Ekklesia/scripts/check-boundaries.ts

import { readdir, readFile, stat } from "node:fs/promises";
import { builtinModules } from "node:module";
import path from "node:path";
import { pathToFileURL } from "node:url";
import { parse } from "yaml";

type Layer = "app" | "builder" | "core" | "module" | "neutral" | "shared" | "surface";

interface Location {
  layer: Layer;
  owner: string;
  relativePath: string;
  role?: string;
}

interface PackageManifest {
  dependencies?: Record<string, string>;
  devDependencies?: Record<string, string>;
  ekklesia?: { layer?: string };
  exports?: unknown;
  name?: string;
  optionalDependencies?: Record<string, string>;
  peerDependencies?: Record<string, string>;
}

interface WorkspacePackage {
  directory: string;
  location: Location;
  manifest: PackageManifest;
  name: string;
}

interface WorkspaceConfiguration {
  packages?: string[];
}

export interface BoundaryViolation {
  from: string;
  message: string;
  rule: string;
  to?: string;
}

export interface BoundaryResult {
  filesChecked: number;
  packagesChecked: number;
  violations: BoundaryViolation[];
}

const CODE_EXTENSIONS = new Set([".cjs", ".cts", ".js", ".jsx", ".mjs", ".mts", ".ts", ".tsx"]);
// Presentation formats a module may NOT contain. `.tsx` is deliberately absent: React is the
// supported module UI authoring model (ADR 0022), so a module's own `.tsx` is legitimate source.
// `.jsx` stays rejected because this repository is strict-TypeScript throughout. `.css` is handled
// separately below rather than listed here: since ADR 0040 a module may author a plain stylesheet,
// but only inside the browser-artifact source roots the canonical builder actually compiles. Every
// other stylesheet dialect stays rejected outright — adding one is a toolchain decision needing its
// own ADR, not a detail of a build pass.
const MODULE_UI_EXTENSIONS = new Set([
  ".astro",
  ".htm",
  ".html",
  ".jsx",
  ".less",
  ".marko",
  ".mdx",
  ".pcss",
  ".postcss",
  ".sass",
  ".scss",
  ".styl",
  ".stylus",
  ".svelte",
  ".svg",
  ".vue",
]);
// UI packages a module may NOT depend on. `react` and `react-dom` are deliberately absent: they are
// the one supported module UI authoring framework (ADR 0022). Everything else stays denied, so
// choosing React does not quietly open every other frontend technology. Three neighbours are worth
// naming: `react-router-dom` stays denied because routing belongs to the host, `react-native` stays
// denied because this pass supports React on the DOM only, and `@vitejs/plugin-react` stays denied
// because the module UI build pipeline is not designed yet.
const MODULE_UI_PACKAGES = new Set([
  "@angular/core",
  "@builder.io/qwik",
  "@emotion/react",
  "@emotion/styled",
  "@lit/react",
  "@mui/material",
  "@preact/signals",
  "@storybook/react",
  "@tamagui/core",
  "alpinejs",
  "astro",
  "bootstrap",
  "bulma",
  "expo",
  "gatsby",
  "htmx.org",
  "lit",
  "marko",
  "nativewind",
  "next",
  "nuxt",
  "preact",
  "qwik",
  "react-native",
  "react-router-dom",
  "remix",
  "solid-js",
  "solid-start",
  "styled-components",
  "svelte",
  "tamagui",
  "tailwindcss",
  "unocss",
  "vue",
  "vue-router",
  "vuetify",
]);
const MODULE_UI_PACKAGE_PREFIXES = [
  "@angular/",
  "@chakra-ui/",
  "@emotion/",
  "@mui/",
  "@radix-ui/",
  "@remix-run/",
  "@solidjs/",
  "@storybook/",
  "@sveltejs/",
  "@tamagui/",
  "@tanstack/react-",
  "@unocss/",
  "@vitejs/plugin-react",
  "@vue/",
];
const IGNORED_DIRECTORIES = new Set([
  ".git",
  ".next",
  ".turbo",
  "coverage",
  "dist",
  "node_modules",
]);
const DEPENDENCY_FIELDS = [
  "dependencies",
  "devDependencies",
  "optionalDependencies",
  "peerDependencies",
] as const;
const SHARED_PACKAGE_ROLES = new Set([
  "api-client",
  "auth-client",
  "builder-sdk",
  "contracts",
  "design-tokens",
  "module-sdk",
  "module-ui-host",
  "module-ui-sdk",
  "shared",
  "surface-sdk",
  "testing",
  "tooling",
  "ui",
]);

/**
 * The module-package-relative directories whose contents `@ekklesia/module-ui-build` compiles into a
 * declared browser artifact (ADR 0023, ADR 0033, ADR 0040).
 *
 * A stylesheet is only meaningful inside one of these: anywhere else in a module it would be a file
 * no build reads, no manifest declares, and no host ever loads — the undeclared-sidecar failure this
 * repository has rejected since ADR 0023, just relocated. Restricting the location is also what
 * keeps the relaxation honest: a module gains stylesheets for its browser artifacts, not the ability
 * to scatter presentation files through its backend.
 */
const MODULE_BROWSER_SOURCE_ROOTS = ["src/ui/", "src/display/", "src/contributions/"];

