Made class for easier access to GitHub-specific environment variables

src/platforms/github/github-context.ts

@@ -0,0 +1,107 @@
+import { getEnvironmentVariable } from "@/utils/environment";
+import { readFileSync } from "node:fs";
+import { GITHUB_API_URL as DEFAULT_GITHUB_API_URL } from "./github-api-client";
+import { GitHubRepositoryIdentifier } from "./github-repository";
+import { GitHubWebhookPayload } from "./github-webhook-payload";
+
+/**
+ * The name of the environment variable that contains the path to the GitHub webhook payload file.
+ */
+const GITHUB_PAYLOAD_PATH = "GITHUB_EVENT_PATH";
+
+/**
+ * The name of the environment variable that contains the repository name in the format "owner/repo".
+ */
+const GITHUB_REPOSITORY = "GITHUB_REPOSITORY";
+
+/**
+ * The name of the environment variable that contains the GitHub API url.
+ */
+const GITHUB_API_URL = "GITHUB_API_URL";
+
+/**
+ * The name of the environment variable that contains the Git ref associated with the workflow run.
+ */
+const GITHUB_REF = "GITHUB_REF";
+
+/**
+ * The prefix for Git tag refs in the format "refs/tags/".
+ */
+const GITHUB_REF_TAG_PREFIX = "refs/tags/";
+
+/**
+ * Represents an execution context of a GitHub action.
+ */
+export class GitHubContext {
+    /**
+     * A container for environment variables.
+     */
+    private readonly _env: Record<string, string>;
+
+    /**
+     * Cached payload associated with the context.
+     */
+    private _payload?: GitHubWebhookPayload;
+
+    /**
+     * Constructs a new {@link GitHubContext} instance.
+     *
+     * @param env - An optional object containing environment variables.
+     */
+    constructor(env?: Record<string, string>) {
+        this._env = env;
+    }
+
+    /**
+     * Gets the ref associated with the context, if available.
+     */
+    get ref(): string | undefined {
+        return getEnvironmentVariable(GITHUB_REF, this._env);
+    }
+
+    /**
+     * Gets the tag associated with the context, if available.
+     */
+    get tag(): string | undefined {
+        const ref = this.ref;
+        return ref?.startsWith(GITHUB_REF_TAG_PREFIX) && ref.substring(GITHUB_REF_TAG_PREFIX.length);
+    }
+
+    /**
+     * Gets the repository associated with the context, if available.
+     */
+    get repo(): GitHubRepositoryIdentifier | undefined {
+        const repository = getEnvironmentVariable(GITHUB_REPOSITORY, this._env);
+        if (repository?.includes("/")) {
+            const [owner, repo] = repository.split("/");
+            return { owner, repo };
+        }
+
+        return undefined;
+    }
+
+    /**
+     * Gets the URL for the GitHub API associated with this context, if available;
+     * otherwise using the base URL (`"https://api.github.com"`).
+     */
+    get apiUrl(): string {
+        return getEnvironmentVariable(GITHUB_API_URL, this._env) || DEFAULT_GITHUB_API_URL;
+    }
+
+    /**
+     * Gets the payload associated with the context.
+     */
+    get payload(): GitHubWebhookPayload {
+        if (this._payload) {
+            return this._payload;
+        }
+
+        const path = getEnvironmentVariable(GITHUB_PAYLOAD_PATH, this._env);
+        try {
+            this._payload = JSON.parse(readFileSync(path, "utf8"));
+        } catch {
+            this._payload = {};
+        }
+        return this._payload;
+    }
+}