Default to ruff-version from pyproject.toml (#30)

Closes: #9 

Changes the default behavior to:

- Search for a pyproject.toml in the repo root
- Search in project.dependencies and dependency-groups.dev for ruff
- If none is found use latest

Support for requirements.txt files can be added later

src/utils/inputs.ts

@@ -5,3 +5,4 @@ export const checkSum = core.getInput("checksum");
 export const githubToken = core.getInput("github-token");
 export const args = core.getInput("args");
 export const src = core.getInput("src");
+export const versionFile = core.getInput("version-file");

src/utils/pyproject.ts

@@ -0,0 +1,30 @@
+import * as fs from "node:fs";
+import * as core from "@actions/core";
+import * as toml from "toml";
+
+export function getRuffVersionFromPyproject(
+  filePath: string,
+): string | undefined {
+  const pyprojectContent = fs.readFileSync(filePath, "utf-8");
+  const pyproject = toml.parse(pyprojectContent);
+
+  const dependencies: string[] = pyproject.project?.dependencies || [];
+  const devDependencies: string[] = pyproject["dependency-groups"]?.dev || [];
+
+  const ruffVersionDefinition =
+    dependencies.find((dep: string) => dep.startsWith("ruff")) ||
+    devDependencies.find((dep: string) => dep.startsWith("ruff"));
+
+  if (ruffVersionDefinition) {
+    const ruffVersion = ruffVersionDefinition
+      .match(/^ruff([^A-Z0-9._-]+.*)$/)?.[1]
+      .trim();
+    if (ruffVersion?.startsWith("==")) {
+      return ruffVersion.slice(2);
+    }
+    core.info(`Found ruff version in pyproject.toml: ${ruffVersion}`);
+    return ruffVersion;
+  }
+
+  return undefined;
+}