extracted the building of template tree

This step is a preparation to extend the functionality of the renderer.
To make the main class easier, the search for templates and building of
the tree is extracted into its own class.

6 files changed, 257 insertions, 49 deletions

diff --git a/lib/zero/renderer.rb b/lib/zero/renderer.rb
index b2b7c94..2a848c2 100644
--- a/lib/zero/renderer.rb
+++ b/lib/zero/renderer.rb
@@ -1,3 +1,5 @@
+require 'zero/renderer/template_finder'
+
 module Zero
   # the base renderer for getting render containers
   #
@@ -34,7 +36,7 @@ module Zero
     # @param template_path [String] a string to templates
     # @param type_map [Hash] a map of simple types to complex ones
     def initialize(template_path, type_map = {})
-      @template_path = template_path + '/'
+      @template_path = template_path
       @type_map = type_map
     end
 
@@ -56,23 +58,7 @@ module Zero
     # the wanted template.
     # @return [Self] returns the object
     def read_template_path!
-      # TODO clean up later
-      @templates = {}
-      search_files.each do |file|
-        parts = file.gsub(/#{template_path}/, '').split('.')
-        @templates[parts[0]] ||= {}
-
-        # Set default value
-        types = 'default'
-        # Overwrite default value, if it's set in template path
-        if parts.count > 2 then
-          types = parts[1]
-        end
-
-        read_type(types).each do |type|
-          @templates[parts[0]][type] = file
-        end
-      end
+      @templates = TemplateFinder.new(template_path, @type_map).get_templates
     end
 
