Add source option to PackageFetchStrategy enum

Author: codedmonkey

docs/configuration-reference.md

@@ -140,11 +140,18 @@ Enable building distribution from the source.
 
 Type: `string` | Default: `mirror`
 
-todo
-
-Fetch mirrored packages from their VCS repositories by default when possible.
-
-Sets the fetch strategy of new mirrored packages to **Fetch from VCS**.
+Configure the default fetch strategy for packages:
+
+**mirror**  
+Always try to mirror package metaddata from mirror registries when possible. Only metadata from the project's
+`composer.json` is available. If mirroring is not possible, it defaults to `source` instead.  
+**source**  
+Try to fetch package metadata directly from the source, but doesn't have to include VCS data. For example, when the
+package is hosted on GitHub the API is used instead which saves on storage and bandwidth, but limits the amount of
+metadata that's available.  
+**vcs**  
+Always fetch package metadata directly from the source through VCS. Package metadata is create directly from the
+source code.
 
 [iso-8601-durations]: https://en.wikipedia.org/wiki/ISO_8601#Durations
 [symfony]: https://symfony.com

src/Doctrine/Entity/PackageFetchStrategy.php

@@ -5,13 +5,19 @@
 enum PackageFetchStrategy: string
 {
     case Mirror = 'mirror';
+    case Source = 'source';
     case Vcs = 'vcs';
 
     public function isMirror(): bool
     {
         return self::Mirror === $this;
     }
 
+    public function isSource(): bool
+    {
+        return self::Source === $this;
+    }
+
     public function isVcs(): bool
     {
         return self::Vcs === $this;

src/Package/PackageMetadataResolver.php

@@ -78,6 +78,7 @@ public function resolve(Package $package): void
     {
         match ($package->getFetchStrategy()) {
             PackageFetchStrategy::Mirror => $this->resolveRegistryPackage($package),
+            PackageFetchStrategy::Source,
             PackageFetchStrategy::Vcs => $this->resolveVcsPackage($package),
         };