/** Whether a repository-relative path inside a module package sits in one of those roots. Module
 * packages live at `modules/<name>/…` and `templates/module/…`, both two segments deep. */
function isModuleBrowserSource(relativePath: string): boolean {
  const withinPackage = relativePath.split("/").slice(2).join("/");
  return MODULE_BROWSER_SOURCE_ROOTS.some((sourceRoot) => withinPackage.startsWith(sourceRoot));
}

function normalizePath(value: string): string {
  return value.split(path.sep).join("/").replace(/^\.\//, "");
}

export function describeRepositoryPath(relativePath: string): Location {
  const normalized = normalizePath(relativePath);
  const [area, owner = area] = normalized.split("/");

  if (area === "core") {
    return { layer: "core", owner: "core", relativePath: normalized };
  }

  if (area === "modules" && owner) {
    return { layer: "module", owner, relativePath: normalized };
  }

  if (area === "surfaces" && owner) {
    return { layer: "surface", owner, relativePath: normalized };
  }

  if ((area === "builders" || area === "surface-builder") && owner) {
    return { layer: "builder", owner, relativePath: normalized };
  }

  if (area === "apps" && owner) {
    return { layer: "app", owner, relativePath: normalized };
  }

  if (area === "packages" && owner) {
    return { layer: "shared", owner, relativePath: normalized, role: owner };
  }

  if (area === "templates" && owner === "module") {
    return { layer: "module", owner: "template-module", relativePath: normalized };
  }

  return { layer: "neutral", owner: area ?? "root", relativePath: normalized };
}

function boundaryRule(from: Location, to: Location): string | undefined {
  if (from.layer === "neutral" || to.layer === "neutral") {
    return undefined;
  }

  if (from.layer === to.layer && from.owner === to.owner) {
    return undefined;
  }

  if (from.layer === "core" && ["app", "builder", "module", "surface"].includes(to.layer)) {
    return "core-is-feature-agnostic";
  }

  if (from.layer === "module") {
    if (["app", "builder", "core", "surface"].includes(to.layer)) {
      return "modules-use-public-platform-contracts";
    }
    if (to.layer === "module" && from.owner !== to.owner) {
      return "modules-do-not-import-other-modules";
    }
    // The approved shared roles a module may reach, and nothing else. `design-tokens` and `ui` are
    // named individually rather than by opening "browser-safe shared packages" generally: a module
    // may consume Ekklesia's global semantic tokens and foundational elements (ADR 0039) precisely
    // so two modules' screens look like one product, but it still may not reach `api-client`,
    // `auth-client`, `surface-sdk`, `module-ui-host`, or any other shared role. Both approved
    // packages are browser-safe by construction — neither has a backend dependency — so this adds
    // no path from module UI to Node's globals.
    if (
      to.layer === "shared" &&
      ![
        "contracts",
        "design-tokens",
        "module-sdk",
        "module-ui-sdk",
        "testing",
        "tooling",
        "ui",
      ].includes(to.role ?? "")
    ) {
      return "modules-use-public-platform-contracts";
    }
  }

  if (from.layer === "surface") {
    if (["app", "builder", "core", "module"].includes(to.layer)) {
      return "surfaces-use-public-contracts";
    }
    if (to.layer === "surface" && from.owner !== to.owner) {
      return "surfaces-are-independent";
    }
    // A surface is browser code, so the roles it may reach are the browser-safe ones plus dev-time
    // tooling. `contracts` is deliberately absent even though it is a "public contract" package:
    // its barrel pulls Drizzle's types, and with them Node's global declarations, into any program
    // that imports it — measured in ADR 0024, which removed exactly that import from
    // `@ekklesia/module-ui-sdk` to close the browser boundary. Allowing it here would reopen the
    // same hole one layer up. `module-sdk` re-exports that barrel and is excluded for the same
    // reason. A surface talks to the server over HTTP and validates what arrives; it does not share
    // the server's type graph.
    if (
      to.layer === "shared" &&
      ![
        "api-client",
        "auth-client",
        "design-tokens",
        "module-ui-host",
        "module-ui-sdk",
        "surface-sdk",
        "testing",
        "tooling",
        "ui",
      ].includes(to.role ?? "")
    ) {
      return "surfaces-use-public-contracts";
    }
  }

  if (from.layer === "builder" && ["app", "core", "module", "surface"].includes(to.layer)) {
    return "builder-composes-contracts";
  }

  if (from.layer === "app" && ["app", "builder", "module"].includes(to.layer)) {
    return "apps-are-composition-roots";
  }

