refactor version resolving (#353)

src/download/download-version.ts

@@ -2,7 +2,6 @@ import { promises as fs } from "node:fs";
 import * as path from "node:path";
 import * as core from "@actions/core";
 import * as tc from "@actions/tool-cache";
-import * as pep440 from "@renovatebot/pep440";
 import * as semver from "semver";
 import {
   ASTRAL_MIRROR_PREFIX,
@@ -12,7 +11,7 @@ import {
 } from "../utils/constants";
 import type { Architecture, Platform } from "../utils/platforms";
 import { validateChecksum } from "./checksum/checksum";
-import { getAllVersions, getArtifact, getLatestVersion } from "./manifest";
+import { getArtifact } from "./manifest";
 
 export function tryGetFromToolCache(
   arch: Architecture,
@@ -162,35 +161,6 @@ async function extractDownloadedArtifact(
   return ruffDir;
 }
 
-export async function resolveVersion(
-  versionInput: string,
-  manifestUrl?: string,
-): Promise<string> {
-  core.debug(`Resolving ${versionInput}...`);
-
-  const version =
-    versionInput === "latest"
-      ? await getLatestVersion(manifestUrl)
-      : versionInput;
-
-  if (tc.isExplicitVersion(version)) {
-    core.debug(`Version ${version} is an explicit version.`);
-    return version;
-  }
-
-  const availableVersions = await getAvailableVersions(manifestUrl);
-  const resolvedVersion = maxSatisfying(availableVersions, version);
-  if (resolvedVersion === undefined) {
-    throw new Error(`No version found for ${version}`);
-  }
-  core.debug(`Resolved version: ${resolvedVersion}`);
-  return resolvedVersion;
-}
-
-async function getAvailableVersions(manifestUrl?: string): Promise<string[]> {
-  return await getAllVersions(manifestUrl);
-}
-
 function getMissingArtifactMessage(
   version: string,
   arch: Architecture,
@@ -245,22 +215,3 @@ function stripVersionPrefix(version: string): string {
 function getExtension(platform: Platform): string {
   return platform === "pc-windows-msvc" ? ".zip" : ".tar.gz";
 }
-
-function maxSatisfying(
-  versions: string[],
-  version: string,
-): string | undefined {
-  const maxSemver = tc.evaluateVersions(versions, version);
-  if (maxSemver !== "") {
-    core.debug(`Found a version that satisfies the semver range: ${maxSemver}`);
-    return maxSemver;
-  }
-  const maxPep440 = pep440.maxSatisfying(versions, version);
-  if (maxPep440 !== null) {
-    core.debug(
-      `Found a version that satisfies the pep440 specifier: ${maxPep440}`,
-    );
-    return maxPep440;
-  }
-  return undefined;
-}

src/ruff-action.ts

@@ -4,7 +4,6 @@ import * as exec from "@actions/exec";
 import * as semver from "semver";
 import {
   downloadVersion,
-  resolveVersion,
   tryGetFromToolCache,
 } from "./download/download-version";
 import {
@@ -22,8 +21,7 @@ import {
   getPlatform,
   type Platform,
 } from "./utils/platforms";
-import { getRuffVersionFromRequirementsFile } from "./utils/pyproject";
-import { findPyprojectToml } from "./utils/pyproject-finder";
+import { resolveRuffVersion } from "./version/resolve";
 
 async function run(): Promise<void> {
   const platform = getPlatform();
@@ -94,44 +92,13 @@ async function setupRuff(
 }
 
 async function determineVersion(): Promise<string> {
-  if (versionFileInput !== "" && version !== "") {
-    throw Error("It is not allowed to specify both version and version-file");
-  }
-  if (version !== "") {
-    return await resolveVersion(version, manifestFile || undefined);
-  }
-  if (versionFileInput !== "") {
-    const versionFromPyproject =
-      getRuffVersionFromRequirementsFile(versionFileInput);
-    if (versionFromPyproject === undefined) {
-      core.warning(
-        `Could not parse version from ${versionFileInput}. Using latest version.`,
-      );
-    }
-    return await resolveVersion(
-      versionFromPyproject || "latest",
-      manifestFile || undefined,
-    );
-  }
-  const pyProjectPath = findPyprojectToml(
-    src,
-    process.env.GITHUB_WORKSPACE || ".",
-  );
-  if (!pyProjectPath) {
-    core.info(`Could not find pyproject.toml. Using latest version.`);
-    return await resolveVersion("latest", manifestFile || undefined);
-  }
-  const versionFromPyproject =
-    getRuffVersionFromRequirementsFile(pyProjectPath);
-  if (versionFromPyproject === undefined) {
-    core.info(
-      `Could not parse version from ${pyProjectPath}. Using latest version.`,
-    );
-  }
-  return await resolveVersion(
-    versionFromPyproject || "latest",
-    manifestFile || undefined,
-  );
+  return await resolveRuffVersion({
+    manifestFile: manifestFile || undefined,
+    sourceDirectory: src,
+    version,
+    versionFile: versionFileInput,
+    workspaceRoot: process.env.GITHUB_WORKSPACE || ".",
+  });
 }
 
