From ee4b418357bab934a2240d015c825ca68daffe2c Mon Sep 17 00:00:00 2001
From: Adam Wathan <adam.wathan@gmail.com>
Date: Tue, 16 Mar 2021 13:31:43 -0400
Subject: [PATCH] WIP

Not exactly the expected behavior yet.
---
 src/lib/expandApplyAtRules.js | 37 ++++++++++++++++++++---------------
 tests/10-apply.test.css       | 26 ++++++++++++++++++++++++
 tests/10-apply.test.html      |  2 ++
 tests/10-apply.test.js        | 11 +++++++++++
 4 files changed, 60 insertions(+), 16 deletions(-)

diff --git a/src/lib/expandApplyAtRules.js b/src/lib/expandApplyAtRules.js
index acf65de..d33dde6 100644
--- a/src/lib/expandApplyAtRules.js
+++ b/src/lib/expandApplyAtRules.js
@@ -43,18 +43,24 @@ function expandApplyAtRules(context) {
     let applyCandidates = new Set()
 
     // Collect all @apply rules and candidates
-    let applies = []
+    let ruleApplies = new Map()
     root.walkAtRules('apply', (rule) => {
       let [candidates, important] = extractApplyCandidates(rule.params)
 
+      if (!ruleApplies.has(rule.parent)) {
+        ruleApplies.set(rule.parent, new Set())
+      }
+
+      let applies = ruleApplies.get(rule.parent)
       for (let util of candidates) {
+        applies.add([util, important])
         applyCandidates.add(util)
       }
-      applies.push(rule)
+      rule.remove()
     })
 
     // Start the @apply process if we have rules with @apply in them
-    if (applies.length > 0) {
+    if (ruleApplies.size > 0) {
       // Fill up some caches!
       let applyClassCache = buildApplyCache(applyCandidates, context)
 
@@ -96,11 +102,9 @@ function expandApplyAtRules(context) {
           .join(', ')
       }
 
-      for (let apply of applies) {
+      for (let [applyParentRule, applyCandidates] of ruleApplies.entries()) {
         let siblings = []
-        let [applyCandidates, important] = extractApplyCandidates(apply.params)
-
-        for (let applyCandidate of applyCandidates) {
+        for (let [applyCandidate, important] of applyCandidates) {
           if (!applyClassCache.has(applyCandidate)) {
             throw apply.error(
               `The \`${applyCandidate}\` class does not exist. If \`${applyCandidate}\` is a custom class, make sure it is defined within a \`@layer\` directive.`
@@ -113,7 +117,11 @@ function expandApplyAtRules(context) {
             let root = postcss.root({ nodes: [node.clone()] })
 
             root.walkRules((rule) => {
-              rule.selector = replaceSelector(apply.parent.selector, rule.selector, applyCandidate)
+              rule.selector = replaceSelector(
+                applyParentRule.selector,
+                rule.selector,
+                applyCandidate
+              )
               rule.walkDecls((d) => {
                 d.important = important
               })
@@ -125,16 +133,13 @@ function expandApplyAtRules(context) {
 
         // Inject the rules, sorted, correctly
         for (let [, sibling] of siblings.sort(([a], [z]) => bigSign(z.sort - a.sort))) {
-          // `apply.parent` is referring to the node at `.abc` in: .abc { @apply mt-2 }
-          apply.parent.after(sibling)
+          // `applyParentRule` is referring to the node at `.abc` in: .abc { @apply mt-2 }
+          applyParentRule.after(sibling)
         }
 
-        // If there are left-over declarations, just remove the @apply
-        if (apply.parent.nodes.length > 1) {
-          apply.remove()
-        } else {
-          // The node is empty, drop the full node
-          apply.parent.remove()
+        // The node is empty, drop the full node
+        if (applyParentRule.nodes.length === 0) {
+          applyParentRule.remove()
         }
       }
     }
diff --git a/tests/10-apply.test.css b/tests/10-apply.test.css
index ceca6f3..ba54b10 100644
--- a/tests/10-apply.test.css
+++ b/tests/10-apply.test.css
@@ -178,3 +178,29 @@
     font-weight: 400;
   }
 }
+.multiple-apply-directives {
+  text-align: center;
+  font-weight: 600;
+}
+.multiple-apply-directives:hover {
+  font-weight: 700;
+}
+.multiple-apply-directives:focus {
+  font-weight: 500;
+}
+@media (min-width: 1024px) {
+  .multiple-apply-directives {
+    font-weight: 300;
+  }
+}
+@media (min-width: 1280px) {
+  .multiple-apply-directives:focus {
+    font-weight: 900;
+  }
+}
+.apply-sandwich {
+  font-weight: 300;
+  text-align: right;
+  font-weight: 500;
+  text-align: center;
+}
diff --git a/tests/10-apply.test.html b/tests/10-apply.test.html
index 7f9c472..48cb5b6 100644
--- a/tests/10-apply.test.html
+++ b/tests/10-apply.test.html
@@ -23,5 +23,7 @@
     <div class="basic-nesting-parent">
       <div class="basic-nesting-child"></div>
     </div>
+    <div class="multiple-apply-directives"></div>
+    <div class="apply-sandwich"></div>
   </body>
 </html>
diff --git a/tests/10-apply.test.js b/tests/10-apply.test.js
index 173f190..3ba6f08 100644
--- a/tests/10-apply.test.js
+++ b/tests/10-apply.test.js
@@ -65,6 +65,16 @@ test('@apply', () => {
         @apply font-bold hover:font-normal;
       }
     }
+    .multiple-apply-directives {
+      @apply xl:focus:font-black hover:font-bold;
+      @apply lg:font-light focus:font-medium;
+      @apply font-semibold text-center;
+    }
+    .apply-sandwich {
+      @apply p-4;
+      padding-top: 11px;
+      @apply py-3;
+    }
   }
 
   @layer utilities {
@@ -82,4 +92,5 @@ test('@apply', () => {
   })
 })
 
+// TODO: Test @apply !important
 // TODO: Test stuff that should throw