# Used for merging results of metadata callbacks
require 'active_support/core_ext/hash/deep_merge'
require 'monitor'

# Extensions
require 'middleman-core/sitemap/extensions/on_disk'
require 'middleman-core/sitemap/extensions/redirects'
require 'middleman-core/sitemap/extensions/request_endpoints'
require 'middleman-core/sitemap/extensions/proxies'
require 'middleman-core/sitemap/extensions/ignores'

module Middleman

  # Sitemap namespace
  module Sitemap

    # The Store class
    #
    # The Store manages a collection of Resource objects, which represent
    # individual items in the sitemap. Resources are indexed by "source path",
    # which is the path relative to the source directory, minus any template
    # extensions. All "path" parameters used in this class are source paths.
    class Store

      # @return [Middleman::Application]
      attr_accessor :app

      # Initialize with parent app
      # @param [Middleman::Application] app
      def initialize(app)
        @app = app
        @resources = []
        @_cached_metadata = {}
        @resource_list_manipulators = []
        @needs_sitemap_rebuild = true
        
        @lock = Monitor.new
        reset_lookup_cache!

        # Handle ignore commands
        Middleman::Sitemap::Extensions::Ignores.new(self)

        # Extensions
        {
          # Register classes which can manipulate the main site map list
          on_disk: Middleman::Sitemap::Extensions::OnDisk,

          # Request Endpoints
          request_endpoints: Middleman::Sitemap::Extensions::RequestEndpoints,

          # Proxies
          proxies: Middleman::Sitemap::Extensions::Proxies,

          # Redirects
          redirects: Middleman::Sitemap::Extensions::Redirects
        }.each do |k, m|
          register_resource_list_manipulator(k, m.new(self))
        end

        app.config_context.class.send :delegate, :sitemap, :to => :app
      end

      # Register a klass which can manipulate the main site map list. Best to register
      # these in a before_configuration or after_configuration hook.
      #
      # @param [Symbol] name Name of the manipulator for debugging
      # @param [Class, Module] inst Abstract namespace which can update the resource list
      # @return [void]
      def register_resource_list_manipulator(name, inst, unused=true)
        @resource_list_manipulators << [name, inst]
        rebuild_resource_list!(:registered_new)
      end

      # Rebuild the list of resources from scratch, using registed manipulators
      # @return [void]
      def rebuild_resource_list!(reason=nil)
        @lock.synchronize do
          @needs_sitemap_rebuild = true
        end
      end

      # Find a resource given its original path
      # @param [String] request_path The original path of a resource.
      # @return [Middleman::Sitemap::Resource]
      def find_resource_by_path(request_path)
        @lock.synchronize do
          request_path = ::Middleman::Util.normalize_path(request_path)
          ensure_resource_list_updated!
          @_lookup_by_path[request_path]
        end
      end

      # Find a resource given its destination path
      # @param [String] request_path The destination (output) path of a resource.
      # @return [Middleman::Sitemap::Resource]
      def find_resource_by_destination_path(request_path)
        @lock.synchronize do
          request_path = ::Middleman::Util.normalize_path(request_path)
          ensure_resource_list_updated!
          @_lookup_by_destination_path[request_path]
        end
      end

      # Get the array of all resources
      # @param [Boolean] include_ignored Whether to include ignored resources
      # @return [Array<Middleman::Sitemap::Resource>]
      def resources(include_ignored=false)
        @lock.synchronize do
          ensure_resource_list_updated!
          if include_ignored
            @resources
          else
            @resources_not_ignored ||= @resources.reject(&:ignored?)
          end
        end
      end

      # Invalidate our cached view of resource that are not ingnored. If your extension
      # adds ways to ignore files, you should call this to make sure #resources works right.
      def invalidate_resources_not_ignored_cache!
        @resources_not_ignored = nil
      end

