Add extract-releases command; start filling in build command

bench

@@ -75,11 +75,62 @@ sub needs-setup ($action) {
     }
 }
 
-multi MAIN ('build') {
-        # %*ENV<GIT_DIR> = $bare;
-        # my $tag_list = open 'git tag', :p;
-        # my @tags = $tag_list.lines;
-        # .say for @tags;
+#= Extract historical releases from cloned components
+multi MAIN ('extract-releases', *@components) {
+    needs-setup('extract releases');
+
+    say 'Parsing components.json ...';
+    my $components = from-json(slurp 'components.json');
+
+    chdir $COMPONENTS_DIR;
+    @components ||= dir('.').sort;
+
+    for @components -> $component-name {
+        say "==> $component-name";
+        chdir "$COMPONENTS_DIR/$component-name";
+
+        my $bare = "$component-name.git";
+        unless $bare.IO.d {
+            say "No bare repository exists for component $component-name; can't extract releases.";
+            next;
+        }
+
+        my $tag_regex = $components{$component-name}<release_tags> || '.';
+        %*ENV<GIT_DIR> = $bare;
+        my $tag_list = open 'git tag', :p;
+        my @tags = grep / <{ $tag_regex }> /, $tag_list.lines;
+        %*ENV.delete('GIT_DIR');
+
+        # Work around Rakudo bug #115390 by splitting into two loops
+        for @tags -> $tag {
+            next if $tag.IO.d;
+            run < git clone -l >, $bare, $tag;
+        }
+        for @tags -> $tag {
+            chdir $tag; LEAVE chdir '..';
+            run < git checkout -q >, $tag;   # > -- Dang syntax highlighting
+        }
+    }
+
+    say 'Extraction complete.';
+}
+
+#= Build checked out component trees
+multi MAIN ('build', *@components) {
+    needs-setup('build components');
+
+    chdir $COMPONENTS_DIR;
+    @components ||= dir('.').sort;
+
+
+    for @components -> $component-name {
+        say "==> $component-name";
+        chdir "$COMPONENTS_DIR/$component-name";
+
+        my $bare = "$component-name.git";
+        my @checkouts = dir('.', test => none('.', '..', $bare)).sort;
+        .say for @checkouts;
+    }
 }
 
 #= Clean up generated files and directories