Derive MIME types for PHP served files from shared JSON (#1360)

## What is this PR doing?

This PR eliminates duplication in the code base where we maintained
separate MIME type mappings for PHPRequestHandler and for files served
via PHP on WP Cloud.

Related to #1197

## How is the problem addressed?

This PR generates `mime-types.php` from shared JSON when deploying the
website to WP Cloud.

## Testing Instructions

- Temporarily adjust WP Cloud deploy workflow to be tested under this PR
- Confirm the workflow completes without error and that
playground-dot-wordpress-dot-net.atomicsites.blog loads properly

.github/workflows/deploy-website-next.yml

@@ -27,6 +27,7 @@ jobs:
             - uses: actions/checkout@v4
               with:
                   sparse-checkout: |
+                      packages/php-wasm/universal/src/lib/mime-types.json
                       packages/playground/website-deployment
             - name: Wait for latest build artifact
               shell: bash
@@ -79,6 +80,11 @@ jobs:
                     packages/playground/website-deployment/ \
                     ${{ secrets.DEPLOY_WEBSITE_TARGET_USER }}@${{ secrets.DEPLOY_WEBSITE_TARGET_HOST }}:'~/website-deployment'
 
+                  # Copy MIME types for use with PHP-served files
+                  scp -i ~/.ssh/id_ed25519 \
+                    packages/php-wasm/universal/src/lib/mime-types.json \
+                    ${{ secrets.DEPLOY_WEBSITE_TARGET_USER }}@${{ secrets.DEPLOY_WEBSITE_TARGET_HOST }}:'~/website-deployment/'
+
                   # Apply update
                   ssh -i ~/.ssh/id_ed25519 \
                     ${{ secrets.DEPLOY_WEBSITE_TARGET_USER }}@${{ secrets.DEPLOY_WEBSITE_TARGET_HOST }} \

packages/php-wasm/universal/src/lib/mime-types.json

@@ -1,5 +1,5 @@
 {
-	"_default": "application-octet-stream",
+	"_default": "application/octet-stream",
 	"3gpp": "video/3gpp",
 	"7z": "application/x-7z-compressed",
 	"asx": "video/x-ms-asf",

packages/playground/website-deployment/apply-update.sh

@@ -19,6 +19,45 @@ echo Copy supporting files for WP Cloud
 cp -r ~/website-deployment/__wp__ ~/website-update/
 cp ~/website-deployment/custom-redirects-lib.php ~/website-update/
 cp ~/website-deployment/custom-redirects.php ~/website-update/
+
+# Generate mime-types.php from mime-types.json in case the PHP can be opcached
+echo Generating mime-types.php
+cat ~/website-deployment/mime-types.json | "$SITE_PHP" -r '
+    $raw_json = file_get_contents( "php://stdin" );
+    if ( false === $raw_json ) {
+        fprintf( STDERR, "Unable to read MIME type JSON\n" );
+        die( -1 );
+    }
+    $types = json_decode( $raw_json, JSON_OBJECT_AS_ARRAY );
+    if ( null === $types ) {
+        fprintf( STDERR, "Unable to decode MIME type JSON\n" );
+        die( -1 );
+    }
+
+    echo "<?php\n";
+    echo "\$mime_types = array(\n";
+    foreach ( $types as $extension => $mime_type ) {
+        echo "  \"$extension\" => \"$mime_type\",\n";
+    }
+    echo ");\n";
+' > ~/website-deployment/mime-types.php
+
+echo Checking mime-types.php
+(
+    cd ~/website-deployment
+    "$SITE_PHP" -r '
+        require( "mime-types.php" );
+        if (
+            $mime_types["_default"] !== "application/octet-stream" ||
+            $mime_types["html"] !== "text/html" ||
+            $mime_types["jpeg"] !== "image/jpeg"
+        ) {
+            fprintf( STDERR, "mime-types.php looks broken\n" );
+            die( -1 );
+        }
+    '
+)
+echo Adding mime-types.php to updated website files
 cp ~/website-deployment/mime-types.php ~/website-update/
 
 function match_files_to_serve_via_php() (

packages/playground/website-deployment/custom-redirects-lib.php

@@ -124,11 +124,9 @@ function playground_handle_request() {
 		: false;
 
 	require_once __DIR__ . '/mime-types.php';
-	if ( isset( $mime_types[ $extension ] ) ) {
-		$content_type = $mime_types[ $extension ];
-		$log( "Setting Content-Type to '$content_type'" );
-		header( "Content-Type: $content_type" );
-	}
+	$content_type = $mime_types[ $extension ] ?? $mime_types['_default'];
+	$log( "Setting Content-Type to '$content_type'" );
+	header( "Content-Type: $content_type" );
 
 	$custom_response_headers = playground_get_custom_response_headers( $filename );
 	if ( ! empty( $custom_response_headers ) ) {