sitegen/framework/hot.ts

// This implements the ability to use TS, TSX, and more plugins
// in Node.js. It cannot be built on the ES module loader,
// because there is no exposed way to replace modules when
// needed (see nodejs#49442).
//
// It also allows using a simple compile cache, which is used by
// the site generator to determine when code changes.
export const projectRoot = path.resolve(import.meta.dirname, "../");
export const projectSrc = path.resolve(projectRoot, "src");

// Create a project-relative require. For convenience, it is generic-typed.
export const load = createRequire(
  pathToFileURL(path.join(projectRoot, "run.js")).toString(),
) as {
  <T = unknown>(id: string): T;
  extensions: NodeJS.Dict<(mod: NodeJS.Module, file: string) => unknown>;
  cache: NodeJS.Dict<NodeJS.Module>;
  resolve: (id: string, o?: { paths: string[] }) => string;
};
export const { cache } = load;

// Register extensions by overwriting `require.extensions`
const require = load;
const exts = require.extensions;
exts[".ts"] = loadEsbuild;
exts[".tsx"] = loadEsbuild;
exts[".jsx"] = loadEsbuild;
exts[".marko"] = loadMarko;
exts[".mdx"] = loadMdx;
exts[".css"] = loadCss;

// Intercept all module load calls to track CSS imports + file times.
export interface FileStat {
  cssImportsRecursive: string[] | null;
  lastModified: number;
  imports: string[];
  /* Used by 'incremental.ts' */
  srcIds: string[];
}
let fsGraph = new Map<string, FileStat>();
export function setFsGraph(g: Map<string, FileStat>) {
  if (fsGraph.size > 0) {
    throw new Error("Cannot restore fsGraph when it has been written into");
  }
  fsGraph = g;
}
export function getFsGraph() {
  return fsGraph;
}

function shouldTrackPath(filename: string) {
  return !filename.includes("node_modules") &&
    !filename.includes(import.meta.dirname);
}

const Module = load<typeof import("node:module")>("node:module");
const ModulePrototypeUnderscoreCompile = Module.prototype._compile;
Module.prototype._compile = function (
  content: string,
  filename: string,
  format: "module" | "commonjs",
) {
  fs.writeMkdirSync(
    ".clover/debug-transpilation/" +
      path.relative(projectRoot, filename).replaceAll("\\", "/").replaceAll(
        "../",
        "_/",
      ).replaceAll("/", "."),
    content,
  );
  const result = ModulePrototypeUnderscoreCompile.call(
    this,
    content,
    filename,
    format,
  );
  const stat = fs.statSync(filename);
  if (shouldTrackPath(filename)) {
    const cssImportsMaybe: string[] = [];
    const imports: string[] = [];
    for (const { filename: file } of this.children) {
      const relative = path.relative(projectRoot, file);
      if (file.endsWith(".css")) cssImportsMaybe.push(relative);
      else {
        const child = fsGraph.get(relative);
        if (!child) continue;
        const { cssImportsRecursive } = child;
        if (cssImportsRecursive) cssImportsMaybe.push(...cssImportsRecursive);
        imports.push(relative);
      }
    }
    const relative = path.relative(projectRoot, filename);
    fsGraph.set(relative, {
      cssImportsRecursive: cssImportsMaybe.length > 0
        ? Array.from(new Set(cssImportsMaybe))
        : null,
      imports,
      lastModified: stat.mtimeMs,
      srcIds: [],
    });
  }
  return result;
};