  if (
    from.layer === "shared" &&
    from.role === "contracts" &&
    ["app", "builder", "core", "module", "surface"].includes(to.layer)
  ) {
    return "contracts-do-not-depend-upward";
  }

  if (
    from.layer === "shared" &&
    ["builder-sdk", "module-sdk", "module-ui-host", "module-ui-sdk", "surface-sdk"].includes(
      from.role ?? "",
    ) &&
    ["app", "builder", "core", "module", "surface"].includes(to.layer)
  ) {
    return "sdks-do-not-depend-on-implementations";
  }

  if (
    from.layer === "shared" &&
    ["design-tokens", "ui"].includes(from.role ?? "") &&
    ["app", "builder", "core", "module", "surface"].includes(to.layer)
  ) {
    return "design-packages-depend-downward-only";
  }

  if (from.layer === "shared" && to.layer === "shared") {
    if (from.role === "contracts" && to.role !== "contracts") {
      return "contracts-do-not-depend-upward";
    }
    if (
      ["module-sdk", "module-ui-sdk", "surface-sdk"].includes(from.role ?? "") &&
      to.role !== "contracts"
    ) {
      return "sdks-do-not-depend-on-implementations";
    }
    // The host loader consumes the module-author contract — that is its whole job — plus dev-time
    // `tooling` (it builds a real artifact in its own tests through the canonical pipeline rather
    // than reimplementing one). It may not reach further: never a module, an app, a surface, or the
    // backend contracts barrel, which is what keeps it browser-safe (ADR 0024).
    if (from.role === "module-ui-host" && !["module-ui-sdk", "tooling"].includes(to.role ?? "")) {
      return "sdks-do-not-depend-on-implementations";
    }
    if (from.role === "builder-sdk" && !["contracts", "surface-sdk"].includes(to.role ?? "")) {
      return "sdks-do-not-depend-on-implementations";
    }
    // The design contract is the bottom of the presentation stack: it depends on nothing, exactly
    // like `module-ui-sdk`, so importing it can never drag another package's type graph into a
    // browser program. The shared elements sit one layer above it and may reach it and nothing
    // else — a shared element package that could reach an API client, an auth client, or the
    // backend contracts barrel would put all three inside every module artifact that renders a
    // button (ADR 0039).
    if (from.role === "design-tokens" && to.role !== "tooling") {
      return "design-packages-depend-downward-only";
    }
    if (from.role === "ui" && !["design-tokens", "tooling"].includes(to.role ?? "")) {
      return "design-packages-depend-downward-only";
    }
  }

  return undefined;
}

function packageNameFromSpecifier(specifier: string): string {
  if (specifier.startsWith("@")) {
    return specifier.split("/").slice(0, 2).join("/");
  }
  return specifier.split("/")[0] ?? specifier;
}

function isModuleUiPackage(packageName: string): boolean {
  const normalizedName = packageName.toLowerCase();
  return (
    MODULE_UI_PACKAGES.has(normalizedName) ||
    MODULE_UI_PACKAGE_PREFIXES.some((prefix) => normalizedName.startsWith(prefix))
  );
}

function npmAliasTarget(range: string): string | undefined {
  if (!range.startsWith("npm:")) {
    return undefined;
  }
  const alias = range.slice(4);
  if (alias.startsWith("@")) {
    const versionMarker = alias.lastIndexOf("@");
    return versionMarker > 0 ? alias.slice(0, versionMarker) : alias;
  }
  return alias.split("@")[0];
}

/**
 * The forbidden UI framework a module dependency actually resolves to, or `undefined` when it
 * resolves to none. Returns the *alias target* when the alias is what matched, so a dependency
 * declared as `"react": "npm:vue@3"` is reported as Vue rather than as the allowed name it hides
 * behind. Now that React is permitted (ADR 0022), that distinction is what keeps an allowed name
 * from becoming a way to smuggle a denied framework past the guard.
 */
function moduleUiDependencyTarget(packageName: string, range: string): string | undefined {
  if (isModuleUiPackage(packageName)) {
    return packageName;
  }
  const aliasTarget = npmAliasTarget(range);
  return aliasTarget && isModuleUiPackage(aliasTarget) ? aliasTarget : undefined;
}

async function isFile(filePath: string): Promise<boolean> {
  try {
    return (await stat(filePath)).isFile();
  } catch {
    return false;
  }
}

async function walkFiles(root: string, current = root): Promise<string[]> {
  const entries = await readdir(current, { withFileTypes: true });
  const files: string[] = [];

  for (const entry of entries) {
    if (entry.isDirectory() && IGNORED_DIRECTORIES.has(entry.name)) {
      continue;
    }

    const absolutePath = path.join(current, entry.name);
    const relativePath = normalizePath(path.relative(root, absolutePath));

    if (entry.isDirectory()) {
      if (relativePath === "tests/fixtures" || relativePath.startsWith("tests/fixtures/")) {
        continue;
      }
      files.push(...(await walkFiles(root, absolutePath)));
      continue;
    }