 function addRuffToPath(cachedPath: string): void {

src/utils/pyproject.ts

@@ -1,130 +0,0 @@
-import * as fs from "node:fs";
-import * as core from "@actions/core";
-import * as toml from "smol-toml";
-
-/**
- * Find ruff version in a dependency specification.
- * Only handles strings that start with "ruff" (e.g., "ruff==0.9.3").
- * Returns undefined for non-ruff dependencies.
- * Strips environment markers (everything after ';').
- * Strips leading '==' from exact version specifiers (PEP 440) for downstream compatibility.
- *
- * @internal This is exported for testing purposes only.
- */
-export function findRuffVersionInSpec(spec: string): string | undefined {
-  const trimmedSpec = spec.trim();
-
-  const fullDepMatch = trimmedSpec.match(/^ruff\s*(.+)$/);
-  let versionSpec: string;
-  if (fullDepMatch) {
-    versionSpec = fullDepMatch[1];
-  } else {
-    return undefined;
-  }
-
-  // Strip trailing backslash (line continuation)
-  versionSpec = versionSpec.replace(/\\$/, "").trim();
-
-  // Strip environment markers (everything after ';')
-  const match = versionSpec.match(/^([^;]+)(?:;.*)?$/);
-
-  if (match) {
-    let version = match[1].trim();
-    if (version) {
-      // Strip leading '==' from exact version specifiers for compatibility with semver
-      if (version.startsWith("==")) {
-        version = version.slice(2);
-      }
-      if (trimmedSpec.includes(";")) {
-        core.warning(
-          "Environment markers are ignored. ruff is a standalone tool that works independently of Python version.",
-        );
-      }
-      core.info(`Found ruff version in requirements file: ${version}`);
-      return version;
-    }
-  }
-
-  return undefined;
-}
-
-function getRuffVersionFromAllDependencies(
-  allDependencies: string[],
-): string | undefined {
-  return allDependencies
-    .map((dep) => findRuffVersionInSpec(dep))
-    .find((version) => version !== undefined);
-}
-
-interface Pyproject {
-  project?: {
-    dependencies?: string[];
-    "optional-dependencies"?: Record<string, string[]>;
-  };
-  "dependency-groups"?: Record<string, Array<string | object>>;
-  tool?: {
-    poetry?: {
-      dependencies?: Record<string, string | object>;
-      group?: Record<string, { dependencies: Record<string, string | object> }>;
-    };
-  };
-}
-
-function parsePyproject(pyprojectContent: string): string | undefined {
-  const pyproject: Pyproject = toml.parse(pyprojectContent);
-  const dependencies: string[] = pyproject?.project?.dependencies || [];
-  const optionalDependencies: string[] = Object.values(
-    pyproject?.project?.["optional-dependencies"] || {},
-  ).flat();
-  const devDependencies: string[] = Object.values(
-    pyproject?.["dependency-groups"] || {},
-  )
-    .flat()
-    .filter((item: string | object) => typeof item === "string");
-  return (
-    getRuffVersionFromAllDependencies(
-      dependencies.concat(optionalDependencies, devDependencies),
-    ) || getRuffVersionFromPoetryGroups(pyproject)
-  );
-}
-
-function getRuffVersionFromPoetryGroups(
-  pyproject: Pyproject,
-): string | undefined {
-  // Special handling for Poetry until it supports PEP 735
-  // See: <https://github.com/python-poetry/poetry/issues/9751>
-  const poetry = pyproject?.tool?.poetry || {};
-  const poetryGroups = Object.values(poetry.group || {});
-  if (poetry.dependencies) {
-    poetryGroups.unshift({ dependencies: poetry.dependencies });
-  }
-  return poetryGroups
-    .flatMap((group) => Object.entries(group.dependencies))
-    .map(([name, spec]) => {
-      if (typeof spec === "string") {
-        return findRuffVersionInSpec(`${name} ${spec}`);
-      }
-      return undefined;
-    })
-    .find((version) => version !== undefined);
-}
-
-export function getRuffVersionFromRequirementsFile(
-  filePath: string,
-): string | undefined {
-  if (!fs.existsSync(filePath)) {
-    core.warning(`Could not find file: ${filePath}`);
-    return undefined;
-  }
-  const pyprojectContent = fs.readFileSync(filePath, "utf-8");
-  if (filePath.endsWith(".txt")) {
-    return getRuffVersionFromAllDependencies(pyprojectContent.split("\n"));
-  }
-  try {
-    return parsePyproject(pyprojectContent);
-  } catch (err) {
-    const message = (err as Error).message;
-    core.warning(`Error while parsing ${filePath}: ${message}`);
-    return undefined;
-  }
-}