// Implement @/ prefix
const ModuleUnderscoreResolveFilename = Module._resolveFilename;
Module._resolveFilename = (...args) => {
  if (args[0].startsWith("@/")) {
    const replacedPath = "." + args[0].slice(1);
    try {
      return require.resolve(replacedPath, { paths: [projectSrc] });
    } catch (err: any) {
      if (err.code === "MODULE_NOT_FOUND" && err.requireStack.length <= 1) {
        err.message.replace(replacedPath, args[0]);
      }
    }
  }
  return ModuleUnderscoreResolveFilename(...args);
};

function loadEsbuild(module: NodeJS.Module, filepath: string) {
  let src = fs.readFileSync(filepath, "utf8");
  return loadEsbuildCode(module, filepath, src);
}

function loadEsbuildCode(module: NodeJS.Module, filepath: string, src: string) {
  if (filepath === import.meta.filename) {
    module.exports = self;
    return;
  }

  let loader: any = "tsx";
  if (filepath.endsWith(".ts")) loader = "ts";
  else if (filepath.endsWith(".jsx")) loader = "jsx";
  else if (filepath.endsWith(".js")) loader = "js";
  if (src.includes("import.meta")) {
    src = `
      import.meta.url = ${JSON.stringify(pathToFileURL(filepath).toString())};
      import.meta.dirname = ${JSON.stringify(path.dirname(filepath))};
      import.meta.filename = ${JSON.stringify(filepath)};
    ` + src;
  }
  src = esbuild.transformSync(src, {
    loader,
    format: "cjs",
    target: "esnext",
    jsx: "automatic",
    jsxImportSource: "#ssr",
  }).code;
  return module._compile(src, filepath, "commonjs");
}

function loadMarko(module: NodeJS.Module, filepath: string) {
  let src = fs.readFileSync(filepath, "utf8");
  // A non-standard thing here is Clover Sitegen implements
  // its own client side scripting stuff, so it overrides
  // bare client import statements to it's own usage.
  if (src.match(/^\s*client\s+import\s+["']/m)) {
    src = src.replace(
      /^\s*client\s+import\s+("[^"]+|'[^']+)[^\n]+/m,
      "<CloverScriptInclude src=$1 />",
    ) + '\nimport { Script as CloverScriptInclude } from "#sitegen";';
  }

  src = marko.compileSync(filepath, {}).code;
  src = src.replace("marko/debug/html", "#ssr/marko");
  return loadEsbuildCode(module, filepath, src);
}

function loadMdx(module: NodeJS.Module, filepath: string) {
  const input = fs.readFileSync(filepath);
  const out = mdx.compileSync(input, { jsxImportSource: "#ssr" }).value;
  const src = typeof out === "string" ? out : Buffer.from(out).toString("utf8");
  return loadEsbuildCode(module, filepath, src);
}

function loadCss(module: NodeJS.Module, filepath: string) {
  module.exports = {};
}

export function reloadRecursive(filepath: string) {
  filepath = path.resolve(filepath);
  const existing = cache[filepath];
  if (existing) deleteRecursive(filepath, existing);
  fsGraph.clear();
  return require(filepath);
}

function deleteRecursive(id: string, module: any) {
  if (id.includes(path.sep + "node_modules" + path.sep)) {
    return;
  }
  delete cache[id];
  for (const child of module.children) {
    if (child.filename.includes("/engine/")) return;
    const existing = cache[child.filename];
    if (existing === child) deleteRecursive(child.filename, existing);
  }
}

export function getCssImports(filepath: string) {
  filepath = path.resolve(filepath);
  if (!require.cache[filepath]) throw new Error(filepath + " was never loaded");
  return fsGraph.get(path.relative(projectRoot, filepath))
    ?.cssImportsRecursive ?? [];
}

export function resolveFrom(src: string, dest: string) {
  try {
    return createRequire(src).resolve(dest);
  } catch (err: any) {
    if (err.code === "MODULE_NOT_FOUND" && err.requireStack.length <= 1) {
      err.message = err.message.split("\n")[0] + " from '" + src + "'";
    }
    throw err;
  }
}

declare global {
  namespace NodeJS {
    interface Module {
      _compile(
        this: NodeJS.Module,
        content: string,
        filepath: string,
        format: "module" | "commonjs",
      ): unknown;
    }
  }
}

import * as fs from "./fs.ts";
import * as path from "node:path";
import { pathToFileURL } from "node:url";
import * as esbuild from "esbuild";
import * as marko from "@marko/compiler";
import { createRequire } from "node:module";
import * as mdx from "@mdx-js/mdx";
import * as self from "./hot.ts";
import { Buffer } from "node:buffer";