    if (entry.isFile()) {
      files.push(absolutePath);
    }
  }

  return files;
}

function workspacePatternMatches(relativeDirectory: string, pattern: string): boolean {
  let expression = "^";
  for (let index = 0; index < pattern.length; index += 1) {
    const character = pattern[index];
    if (character === "*" && pattern[index + 1] === "*") {
      expression += ".*";
      index += 1;
    } else if (character === "*") {
      expression += "[^/]*";
    } else if (character && /[\\^$.*+?()[\]{}|]/u.test(character)) {
      expression += `\\${character}`;
    } else {
      expression += character;
    }
  }
  expression += "$";
  return new RegExp(expression, "u").test(relativeDirectory);
}

function workspaceDirectoryIsIncluded(relativeDirectory: string, patterns: string[]): boolean {
  const included = patterns
    .filter((pattern) => !pattern.startsWith("!"))
    .some((pattern) => workspacePatternMatches(relativeDirectory, pattern));
  const excluded = patterns
    .filter((pattern) => pattern.startsWith("!"))
    .some((pattern) => workspacePatternMatches(relativeDirectory, pattern.slice(1)));
  return included && !excluded;
}

function workspacePatternIsSupported(pattern: string): boolean {
  const normalizedPattern = pattern.startsWith("!") ? pattern.slice(1) : pattern;
  return !/[?[\]{}]/u.test(normalizedPattern);
}

async function readWorkspacePatterns(root: string): Promise<string[] | undefined> {
  const workspaceFile = path.join(root, "pnpm-workspace.yaml");
  if (!(await isFile(workspaceFile))) {
    return undefined;
  }
  const workspace = parse(await readFile(workspaceFile, "utf8")) as WorkspaceConfiguration;
  return workspace.packages;
}

function collectImportSpecifiers(sourceText: string): string[] {
  const specifiers = new Set<string>();
  const staticImport = /\b(?:import|export)\s+(?:type\s+)?[^;]*?\bfrom\s*["']([^"'\n]+)["']/gu;
  const sideEffectImport = /\bimport\s*["']([^"'\n]+)["']/gu;
  const dynamicImport = /\b(?:import|require)\s*\(\s*["']([^"'\n]+)["']\s*\)/gu;

  for (const pattern of [staticImport, sideEffectImport, dynamicImport]) {
    for (const match of sourceText.matchAll(pattern)) {
      const specifier = match[1];
      if (specifier) {
        specifiers.add(specifier);
      }
    }
  }

  return [...specifiers];
}

/**
 * Whether a file is code a workspace package ships and executes: anything under its `src/` or
 * `bin/`, except tests and declaration files. Build scripts, configuration files, and tests run with
 * development dependencies installed, so they are outside this rule.
 */
function isRuntimeSourceFile(packageRelativePath: string): boolean {
  const normalized = normalizePath(packageRelativePath);
  if (!normalized.startsWith("src/") && !normalized.startsWith("bin/")) {
    return false;
  }
  const segments = normalized.split("/");
  if (segments.some((segment) => ["__tests__", "test", "tests"].includes(segment))) {
    return false;
  }
  const fileName = segments.at(-1) ?? "";
  return !/\.(?:test|spec)\.[cm]?[jt]sx?$/u.test(fileName) && !/\.d\.[cm]?ts$/u.test(fileName);
}

/** `import { type A, type B } from "x"` has no runtime binding: without `verbatimModuleSyntax`, the
 * compiler erases it exactly like `import type`. A default or namespace binding, or any specifier
 * without `type`, is a runtime import. */
function importClauseIsTypeOnly(clause: string): boolean {
  const trimmed = clause.trim();
  if (!trimmed.startsWith("{") || !trimmed.endsWith("}")) {
    return false;
  }
  const specifiers = trimmed
    .slice(1, -1)
    .split(",")
    .map((specifier) => specifier.trim())
    .filter((specifier) => specifier.length > 0);
  return specifiers.length > 0 && specifiers.every((specifier) => /^type\s/u.test(specifier));
}

/**
 * Bare specifiers a source file needs at run time: every static, side-effect, and dynamic import
 * except type-only ones. A `.tsx`/`.jsx` file also needs `react`, because the platform compiles JSX
 * with the automatic runtime (`"jsx": "react-jsx"`), which imports `react/jsx-runtime` without that
 * import appearing in the source.
 */
function collectRuntimeImportSpecifiers(sourceText: string, extension: string): string[] {
  const specifiers = new Set<string>();
  const staticImport = /\b(?:import|export)\s+(type\s+)?([^;]*?)\bfrom\s*["']([^"'\n]+)["']/gu;
  for (const match of sourceText.matchAll(staticImport)) {
    const [, typeKeyword, clause = "", specifier] = match;
    if (specifier && !typeKeyword && !importClauseIsTypeOnly(clause)) {
      specifiers.add(specifier);
    }
  }
  const sideEffectImport = /\bimport\s*["']([^"'\n]+)["']/gu;
  const dynamicImport = /\b(?:import|require)\s*\(\s*["']([^"'\n]+)["']\s*\)/gu;
  for (const pattern of [sideEffectImport, dynamicImport]) {
    for (const match of sourceText.matchAll(pattern)) {
      if (match[1]) {
        specifiers.add(match[1]);
      }
    }
  }
  if (extension === ".tsx" || extension === ".jsx") {
    specifiers.add("react/jsx-runtime");
  }
  return [...specifiers];
}