     # render a template
@@ -89,32 +75,6 @@ module Zero
 
     private
 
-    # search in `template_path` for templates beginning with `template_name`
-    # @api private
-    # @param template_name [String] the name of the template
-    # @return [#each] a list of all templates found
-    def search_files
-      Dir[template_path + '**/*.*']
-    end
-
-    # gets the type information from a file and converts it to an array of
-    # possible matching types
-    # @api private
-    # @param short_notation [String] a short notation of a type, like `html`
-    # @return [Array] a list of matching types, like `text/html`
-    def read_type(short_notation)
-      to_type_list(type_map[short_notation] || short_notation)
-    end
-
-    # convert a map to an array if it is not one
-    # @api private
-    # @param original_map [Object] the type(s) to convert
-    # @return [Array] a list of objects
-    def to_type_list(original_map)
-      return original_map if original_map.respond_to?(:each)
-      [original_map]
-    end
-
     # get the prepared template for the name and type
     # @api private
     # @param name [String] the name of the template
diff --git a/lib/zero/renderer/template_finder.rb b/lib/zero/renderer/template_finder.rb
new file mode 100644
index 0000000..39fb8cb
--- /dev/null
+++ b/lib/zero/renderer/template_finder.rb
@@ -0,0 +1,164 @@
+module Zero
+  class Renderer
+    # finds templates in a path and builds a map for the renderer to use
+    #
+    # When this class is feeded with a path and a type map it will generate
+    # a map of templates and types for the renderer to use.
+    # For that to work, it first needs a path ending on '/' and a map of type
+    # names to mime types. The short type name is used in template names to find
+    # out, for which mime types they are built, so that they can be rendered
+    # for the correct request.
+    #
+    # The template files can be named in two different formats
+    # * filename.extension
+    # * filename.type.extension
+    # The type is used to access the `type_map`. It will be used to find all
+    # mime types this template can be used to answer. If no type is given in the
+    # filename, the type will be set to `default`.
+    # So `default` can be used in the `type_map` to map these files too.
+    #
+    # @example building a TemplateFinder
+    # As an example, lets assume we have the following files in our path
+    # * `index.erb`
+    # * `index.json.erb`
+    #
+    # We want these to render for either html requests or json requests. To make
+    # this work, we need to build a TemplateFinder like following
+    #
+    #     TemplateFinder.new('path/', {
+    #       'default' => ['text/html', '*/*'],
+    #       'json'    => ['application/json']
+    #     })
+    #
+    # This will build a structure, so that requests with 'text/html' will render
+    # `index.erb`.
+    class TemplateFinder
+      # the search mask to search for files
+      # @example foo/bar/**/*.*
+      MARK_ALL_FILES = '**/*.*'
+      # for finding the last slash
+      SLASH_END    = '/'
+      # empty string to replace the path in the filename
+      EMPTY_STRING = ''
+      # split filename at this character
+      SPLIT_CHAR   = '.'
+      # default type
+      DEFAULT_TYPE = 'default'
+
+      # the path to all templates
+      # @api private
+      # @returns [String] the path given at initialization
+      attr_reader :path
+
+      # a map of simple type names to a list of mime types
+      # @api private
+      # @example 'html' => ['text/html', 'text/xml', 'text/html+xml']
+      # @returns [Hash] a hash with types to mime types
+      attr_reader :type_map
+
+      # this returns the regex for the specified path
+      # @api private
+      # @returns [Regex] the regex built from the path
+      attr_reader :path_regex
+
+      # initialize a new template finder
+      #
+      # @example
+      #   TemplateFinder.new('foo/bar/', {
+      #     'default' => ['text/html', 'text/xml'],
+      #     'json' => ['application/json']
+      #   })
+      # @param path [String] the path to all templates ending on '/'
+      # @param type_map [Hash] a map of short type names to mime types
+      def initialize(path, type_map)
+        raise ArgumentError.new("Has to end on '/'!") if path[-1] != SLASH_END
+        @path = path
+        @type_map  = sanity_map(type_map)
+        @path_regex = /#{path}/
+      end
+
+      # traverses the template path to gather all templates
+      #
+      # This function traverses the template path, collects and sorts all
+      # templates into the target types given at initialization.
+      # @return [Hash] the map of type to template
+      def get_templates
+        result = Hash.new {|hash, key| hash[key] = {} }
+
+        search_files.each do |file|
+          key, value = add_template(file)
+          result[key] = result[key].merge(value)
+        end
+        result
+      end
+
+      private
+
+      # returns a list of files found at @path
+      #
+      # This method returns all files found in @path, which look like a template.
+      # Look for `MARK_ALL_FILES` for the eact schema.
+      # @api private
+      # @return [Array] a list of all files found
+      def search_files
+        Dir[@path + MARK_ALL_FILES]
+      end
+
+      # splits the path into a filename and its type
+      #
+      # This function takes a filepath and extracts the filename and short
+      # notation for the type.
+      # The filename is later used at rendering time to find the template.
+      # @api private
+      # @param filepath [String] the filename to split
+      # @return [Array] an Array of the following example `[filename, type]`
+      def get_fields(filepath)
+        filename, *options = filepath.gsub(@path_regex, EMPTY_STRING).split(SPLIT_CHAR)
+        [filename, (options.length == 1 ? DEFAULT_TYPE : options[0])]
+      end
+
+      # add a template with its type variants
+      #
+      # This method adds a template with all type variants to the map of all
+      # types and templates.
+      # @api private
+      # @param filename [String] the short name of the template
+      # @param type [String] the short type of the template
+      # @param path [String] the actual path to the template
+      # @return [Array] a hashable array for the end result:
+      def add_template(path)
+        filename, type = get_fields(path)
+        result = [filename, {}]
+        get_types(type).each do |mime_type|
+          result[1][mime_type] = path
+        end
+        result
+      end
+
+      # get the types for the shorthand type
+      #
+      # This method returns all types associated with the short notation
+      # of this type in the type_map.
+      # @api private
+      # @param short_type [String] the short notation of a type
+      # @return [Array] a list of all types found in the type_map
+      def get_types(short_type)
+        return [short_type] unless @type_map.has_key?(short_type)
+        @type_map[short_type]
+      end
+
+      # make a cleanup of the map
+      #
+      # This function converts all map values to arrays, to make the processing
+      # easier.
+      # @api private
+      # @param map [Hash] a type map
+      # @return [Hash] the cleaned up map
+      def sanity_map(map)
+        map.each do |key, value|
+          map[key] = [value] unless value.respond_to?(:each)
+        end
+      end
+    end
+  end
+end
diff --git a/spec/unit/zero/renderer/read_template_path_bang_spec.rb b/spec/unit/zero/renderer/read_template_path_bang_spec.rb
index 8655777..948a3cc 100644
--- a/spec/unit/zero/renderer/read_template_path_bang_spec.rb
+++ b/spec/unit/zero/renderer/read_template_path_bang_spec.rb
@@ -1,14 +1,14 @@
 require 'spec_helper'
 
-describe Zero::Renderer, 'read_template_path!' do
+describe Zero::Renderer, '#read_template_path!' do
   subject { Zero::Renderer.new(template_path, type_map) }
-  let(:template_path) { 'foo' }
+  let(:template_path) { 'foo/' }
   let(:file_list) { ['foo/welcome/index.html.erb'] }
 
   before :each do
     Dir.stub(:[]) do |arg|
       if arg == 'foo/**/*.*'
-        file_list 
+        file_list
       else
         []
       end
@@ -58,7 +58,7 @@ describe Zero::Renderer, 'read_template_path!' do
   end
 
   it 'creates an empty templates list without templates in path' do
-    subject = Zero::Renderer.new("bar", {})
+    subject = Zero::Renderer.new("bar/", {})
     subject.read_template_path!
 
