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|
      record_compilation_digest if success
    end
  else
    true
  end
end

def default_watched_paths
  [
    *config.resolved_paths_globbed,
    "#{config.source_path.relative_path_from(config.root_path)}/**/*",
    "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?
  else
    logger.error "Compilation failed:\n#{stderr}"
  end
  if config.webpack_compile_output?
    logger.info stdout
  end
  status.success?
end

def stale?
  !fresh?
end

def watched_files_digest
  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))
end