const NODE_BUILTIN_MODULES = new Set(builtinModules);

function isBareSpecifier(specifier: string): boolean {
  return !(
    specifier.startsWith(".") ||
    specifier.startsWith("/") ||
    specifier.startsWith("#") ||
    specifier.startsWith("node:") ||
    /^[a-z][a-z0-9+.-]*:/u.test(specifier)
  );
}

async function resolveSourceImport(
  fromFile: string,
  specifier: string,
): Promise<string | undefined> {
  if (!specifier.startsWith(".")) {
    return undefined;
  }

  const candidate = path.resolve(path.dirname(fromFile), specifier);
  const extension = path.extname(candidate);
  const withoutExtension = extension ? candidate.slice(0, -extension.length) : candidate;
  const candidates = [candidate];

  if ([".js", ".jsx", ".mjs", ".cjs"].includes(extension)) {
    candidates.push(
      `${withoutExtension}.ts`,
      `${withoutExtension}.tsx`,
      `${withoutExtension}.mts`,
      `${withoutExtension}.cts`,
    );
  } else if (!extension) {
    for (const codeExtension of CODE_EXTENSIONS) {
      candidates.push(
        `${candidate}${codeExtension}`,
        path.join(candidate, `index${codeExtension}`),
      );
    }
  }

  for (const possibleFile of candidates) {
    if (await isFile(possibleFile)) {
      return possibleFile;
    }
  }

  return candidate;
}

function findCycles(graph: Map<string, Set<string>>): string[][] {
  const visited = new Set<string>();
  const active = new Set<string>();
  const stack: string[] = [];
  const cycles: string[][] = [];
  const seenCycles = new Set<string>();

  function visit(node: string): void {
    if (active.has(node)) {
      const start = stack.indexOf(node);
      const cycle = [...stack.slice(start), node];
      const key = [...new Set(cycle)].sort().join("|");
      if (!seenCycles.has(key)) {
        seenCycles.add(key);
        cycles.push(cycle);
      }
      return;
    }

    if (visited.has(node)) {
      return;
    }

    visited.add(node);
    active.add(node);
    stack.push(node);
    for (const target of graph.get(node) ?? []) {
      if (graph.has(target)) {
        visit(target);
      }
    }
    stack.pop();
    active.delete(node);
  }

  for (const node of graph.keys()) {
    visit(node);
  }

  return cycles;
}

function exportedSubpath(
  manifest: PackageManifest,
  specifier: string,
  packageName: string,
): boolean {
  function hasAvailableTarget(target: unknown): boolean {
    if (typeof target === "string") {
      return true;
    }
    if (Array.isArray(target)) {
      return target.some(hasAvailableTarget);
    }
    if (target && typeof target === "object") {
      return Object.values(target).some(hasAvailableTarget);
    }
    return false;
  }

  const suffix = specifier.slice(packageName.length);
  const packageExports = manifest.exports;
  if (packageExports === undefined || packageExports === null) {
    return false;
  }

  if (!suffix) {
    if (typeof packageExports === "string") {
      return true;
    }
    if (Array.isArray(packageExports)) {
      return hasAvailableTarget(packageExports);
    }
    if (typeof packageExports !== "object") {
      return false;
    }

    const exportMap = packageExports as Record<string, unknown>;
    const exportKeys = Object.keys(exportMap);
    if (Object.hasOwn(exportMap, ".")) {
      return hasAvailableTarget(exportMap["."]);
    }
    return exportKeys.some((key) => !key.startsWith(".") && hasAvailableTarget(exportMap[key]));
  }

  if (typeof packageExports !== "object" || Array.isArray(packageExports)) {
    return false;
  }

  const exportMap = packageExports as Record<string, unknown>;
  const requested = `.${suffix}`;
  if (Object.hasOwn(exportMap, requested)) {
    return hasAvailableTarget(exportMap[requested]);
  }

  function comparePatternKeys(left: string, right: string): number {
    const leftBaseLength = left.indexOf("*") + 1;
    const rightBaseLength = right.indexOf("*") + 1;
    if (leftBaseLength > rightBaseLength) {
      return -1;
    }
    if (rightBaseLength > leftBaseLength) {
      return 1;
    }
    if (left.length > right.length) {
      return -1;
    }
    if (right.length > left.length) {
      return 1;
    }
    return 0;
  }

