Support extend in variants config (#2651)

* WIP

* It's alive

* Pull default variant order from config

__tests__/resolveConfig.test.js

@@ -1738,6 +1738,133 @@ test('user theme extensions take precedence over plugin theme extensions with th
   })
 })
 
+test('variants can be extended', () => {
+  const userConfig = {
+    variants: {
+      borderColor: ({ after }) => after(['group-focus'], 'hover'),
+      extend: {
+        backgroundColor: ['active', 'disabled', 'group-hover'],
+      },
+    },
+  }
+
+  const otherConfig = {
+    variants: {
+      extend: {
+        textColor: ['hover', 'focus-within'],
+      },
+    },
+  }
+
+  const defaultConfig = {
+    prefix: '',
+    important: false,
+    separator: ':',
+    theme: {},
+    variants: {
+      borderColor: ['hover', 'focus'],
+      backgroundColor: ['responsive', 'hover', 'focus'],
+      textColor: ['responsive', 'focus'],
+    },
+  }
+
+  const result = resolveConfig([userConfig, otherConfig, defaultConfig])
+
+  expect(result).toMatchObject({
+    variants: {
+      borderColor: ['hover', 'group-focus', 'focus'],
+      backgroundColor: ['responsive', 'group-hover', 'hover', 'focus', 'active', 'disabled'],
+      textColor: ['responsive', 'focus-within', 'hover', 'focus'],
+    },
+  })
+})
+
+test('variant sort order can be customized', () => {
+  const userConfig = {
+    variantOrder: [
+      'disabled',
+      'focus',
+      'group-hover',
+      'focus-within',
+      'active',
+      'hover',
+      'responsive',
+    ],
+    variants: {
+      borderColor: ({ after }) => after(['group-focus'], 'hover'),
+      extend: {
+        backgroundColor: ['active', 'disabled', 'group-hover'],
+      },
+    },
+  }
+
+  const otherConfig = {
+    variants: {
+      extend: {
+        textColor: ['hover', 'focus-within'],
+      },
+    },
+  }
+
+  const defaultConfig = {
+    prefix: '',
+    important: false,
+    separator: ':',
+    theme: {},
+    variants: {
+      borderColor: ['hover', 'focus'],
+      backgroundColor: ['responsive', 'hover', 'focus'],
+      textColor: ['responsive', 'focus'],
+    },
+  }
+
+  const result = resolveConfig([userConfig, otherConfig, defaultConfig])
+
+  expect(result).toMatchObject({
+    variants: {
+      borderColor: ['hover', 'group-focus', 'focus'],
+      backgroundColor: ['disabled', 'focus', 'group-hover', 'active', 'hover', 'responsive'],
+      textColor: ['focus', 'focus-within', 'hover', 'responsive'],
+    },
+  })
+})
+
+test('custom variants go to the beginning by default when sort is applied', () => {
+  const userConfig = {
+    variants: {
+      extend: {
+        backgroundColor: ['active', 'custom-variant-1', 'group-hover', 'custom-variant-2'],
+      },
+    },
+  }
+
+  const defaultConfig = {
+    prefix: '',
+    important: false,
+    separator: ':',
+    theme: {},
+    variants: {
+      backgroundColor: ['responsive', 'hover', 'focus'],
+    },
+  }
+
+  const result = resolveConfig([userConfig, defaultConfig])
+
+  expect(result).toMatchObject({
+    variants: {
+      backgroundColor: [
+        'responsive',
+        'custom-variant-1',
+        'custom-variant-2',
+        'group-hover',
+        'hover',
+        'focus',
+        'active',
+      ],
+    },
+  })
+})
+
 test('variants can be defined as a function', () => {
   const userConfig = {
     variants: {

src/util/resolveConfig.js

@@ -5,10 +5,12 @@ import isUndefined from 'lodash/isUndefined'
 import defaults from 'lodash/defaults'
 import map from 'lodash/map'
 import get from 'lodash/get'
+import uniq from 'lodash/uniq'
 import toPath from 'lodash/toPath'
 import negateValue from './negateValue'
 import { corePluginList } from '../corePluginList'
 import configurePlugins from './configurePlugins'
+import defaultConfig from '../../stubs/defaultConfig.stub'
 
 const configUtils = {
   negative(scale) {
@@ -39,31 +41,29 @@ function value(valueToResolve, ...args) {
   return isFunction(valueToResolve) ? valueToResolve(...args) : valueToResolve
 }
 
-function mergeThemes(themes) {
-  const theme = (({ extend: _, ...t }) => t)(
-    themes.reduce((merged, t) => {
-      return defaults(merged, t)
-    }, {})
-  )
+function collectExtends(items) {
+  return items.reduce((merged, { extend }) => {
+    return mergeWith(merged, extend, (mergedValue, extendValue) => {
+      if (isUndefined(mergedValue)) {
+        return [extendValue]
+      }
 
+      if (Array.isArray(mergedValue)) {
+        return [extendValue, ...mergedValue]
+      }
+
+      return [extendValue, mergedValue]
+    })
+  }, {})
+}
+
+function mergeThemes(themes) {
   return {
-    ...theme,
+    ...themes.reduce((merged, theme) => defaults(merged, theme), {}),
 
