dev-cmd/generate-formula-api: generate homebrew-core.json

This adds the code to generate the homebrew-core.json file which
represents the entire tap instead of just the previous array of
formula hashes. Any shared logic has been moved into the top-level
hash scope including aliases, renames, tap_git_head and tap_migrations.

I also added a check to skip adding the variations hash to the api
hash if it is empty.

Now we're down to 10MB from 24MB!!!

Library/Homebrew/dev-cmd/generate-formula-api.rb

@@ -46,7 +46,7 @@ module Homebrew
     raise TapUnavailableError, tap.name unless tap.installed?
 
     unless args.dry_run?
-      directories = ["_data/formula", "api/formula", "formula"]
+      directories = ["_data/formula", "api/formula", "formula", "api/internal/v3"]
       FileUtils.rm_rf directories + ["_data/formula_canonical.json"]
       FileUtils.mkdir_p directories
     end
@@ -58,6 +58,14 @@ module Homebrew
       Formulary.enable_factory_cache!
       Formula.generating_hash!
 
+      homebrew_core_tap_hash = {
+        "tap_git_head"   => tap.git_head,
+        "aliases"        => tap.alias_table,
+        "renames"        => tap.formula_renames,
+        "tap_migrations" => tap.tap_migrations,
+        "formulae"       => {},
+      }
+
       tap.formula_names.each do |name|
         formula = Formulary.factory(name)
         name = formula.name
@@ -69,11 +77,16 @@ module Homebrew
           File.write("api/formula/#{name}.json", FORMULA_JSON_TEMPLATE)
           File.write("formula/#{name}.html", html_template_name)
         end
+
+        homebrew_core_tap_hash["formulae"][formula.name] =
+          formula.to_hash_with_variations(hash_method: :to_api_hash)
       rescue
         onoe "Error while generating data for formula '#{name}'."
         raise
       end
 
+      homebrew_core_tap_json = JSON.generate(homebrew_core_tap_hash)
+      File.write("api/internal/v3/homebrew-core.json", homebrew_core_tap_json) unless args.dry_run?
       canonical_json = JSON.pretty_generate(tap.formula_renames.merge(tap.alias_table))
       File.write("_data/formula_canonical.json", "#{canonical_json}\n") unless args.dry_run?
     end

Library/Homebrew/formula.rb

@@ -2407,7 +2407,7 @@ class Formula
       end
     end
 
-    hash["variations"] = variations
+    hash["variations"] = variations if hash_method != :to_api_hash || variations.present?
     hash
   end