  const matchingPatterns = Object.keys(exportMap)
    .filter((exportKey) => {
      const wildcard = exportKey.indexOf("*");
      if (wildcard === -1) {
        return false;
      }
      return (
        requested.startsWith(exportKey.slice(0, wildcard)) &&
        requested.endsWith(exportKey.slice(wildcard + 1))
      );
    })
    .sort(comparePatternKeys);
  const matchingPattern = matchingPatterns[0];
  return matchingPattern ? hasAvailableTarget(exportMap[matchingPattern]) : false;
}

function findContainingPackage(
  filePath: string,
  packagesByDepth: WorkspacePackage[],
): WorkspacePackage | undefined {
  return packagesByDepth.find(
    (workspacePackage) =>
      filePath === workspacePackage.directory ||
      filePath.startsWith(`${workspacePackage.directory}${path.sep}`),
  );
}

function dependencyRange(manifest: PackageManifest, dependencyName: string): string | undefined {
  for (const dependencyField of DEPENDENCY_FIELDS) {
    const range = manifest[dependencyField]?.[dependencyName];
    if (range !== undefined) {
      return range;
    }
  }
  return undefined;
}

function workspaceAliasPackageName(range: string): string | undefined {
  if (!range.startsWith("workspace:")) {
    return undefined;
  }
  const target = range.slice("workspace:".length);
  if (target.startsWith("@")) {
    const versionMarker = target.lastIndexOf("@");
    return versionMarker > 0 ? target.slice(0, versionMarker) : target;
  }
  const versionMarker = target.lastIndexOf("@");
  return versionMarker > 0 ? target.slice(0, versionMarker) : undefined;
}

function resolveWorkspaceDependency(
  dependencyName: string,
  range: string,
  sourcePackage: WorkspacePackage,
  workspacePackages: Map<string, WorkspacePackage>,
  packageByDirectory: Map<string, WorkspacePackage>,
): { aliased: boolean; target: WorkspacePackage | undefined } {
  if (range.startsWith("workspace:.")) {
    const relativeTarget = range.slice("workspace:".length);
    return {
      aliased: true,
      target: packageByDirectory.get(path.resolve(sourcePackage.directory, relativeTarget)),
    };
  }

  const aliasName = workspaceAliasPackageName(range);
  if (aliasName) {
    return { aliased: true, target: workspacePackages.get(aliasName) };
  }

  const directTarget = workspacePackages.get(dependencyName);
  if (directTarget) {
    return { aliased: false, target: directTarget };
  }

  return { aliased: false, target: undefined };
}

export async function checkBoundaries(rootDirectory: string): Promise<BoundaryResult> {
  const root = path.resolve(rootDirectory);
  const allFiles = await walkFiles(root);
  const workspacePatterns = await readWorkspacePatterns(root);
  const manifestFiles = allFiles.filter((file) => path.basename(file) === "package.json");
  const codeFiles = allFiles.filter((file) => CODE_EXTENSIONS.has(path.extname(file)));
  const workspacePackages = new Map<string, WorkspacePackage>();
  const packageByDirectory = new Map<string, WorkspacePackage>();
  const violations: BoundaryViolation[] = [];

  for (const pattern of workspacePatterns ?? []) {
    if (!workspacePatternIsSupported(pattern)) {
      violations.push({
        from: "pnpm-workspace.yaml",
        message: `Workspace pattern ${pattern} uses unsupported glob syntax.`,
        rule: "workspace-patterns-use-supported-syntax",
      });
    }
  }

  for (const manifestFile of manifestFiles) {
    const manifest = JSON.parse(await readFile(manifestFile, "utf8")) as PackageManifest;
    if (!manifest.name) {
      continue;
    }
    const directory = path.dirname(manifestFile);
    const relativeDirectory = normalizePath(path.relative(root, directory)) || ".";
    if (
      directory !== root &&
      workspacePatterns &&
      !workspaceDirectoryIsIncluded(relativeDirectory, workspacePatterns)
    ) {
      continue;
    }
    const location = describeRepositoryPath(relativeDirectory);
    if (manifest.ekklesia?.layer) {
      location.role = manifest.ekklesia.layer;
    }
    if (
      location.layer === "shared" &&
      (!manifest.ekklesia?.layer || !SHARED_PACKAGE_ROLES.has(manifest.ekklesia.layer))
    ) {
      violations.push({
        from: relativeDirectory,
        message: `Shared package ${manifest.name} must declare a recognized ekklesia.layer role.`,
        rule: "shared-packages-declare-known-roles",
      });
    }
    const workspacePackage = { directory, location, manifest, name: manifest.name };
    const existingPackage = workspacePackages.get(manifest.name);
    if (existingPackage) {
      violations.push({
        from: relativeDirectory,
        message: `Workspace package name ${manifest.name} is already used by ${existingPackage.location.relativePath}.`,
        rule: "workspace-package-names-are-unique",
        to: existingPackage.location.relativePath,
      });
    } else {
      workspacePackages.set(manifest.name, workspacePackage);
    }
    packageByDirectory.set(directory, workspacePackage);
  }

