require 'uri'

module SewingKit
  module Webpack
    # Webpack manifest loading, caching & entry point retrieval
    class Manifest
      # Raised if we can't read our webpack manifest for whatever reason
      class ManifestLoadError < StandardError
        def initialize(message, orig)
          super "#{message} (original error #{orig})"
        end
      end

      class LegacyManifestError < StandardError
        def initialize(manifest)
          super "manifest must contain 'entrypoints' key (found: #{manifest})"
        end
      end

      class << self
        # :nodoc:
        def asset_paths(entrypointName)
          metadata['entrypoints'][entrypointName]
        end

        def clear_cache!
          @metadata = nil
          @metadata_expiry_time = nil
        end

        def manifest
          metadata['assets']
        end

        private

        def metadata
          if ::Rails.env.production?
            # Cache at class level, as JSON loading/parsing can be expensive.
            @metadata ||= load_metadata
          else
            # In development, the manifest may change.
            # A short cache lifetime avoids time consuming node callouts.
            if self.instance_variable_defined?('@metadata_expiry_time') && @metadata_expiry_time && @metadata_expiry_time >= Time.now
              @metadata
            else
              @metadata = load_metadata
              @metadata_expiry_time = Time.now + 4
            end
          end

          raise LegacyManifestError.new(@metadata) if !@metadata['entrypoints']

          @metadata
        end

        def manifest_bundled?
          !manifest["errors"].any? { |error| error.include? "Module build failed" }
        end

        def load_metadata
          JSON.parse(`node_modules/.bin/sewing-kit manifest --mode #{mode}`)
        rescue => e
          raise ManifestLoadError.new("Could not load compiled manifest - have you run `rake sewing_kit:build`?", e)
        end

        def mode
          ENV['NODE_ENV'] || Rails.env.to_s || 'production'
        end
      end
    end
  end
end