improve compat mode

We will use a glob so that we can move all *.postcss7.* files to just
*.* likewise we will also backup to *.* to *.postcss8.* for restoring
purposes.

Concrete example:

- Current state:
  - index.js            // PostCSS 8 implementation
  - index.postcss7.js   // PostCSS 7 implementation

- Run "compat"
  - index.js            // PostCSS 7 implementation
  - index.postcss7.js   // PostCSS 7 implementation
  - index.postcss8.js   // PostCSS 8 implementation (Backup of original)

- Run "compat:restore"
  - index.js            // PostCSS 8 implementation
  - index.postcss7.js   // PostCSS 7 implementation
  - X index.postcss8.js // PostCSS 8 implementation (Removed)

scripts/compat.js

@@ -1,81 +1,85 @@
-const fs = require('fs')
-const path = require('path')
-const merge = require('lodash/merge')
+let fs = require('fs')
+let path = require('path')
+let merge = require('lodash/merge')
+let fastGlob = require('fast-glob')
 
-function fromRootPath(...paths) {
-  return path.resolve(process.cwd(), ...paths)
-}
-
-function copy(fromPath, toPath) {
-  fs.copyFileSync(fromPath, toPath)
-}
+let postcss7 = fastGlob.sync(['./**/*.postcss7.*']).filter((file) => !file.startsWith('lib/'))
+let postcss8 = fastGlob.sync(['./**/*.postcss8.*']).filter((file) => !file.startsWith('lib/'))
 
 if (process.argv.includes('--prepare')) {
-  if (
-    fs.existsSync(fromRootPath('package.postcss8.json')) ||
-    fs.existsSync(fromRootPath('src', 'index.postcss8.js'))
-  ) {
+  if (postcss8.length > 0) {
     console.error('\n\n[ABORT] Already in PostCSS 7 compatibility mode!\n\n')
     process.exit(1)
   }
 
-  const mainPackageJson = require('../package.json')
-  const compatPackageJson = require('../package.postcss7.json')
+  let mainPackageJson = require('../package.json')
+  let compatPackageJson = require('../package.postcss7.json')
 
-  // 1. Backup original package.json file
-  copy(fromRootPath('package.json'), fromRootPath('package.postcss8.json'))
+  // Use postcss7 files
+  for (let file of postcss7) {
+    let bareFile = file.replace('.postcss7', '')
+    let postcss8File = file.replace('.postcss7', '.postcss8')
 
-  // 2. Backup src/index.js file
-  copy(fromRootPath('src', 'index.js'), fromRootPath('src', 'index.postcss8.js'))
+    // Backup
+    copy(fromRootPath(bareFile), fromRootPath(postcss8File))
 
-  // 3. Use the PostCSS 7 compat file
-  copy(fromRootPath('src', 'index.postcss7.js'), fromRootPath('src', 'index.js'))
+    // Swap
+    copy(fromRootPath(file), fromRootPath(bareFile))
+  }
 
-  // 4. Deep merge package.json contents
-  const packageJson = merge({}, mainPackageJson, compatPackageJson)
+  // Deep merge package.json contents
+  let packageJson = merge({}, mainPackageJson, compatPackageJson)
 
-  // 5. Remove peerDependencies
+  // Remove peerDependencies
   delete packageJson.peerDependencies
 
-  // 6. Cleanup devDependencies
+  // Cleanup devDependencies
   for (let key in packageJson.devDependencies) {
     if (key.includes('postcss')) delete packageJson.devDependencies[key]
   }
 
-  // 7. Use new name
+  // Use new name
   packageJson.name = '@tailwindcss/postcss7-compat'
 
-  // 8. Make sure you can publish
+  // Make sure you can publish
   packageJson.publishConfig = { access: 'public' }
 
-  // 9. Write package.json with the new contents
+  // Write package.json with the new contents
   fs.writeFileSync(fromRootPath('package.json'), JSON.stringify(packageJson, null, 2), 'utf8')
 
-  // 10. Print some useful information to make publishing easy
+  // Print some useful information to make publishing easy
   console.log()
   console.log('You can safely publish `tailwindcss` in PostCSS 7 compatibility mode:\n')
   console.log()
 } else if (process.argv.includes('--restore')) {
-  if (
-    !fs.existsSync(fromRootPath('package.postcss8.json')) ||
-    !fs.existsSync(fromRootPath('src', 'index.postcss8.js'))
-  ) {
+  if (postcss8.length === 0) {
     console.error('\n\n[ABORT] Already in latest PostCSS mode!\n\n')
     process.exit(1)
   }
 
-  // 1. Restore original package.json file
-  copy(fromRootPath('package.postcss8.json'), fromRootPath('package.json'))
+  // Use postcss8 files
+  for (let file of postcss8) {
+    let bareFile = file.replace('.postcss8', '')
 
-  // 2. Restore src/index.js file
-  copy(fromRootPath('src', 'index.postcss8.js'), fromRootPath('src', 'index.js'))
+    // Restore
+    copy(fromRootPath(file), fromRootPath(bareFile))
 
-  // 3. Cleanup PostCSS 8 related files
-  fs.unlinkSync(fromRootPath('package.postcss8.json'))
-  fs.unlinkSync(fromRootPath('src', 'index.postcss8.js'))
+    // Remove
+    fs.unlinkSync(fromRootPath(file))
+  }
 
-  // 4. Done
+  // Done
   console.log()
   console.log('Restored from PostCSS 7 mode to latest PostCSS mode!')
   console.log()
 }
+
+// ---
+
+function fromRootPath(...paths) {
+  return path.resolve(process.cwd(), ...paths)
+}
+
+function copy(fromPath, toPath) {
+  fs.copyFileSync(fromPath, toPath)
+}