  const packageGraph = new Map<string, Set<string>>();
  for (const workspacePackage of workspacePackages.values()) {
    packageGraph.set(workspacePackage.name, new Set());
    for (const dependencyField of DEPENDENCY_FIELDS) {
      for (const [dependencyName, range] of Object.entries(
        workspacePackage.manifest[dependencyField] ?? {},
      )) {
        const uiDependencyTarget =
          workspacePackage.location.layer === "module"
            ? moduleUiDependencyTarget(dependencyName, range)
            : undefined;
        if (uiDependencyTarget) {
          violations.push({
            from: workspacePackage.location.relativePath,
            message:
              uiDependencyTarget === dependencyName
                ? `Module package depends on UI framework ${dependencyName}.`
                : `Module package depends on UI framework ${uiDependencyTarget} aliased as ${dependencyName}.`,
            rule: "modules-do-not-own-ui",
          });
        }

        const resolvedDependency = resolveWorkspaceDependency(
          dependencyName,
          range,
          workspacePackage,
          workspacePackages,
          packageByDirectory,
        );
        const targetPackage = resolvedDependency.target;
        if (!targetPackage) {
          continue;
        }
        if (resolvedDependency.aliased) {
          violations.push({
            from: workspacePackage.location.relativePath,
            message: `Internal dependency alias ${dependencyName} obscures ${targetPackage.name}; use the real package name.`,
            rule: "workspace-dependency-aliases-are-forbidden",
            to: targetPackage.location.relativePath,
          });
        }
        if (!range.startsWith("workspace:")) {
          violations.push({
            from: workspacePackage.location.relativePath,
            message: `Internal dependency ${dependencyName} must use the workspace: protocol, not ${range}.`,
            rule: "internal-dependencies-use-workspace-protocol",
            to: targetPackage.location.relativePath,
          });
        }
        packageGraph.get(workspacePackage.name)?.add(targetPackage.name);
        const rule = boundaryRule(workspacePackage.location, targetPackage.location);
        if (rule) {
          violations.push({
            from: workspacePackage.location.relativePath,
            message: `${workspacePackage.name} may not depend on ${targetPackage.name}.`,
            rule,
            to: targetPackage.location.relativePath,
          });
        }
      }
    }
  }

  const packagesByDepth = [...packageByDirectory.values()].sort(
    (left, right) => right.directory.length - left.directory.length,
  );

  for (const cycle of findCycles(packageGraph)) {
    violations.push({
      from: cycle[0] ?? "unknown-package",
      message: `Workspace package cycle: ${cycle.join(" -> ")}`,
      rule: "no-circular-package-dependencies",
    });
  }

  for (const repositoryFile of allFiles) {
    const relativeFile = normalizePath(path.relative(root, repositoryFile));
    const location = describeRepositoryPath(relativeFile);
    if (location.layer !== "module") {
      continue;
    }
    const extension = path.extname(repositoryFile).toLowerCase();
    if (extension === ".css") {
      if (!isModuleBrowserSource(location.relativePath)) {
        violations.push({
          from: relativeFile,
          message: `A module stylesheet must live inside a compiled browser source root (${MODULE_BROWSER_SOURCE_ROOTS.join(", ")}).`,
          rule: "modules-do-not-own-ui",
        });
      }
      continue;
    }
    if (MODULE_UI_EXTENSIONS.has(extension)) {
      violations.push({
        from: relativeFile,
        message: "UI source files belong in a surface, not a module.",
        rule: "modules-do-not-own-ui",
      });
    }
  }

  const sourceGraph = new Map<string, Set<string>>();
  for (const codeFile of codeFiles) {
    const relativeFile = normalizePath(path.relative(root, codeFile));
    const from = describeRepositoryPath(relativeFile);
    sourceGraph.set(relativeFile, new Set());

    const sourceText = await readFile(codeFile, "utf8");

    // A workspace package is linked into its consumers as a directory, so Node resolves the
    // package's own imports from the package's own `node_modules`. A peer dependency is never
    // satisfied there by the consumer, and a production install (`pnpm install --prod`, as the
    // production image runs) omits development dependencies. Code a package ships must therefore
    // declare every runtime import as a production dependency. A peer declaration may stay beside it.
    const runtimePackage = findContainingPackage(codeFile, packagesByDepth);
    if (runtimePackage && isRuntimeSourceFile(path.relative(runtimePackage.directory, codeFile))) {
      const reported = new Set<string>();
      for (const specifier of collectRuntimeImportSpecifiers(
        sourceText,
        path.extname(codeFile).toLowerCase(),
      )) {
        if (!isBareSpecifier(specifier)) {
          continue;
        }
        const dependencyName = packageNameFromSpecifier(specifier);
        const manifest = runtimePackage.manifest;
        if (
          reported.has(dependencyName) ||
          dependencyName === runtimePackage.name ||
          NODE_BUILTIN_MODULES.has(dependencyName) ||
          manifest.dependencies?.[dependencyName] !== undefined ||
          manifest.optionalDependencies?.[dependencyName] !== undefined
        ) {
          continue;
        }
        reported.add(dependencyName);
        const declaredAs =
          manifest.peerDependencies?.[dependencyName] !== undefined
            ? "only as a peer dependency"
            : manifest.devDependencies?.[dependencyName] !== undefined
              ? "only as a development dependency"
              : "not at all";
        violations.push({
          from: relativeFile,
          message: `${runtimePackage.name} imports ${dependencyName} at run time but declares it ${declaredAs}; a runtime import must be in dependencies.`,
          rule: "runtime-imports-are-production-dependencies",
          to: dependencyName,
        });
      }
    }

