fix: union discriminator

README.md

@@ -49,14 +49,16 @@ button {
 ```jsx
 <>
   <button data-variant="primary">Save</button>
-  <button data-variant="tertiary">Save</button> {/* TS error, tertiary isn't valid */}
+
+  {/* TS error, tertiary isn't valid */}
+  <button data-variant="tertiary">Save</button>
 </>
 ```
 
 Output
 
 ```jsx
-<button data-variant="primary">Save</button> {/* Same as in Page.tsx */} 
+<button data-variant="primary">Save</button> {/* Same as in Page.tsx */}
 ```
 
 _This example demonstrates enums, but MistCSS also supports boolean and string props. For more details, see the FAQ._
@@ -67,6 +69,7 @@ MistCSS parses your `mist.css` file and generates `mist.d.ts` for type safety.
 
 For instance, here’s the generated `mist.d.ts` for our button component:
 
+<!-- prettier-ignore-start -->
 ```typescript
 interface Mist_button extends React.DetailedHTMLProps<React.HTMLAttributes<HTMLButtonElement>, HTMLButtonElement> {
   'data-variant'?: 'primary' | 'secondary'
@@ -78,6 +81,7 @@ declare namespace JSX {
   }
 }
 ```
+<!-- prettier-ignore-stop -->
 
 That’s it! Simple yet powerful, built entirely on browser standards and TypeScript/JSX.
 
@@ -132,8 +136,7 @@ button {
 
 #### Tailwind v4
 
-Tailwind v4 will support CSS variables natively (see [blog post](https://tailwindcss.com/blog/tailwindcss-v4-alpha
-)).
+Tailwind v4 will support CSS variables natively (see [blog post](https://tailwindcss.com/blog/tailwindcss-v4-alpha)).
 
 #### Tailwind (inline style)
 
@@ -190,7 +193,7 @@ div[data-component='section']
   &[data-size="lg"] { ... }
 
   /* Boolean props */
-  &[data-is-active] { ... }  
+  &[data-is-active] { ... }
 
   /* Condition: size="lg" && is-active */
   &[data-size="lg"]&[data-is-active] { ... }
@@ -216,39 +219,48 @@ If you want both basic links and button-styled links, here’s how you can do:
 ```css
 a:not([data-component]) { /* ... */ }
 
-a[data-component='button'] { /* ... */ }
+a[data-component='button'] {
   &[data-variant='primary'] { /* ... */ }
 }
 ```
 
+<!-- prettier-ignore-start -->
 ```jsx
 <>
   <a href="/home">Home</a>
   <a href="/home" data-component="button">Home</a>
   <a href="/home" data-component="button" data-variant="primary">Home</a>
-  <a href="/home" data-variant="primary">Home</a> {/* TS error, `data-variant` is only valid with `data-component="button"` */}
+
+  {/* TS error, `data-variant` is only valid with `data-component="button"` */}
+  <a href="/home" data-variant="primary">Home</a>
 </>
 ```
+<!-- prettier-ignore-stop -->
 
-> [!NOTE]
-> `data-component` is just a naming convention. Feel free to use any attribute, like `data-kind='button'` or just `data-c`. It’s simply a way to differentiate between components using the same tag.
+> [!NOTE] > `data-component` is just a naming convention. Feel free to use any attribute, like `data-kind='button'` or just `data-c`. It’s simply a way to differentiate between components using the same tag.
 
 ### How to split my code?
 
 You can use CSS [@import](https://developer.mozilla.org/en-US/docs/Web/CSS/@import). For example, in your `mist.css` file:
 
 ```css
-@import './button.css'
+@import './button.css';
 ```
 
 ### How to build complex components?
 
 `mist.css`
 
 ```css
-article[data-component='card'] { /* ... */ }
-div[data-component='card-title'] { /* ... */ }
-div[data-component='card-content'] { /* ... */ }
+article[data-component='card'] {
+  /* ... */
+}
+div[data-component='card-title'] {
+  /* ... */
+}
+div[data-component='card-content'] {
+  /* ... */
+}
 ```
 