     // In order to resolve n config objects, we combine all of their `extend` properties
     // into arrays instead of objects so they aren't overridden.
-    extend: themes.reduce((merged, { extend }) => {
-      return mergeWith(merged, extend, (mergedValue, extendValue) => {
-        if (isUndefined(mergedValue)) {
-          return [extendValue]
-        }
-
-        if (Array.isArray(mergedValue)) {
-          return [extendValue, ...mergedValue]
-        }
-
-        return [extendValue, mergedValue]
-      })
-    }, {}),
+    extend: collectExtends(themes),
   }
 }
 
@@ -130,12 +130,8 @@ function extractPluginConfigs(configs) {
   return allConfigs
 }
 
-function resolveVariants([firstConfig, ...variantConfigs]) {
-  if (Array.isArray(firstConfig)) {
-    return firstConfig
-  }
-
-  return [firstConfig, ...variantConfigs].reverse().reduce((resolved, variants) => {
+function mergeVariants(variants) {
+  const mergedVariants = variants.reduce((resolved, variants) => {
     Object.entries(variants || {}).forEach(([plugin, pluginVariants]) => {
       if (isFunction(pluginVariants)) {
         resolved[plugin] = pluginVariants({
@@ -187,10 +183,39 @@ function resolveVariants([firstConfig, ...variantConfigs]) {
 
     return resolved
   }, {})
+
+  return {
+    ...mergedVariants,
+    extend: collectExtends(variants),
+  }
+}
+
+function mergeVariantExtensions({ extend, ...variants }, variantOrder) {
+  return mergeWith(variants, extend, (variantsValue, extensions) => {
+    const merged = uniq([...variantsValue, ...extensions].flat())
+
+    if (extensions.flat().length === 0) {
+      return merged
+    }
+
+    return merged.sort((a, z) => variantOrder.indexOf(a) - variantOrder.indexOf(z))
+  })
+}
+
+function resolveVariants([firstConfig, ...variantConfigs], variantOrder) {
+  // Global variants configuration like `variants: ['hover', 'focus']`
+  if (Array.isArray(firstConfig)) {
+    return firstConfig
+  }
+
+  return mergeVariantExtensions(
+    mergeVariants([firstConfig, ...variantConfigs].reverse()),
+    variantOrder
+  )
 }
 
 function resolveCorePlugins(corePluginConfigs) {
-  const result = [...corePluginConfigs].reverse().reduce((resolved, corePluginConfig) => {
+  const result = [...corePluginConfigs].reduceRight((resolved, corePluginConfig) => {
     if (isFunction(corePluginConfig)) {
       return corePluginConfig({ corePlugins: resolved })
     }
@@ -201,31 +226,38 @@ function resolveCorePlugins(corePluginConfigs) {
 }
 
 function resolvePluginLists(pluginLists) {
-  const result = [...pluginLists].reverse().reduce((resolved, pluginList) => {
+  const result = [...pluginLists].reduceRight((resolved, pluginList) => {
     return [...resolved, ...pluginList]
   }, [])
 
   return result
 }
 
 export default function resolveConfig(configs) {
-  const allConfigs = extractPluginConfigs(configs)
+  const allConfigs = [
+    ...extractPluginConfigs(configs),
+    {
+      darkMode: false,
+      prefix: '',
+      important: false,
+      separator: ':',
+      variantOrder: defaultConfig.variantOrder,
+    },
+  ]
+  const { variantOrder } = allConfigs.find((c) => c.variantOrder)
 
   return defaults(
     {
       theme: resolveFunctionKeys(
         mergeExtensions(mergeThemes(map(allConfigs, (t) => get(t, 'theme', {}))))
       ),
-      variants: resolveVariants(allConfigs.map((c) => c.variants)),
+      variants: resolveVariants(
+        allConfigs.map((c) => get(c, 'variants', {})),
+        variantOrder
+      ),
       corePlugins: resolveCorePlugins(allConfigs.map((c) => c.corePlugins)),
       plugins: resolvePluginLists(configs.map((c) => get(c, 'plugins', []))),
     },
-    ...allConfigs,
-    {
-      darkMode: false,
-      prefix: '',
-      important: false,
-      separator: ':',
-    }
+    ...allConfigs
   )
 }

stubs/defaultConfig.stub.js

@@ -668,6 +668,22 @@ module.exports = {
       },
     },
   },
+  variantOrder: [
+    'first',
+    'last',
+    'odd',
+    'even',
+    'visited',
+    'checked',
+    'group-hover',
+    'group-focus',
+    'focus-within',
+    'hover',
+    'focus',
+    'focus-visible',
+    'active',
+    'disabled',
+  ],
   variants: {
     accessibility: ['responsive', 'focus'],
     alignContent: ['responsive'],

stubs/simpleConfig.stub.js

@@ -4,6 +4,8 @@ module.exports = {
   theme: {
     extend: {},
   },
-  variants: {},
+  variants: {
+    extend: {},
+  },
   plugins: [],
 }