    for (const specifier of collectImportSpecifiers(sourceText)) {
      const dependencyName = packageNameFromSpecifier(specifier);
      if (from.layer === "module" && isModuleUiPackage(dependencyName)) {
        violations.push({
          from: relativeFile,
          message: `Module source imports UI framework ${dependencyName}.`,
          rule: "modules-do-not-own-ui",
          to: specifier,
        });
      }

      let targetFile: string | undefined;
      let to: Location | undefined;
      if (specifier.startsWith(".")) {
        targetFile = await resolveSourceImport(codeFile, specifier);
        if (targetFile) {
          to = describeRepositoryPath(normalizePath(path.relative(root, targetFile)));
          if (await isFile(targetFile)) {
            sourceGraph.get(relativeFile)?.add(normalizePath(path.relative(root, targetFile)));
            const sourcePackage = findContainingPackage(codeFile, packagesByDepth);
            const targetPackage = findContainingPackage(targetFile, packagesByDepth);
            if (
              sourcePackage &&
              targetPackage &&
              sourcePackage.directory !== targetPackage.directory
            ) {
              violations.push({
                from: relativeFile,
                message: `Cross-package import ${specifier} must use ${targetPackage.name}'s public exports.`,
                rule: "workspace-imports-use-public-exports",
                to: targetPackage.location.relativePath,
              });
            }
          }
        }
      } else {
        const sourcePackage = findContainingPackage(codeFile, packagesByDepth);
        const declaredRange = sourcePackage
          ? dependencyRange(sourcePackage.manifest, dependencyName)
          : undefined;
        const targetPackage =
          sourcePackage && declaredRange
            ? resolveWorkspaceDependency(
                dependencyName,
                declaredRange,
                sourcePackage,
                workspacePackages,
                packageByDirectory,
              ).target
            : workspacePackages.get(dependencyName);
        if (targetPackage) {
          to = targetPackage.location;
          if (sourcePackage && sourcePackage.directory !== targetPackage.directory) {
            if (declaredRange === undefined) {
              violations.push({
                from: relativeFile,
                message: `${sourcePackage.name} imports ${dependencyName} without declaring it.`,
                rule: "workspace-dependencies-are-declared",
                to: targetPackage.location.relativePath,
              });
            }
          }
          const publicSpecifier =
            dependencyName === targetPackage.name ? specifier : targetPackage.name;
          if (!exportedSubpath(targetPackage.manifest, publicSpecifier, targetPackage.name)) {
            violations.push({
              from: relativeFile,
              message: `${specifier} is not a public package export.`,
              rule: "workspace-imports-use-public-exports",
              to: targetPackage.location.relativePath,
            });
          }
        }
      }

      if (to) {
        const rule = boundaryRule(from, to);
        if (rule) {
          violations.push({
            from: relativeFile,
            message: `${from.layer} code may not import ${to.layer} code directly.`,
            rule,
            to: to.relativePath,
          });
        }
      }
    }
  }

  for (const cycle of findCycles(sourceGraph)) {
    violations.push({
      from: cycle[0] ?? "unknown-source",
      message: `Source dependency cycle: ${cycle.join(" -> ")}`,
      rule: "no-circular-source-dependencies",
    });
  }

  return {
    filesChecked: codeFiles.length,
    packagesChecked: packageByDirectory.size,
    violations,
  };
}

async function main(): Promise<void> {
  const root = process.argv[2] ? path.resolve(process.argv[2]) : process.cwd();
  const result = await checkBoundaries(root);
  if (result.violations.length > 0) {
    console.error(`Boundary validation failed with ${result.violations.length} violation(s):`);
    for (const violation of result.violations) {
      const target = violation.to ? ` -> ${violation.to}` : "";
      console.error(`- [${violation.rule}] ${violation.from}${target}: ${violation.message}`);
    }
    process.exitCode = 1;
    return;
  }

  console.log(
    `Boundary validation passed (${result.packagesChecked} packages, ${result.filesChecked} source files).`,
  );
}

const entryPoint = process.argv[1];
if (entryPoint && import.meta.url === pathToFileURL(path.resolve(entryPoint)).href) {
  await main();
}