src/version/file-parser.ts

@@ -0,0 +1,185 @@
+import fs from "node:fs";
+import * as core from "@actions/core";
+import * as toml from "smol-toml";
+import { normalizeVersionSpecifier } from "./specifier";
+import type { ParsedVersionFile, VersionFileFormat } from "./types";
+
+interface VersionFileParser {
+  format: VersionFileFormat;
+  parse(filePath: string): string | undefined;
+  supports(filePath: string): boolean;
+}
+
+interface Pyproject {
+  project?: {
+    dependencies?: string[];
+    "optional-dependencies"?: Record<string, string[]>;
+  };
+  "dependency-groups"?: Record<string, Array<string | object>>;
+  tool?: {
+    poetry?: {
+      dependencies?: Record<string, string | object>;
+      group?: Record<string, { dependencies: Record<string, string | object> }>;
+    };
+  };
+}
+
+const VERSION_FILE_PARSERS: VersionFileParser[] = [
+  {
+    format: "pyproject.toml",
+    parse: (filePath) => {
+      const fileContent = fs.readFileSync(filePath, "utf-8");
+      return getRuffVersionFromPyprojectContent(fileContent);
+    },
+    supports: (filePath) => filePath.endsWith("pyproject.toml"),
+  },
+  {
+    format: "requirements",
+    parse: (filePath) => {
+      const fileContent = fs.readFileSync(filePath, "utf-8");
+      return getRuffVersionFromRequirementsText(fileContent);
+    },
+    supports: (filePath) => filePath.endsWith(".txt"),
+  },
+];
+
+export function getParsedVersionFile(
+  filePath: string,
+): ParsedVersionFile | undefined {
+  core.info(`Trying to find version for ruff in: ${filePath}`);
+
+  if (!fs.existsSync(filePath)) {
+    core.warning(`Could not find file: ${filePath}`);
+    return undefined;
+  }
+
+  const parser = getVersionFileParser(filePath);
+  if (parser === undefined) {
+    return undefined;
+  }
+
+  try {
+    const specifier = parser.parse(filePath);
+    if (specifier === undefined) {
+      return undefined;
+    }
+
+    const normalizedSpecifier = normalizeVersionSpecifier(specifier);
+    core.info(`Found version for ruff in ${filePath}: ${normalizedSpecifier}`);
+    return {
+      format: parser.format,
+      specifier: normalizedSpecifier,
+    };
+  } catch (error) {
+    core.warning(
+      `Error while parsing ${filePath}: ${(error as Error).message}`,
+    );
+    return undefined;
+  }
+}
+
+export function getRuffVersionFromFile(filePath: string): string | undefined {
+  return getParsedVersionFile(filePath)?.specifier;
+}
+
+export function findRuffVersionInSpec(spec: string): string | undefined {
+  const trimmedSpec = spec.trim();
+
+  if (!trimmedSpec.startsWith("ruff")) {
+    return undefined;
+  }
+
+  let versionSpec = trimmedSpec.slice("ruff".length);
+  if (!versionSpec.match(/^(?:\s+|[=<>~!])/)) {
+    return undefined;
+  }
+
+  versionSpec = versionSpec.replace(/\\$/, "").trim();
+
+  const match = versionSpec.match(/^([^;]+)(?:;.*)?$/);
+
+  if (match) {
+    let version = match[1].trim();
+    if (version) {
+      version = normalizeVersionSpecifier(version);
+      if (trimmedSpec.includes(";")) {
+        core.warning(
+          "Environment markers are ignored. ruff is a standalone tool that works independently of Python version.",
+        );
+      }
+      core.info(`Found ruff version in requirements file: ${version}`);
+      return version;
+    }
+  }
+
+  return undefined;
+}
+
+export function getRuffVersionFromRequirementsText(
+  fileContent: string,
+): string | undefined {
+  return getRuffVersionFromAllDependencies(fileContent.split("\n"));
+}
+
+export function getRuffVersionFromPyprojectContent(
+  pyprojectContent: string,
+): string | undefined {
+  const pyproject = parsePyprojectContent(pyprojectContent);
+  return getRuffVersionFromParsedPyproject(pyproject);
+}
+
+export function parsePyprojectContent(pyprojectContent: string): Pyproject {
+  return toml.parse(pyprojectContent) as Pyproject;
+}
+
+function getVersionFileParser(filePath: string): VersionFileParser | undefined {
+  return VERSION_FILE_PARSERS.find((parser) => parser.supports(filePath));
+}
+
+function getRuffVersionFromParsedPyproject(
+  pyproject: Pyproject,
+): string | undefined {
+  const dependencies: string[] = pyproject.project?.dependencies || [];
+  const optionalDependencies: string[] = Object.values(
+    pyproject.project?.["optional-dependencies"] || {},
+  ).flat();
+  const devDependencies: string[] = Object.values(
+    pyproject["dependency-groups"] || {},
+  )
+    .flat()
+    .filter((item: string | object) => typeof item === "string");
+
+  return (
+    getRuffVersionFromAllDependencies(
+      dependencies.concat(optionalDependencies, devDependencies),
+    ) || getRuffVersionFromPoetryGroups(pyproject)
+  );
+}
+
+function getRuffVersionFromPoetryGroups(
+  pyproject: Pyproject,
+): string | undefined {
+  const poetry = pyproject.tool?.poetry || {};
+  const poetryGroups = Object.values(poetry.group || {});
+  if (poetry.dependencies) {
+    poetryGroups.unshift({ dependencies: poetry.dependencies });
+  }
+
+  return poetryGroups
+    .flatMap((group) => Object.entries(group.dependencies))
+    .map(([name, spec]) => {
+      if (typeof spec === "string") {
+        return findRuffVersionInSpec(`${name} ${spec}`);
+      }
+      return undefined;
+    })
+    .find((version) => version !== undefined);
+}
+
+function getRuffVersionFromAllDependencies(
+  allDependencies: string[],
+): string | undefined {
+  return allDependencies
+    .map((dependency) => findRuffVersionInSpec(dependency))
+    .find((version) => version !== undefined);
+}

