4bnode/lib/indexFile.js

4bnode is a CLI-powered backend development platform with a built-in visual dashboard to generate, manage, and test Node.js/Express APIs faster.

import fs from "fs";
import path from "path";
import { getProjectRoot } from "./project.js";
import { ERROR_HANDLER_MARKER, insertBeforeListenContent } from "./codegen.js";

function getIndexPath() {
  return path.join(getProjectRoot(), "index.js");
}

function readIndex() {
  return fs.readFileSync(getIndexPath(), "utf8");
}

function writeIndex(content) {
  fs.writeFileSync(getIndexPath(), content, "utf8");
}

export function addImport(importStatement) {
  let content = readIndex();
  if (!content.includes(importStatement.trim())) {
    content = importStatement.trim() + "\n" + content;
    writeIndex(content);
  }
}

export function addRouteRegistration(importLine, useLine) {
  let content = readIndex();

  if (!content.includes(importLine.trim())) {
    content = importLine.trim() + "\n" + content;
  }

  if (!content.includes(useLine.trim())) {
    // The central error handler (added by `add security`) must stay last. If it's
    // present, register new routes ABOVE it so notFound doesn't swallow them.
    if (content.includes(ERROR_HANDLER_MARKER)) {
      content = content.replace(
        ERROR_HANDLER_MARKER,
        useLine.trim() + "\n\n" + ERROR_HANDLER_MARKER
      );
    } else if (content.includes("app.listen(port")) {
      content = content.replace(
        "app.listen(port",
        useLine.trim() + "\n" + "app.listen(port"
      );
    } else if (content.includes("server.listen(port")) {
      content = content.replace(
        "server.listen(port",
        useLine.trim() + "\n" + "server.listen(port"
      );
    } else if (content.match(/^startServer\(/m)) {
      content = content.replace(
        /^startServer\(/m,
        useLine.trim() + "\n" + "startServer("
      );
    }
  }

  writeIndex(content);
}

export function insertBeforeListen(codeBlock) {
  writeIndex(insertBeforeListenContent(readIndex(), codeBlock));
}

export function replaceAppListen(newListenBlock) {
  let content = readIndex();

  // If using startServer() pattern, just swap app.listen → server.listen inside it
  if (content.includes("startServer(")) {
    content = content.replace(
      /const listener = app\.listen\(tryPort\)/,
      "const listener = server.listen(tryPort)"
    );
    // Also swap standalone app.listen(tryPort) if no 'const listener' pattern
    if (!content.includes("server.listen(tryPort)")) {
      content = content.replace(
        /app\.listen\(tryPort\)/,
        "server.listen(tryPort)"
      );
    }
  } else {
    content = content.replace(/app\.listen\(port[\s\S]*?\}\);?\n?/m, "");
    if (!content.includes("server.listen(port")) {
      content += "\n" + newListenBlock.trim() + "\n";
    }
  }
  writeIndex(content);
}

export function insertBeforeRoutes(codeBlock) {
  let content = readIndex();

  // Insert before startServer() or the start server section
  const markers = [
    "// ── Start Server",
    "// ── Helpers",
    "startServer(",
  ];
  let inserted = false;
  for (const marker of markers) {
    const idx = content.indexOf(marker);
    if (idx !== -1) {
      content =
        content.slice(0, idx) +
        codeBlock.trim() +
        "\n\n" +
        content.slice(idx);
      inserted = true;
      break;
    }
  }

  if (!inserted) {
    // Fallback: before first app.use that isn't middleware
    const routeUseMatch = content.match(/app\.use\(['"]\/(?!_dev)/);
    if (routeUseMatch) {
      const idx = content.indexOf(routeUseMatch[0]);
      content =
        content.slice(0, idx) +
        codeBlock.trim() +
        "\n\n" +
        content.slice(idx);
    } else {
      content += "\n" + codeBlock.trim() + "\n";
    }
  }

  writeIndex(content);
}

export { readIndex, writeIndex, getIndexPath };