Add pipeline, scope out entrypoint.example.ts

entrypoint.example.ts

@@ -1,4 +1,22 @@
 #!/bin/sh
 //bin/true; exec deno run -A "$0" "$@"
+import {
+  antiDuplicationPolicy,
+  hellthreadPolicy,
+  noopPolicy,
+  pipeline,
+  rateLimitPolicy,
+  readStdin,
+  writeStdout,
+} from './mod.ts';
 
-// TODO
+const msg = await readStdin();
+
+const result = await pipeline(msg, [
+  noopPolicy,
+  hellthreadPolicy,
+  antiDuplicationPolicy,
+  rateLimitPolicy,
+]);
+
+writeStdout(result);

mod.ts

@@ -3,3 +3,6 @@ export { default as hellthreadPolicy } from './src/policies/hellthread-policy.ts
 export { default as noopPolicy } from './src/policies/noop-policy.ts';
 export { default as rateLimitPolicy } from './src/policies/rate-limit-policy.ts';
 export { default as readOnlyPolicy } from './src/policies/read-only-policy.ts';
+
+export { readStdin, writeStdout } from './src/io.ts';
+export { default as pipeline } from './src/pipeline.ts';

src/io.ts

@@ -1,6 +1,6 @@
 import { readLines } from './deps.ts';
 
-import type { InputMessage } from './types.ts';
+import type { InputMessage, OutputMessage } from './types.ts';
 
 /**
  * Get the first line from stdin.
@@ -11,4 +11,9 @@ async function readStdin(): Promise<InputMessage> {
   return JSON.parse(value);
 }
 
-export { readStdin };
+/** Writes the output message to stdout. */
+function writeStdout(msg: OutputMessage): void {
+  console.log(JSON.stringify(msg));
+}
+
+export { readStdin, writeStdout };

src/pipeline.ts

@@ -1,3 +1,19 @@
-import { readStdin } from './stdin.ts';
+import { InputMessage, OutputMessage, Policy } from './types.ts';
 
-console.log(await readStdin());
+/** Processes messages through multiple policies, bailing early on rejection. */
+async function pipeline(msg: InputMessage, policies: Policy[]): Promise<OutputMessage> {
+  for (const policy of policies) {
+    const result = await policy(msg);
+    if (result.action !== 'accept') {
+      return result;
+    }
+  }
+
+  return {
+    id: msg.event.id,
+    action: 'accept',
+    msg: '',
+  };
+}
+
+export default pipeline;