src/version/resolve.ts

@@ -0,0 +1,125 @@
+import * as core from "@actions/core";
+import * as tc from "@actions/tool-cache";
+import * as pep440 from "@renovatebot/pep440";
+import { getAllVersions, getLatestVersion } from "../download/manifest";
+import {
+  type ParsedVersionSpecifier,
+  parseVersionSpecifier,
+} from "./specifier";
+import type { ResolveRuffVersionOptions } from "./types";
+import { resolveVersionRequest } from "./version-request-resolver";
+
+interface ConcreteVersionResolutionContext {
+  manifestUrl?: string;
+  parsedSpecifier: ParsedVersionSpecifier;
+}
+
+interface ConcreteVersionResolver {
+  resolve(
+    context: ConcreteVersionResolutionContext,
+  ): Promise<string | undefined>;
+}
+
+class ExactVersionResolver implements ConcreteVersionResolver {
+  async resolve(
+    context: ConcreteVersionResolutionContext,
+  ): Promise<string | undefined> {
+    if (context.parsedSpecifier.kind !== "exact") {
+      return undefined;
+    }
+
+    core.debug(
+      `Version ${context.parsedSpecifier.normalized} is an explicit version.`,
+    );
+    return context.parsedSpecifier.normalized;
+  }
+}
+
+class LatestVersionResolver implements ConcreteVersionResolver {
+  async resolve(
+    context: ConcreteVersionResolutionContext,
+  ): Promise<string | undefined> {
+    if (context.parsedSpecifier.kind !== "latest") {
+      return undefined;
+    }
+
+    return await getLatestVersion(context.manifestUrl);
+  }
+}
+
+class RangeVersionResolver implements ConcreteVersionResolver {
+  async resolve(
+    context: ConcreteVersionResolutionContext,
+  ): Promise<string | undefined> {
+    if (context.parsedSpecifier.kind !== "range") {
+      return undefined;
+    }
+
+    const availableVersions = await getAllVersions(context.manifestUrl);
+    const resolvedVersion = maxSatisfying(
+      availableVersions,
+      context.parsedSpecifier.normalized,
+    );
+    if (resolvedVersion === undefined) {
+      throw new Error(`No version found for ${context.parsedSpecifier.raw}`);
+    }
+
+    core.debug(`Resolved version: ${resolvedVersion}`);
+    return resolvedVersion;
+  }
+}
+
+const CONCRETE_VERSION_RESOLVERS: ConcreteVersionResolver[] = [
+  new ExactVersionResolver(),
+  new LatestVersionResolver(),
+  new RangeVersionResolver(),
+];
+
+export async function resolveRuffVersion(
+  options: ResolveRuffVersionOptions,
+): Promise<string> {
+  const request = resolveVersionRequest(options);
+  return await resolveVersion(request.specifier, options.manifestFile);
+}
+
+export async function resolveVersion(
+  versionInput: string,
+  manifestUrl?: string,
+): Promise<string> {
+  core.debug(`Resolving ${versionInput}...`);
+
+  const context: ConcreteVersionResolutionContext = {
+    manifestUrl,
+    parsedSpecifier: parseVersionSpecifier(versionInput),
+  };
+
+  for (const resolver of CONCRETE_VERSION_RESOLVERS) {
+    const version = await resolver.resolve(context);
+    if (version !== undefined) {
+      return version;
+    }
+  }
+
+  throw new Error(`No version found for ${versionInput}`);
+}
+
+function maxSatisfying(
+  versions: string[],
+  version: string,
+): string | undefined {
+  const maxSemver = tc.evaluateVersions(versions, version);
+  if (maxSemver !== "") {
+    core.debug(`Found a version that satisfies the semver range: ${maxSemver}`);
+    return maxSemver;
+  }
+
+  const maxPep440 = pep440.maxSatisfying(versions, version);
+  if (maxPep440 !== null) {
+    core.debug(
+      `Found a version that satisfies the pep440 specifier: ${maxPep440}`,
+    );
+    return maxPep440;
+  }
+
+  return undefined;
+}

