class Webpacker::Compiler

def compilation_digest_path
  config.cache_path.join("last-compilation-digest-#{webpacker.env}")
end

def compile
  if stale?
    run_webpack.tap do |success|
      # We used to only record the digest on success
      # However, the output file is still written on error, meaning that the digest should still be updated.
      # If it's not, you can end up in a situation where a recompile doesn't take place when it should.
      # See https://github.com/rails/webpacker/issues/2113
      record_compilation_digest
    end
  else
    logger.info "Everything's up-to-date. Nothing to do"
    true
  end
end

def default_watched_paths
  [
    *config.additional_paths_globbed,
    config.source_path_globbed,
    "yarn.lock", "package.json",
    "config/webpack/**/*"
  ].freeze
end

def fresh?
  watched_files_digest == last_compilation_digest
end

def initialize(webpacker)
  @webpacker = webpacker
end

def last_compilation_digest
  compilation_digest_path.read if compilation_digest_path.exist? && config.public_manifest_path.exist?
rescue Errno::ENOENT, Errno::ENOTDIR
end

def record_compilation_digest
  config.cache_path.mkpath
  compilation_digest_path.write(watched_files_digest)
end

def run_webpack
  logger.info "Compiling..."
  stdout, stderr, status = Open3.capture3(
    webpack_env,
    "#{RbConfig.ruby} ./bin/webpack",
    chdir: File.expand_path(config.root_path)
  )
  if status.success?
    logger.info "Compiled all packs in #{config.public_output_path}"
    logger.error "#{stderr}" unless stderr.empty?
    if config.webpack_compile_output?
      logger.info stdout
    end
  else
    non_empty_streams = [stdout, stderr].delete_if(&:empty?)
    logger.error "Compilation failed:\n#{non_empty_streams.join("\n\n")}"
  end
  status.success?
end

def stale?
  !fresh?
end

def watched_files_digest
  warn "Webpacker::Compiler.watched_paths has been deprecated. Set additional_paths in webpacker.yml instead." unless watched_paths.empty?
  files = Dir[*default_watched_paths, *watched_paths].reject { |f| File.directory?(f) }
  file_ids = files.sort.map { |f| "#{File.basename(f)}/#{Digest::SHA1.file(f).hexdigest}" }
  Digest::SHA1.hexdigest(file_ids.join("/"))
end

def webpack_env
  return env unless defined?(ActionController::Base)
  env.merge("WEBPACKER_ASSET_HOST"        => ENV.fetch("WEBPACKER_ASSET_HOST", ActionController::Base.helpers.compute_asset_host),
            "WEBPACKER_RELATIVE_URL_ROOT" => ENV.fetch("WEBPACKER_RELATIVE_URL_ROOT", ActionController::Base.relative_url_root),
            "WEBPACKER_CONFIG" => webpacker.config_path.to_s)
end