Add config file for tweaking behavior (#6)

package.json

@@ -37,6 +37,7 @@
   "dependencies": {
     "@cfworker/sentry": "^2.0.0",
     "@octokit/auth-app": "^6.0.3",
+    "js-toml": "^1.0.0",
     "octokit": "^3.1.2",
     "parse-git-diff": "^0.0.15",
     "zod": "^3.22.4"

src/config.ts

@@ -1,9 +1,80 @@
-export const Config = {
+import { RequestError } from "octokit";
+import { z } from "zod";
+import { load } from "js-toml";
+import type { Context } from "./context";
+
+const ConfigSchema = z.object({
+  labels: z
+    .array(
+      z.object({
+        name: z.string(),
+        color: z.string(),
+        threshold: z.number().gte(0),
+      }),
+    )
+    .refine(
+      (labels) => {
+        const set = new Set(labels.map((label) => label.name));
+        return set.size === labels.length;
+      },
+      { message: "Label name should be unique" },
+    )
+    .transform((labels) => {
+      // Make sure all labels are ordered in descending order of threshold.
+      // Size logic depends on this property.
+      const clone = [...labels];
+      clone.sort((a, b) => b.threshold - a.threshold);
+      return clone;
+    }),
+});
+
+export type ConfigType = z.infer<typeof ConfigSchema>;
+
+const CONFIG_PATH = ".github/prsize.toml";
+
+const DEFAULT_CONFIG: ConfigType = {
   labels: [
-    { name: "size/x-small", color: "008000", threshold: 0 },
-    { name: "size/small", color: "008000", threshold: 100 },
-    { name: "size/medium", color: "FFFF00", threshold: 200 },
-    { name: "size/large", color: "FF0000", threshold: 500 },
     { name: "size/x-large", color: "FF0000", threshold: 1000 },
+    { name: "size/large", color: "FF0000", threshold: 500 },
+    { name: "size/medium", color: "FFFF00", threshold: 200 },
+    { name: "size/small", color: "008000", threshold: 100 },
+    { name: "size/x-small", color: "008000", threshold: 0 },
   ],
 };
+
+export async function readConfig(ctx: Context): Promise<ConfigType> {
+  let content: unknown;
+
+  try {
+    const resp = await ctx.octo.request(
+      "GET /repos/{owner}/{repo}/contents/{path}",
+      {
+        owner: ctx.owner,
+        repo: ctx.repo,
+        path: CONFIG_PATH,
+        ref: ctx.pr.base.ref,
+        mediaType: {
+          format: "raw",
+        },
+      },
+    );
+
+    content = resp.data as unknown;
+  } catch (error) {
+    if (error instanceof RequestError && error.status === 404) {
+      console.info("Config not found. Using default config");
+      return DEFAULT_CONFIG;
+    }
+
+    throw error;
+  }
+
+  if (typeof content !== "string") {
+    throw new Error(
+      `Config path ${CONFIG_PATH} seems to be a directory. Cannot read config content`,
+    );
+  }
+
+  const tom = load(content);
+  return ConfigSchema.parse(tom);
+}

src/context.ts

@@ -0,0 +1,21 @@
+import type { Octokit } from "octokit";
+import type { PullRequest } from "@octokit/webhooks-types";
+
+export class Context {
+  public constructor(
+    public readonly octo: Octokit,
+    public readonly pr: PullRequest,
+  ) {}
+
+  public get owner() {
+    return this.pr.base.repo.owner.login;
+  }
+
+  public get repo() {
+    return this.pr.base.repo.name;
+  }
+
+  public get prNum() {
+    return this.pr.number;
+  }
+}

src/handler.ts

@@ -1,4 +1,5 @@
 import parseGitDiff, { type AnyChunk } from "parse-git-diff";
+import { ConfigType } from "./config";
 
 export interface HandlerResponse {
   label: string | null;
@@ -33,6 +34,8 @@ function summarizeChunk(chunk: AnyChunk): Summary {
 }
 
 export class Handler {
+  public constructor(private readonly config: ConfigType) {}
+
   public async run(diffFile: string): Promise<HandlerResponse> {
     const summaryMap = this.genDiffSummary(diffFile);
     const summary: Summary = { add: 0, del: 0 };
@@ -74,26 +77,15 @@ export class Handler {
     return summary;
   }
 
-  private getSize(summary: Summary): string {
-    // TODO: Respect config settings
+  private getSize(summary: Summary): string | null {
     const size = summary.add + summary.del;
 
-    if (size >= 1000) {
-      return "size/x-large";
-    }
-
-    if (size >= 500) {
-      return "size/large";
-    }
-
-    if (size >= 200) {
-      return "size/medium";
-    }
-
-    if (size >= 100) {
-      return "size/small";
+    for (const preset of this.config.labels) {
+      if (size >= preset.threshold) {
+        return preset.name;
+      }
     }
 
-    return "size/x-small";
+    return null;
   }
 }

src/octo.ts

@@ -2,22 +2,25 @@ import { App } from "octokit";
 import type { PullRequest } from "@octokit/webhooks-types";
 import { Handler } from "./handler";
 import { unwrap } from "./utils";
-import { Updater } from "./updater";
+import { CommentUpdater, LabelUpdater } from "./updater";
+import { ConfigType, readConfig } from "./config";
+import { Context } from "./context";
 
 async function handle(app: App, installation_id: number, pr: PullRequest) {
   console.log(
     `Handling PR ${pr.base.repo.full_name}#${pr.number}. Installation ID = ${installation_id}`,
   );
 
   const octo = await app.getInstallationOctokit(installation_id);
+  const ctx = new Context(octo, pr);
 
-  if (pr.state === "closed") {
+  if (ctx.pr.state === "closed") {
     console.info("PR is closed. Ignoring the webhook");
     return;
   }
 
   console.log("Fetching diff for the PR");
-  const response = await octo.request(
+  const response = await ctx.octo.request(
     "GET /repos/{owner}/{repo}/pulls/{pull_number}",
     {
       owner: pr.base.repo.owner.login,
@@ -33,15 +36,32 @@ async function handle(app: App, installation_id: number, pr: PullRequest) {
   // https://github.com/octokit/request.js/issues/463#issuecomment-1164800888
   const diffFile = response.data as unknown as string;
 
-  const handler = new Handler();
+  const commentUpdater = new CommentUpdater(ctx);
+
+  let config: ConfigType;
+  try {
+    config = await readConfig(ctx);
+  } catch (error) {
+    console.error("Failed to read config", error);
+    await commentUpdater.updateComment(`Failed to read config. Pullsize bot is not operating!
+
+Exception detail:
+\`\`\`
+${error}
+\`\`\`
+`);
+    return;
+  }
+
+  const handler = new Handler(config);
   const resp = await handler.run(diffFile);
 
   console.log("Ran handler. Updating PR comment and label", resp);
 
-  const updater = new Updater(octo, pr);
-  await updater.updateComment(resp.comment);
-  await updater.createLabels();
-  await updater.updateLabel(resp.label);
+  const labelUpdater = new LabelUpdater(ctx, config);
+  await commentUpdater.updateComment(resp.comment);
+  await labelUpdater.createLabels();
+  await labelUpdater.updateLabel(resp.label);
 }
 
 export function useOctoApp(env: Env) {