src/version/specifier.ts

@@ -0,0 +1,57 @@
+import * as tc from "@actions/tool-cache";
+
+export type ParsedVersionSpecifier =
+  | {
+      kind: "exact";
+      normalized: string;
+      raw: string;
+    }
+  | {
+      kind: "latest";
+      normalized: "latest";
+      raw: string;
+    }
+  | {
+      kind: "range";
+      normalized: string;
+      raw: string;
+    };
+
+export function normalizeVersionSpecifier(specifier: string): string {
+  const trimmedSpecifier = specifier.trim();
+
+  if (trimmedSpecifier.startsWith("==")) {
+    return trimmedSpecifier.slice(2);
+  }
+
+  return trimmedSpecifier;
+}
+
+export function parseVersionSpecifier(
+  specifier: string,
+): ParsedVersionSpecifier {
+  const raw = specifier.trim();
+  const normalized = normalizeVersionSpecifier(raw);
+
+  if (normalized === "latest") {
+    return {
+      kind: "latest",
+      normalized: "latest",
+      raw,
+    };
+  }
+
+  if (tc.isExplicitVersion(normalized)) {
+    return {
+      kind: "exact",
+      normalized,
+      raw,
+    };
+  }
+
+  return {
+    kind: "range",
+    normalized,
+    raw,
+  };
+}

src/version/types.ts

@@ -0,0 +1,27 @@
+export type VersionSource =
+  | "input"
+  | "version-file"
+  | "pyproject.toml"
+  | "default";
+
+export type VersionFileFormat = "pyproject.toml" | "requirements";
+
+export interface ParsedVersionFile {
+  format: VersionFileFormat;
+  specifier: string;
+}
+
+export interface ResolveRuffVersionOptions {
+  manifestFile?: string;
+  sourceDirectory: string;
+  version?: string;
+  versionFile?: string;
+  workspaceRoot: string;
+}
+
+export interface VersionRequest {
+  format?: VersionFileFormat;
+  source: VersionSource;
+  sourcePath?: string;
+  specifier: string;
+}

