@embeddable.com/sdk-core/loader/custom-esm-loader.mjs

Core Embeddable SDK module responsible for web-components bundling and publishing.

/**
 * Most of the code in this file is copied from the following file:
 * https://github.com/swc-project/swc-node/blob/master/packages/register/esm.mts
 *
 * The main difference is that resolve function is modified to handle non-TS files.
 *
 * */

import { fileURLToPath, pathToFileURL } from "url";
import { dirname, join } from "path";
import ts from "typescript";
import { readDefaultTsConfig } from "@swc-node/register/read-default-tsconfig";
import { compile } from "./custom-esm-register.cjs";
import fs from "fs";
import path from "path";

// Find the tsconfig.json in the customer's project directory
const tsconfigPath = ts.findConfigFile(
  process.cwd(),
  fs.existsSync,
  "tsconfig.json",
);

let tsconfig;
if (tsconfigPath) {
  // Read and parse the tsconfig.json
  const configFile = ts.readConfigFile(tsconfigPath, ts.sys.readFile);

  const parsedConfig = ts.parseJsonConfigFileContent(
    configFile.config,
    ts.sys,
    dirname(tsconfigPath),
  );

  tsconfig = parsedConfig.options;
} else {
  tsconfig = await readDefaultTsConfig();
}

// Set necessary compiler options
tsconfig.module = ts.ModuleKind.ESNext;
tsconfig.moduleResolution = ts.ModuleResolutionKind.Node16;

const moduleResolutionCache = ts.createModuleResolutionCache(
  ts.sys.getCurrentDirectory(),
  (x) => x,
  tsconfig,
);

const host = {
  fileExists: ts.sys.fileExists,
  readFile: ts.sys.readFile,
};

const EXTENSIONS = [ts.Extension.Ts, ts.Extension.Tsx, ts.Extension.Mts];
const NON_JS_TS_EXTENSIONS =
  /\.(css|scss|less|sass|styl|json|svg|woff|woff2|png|jpg|jpeg|gif|webp|md|yml|yaml)$/;

const currentDir = dirname(fileURLToPath(import.meta.url));

const isWindows = process.platform === "win32";

function cleanWindowsFileURL(url) {
  // Remove any duplicate file:/ prefixes and normalize slashes
  return url
    .replace(/file:\/+/g, "file:///")
    .replace(/\\/g, "/")
    .replace(/file:\/+([A-Za-z]:)/, "file:///$1");
}

export const resolve = async (specifier, context, nextResolve) => {
  if (NON_JS_TS_EXTENSIONS.test(specifier)) {
    const mockModulePath = pathToFileURL(
      join(currentDir, "mock-module.js"),
    ).href;

    return {
      format: "module",
      url: mockModulePath,
      shortCircuit: true,
    };
  }

  const isTS = EXTENSIONS.some((ext) => specifier.endsWith(ext));

  // Entry point
  if (!context.parentURL) {
    if (isWindows) {
      // Handle the case where the specifier contains both the cwd and the actual path
      const parts = specifier.split("file:/");
      const lastPart = parts[parts.length - 1];

      // Convert the path to a proper file URL
      const cleanPath = lastPart.replace(/^\/+/, "");
      const entryPointPath = pathToFileURL(cleanPath).href;

      return {
        format: isTS ? "ts" : undefined,
        url: cleanWindowsFileURL(entryPointPath),
        shortCircuit: true,
      };
    }

    return {
      format: isTS ? "ts" : undefined,
      url: specifier,
      shortCircuit: true,
    };
  }

  // Handle SDK relative imports
  if (
    isWindows &&
    specifier.startsWith(".") &&
    context.parentURL?.includes("embeddable-sdk")
  ) {
    const parentPath = fileURLToPath(context.parentURL);
    const parentDir = dirname(parentPath);
    let resolvedPath = join(parentDir, specifier);

    // If no extension is provided, try common extensions
    if (!path.extname(resolvedPath)) {
      const extensions = [".js", ".mjs", ".cjs", ".ts", ".mts"];
      for (const ext of extensions) {
        const pathWithExt = resolvedPath + ext;
        if (fs.existsSync(pathWithExt) && fs.statSync(pathWithExt).isFile()) {
          resolvedPath = pathWithExt;
          break;
        }
      }
    }

    // Check if the resolved path exists and is a file
    if (fs.existsSync(resolvedPath) && fs.statSync(resolvedPath).isFile()) {
      return {
        url: pathToFileURL(resolvedPath).href,
        shortCircuit: true,
      };
    }
  }

  // Determine if this is a package import
  const isPackageImport =
    !specifier.startsWith(".") &&
    !specifier.startsWith("/") &&
    !/^[A-Z]:/.test(specifier); // Windows path

  // External library import
  if (
    (context.parentURL?.includes("/node_modules/") || isPackageImport) &&
    !isTS
  ) {
    return nextResolve(specifier);
  }

  const isFileUrl = specifier.startsWith("file://");
  const isParentFileUrl = context.parentURL?.startsWith("file://");

  // Resolve the module using TypeScript's module resolution
  const { resolvedModule } = ts.resolveModuleName(
    isFileUrl ? fileURLToPath(specifier) : specifier,
    isParentFileUrl ? fileURLToPath(context.parentURL) : context.parentURL,
    tsconfig,
    host,
    moduleResolutionCache,
  );

  // Local project TS file
  if (
    resolvedModule &&
    !resolvedModule.resolvedFileName.includes("/node_modules/") &&
    EXTENSIONS.includes(resolvedModule.extension)
  ) {
    const resolved = {
      format: "ts",
      url:
        pathToFileURL(resolvedModule.resolvedFileName).href +
        `?update=${Date.now()}`,
      shortCircuit: true,
    };

    return resolved;
  }

  // Fallback for non-TS files or unresolved modules
  const specifierPathOrUrl =
    !resolvedModule?.resolvedFileName?.includes("/node_modules/") && isWindows
      ? pathToFileURL(specifier).href
      : specifier;

  return nextResolve(specifierPathOrUrl);
};

export const load = async (url, context, nextLoad) => {
  if (context.format === "ts") {
    const { source } = await nextLoad(url, context);
    const code =
      typeof source === "string" ? source : Buffer.from(source).toString();

    // Compile the code using @swc-node with the customer's tsconfig
    const compiled = await compile(code, fileURLToPath(url), tsconfig, true);
    const resolved = {
      format: "module",
      source: compiled,
      shortCircuit: true,
    };

    return resolved;
  } else {
    if (
      isWindows &&
      !url.startsWith("file://") &&
      url.includes("node_modules")
    ) {
      return nextLoad(pathToFileURL(url).href, context);
    }
    return nextLoad(url, context);
  }
};