      # Register a handler to provide metadata on a file path
      # @param [Regexp] matcher
      # @return [Array<Array<Proc, Regexp>>]
      def provides_metadata(matcher=nil, &block)
        @_provides_metadata ||= []
        @_provides_metadata << [block, matcher] if block_given?
        @_provides_metadata
      end

      # Get the metadata for a specific file
      # @param [String] source_file
      # @return [Hash]
      def metadata_for_file(source_file)
        blank_metadata = { :options => {}, :locals => {} }

        provides_metadata.inject(blank_metadata) do |result, (callback, matcher)|
          next result if matcher && !source_file.match(matcher)

          metadata = callback.call(source_file).dup
          result.deep_merge(metadata)
        end
      end

      # Register a handler to provide metadata on a url path
      # @param [Regexp] matcher
      # @return [Array<Array<Proc, Regexp>>]
      def provides_metadata_for_path(matcher=nil, &block)
        @_provides_metadata_for_path ||= []
        if block_given?
          @_provides_metadata_for_path << [block, matcher]
          @_cached_metadata = {}
        end
        @_provides_metadata_for_path
      end

      # Get the metadata for a specific URL
      # @param [String] request_path
      # @return [Hash]
      def metadata_for_path(request_path)
        return @_cached_metadata[request_path] if @_cached_metadata[request_path]

        blank_metadata = { :options => {}, :locals => {} }

        @_cached_metadata[request_path] = provides_metadata_for_path.inject(blank_metadata) do |result, (callback, matcher)|
          case matcher
          when Regexp
            next result unless request_path =~ matcher
          when String
            next result unless File.fnmatch('/' + Util.strip_leading_slash(matcher), "/#{request_path}")
          end

          metadata = callback.call(request_path).dup

          result.deep_merge(metadata)
        end
      end

      # Get the URL path for an on-disk file
      # @param [String] file
      # @return [String]
      def file_to_path(file)
        file = File.join(@app.root, file)

        prefix = @app.source_dir.sub(/\/$/, '') + '/'
        return false unless file.start_with?(prefix)

        path = file.sub(prefix, '')

        # Replace a file name containing automatic_directory_matcher with a folder
        unless @app.config[:automatic_directory_matcher].nil?
          path = path.gsub(@app.config[:automatic_directory_matcher], '/')
        end

        extensionless_path(path)
      end

      # Get a path without templating extensions
      # @param [String] file
      # @return [String]
      def extensionless_path(file)
        path = file.dup
        remove_templating_extensions(path)
      end

      # Actually update the resource list, assuming anything has called
      # rebuild_resource_list! since the last time it was run. This is
      # very expensive!
      def ensure_resource_list_updated!
        @lock.synchronize do
          return unless @needs_sitemap_rebuild
          @needs_sitemap_rebuild = false

          @app.logger.debug '== Rebuilding resource list'

          @resources = @resource_list_manipulators.inject([]) do |result, (_, inst)|
            newres = inst.manipulate_resource_list(result)

            # Reset lookup cache
            reset_lookup_cache!
            newres.each do |resource|
              @_lookup_by_path[resource.path] = resource
              @_lookup_by_destination_path[resource.destination_path] = resource
            end

            newres
          end

          invalidate_resources_not_ignored_cache!
        end
      end

      private

      def reset_lookup_cache!
        @lock.synchronize {
          @_lookup_by_path = {}
          @_lookup_by_destination_path = {}
        }
      end

      # Removes the templating extensions, while keeping the others
      # @param [String] path
      # @return [String]
      def remove_templating_extensions(path)
        # Strip templating extensions as long as Tilt knows them
        path = path.sub(File.extname(path), '') while ::Tilt[path]
        path
      end

      # Remove the locale token from the end of the path
      # @param [String] path
      # @return [String]
      def strip_away_locale(path)
        if @app.respond_to? :langs
          path_bits = path.split('.')
          lang = path_bits.last
          if @app.langs.include?(lang.to_sym)
            return path_bits[0..-2].join('.')
          end
        end

        path
      end
    end
  end
end