aimedb/cmd.ts: Split into decoder, encoder

src/aimedb/decoder.ts

@@ -0,0 +1,96 @@
+import { Transform } from "stream";
+
+export class Decoder extends Transform {
+  constructor(options) {
+    super({
+      readableObjectMode: true,
+      writableObjectMode: true,
+      ...options,
+    });
+  }
+
+  static ident(chunk) {
+    const gameId = chunk.toString("ascii", 0x000a, 0x000e);
+    const keychipId = chunk.toString("ascii", 0x0014, 0x001f);
+
+    return { gameId, keychipId };
+  }
+
+  static cardId(chunk) {
+    const luid = chunk.slice(0x0020, 0x002a);
+
+    return { luid, ...Decoder.ident(chunk) };
+  }
+
+  static log(chunk) {
+    // idk what any of this stuff means yet
+    // field20 and field28 appear to be an aime id but that is all.
+
+    const field20 = chunk.readUInt32LE(0x20);
+    const field24 = chunk.readUInt32LE(0x24);
+    const field28 = chunk.readUInt32LE(0x28);
+    const field2C = chunk.readUInt32LE(0x2c);
+    const field30 = chunk.readUInt32LE(0x30);
+    const field34 = chunk.readUInt32LE(0x34);
+    const field38 = chunk.readUInt32LE(0x38);
+    const field3C = chunk.readUInt32LE(0x3c);
+
+    return {
+      field20,
+      field24,
+      field28,
+      field2C,
+      field30,
+      field34,
+      field38,
+      field3C,
+      ...Decoder.ident(chunk),
+    };
+  }
+
+  _transform(chunk, encoding, callback) {
+    const cmd = chunk.readUInt16LE(0x04);
+
+    switch (cmd) {
+      case 0x0005:
+        return callback(null, {
+          cmd: "register",
+          ...Decoder.cardId(chunk),
+        });
+
+      case 0x0009:
+        return callback(null, {
+          cmd: "log",
+          ...Decoder.log(chunk),
+        });
+
+      case 0x000b:
+        return callback(null, {
+          cmd: "campaign",
+          ...Decoder.ident(chunk),
+        });
+
+      case 0x000f:
+        return callback(null, {
+          cmd: "lookup",
+          ...Decoder.cardId(chunk),
+        });
+
+      case 0x0064:
+        return callback(null, {
+          cmd: "hello",
+          ...Decoder.ident(chunk),
+        });
+
+      case 0x0066:
+        return callback(null, {
+          cmd: "goodbye",
+        });
+
+      default:
+        return callback(null, {
+          cmd: `unknown_${cmd}`,
+        });
+    }
+  }
+}