src/version/version-request-resolver.ts

@@ -0,0 +1,162 @@
+import * as core from "@actions/core";
+import { findPyprojectToml } from "../utils/pyproject-finder";
+import { getParsedVersionFile } from "./file-parser";
+import { normalizeVersionSpecifier } from "./specifier";
+import type {
+  ParsedVersionFile,
+  ResolveRuffVersionOptions,
+  VersionRequest,
+} from "./types";
+
+export interface VersionRequestResolver {
+  resolve(context: VersionRequestContext): VersionRequest | undefined;
+}
+
+export class VersionRequestContext {
+  readonly sourceDirectory: string;
+  readonly version: string | undefined;
+  readonly versionFile: string | undefined;
+  readonly workspaceRoot: string;
+
+  private readonly parsedFiles = new Map<
+    string,
+    ParsedVersionFile | undefined
+  >();
+
+  constructor(
+    version: string | undefined,
+    versionFile: string | undefined,
+    sourceDirectory: string,
+    workspaceRoot: string,
+  ) {
+    this.version = version;
+    this.versionFile = versionFile;
+    this.sourceDirectory = sourceDirectory;
+    this.workspaceRoot = workspaceRoot;
+  }
+
+  getVersionFile(filePath: string): ParsedVersionFile | undefined {
+    const cachedResult = this.parsedFiles.get(filePath);
+    if (cachedResult !== undefined || this.parsedFiles.has(filePath)) {
+      return cachedResult;
+    }
+
+    const result = getParsedVersionFile(filePath);
+    this.parsedFiles.set(filePath, result);
+    return result;
+  }
+
+  getWorkspacePyprojectPath(): string | undefined {
+    return findPyprojectToml(this.sourceDirectory, this.workspaceRoot);
+  }
+}
+
+export class ExplicitInputVersionResolver implements VersionRequestResolver {
+  resolve(context: VersionRequestContext): VersionRequest | undefined {
+    if (context.version === undefined) {
+      return undefined;
+    }
+
+    return {
+      source: "input",
+      specifier: normalizeVersionSpecifier(context.version),
+    };
+  }
+}
+
+export class VersionFileVersionResolver implements VersionRequestResolver {
+  resolve(context: VersionRequestContext): VersionRequest | undefined {
+    if (context.versionFile === undefined) {
+      return undefined;
+    }
+
+    const versionFile = context.getVersionFile(context.versionFile);
+    if (versionFile === undefined) {
+      core.warning(
+        `Could not parse version from ${context.versionFile}. Using latest version.`,
+      );
+      return undefined;
+    }
+
+    return {
+      format: versionFile.format,
+      source: "version-file",
+      sourcePath: context.versionFile,
+      specifier: versionFile.specifier,
+    };
+  }
+}
+
+export class WorkspaceVersionResolver implements VersionRequestResolver {
+  resolve(context: VersionRequestContext): VersionRequest | undefined {
+    const pyprojectPath = context.getWorkspacePyprojectPath();
+    if (!pyprojectPath) {
+      core.info("Could not find pyproject.toml. Using latest version.");
+      return undefined;
+    }
+
+    const versionFile = context.getVersionFile(pyprojectPath);
+    if (versionFile === undefined) {
+      core.info(
+        `Could not parse version from ${pyprojectPath}. Using latest version.`,
+      );
+      return undefined;
+    }
+
+    return {
+      format: versionFile.format,
+      source: "pyproject.toml",
+      sourcePath: pyprojectPath,
+      specifier: versionFile.specifier,
+    };
+  }
+}
+
+export class LatestVersionResolver implements VersionRequestResolver {
+  resolve(): VersionRequest {
+    return {
+      source: "default",
+      specifier: "latest",
+    };
+  }
+}
+
+const VERSION_REQUEST_RESOLVERS: VersionRequestResolver[] = [
+  new ExplicitInputVersionResolver(),
+  new VersionFileVersionResolver(),
+  new WorkspaceVersionResolver(),
+  new LatestVersionResolver(),
+];
+
+export function resolveVersionRequest(
+  options: ResolveRuffVersionOptions,
+): VersionRequest {
+  const version = emptyToUndefined(options.version);
+  const versionFile = emptyToUndefined(options.versionFile);
+
+  if (version !== undefined && versionFile !== undefined) {
+    throw new Error(
+      "It is not allowed to specify both version and version-file",
+    );
+  }
+
+  const context = new VersionRequestContext(
+    version,
+    versionFile,
+    options.sourceDirectory,
+    options.workspaceRoot,
+  );
+
+  for (const resolver of VERSION_REQUEST_RESOLVERS) {
+    const request = resolver.resolve(context);
+    if (request !== undefined) {
+      return request;
+    }
+  }
+
+  throw new Error("Could not resolve a requested Ruff version.");
+}
+
+function emptyToUndefined(value: string | undefined): string | undefined {
+  return value === undefined || value === "" ? undefined : value;
+}