
      // if the value is ignored or not positive, keepalive will be disabled
      "keepalive": 20000
    },
    {
      // not implemented yet, may be added in future version
      "type": "json-rpc",
      "id": "rpc",
      "enabled": true,
      "listen": ["127.0.0.1", 8008],
      "methods": {
        "get": "getMessage",
        "put": "sendMessage"
      }
    }
  ],
  "routing": [
    // all rules are processed sequentially
    // a message may match multiple rules and thus may be duplicate in your case
    // if the message is dropped in an action in one rule,
    // (the action type is just "drop" and it does not have any argument)
    // all subsequent rules will NOT see this message
    {
      // inbound chat messages (remote -> all servers)
      "object": "chat_message",
      // match chat messages
      "from": "remote:.*",
      // regexp matching source,
      // only messages with matched source will be
      // processed by this rule, otherwise this rule is skipped
      "actions": [
        // actions run sequentially
        {
          "type": "format",
          "color": "green"
        },
        {
          // route this message to matched destinations
          "type": "route",
          // the regexp matching destinations
          "to": "server:.*"
        }
      ]
    },
    {
      // outbound messages (starting with '#', server -> all remotes)
      "object": "chat_message",
      "from": "server:.*",
      "actions": [
        {
          // filter the message using given regexp
          // if the message does not match given pattern,
          // it won't be passed into subsequent actions
          "type": "filter",
          // match all messages starts with char '#'
          "pattern": "#.+"
        },
        {
          // replace the message
          "type": "replace",
          // removing heading '#' capture all chars after the heading '#'
          // and make them as the output
          "from": "^#(.*)",
          "to": "$1"
        },
        {
          // send the message to all remotes
          "type": "route",
          "to": "remote:.*"
        }
      ]
    },
    {
      // cross-server messages (server -> all other servers)
      "object": "chat_message",
      "from": "server:.*",
      "actions": [
        {
          "type": "route",
          "to": "server:.*",
          // do not repeat to sender, true by default
          // since the destination pattern will match the source,
          // setting backflow to false will prevent
          // players from seeing duplicate messages
          "backflow": false
        }
      ]
    }
  ]
}
```

## 3.2 Example `api.json`

```json5
{
    "host": "127.0.0.1",        // which host to listen on
    "port": 8008,               // which port to listen on
    "token": "===secret==="     // if defined, only requests with GET parameter `token`
                                // which equals to this value will be processed
                                // invalid requests will only get a 403 error
}
```


# 4. Open-source notice

CrossLink is a free software and licensed under GPLv3.
You can find the source code in [CrossLink's Homepage](https://github.com/keuin/crosslink).

CrossLink is made with the help of many open-source libraries. You can obtain the licenses and notices from their homepage:

- [java-annotations](https://github.com/JetBrains/java-annotations)
- [junit-5](https://github.com/junit-team/junit5)
- [Time4J](https://github.com/MenoData/Time4J)
- [Guice](https://github.com/google/guice)
- [adventure](https://github.com/KyoriPowered/adventure)
- [jackson-core](https://github.com/FasterXML/jackson-core)
- [java-telegram-bot-api](https://github.com/pengrad/java-telegram-bot-api)
- [bson](https://mvnrepository.com/artifact/org.mongodb/bson)