1 files changed, 104 insertions, 0 deletions
diff --git a/@linaria/packages/babel/src/evaluators/buildOptions.ts b/@linaria/packages/babel/src/evaluators/buildOptions.ts
new file mode 100644
index 0000000..a938d4b
--- /dev/null
+++ b/@linaria/packages/babel/src/evaluators/buildOptions.ts
@@ -0,0 +1,104 @@
+/**
+ * This file handles preparing babel config for Linaria preevaluation.
+ */
+
+import type { PluginItem, TransformOptions } from '@babel/core';
+import type { StrictOptions } from '../types';
+
+type DefaultOptions = Partial<TransformOptions> & {
+  plugins: PluginItem[];
+  presets: PluginItem[];
+  caller: { evaluate: boolean };
+};
+
+export default function buildOptions(
+  filename: string,
+  options?: StrictOptions
+): TransformOptions {
+  const plugins: Array<string | object> = [
+    // Include these plugins to avoid extra config when using { module: false } for webpack
+    '@babel/plugin-transform-modules-commonjs',
+    '@babel/plugin-proposal-export-namespace-from',
+  ];
+
+  const defaults: DefaultOptions = {
+    caller: { name: 'linaria', evaluate: true },
+    filename: filename,
+    presets: [
+      [
+        require.resolve('../index'),
+        {
+          ...(options || {}),
+        },
+      ],
+    ],
+    plugins: [
+      ...plugins.map((name) => require.resolve(name as string)),
+      // We don't support dynamic imports when evaluating, but don't wanna syntax error
+      // This will replace dynamic imports with an object that does nothing
+      require.resolve('../dynamic-import-noop'),
+    ],
+  };
+
+  const babelOptions =
+    // Shallow copy the babel options because we mutate it later
+    options?.babelOptions ? { ...options.babelOptions } : {};
+
+  // If we programmatically pass babel options while there is a .babelrc, babel might throw
+  // We need to filter out duplicate presets and plugins so that this doesn't happen
+  // This workaround isn't full proof, but it's still better than nothing
+  const keys: Array<keyof TransformOptions & ('presets' | 'plugins')> = [
+    'presets',
+    'plugins',
+  ];
+  keys.forEach((field) => {
+    babelOptions[field] = babelOptions[field]
+      ? babelOptions[field]!.filter((item: PluginItem) => {
+          // If item is an array it's a preset/plugin with options ([preset, options])
+          // Get the first item to get the preset.plugin name
+          // Otherwise it's a plugin name (can be a function too)
+          const name = Array.isArray(item) ? item[0] : item;
+
+          if (
+            // In our case, a preset might also be referring to linaria/babel
+            // We require the file from internal path which is not the same one that we export
+            // This case won't get caught and the preset won't filtered, even if they are same
+            // So we add an extra check for top level linaria/babel
+            name === 'linaria/babel' ||
+            name === '@linaria' ||
+            name === '@linaria/babel-preset' ||
+            name === require.resolve('../index') ||
+            // Also add a check for the plugin names we include for bundler support
+            plugins.includes(name)
+          ) {
+            return false;
+          }
+
+          // Loop through the default presets/plugins to see if it already exists
+          return !defaults[field].some((it) =>
+            // The default presets/plugins can also have nested arrays,
+            Array.isArray(it) ? it[0] === name : it === name
+          );
+        })
+      : [];
+  });
+
+  return {
+    // Passed options shouldn't be able to override the options we pass
+    // Linaria's plugins rely on these (such as filename to generate consistent hash)
+    ...babelOptions,
+    ...defaults,
+    presets: [
+      // Preset order is last to first, so add the extra presets to start
+      // This makes sure that our preset is always run first
+      ...babelOptions.presets!,
+      ...defaults.presets,
+    ],
+    plugins: [
+      ...defaults.plugins,
+      // Plugin order is first to last, so add the extra presets to end
+      // This makes sure that the plugins we specify always run first
+      ...babelOptions.plugins!,
+    ],
+  };
+}