 `Card.jsx`
@@ -294,7 +306,7 @@ import 'my-ui/mist.css'
 
 `app/mist.d.ts`
 
-```
+```typescript
 import 'my-ui/mist.d.ts
 ```
 

src/index.ts

@@ -1,8 +1,8 @@
 import fs = require('node:fs')
 import { type PluginCreator } from 'postcss'
-import selectorParser = require('postcss-selector-parser');
-import atImport = require("postcss-import")
-import path = require('node:path');
+import selectorParser = require('postcss-selector-parser')
+import atImport = require('postcss-import')
+import path = require('node:path')
 const html = require('./html')
 const key = require('./key')
 
@@ -30,49 +30,123 @@ function render(parsed: Parsed): string {
   let interfaceDefinitions = ''
   const jsxElements: Record<string, string[]> = {}
 
-  Object.entries(parsed).forEach(
-    ([key, { tag, rootAttribute, attributes, booleanAttributes, properties }]) => {
-      const interfaceName = `Mist_${key}`
+  // Normalize
+  type Component = {
+    rootAttribute: string
+    discriminatorAttributes: Set<string>
+    attributes: Record<string, Set<string>>
+    booleanAttributes: Set<string>
+    properties: Set<string>
+  }
 
-      const attributeEntries = Object.entries(attributes)
+  const normalized: Record<
+    string,
+    {
+      _base: Component
+      [other: string]: Component
+    }
+  > = {}
 
-      let htmlElement = 'HTMLElement'
-      if (tag in html) {
-        htmlElement = html[tag as keyof typeof html]
+  console.log(parsed)
+
+  Object.entries(parsed).forEach(
+    ([
+      key,
+      { tag, rootAttribute, attributes, booleanAttributes, properties },
+    ]) => {
+      // Default base tag, always there
+      normalized[tag] ??= {
+        _base: {
+          rootAttribute: '',
+          discriminatorAttributes: new Set<string>(),
+          attributes: {},
+          booleanAttributes: new Set<string>(),
+          properties: new Set<string>(),
+        },
       }
 
-      let interfaceDefinition = `interface ${interfaceName} extends React.DetailedHTMLProps<React.HTMLAttributes<${htmlElement}>, ${htmlElement}> {\n`
+      if (rootAttribute !== '') {
+        normalized[tag][key] ??= {
+          rootAttribute,
+          discriminatorAttributes: new Set<string>(),
+          attributes,
+          booleanAttributes,
+          properties,
+        }
+        normalized[tag]['_base']['discriminatorAttributes'] ??= new Set()
+        normalized[tag]['_base']['discriminatorAttributes'].add(rootAttribute)
+      } else {
+        normalized[tag]['_base'] = {
+          rootAttribute,
+          discriminatorAttributes: new Set<string>(),
+          attributes,
+          booleanAttributes,
+          properties,
+        }
+      }
+    },
+  )
 
-      attributeEntries.forEach(([attr, values]) => {
-        const valueType = Array.from(values)
-          .map((v) => `'${v}'`)
-          .join(' | ')
-        // Root attribute is used to narrow type and therefore is the only attribute
-        // that shouldn't be optional (i.e. attr: ... and not attr?: ...)
-        interfaceDefinition += `  '${attr}'${rootAttribute === attr ? '' : '?'}: ${valueType}\n`
-      })
+  console.dir(normalized, { depth: null })
+
+  Object.entries(normalized).forEach(([tag, components]) => {
+    Object.entries(components).forEach(
+      ([
+        key,
+        {
+          rootAttribute,
+          discriminatorAttributes,
+          attributes,
+          booleanAttributes,
+          properties,
+        },
+      ]) => {
+        const interfaceName = `Mist_${key === '_base' ? tag : key}`
+
+        const attributeEntries = Object.entries(attributes)
+