     subject.templates.should eq({})
diff --git a/spec/unit/zero/renderer/render_spec.rb b/spec/unit/zero/renderer/render_spec.rb
index 30d2225..3270ac3 100644
--- a/spec/unit/zero/renderer/render_spec.rb
+++ b/spec/unit/zero/renderer/render_spec.rb
@@ -2,7 +2,7 @@ require 'spec_helper'
 
 describe Zero::Renderer, '#render' do
   subject { Zero::Renderer.new(template_path, type_map) }
-  let(:template_path) { 'spec/fixtures/templates' }
+  let(:template_path) { 'spec/fixtures/templates/' }
   let(:type_map) {{
     'html' => ['text/html', 'text/xml', '*/*'],
     'json' => ['application/json', 'plain/text']
diff --git a/spec/unit/zero/renderer/template_finder/get_templates_spec.rb b/spec/unit/zero/renderer/template_finder/get_templates_spec.rb
new file mode 100644
index 0000000..5928e66
--- /dev/null
+++ b/spec/unit/zero/renderer/template_finder/get_templates_spec.rb
@@ -0,0 +1,65 @@
+require 'spec_helper'
+
+describe Zero::Renderer::TemplateFinder, '#initialize' do
+  subject { described_class.new(template_path, type_map) }
+  let(:template_path) { 'foo/' }
+  let(:file_list) { ['foo/welcome/index.html.erb'] }
+
+  before :each do
+    Dir.stub(:[]) do |arg|
+      if arg == 'foo/**/*.*'
+        file_list
+      else
+        []
+      end
+    end
+  end
+
+  shared_examples_for 'a template loader' do
+    it 'creates a template tree' do
+      subject.get_templates['welcome/index'].should eq(result)
+    end
+  end
+
+  context 'without mapping' do
+    let(:type_map) { {} }
+    let(:result) { { 'html' => 'foo/welcome/index.html.erb' } }
+
+    it_behaves_like 'a template loader'
+  end
+
+  context 'with a single mapping' do
+    let(:type_map) { {'html' => 'text/html' } }
+    let(:result) { { 'text/html' => 'foo/welcome/index.html.erb' } }
+
+    it_behaves_like 'a template loader'
+  end
+
+  context 'with multiple mappings' do
+    let(:type_map) { {'html' => ['text/html', 'text/xml'] } }
+    let(:result) { {
+      'text/html' => 'foo/welcome/index.html.erb',
+      'text/xml'  => 'foo/welcome/index.html.erb'
+    } }
+
+    it_behaves_like 'a template loader'
+  end
+
+  context 'with default template' do
+    let(:file_list) {['foo/welcome/index.erb']}
+    let(:type_map) { {'default' => ['text/html', 'text/xml'] } }
+    let(:result) { {
+      'text/html' => 'foo/welcome/index.erb',
+      'text/xml'  => 'foo/welcome/index.erb'
+    } }
+
+    it_behaves_like 'a template loader'
+  end
+
+  it 'creates an empty templates list without templates in path' do
+    subject = Zero::Renderer.new("bar/", {})
+    subject.read_template_path!
+
+    subject.templates.should eq({})
+  end
+end
diff --git a/spec/unit/zero/renderer/template_finder/initialize_spec.rb b/spec/unit/zero/renderer/template_finder/initialize_spec.rb
new file mode 100644
index 0000000..5ed9502
--- /dev/null
+++ b/spec/unit/zero/renderer/template_finder/initialize_spec.rb
@@ -0,0 +1,19 @@
+require 'spec_helper'
+
+describe Zero::Renderer::TemplateFinder, '#initialize' do
+  subject { described_class.new(template_path, type_map) }
+  let(:template_path) { 'foo/' }
+  let(:type_map) { {'html' => ['text/html']} }
+
+  its(:path)       { should be(template_path) }
+  its(:path_regex) { should eq(/#{template_path}/) }
+  its(:type_map)   { should be(type_map) }
+
+  context 'with broken path' do
+    let(:template_path) { 'foo' }
+
+    it "raises an error" do
+      expect { subject }.to raise_error(ArgumentError, "Has to end on '/'!")
+    end
+  end
+end