auto-generate type definitions from the json schema

lib/build.js

@@ -1,3 +1,4 @@
+import { fileURLToPath } from 'node:url';
 import { styleText } from 'node:util';
 import fs from 'fs';
 import jsonschema from 'jsonschema';
@@ -6,6 +7,7 @@ import shell from 'shelljs';
 import YAML from 'js-yaml';
 import marky from 'marky';
 import { createRequire } from 'module';
+import { compile, toSafeIdentifier } from 'json-schema-to-typescript-lite';
 
 import fetchTranslations from './translations.js';
 
@@ -186,7 +188,8 @@ function processData(options, type) {
     minifyJSON(distDir + '/preset_defaults.json', distDir + '/preset_defaults.min.json'),
     minifyJSON(distDir + '/deprecated.json', distDir + '/deprecated.min.json'),
     minifyJSON(distDir + '/discarded.json', distDir + '/discarded.min.json'),
-    minifyJSON(distDir + '/translations/' + sourceLocale + '.json', distDir + '/translations/' + sourceLocale + '.min.json')
+    minifyJSON(distDir + '/translations/' + sourceLocale + '.json', distDir + '/translations/' + sourceLocale + '.min.json'),
+    generateTypeDefs(distDir),
   ];
 
   if (doFetchTranslations) {
@@ -746,6 +749,91 @@ function generateIconsList(presets, fields, categories) {
   return Object.keys(icons).sort();
 }
 
+/** @param {string} string */
+const toPascalCase = string => string.replace(/(_.|^.)/g, match => match.at(-1).toUpperCase());
+
+/** @param {string} string */
+const createTypeIdentifier = (string) => toPascalCase(toSafeIdentifier(string));
+
+
+/** @param {string} distDir */
+async function generateTypeDefs(distDir) {
+  const __dirname = path.dirname(fileURLToPath(import.meta.url));
+  const inputFolder = path.join(__dirname, '../schemas');
+
+  /**
+   * Some generated files use plural names because they
+   * export an object, e.g. `Fields = Record<string, Field>`
+   * @type {Record<string, string>}
+   */
+  const KEY_MAP = {
+    field: 'fields',
+    preset: 'presets',
+    preset_category: 'preset_categories',
+  };
+  const fileNames = fs.globSync(path.join(inputFolder, '/**/*.json'));
+
+  /** @param {string} fileName */
+  async function processFile(fileName) {
+    const key = path.parse(fileName).name;
+    const pluralKey = KEY_MAP[key];
+
+    const mainExport = createTypeIdentifier(pluralKey || key);
+
+    const output = [''];
+
+    if (pluralKey) {
+      output.push(
+        `export interface ${createTypeIdentifier(pluralKey)} {`,
+        `  [id: string]: ${createTypeIdentifier(key)}`,
+        '}'
+      );
+    }
+
+    output.push(
+      `declare const json: ${mainExport};`,
+      'export default json;'
+    );
+
+    const fileContent = JSON.parse(await fs.promises.readFile(fileName, 'utf8'));
+    if (key === 'field') delete fileContent.anyOf;
+
+    const tsFile = await compile(fileContent, mainExport, {
+      additionalProperties: false,
+      ignoreMinAndMaxItems: true,
+      cwd: path.join(__dirname, '../schemas'),
+
+      // ensure that the default export uses a consistent name
+      customName: (schema, fallback) =>
+        schema.$schema && schema.$id
+          ? createTypeIdentifier(path.parse(schema.$id).name)
+          : (schema.$id || schema.title || fallback || ''),
+    });
+
+
+    output.unshift(tsFile);
+    output.push('');
+    await fs.promises.writeFile(
+      path.join(distDir, `${pluralKey || key}.d.json.ts`),
+      output.join('\n'),
+    );
+  }
+  await Promise.all(fileNames.map(processFile));
+
+  // finally, create the index file which re-exports everything
+  // as named types.
+  const indexFile = fileNames
+    .map((fileName) => {
+      const key = path.parse(fileName).name;
+      return `export type * from './${KEY_MAP[key] || key}.d.json.ts';`;
+    })
+    .join('\n');
+
+  await fs.promises.writeFile(
+    path.join(distDir, 'index.d.ts'),
+    indexFile + '\n',
+  );
+}
 
 function validateCategoryPresets(categories, presets) {
   Object.keys(categories).forEach(id => {

package.json

@@ -14,6 +14,7 @@
   "dependencies": {
     "@transifex/api": "^7.1.0",
     "js-yaml": "^4.0.0",
+    "json-schema-to-typescript-lite": "^15.0.0",
     "jsonschema": "^1.1.0",
     "marky": "^1.2.4",
     "node-fetch": "^3.2.10",