From 42e78df4dbc3d6c34834657d6decc1bf3904a3ee Mon Sep 17 00:00:00 2001
From: Justin Halsall <Juice10@users.noreply.github.com>
Date: Thu, 21 Jan 2021 16:57:23 +0100
Subject: [PATCH] largeFileCallback support

---
 README.md                             | 9 +++++++++
 index.js                              | 1 +
 lib/image.js                          | 5 +++++
 test/fixtures/styles/big.modified.css | 3 +++
 test/test.js                          | 8 ++++++++
 5 files changed, 26 insertions(+)
 create mode 100644 test/fixtures/styles/big.modified.css

diff --git a/README.md b/README.md
index cd26a79..6d95a3a 100644
--- a/README.md
+++ b/README.md
@@ -57,6 +57,15 @@ You can define local directories (globs supported) or URLs.
 
 Sets a max file size (in bytes) for inlined images. Set to `0` to disable size checking.
 
+#### largeFileCallback
+
+* Type: `function`
+* Default: undefined
+* Example: `function (file) { console.log('big file found:', file.path); return file.path }`
+* Required: `false`
+
+Allows you to act on large files and change the url if you'd like. Make sure you have `strict` set to `false` when using this.
+
 #### b64Svg
 
 * Type: `bool`
diff --git a/index.js b/index.js
index 6e31189..a35171e 100644
--- a/index.js
+++ b/index.js
@@ -10,6 +10,7 @@ const DEFAULTS = {
   maxFileSize: 10240,
   b64Svg: false,
   strict: false,
+  largeFileCallback: undefined,
 };
 
 const loop = (cb) => {
diff --git a/lib/image.js b/lib/image.js
index f30add3..b56865f 100644
--- a/lib/image.js
+++ b/lib/image.js
@@ -80,6 +80,11 @@ function getDataUriMapping(urls = [], options = {}) {
       const file = await resolve(url, options);
       if (file && file.mime && /image/.test(file.mime)) {
         result[url] = await getDataUri(file, options);
+      } else if (options.largeFileCallback) {
+        const largeFile = await resolve(url, {...options, maxFileSize: 0});
+        if (largeFile && largeFile.mime && /image/.test(largeFile.mime)) {
+          result[url] = await options.largeFileCallback(largeFile);
+        }
       }
 
       return result;
diff --git a/test/fixtures/styles/big.modified.css b/test/fixtures/styles/big.modified.css
new file mode 100644
index 0000000..28bba40
--- /dev/null
+++ b/test/fixtures/styles/big.modified.css
@@ -0,0 +1,3 @@
+.big {
+    background-image: url('https://cdn.example.com/images/blank.gif');
+}
diff --git a/test/test.js b/test/test.js
index 4a5d185..d1a79e9 100644
--- a/test/test.js
+++ b/test/test.js
@@ -59,6 +59,14 @@ describe('postcss-image-inliner', () => {
     test('big.css', 'big.css', {maxFileSize: 1}, done);
   });
 
+  it('should trigger callback on too big images', (done) => {
+    const largeFileCallback = (file) => {
+      return file.path.replace('http://localhost:3000/', 'https://cdn.example.com/');
+    };
+
+    test('big.css', 'big.modified.css', {maxFileSize: 1, largeFileCallback}, done);
+  });
+
   it('should handle multiple background images', (done) => {
     test('multi.in.css', 'multi.out.css', {}, done);
   });