Replace on-demand libpg_query source download with bundled source code

Its unnecessary to download the source on-demand, and makes this more
complex than it needs to be. Instead, introduce a new "update_source" rake
task that can be called to refresh the source for a specified revision.

Rakefile

@@ -2,6 +2,10 @@ require 'bundler/gem_tasks'
 require 'rake/extensiontask'
 require 'rspec/core/rake_task'
 require 'rubocop/rake_task'
+require 'open-uri'
+
+LIB_PG_QUERY_TAG = '13-latest-develop'.freeze
+LIB_PG_QUERY_SHA256SUM = 'FIXFORRELEASE'.freeze
 
 Rake::ExtensionTask.new 'pg_query' do |ext|
   ext.lib_dir = 'lib/pg_query'
@@ -21,3 +25,62 @@ task :clean do
   FileUtils.rm_f Dir.glob(File.join(__dir__, 'ext/pg_query/*.o'))
   FileUtils.rm_f File.join(__dir__, 'lib/pg_query/pg_query.bundle')
 end
+
+task :update_source do
+  workdir = File.join(__dir__, 'tmp')
+  libdir = File.join(workdir, 'libpg_query-' + LIB_PG_QUERY_TAG)
+  filename = File.join(workdir, 'libpg_query-' + LIB_PG_QUERY_TAG + '.tar.gz')
+  testfilesdir = File.join(__dir__, 'spec/files')
+  extdir = File.join(__dir__, 'ext/pg_query')
+  extbakdir = File.join(workdir, 'extbak')
+
+  unless File.exist?(filename)
+    File.open(filename, 'wb') do |target_file|
+      URI.open('https://codeload.github.com/lfittl/libpg_query/tar.gz/' + LIB_PG_QUERY_TAG, 'rb') do |read_file|
+        target_file.write(read_file.read)
+      end
+    end
+
+    checksum = Digest::SHA256.hexdigest(File.read(filename))
+
+    #if checksum != LIB_PG_QUERY_SHA256SUM
+    #  raise "SHA256 of #{filename} does not match: got #{checksum}, expected #{expected_sha256}"
+    #end
+  end
+
+  unless Dir.exist?(libdir)
+    system("tar -xzf #{filename} -C #{workdir}") || raise('ERROR')
+  end
+
+  # Backup important files from ext dir
+  system("rm -fr #{extbakdir}")
+  system("mkdir #{extbakdir}")
+  system("cp -a #{extdir}/pg_query_ruby.{c,sym} #{extdir}/extconf.rb #{extbakdir}")
+
+  FileUtils.rm_rf extdir
+
+  # Reduce everything down to one directory
+  system("mkdir #{extdir}")
+  system("cp -a #{libdir}/src/* #{extdir}/")
+  system("mv #{extdir}/postgres/* #{extdir}/")
+  system("rmdir #{extdir}/postgres")
+  system("cp -a #{libdir}/pg_query.h #{extdir}/include")
+  # Make sure every .c file in the top-level directory is its own translation unit
+  system("mv #{extdir}/*{_conds,_defs,_helper}.c #{extdir}/include")
+  # Protobuf definitions
+  #system("cp -a #{libdir}/protobuf/parse_tree.proto nodes/")
+  #system("PATH=$(PWD)/bin:$(PATH) protoc --go_out=. nodes/parse_tree.proto")
+  system("protoc --proto_path=#{libdir}/protobuf --ruby_out=#{File.join(__dir__, 'lib/pg_query')} #{libdir}/protobuf/pg_query.proto")
+  # Protobuf library code
+  system("mkdir -p #{extdir}/include/protobuf")
+  system("cp -a #{libdir}/protobuf/*.h #{extdir}/include/protobuf")
+  system("mkdir -p #{extdir}/include/protobuf-c")
+  system("cp -a #{libdir}/protobuf-c/*.h #{extdir}/include/protobuf-c")
+  system("cp -a #{libdir}/protobuf-c/*.h #{extdir}/include")
+  system("cp -a #{libdir}/protobuf/*.c #{extdir}/")
+  system("cp -a #{libdir}/protobuf-c/*.c #{extdir}/")
+  # Other support files
+  system("cp -a #{libdir}/testdata/* #{testfilesdir}")
+  # Copy back the custom ext files
+  system("cp -a #{extbakdir}/pg_query_ruby.{c,sym} #{extbakdir}/extconf.rb #{extdir}")
+end