Use the latest Velocity API.

Implement API server for online players and server status.
Implement core message routing abstraction and concrete BungeeCross, Velocity, Telegram endpoint impl.
Load config from config file "crosslink/config.json".
Test core components. Proxy API related stuff are not tested.
Add README in English and Chinese.

TODO: Add config hot reloading. More configurable system. PSMB endpoint impl.

1 files changed, 155 insertions, 0 deletions

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+# CrossLink: 基于规则路由的 BungeeCord/Velocity 消息互联框架
+
+CrossLink 的目的是连接Minecraft群组服务器和即时通讯软件。
+
+CrossLink 将每个子服务器的聊天窗口视为独立的端点，将每个即时通讯软件的群聊也视为独立的端点。
+服务器管理员编写配置文件，描述消息将如何在这些端点之间互相转发，从而让玩家无论在哪个子服务器
+或者哪个即时通讯软件里，都可以在一起聊天。
+
+路由策略可根据需求灵活配置。由于 CrossLink 的代码完全不关心消息该从哪出现、又要被发送到哪里，
+因此转发操作可被用户完全控制。用户将`按来源过滤`、`按内容过滤`、`字符串替换`、`丢弃`、`转发`
+这些**基本操作（action）** 组合成为**路由规则（rule）**，有限个路由规则的有序排列形成**路由表**。
+CrossLink 按照路由表转发消息，基本操作的组合可实现自由而强大的消息转发，从而
+提供高度定制化的 Minecraft 群组服务器消息互联方案。
+
+
+# 运行环境
+
+- Minecraft 反向代理服务器：
+  - BungeeCord （未测试，理论上完全兼容）
+  - Waterfall （在 `waterfall-1.18-470` 版本测试通过）
+  - Velocity （在 `velocity-3.1.1-98` 版本测试通过）
+
+- Java 运行时环境：
+  - OpenJDK 17 （在 `OpenJDK 64-Bit Server VM (build 17.0.1+12-LTS, mixed mode, sharing)` 版本测试通过）
+
+
+# 配置说明
+
+1. 在插件目录 `plugins` 里放置插件 `.jar` 文件。
+2. 在此目录下新建子目录 `crosslink`。
+3. 在子目录 `crosslink` 下新建 `messaging.json` 文本文件和 `api.json` 文本文件。
+4. 按照以下样例编写配置文件。
+
+## `messaging.json` 示例
+
+```json5
+{
+    "remotes": [
+        {
+          "type": "telegram",
+          "id": "Telegram",                       // this endpoint is identified with "remote:Telegram"
+          "enabled": true,                        // default: true, if set to false, this remote will be ignored
+          "token": "======SECRET======",          // Telegram Bot token
+          "chat_id": 123456789,                   // repeat to and from this chat
+          "proxy": "socks://127.0.0.1:10809",     // connect to Telegram API using this proxy
+          "api": "https://my-telegram-api.com"    // url to custom Telegram API
+        },
+         {
+             "type": "psmb",            // psmb is a special case, since it is not an endpoint
+             "id": "mypsmb",            // this stub endpoint is identified with "remote:mypsmb"
+             "enabled": true,           // but it creates zero or one or more than one sub "virtual" endpoints
+             "host": "1.onesmp.org",
+             "port": 3456,
+             "subscribe_to": "chat_.+", // psmb subscription pattern
+                                        // for example: if you have topic chat_1 and chat_2
+                                        // then they are identified with "remote:mypsmb:chat_1" and "remote:mypsmb:chat_2"
+                                        // dispatching messages from "remote:mypsmb" to virtual endpoints
+                                        // such as "remote:mypsmb:chat_1", is done by psmb stub endpoint
+             "topics": [                // all topics this endpoint can actually "see"
+                 "chat_qq",             // regexp in "subscribe_to" and action route "to"
+                 "chat_wechat"          // will only match endpoints declared in this list
+             ]
+         },
+         {
+             "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": [{
+                "type": "format",
+                "color": "green"
+            }, {                      // actions run sequentially
+                "type": "route",      // route this message to matched destinations
+                "to": "server:.*"     // regexp matching destination  
+            }]
+        },
+        {
+            // outbound messages (starting with '#', server -> all remotes)
+            "object": "chat_message",
+            "from": "server:.*",
+            "actions": [{
+                "type": "filter",     // filter the message using given regexp
+                                      // if the message does not match given pattern,
+                                      // it won't be passed into subsequent actions
+                "pattern": "#.+"      // match all messages starts with char '#'
+            }, {
+                "type": "replace",    // replace the message, removing heading '#'
+                "from": "^#(.*)",     // capture all chars after the heading '#'
+                "to": "$1"            // and make them as the output
+            }, {
+                "type": "route",      // send the message to all remotes
+                "to": "remote:.*"
+            }]
+        },
+        {
+            // cross-server messages (server -> all other servers)
+            "object": "chat_message",
+            "from": "server:.*",
+            "actions": [{
+                "type": "route",
+                "to": "server:.*",
+                "backflow": false      // do not repeat to sender, true by default
+                                       // since the destination pattern will match the source,
+                                       // we have to set backflow to false to prevent
+                                       // players from seeing duplicate messages
+            }]
+        }
+    ]
+}
+```
+
+## `api.json` 示例
+
+```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
+}
+```
+
+
+# 开源声明
+
+CrossLink 至今的所有版本均在 GPLv3 协议下开源，您可以在 [CrossLink 项目主页](https://github.com/keuin/crosslink) 上找到他的源代码。
+CrossLink 基于许多开源组件，这些开源组件的许可协议和声明可以在他们的项目主页找到：
+
+- [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)
+- [gson](https://github.com/google/gson)
+- [java-telegram-bot-api](https://github.com/pengrad/java-telegram-bot-api)
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