+        let htmlElement = 'HTMLElement'
+        if (tag in html) {
+          htmlElement = html[tag as keyof typeof html]
+        }
+
+        let interfaceDefinition = `interface ${interfaceName} extends React.DetailedHTMLProps<React.HTMLAttributes<${htmlElement}>, ${htmlElement}> {\n`
+
+        discriminatorAttributes.forEach((attr) => {
+          interfaceDefinition += `  '${attr}'?: never\n`
+        })
 
-      booleanAttributes.forEach((attr) => {
-        interfaceDefinition += `  '${attr}'?: boolean\n`
-      })
+        attributeEntries.forEach(([attr, values]) => {
+          const valueType = Array.from(values)
+            .map((v) => `'${v}'`)
+            .join(' | ')
+          // Root attribute is used to narrow type and therefore is the only attribute
+          // that shouldn't be optional (i.e. attr: ... and not attr?: ...)
+          interfaceDefinition += `  '${attr}'${rootAttribute === attr ? '' : '?'}: ${valueType}\n`
+        })
 
-      if (Array.from(properties).length > 0) {
-        const propertyEntries = Array.from(properties)
-          .map((prop) => `'${prop}': string`)
-          .join(', ')
-        interfaceDefinition += `  style?: { ${propertyEntries} } & React.CSSProperties\n`
-      }
+        booleanAttributes.forEach((attr) => {
+          interfaceDefinition += `  '${attr}'?: boolean\n`
+        })
 
-      interfaceDefinition += '}\n\n'
+        if (Array.from(properties).length > 0) {
+          const propertyEntries = Array.from(properties)
+            .map((prop) => `'${prop}': string`)
+            .join(', ')
+          interfaceDefinition += `  style?: { ${propertyEntries} } & React.CSSProperties\n`
+        }
 
-      interfaceDefinitions += interfaceDefinition
+        interfaceDefinition += '}\n\n'
 
-      if (!jsxElements[tag]) {
-        jsxElements[tag] = []
-      }
-      jsxElements[tag].push(interfaceName)
-    },
-  )
+        interfaceDefinitions += interfaceDefinition
+
+        if (!jsxElements[tag]) {
+          jsxElements[tag] = []
+        }
+        jsxElements[tag].push(interfaceName)
+      },
+    )
+  })
 
   // Generate the JSX namespace declaration dynamically
   let jsxDeclaration =
@@ -151,7 +225,7 @@ _mistcss.postcss = true
 const mistcss: PluginCreator<{}> = (_opts = {}) => {
   return {
     postcssPlugin: 'mistcss',
-    plugins: [atImport(), _mistcss()]
+    plugins: [atImport(), _mistcss()],
   }
 }
 

test/card.mist.css

@@ -0,0 +1,12 @@
+/* Testing union discriminator */
+div[data-component='card'] {
+  background: gray;
+  &[data-size='sm'] {
+  }
+  &[data-size='xl'] {
+  }
+}
+
+div[data-component='card-title'] {
+  background: gray;
+}

test/mist.css

@@ -1 +1,2 @@
 @import './button.mist.css';
+@import './card.mist.css';

test/mist.d.ts

@@ -2,8 +2,22 @@ interface Mist_button extends React.DetailedHTMLProps<React.HTMLAttributes<HTMLB
   'data-variant'?: 'primary' | 'secondary'
 }
 
+interface Mist_div extends React.DetailedHTMLProps<React.HTMLAttributes<HTMLDivElement>, HTMLDivElement> {
+  'data-component'?: never
+}
+
+interface Mist_div_data_component_card extends React.DetailedHTMLProps<React.HTMLAttributes<HTMLDivElement>, HTMLDivElement> {
+  'data-component': 'card'
+  'data-size'?: 'sm' | 'xl'
+}
+
+interface Mist_div_data_component_card_title extends React.DetailedHTMLProps<React.HTMLAttributes<HTMLDivElement>, HTMLDivElement> {
+  'data-component': 'card-title'
+}
+
 declare namespace JSX {
   interface IntrinsicElements {
     button: Mist_button
+    div: Mist_div | Mist_div_data_component_card | Mist_div_data_component_card_title
   }
 }