split-bundler-friendly-vfss.mjs

import { mkdir, readFile, writeFile } from 'node:fs/promises';
import path from 'node:path';
import { fileURLToPath } from 'node:url';

const rootDir = path.resolve(path.dirname(fileURLToPath(import.meta.url)), '..');
const sourcePath = path.join(rootDir, 'src/bin/sqlite3-bundler-friendly.mjs');
const outputDir = path.join(rootDir, 'src/bin');

const generatedHeader = (
  sourceFile,
) => `// Generated by scripts/split-bundler-friendly-vfss.mjs from ${sourceFile}.
// Do not edit this file directly.

`;

const initRegistry = `const sqlite3BundlerFriendlyOptionalState =
  (globalThis.__sqlite3BundlerFriendlyOptional ??= {
    initializers: Object.create(null),
  });

const sqlite3BundlerFriendlyRegisterOptionalInitializer = (slot, initializer) => {
  if (globalThis.sqlite3ApiBootstrap?.initializers) {
    globalThis.sqlite3ApiBootstrap.initializers.push(initializer);
  } else {
    (sqlite3BundlerFriendlyOptionalState.initializers[slot] ??= []).push(initializer);
  }
};

`;

const baseHook = `const sqlite3BundlerFriendlyInstallOptionalInitializers = (slot) => {
  const sqlite3BundlerFriendlyOptionalState = globalThis.__sqlite3BundlerFriendlyOptional;
  const initializers = sqlite3BundlerFriendlyOptionalState?.initializers?.[slot];
  if (initializers?.length) {
    globalThis.sqlite3ApiBootstrap.initializers.push(
      ...initializers,
    );
  }
};

`;

const markerSpecs = {
  worker1: 'This file implements the initializer for SQLite\'s "Worker API #1"',
  helper: 'This file installs sqlite3.vfs, a namespace of helpers',
  vtab: 'This file installs sqlite3.vtab, a namespace of helpers',
  kvvfs: 'This file houses the "kvvfs" pieces of the SQLite3 JS API',
  opfsShared: 'This file holds code shared by sqlite3-vfs-opfs{,-wl}.c-pp.js',
  opfs: 'This file holds the synchronous half of an sqlite3_vfs',
  sahpool: 'This file holds a sqlite3_vfs backed by OPFS storage',
  opfsWl: 'This file is a reimplementation of the "opfs" VFS',
  tail: 'This file is the tail end of the sqlite3-api.js constellation',
};

const findCommentStart = (source, marker) => {
  const markerIndex = source.indexOf(marker);
  if (markerIndex < 0) {
    throw new Error(`Unable to find marker: ${marker}`);
  }
  const commentStart = source.lastIndexOf('/*', markerIndex);
  if (commentStart < 0) {
    throw new Error(`Unable to find comment start for marker: ${marker}`);
  }
  return commentStart;
};

const replaceAll = (value, replacements) => {
  let result = value;
  for (const [from, to] of replacements) {
    result = result.split(from).join(to);
  }
  return result;
};

const source = await readFile(sourcePath, 'utf8');
const markers = Object.fromEntries(
  Object.entries(markerSpecs).map(([name, marker]) => [name, findCommentStart(source, marker)]),
);

const ranges = {
  worker1: [markers.worker1, markers.helper],
  helper: [markers.helper, markers.vtab],
  vtab: [markers.vtab, markers.kvvfs],
  kvvfs: [markers.kvvfs, markers.opfsShared],
  opfsShared: [markers.opfsShared, markers.opfs],
  opfs: [markers.opfs, markers.sahpool],
  sahpool: [markers.sahpool, markers.opfsWl],
  opfsWl: [markers.opfsWl, markers.tail],
};

for (const [name, [start, end]] of Object.entries(ranges)) {
  if (start >= end) {
    throw new Error(`Invalid ${name} range: ${start} >= ${end}`);
  }
}

const bootstrapAsyncMarker = 'globalThis.sqlite3ApiBootstrap.initializersAsync = [];\n';
if (!source.includes(bootstrapAsyncMarker)) {
  throw new Error(`Unable to find bootstrap hook marker: ${bootstrapAsyncMarker.trim()}`);
}

const strippedSource = Object.entries(ranges)
  .sort((a, b) => b[1][0] - a[1][0])
  .reduce(
    (current, [name, [start, end]]) =>
      current.slice(0, start) +
      `\n/* Optional initializer slot removed by scripts/split-bundler-friendly-vfss.mjs: ${name} */\n` +
      `sqlite3BundlerFriendlyInstallOptionalInitializers('${name}');\n` +
      current.slice(end),
    source,
  )
  .replace(bootstrapAsyncMarker, bootstrapAsyncMarker + baseHook);

const outputFileNames = {
  worker1: 'sqlite3-worker1-api.mjs',
};

const toOptionalModule = (slot, chunk) =>
  generatedHeader('sqlite3-bundler-friendly.mjs') +
  initRegistry +
  replaceAll(chunk, [
    [
      'globalThis.sqlite3ApiBootstrap.initializers.push(',
      `sqlite3BundlerFriendlyRegisterOptionalInitializer('${slot}', `,
    ],
  ]);

await mkdir(outputDir, { recursive: true });

await writeFile(
  path.join(outputDir, 'sqlite3-bundler-friendly.core.mjs'),
  generatedHeader('sqlite3-bundler-friendly.mjs') + strippedSource,
);

await Promise.all(
  Object.entries(ranges).map(([name, [start, end]]) =>
    writeFile(
      path.join(outputDir, outputFileNames[name] ?? `sqlite3-vfs-${name}.mjs`),
      toOptionalModule(name, source.slice(start, end)),
    ),
  ),
);