# A view helper to standartize often used functions like formatting,
# tables, forms or action links. This helper is ideally defined in the
# ApplicationController.
module StandardHelper

  EMPTY_STRING = " ".html_safe   # non-breaking space asserts better css styling.

  ################  FORMATTING HELPERS  ##################################

  # Formats a single value
  def f(value)
    case value
      when Fixnum then number_with_delimiter(value)
      when Float, BigDecimal then number_with_precision(value, :precision => 2)
      when Date   then l(value)
      when Time   then l(value, :format => :time)
      when true   then t(:"global.yes")
      when false  then t(:"global.no")
      when nil    then EMPTY_STRING
      else value.to_s
    end
  end

  # Formats an arbitrary attribute of the given ActiveRecord object.
  # If no specific format_{type}_{attr} or format_{attr} method is found, 
  # formats the value as follows:
  # If the value is an associated model, renders the label of this object.
  # Otherwise, calls format_type.
  def format_attr(obj, attr)
    format_type_attr_method = obj.class.respond_to?(:model_name) ? :"format_#{obj.class.model_name.underscore}_#{attr.to_s}" : :"format_#{obj.class.name.underscore}_#{attr.to_s}"
    format_attr_method = :"format_#{attr.to_s}"
    if respond_to?(format_type_attr_method)
      send(format_type_attr_method, obj)
    elsif respond_to?(format_attr_method)
      send(format_attr_method, obj)
    elsif assoc = association(obj, attr, :belongs_to)
      format_assoc(obj, assoc)
    else
      format_type(obj, attr)
    end
  end


  ##############  STANDARD HTML SECTIONS  ############################


  # Renders an arbitrary content with the given label. Used for uniform presentation.
  def labeled(label, content = nil, &block)
    content = capture(&block) if block_given?
    render 'shared/labeled', :label => label, :content => content
  end

  # Transform the given text into a form as used by labels or table headers.
  def captionize(text, clazz = nil)
    if clazz.respond_to?(:human_attribute_name)
      clazz.human_attribute_name(text)
    else
      text.to_s.humanize.titleize
    end
  end

  # Renders a list of attributes with label and value for a given object.
  # Optionally surrounded with a div.
  def render_attrs(obj, *attrs)
    attrs.collect { |a| labeled_attr(obj, a) }.join("\n").html_safe
  end

  # Renders the formatted content of the given attribute with a label.
  def labeled_attr(obj, attr)
    labeled(captionize(attr, obj.class), format_attr(obj, attr))
  end

  # Renders a table for the given entries. One column is rendered for each attribute passed.
  # If a block is given, the columns defined therein are appended to the attribute columns.
  # If entries is empty, an appropriate message is rendered.
  # An options hash may be given as the last argument.
  def table(entries, *attrs, &block)
    if entries.present?
      StandardTableBuilder.table(entries, self, attrs.extract_options!) do |t|
        t.attrs(*attrs)
        yield t if block_given?
      end
    else
      content_tag(:div, ti(:no_list_entries), :class => 'table')
    end
  end

  # Renders a generic form for all given attributes using StandardFormBuilder.
  # Before the input fields, the error messages are rendered, if present.
  # The form is rendered with a basic save button.
  # If a block is given, custom input fields may be rendered and attrs is ignored.
  # An options hash may be given as the last argument.
  def standard_form(object, *attrs, &block)
    options = attrs.extract_options!
    options[:builder] ||= StandardFormBuilder
    options[:html] ||= {}
    add_css_class options[:html], 'form-horizontal'
    
    form_for(object, options) do |form|
      record = object.is_a?(Array) ? object.last : object
      content = render('shared/error_messages', :errors => record.errors, :object => record)

      content << if block_given?
        capture(form, &block)
      else
        form.labeled_input_fields(*attrs)
      end

      content << content_tag(:div, 
                             form.button(ti(:"button.save"), :class => 'btn btn-primary') + 
                             ' ' + 
                             cancel_link(object),
                             :class => 'form-actions')
      content.html_safe
    end
  end

  def cancel_link(object)
    link_to(ti(:"button.cancel"), polymorphic_path(object), :class => 'cancel')
  end


  ######## ACTION LINKS ###################################################### :nodoc:

  # A generic helper method to create action links.
  # These link could be styled to look like buttons, for example.
  def link_action(label, icon = nil, url = {}, html_options = {})
    add_css_class html_options, 'action btn'
    link_to(icon ? action_icon(icon, label) : label,
            url, html_options)
  end

  # Outputs an icon for an action with an optional label.
  def action_icon(icon, label = nil)
    html = content_tag(:i, "", :class => "icon-#{icon}")
    html << ' ' << label if label
    html
  end
  
  # Translates the passed key by looking it up over the controller hierarchy. 
  # The key is searched in the following order:
  #  - {controller}.{current_partial}.{key}
  #  - {controller}.{current_action}.{key}
  #  - {controller}.global.{key}
  #  - {parent_controller}.{current_partial}.{key}
  #  - {parent_controller}.{current_action}.{key}
  #  - {parent_controller}.global.{key}
  #  - ...
  #  - global.{key}
  def translate_inheritable(key, variables = {})
    defaults = []
    partial = @virtual_path ? @virtual_path.gsub(%r{.*/_?}, "") : nil
    current = controller.class
    while current < ActionController::Base
      folder = current.controller_path
      if folder.present?
        defaults << :"#{folder}.#{partial}.#{key}" if partial
        defaults << :"#{folder}.#{action_name}.#{key}"
        defaults << :"#{folder}.global.#{key}"
      end
      current = current.superclass
    end
    defaults << :"global.#{key}"
    
    variables[:default] ||= defaults
    t(defaults.shift, variables)
  end
  
  alias_method :ti, :translate_inheritable

  # Translates the passed key for an active record association. This helper is used
  # for rendering association dependent keys in forms like :no_entry, :none_available or 
  # :please_select.
  # The key is looked up in the following order:
  #  - activerecord.associations.models.{model_name}.{association_name}.{key}
  #  - activerecord.associations.{association_model_name}.{key}
  #  - global.associations.{key}
  def translate_association(key, assoc = nil, variables = {})
    primary = if assoc
      variables[:default] ||= [:"activerecord.associations.#{assoc.klass.model_name.underscore}.#{key}",
                               :"global.associations.#{key}"]
      :"activerecord.associations.models.#{assoc.active_record.model_name.underscore}.#{assoc.name}.#{key}"
    else
      :"global.associations.#{key}"
    end
    t(primary, variables)
  end
  
  alias_method :ta, :translate_association
  
  
  # Returns the css class for the given flash level.
  def flash_class(level)
    case level
    when :notice then 'success'
    when :error then 'error'
    when :alert then 'error'
    end
  end
  
  # Adds a class to the given options, even if there are already classes.
  def add_css_class(options, classes)
    if options[:class]
      options[:class] += ' ' + classes
    else
      options[:class] = classes
    end
  end
  
  protected

  # Helper methods that are not directly called from templates.

  # Formats an arbitrary attribute of the given object depending on its data type.
  # For ActiveRecords, take the defined data type into account for special types
  # that have no own object class.
  def format_type(obj, attr)
    val = obj.send(attr)
    return EMPTY_STRING if val.nil?
    case column_type(obj, attr)
      when :time    then f(val.to_time)
      when :date    then f(val.to_date)
      when :datetime, :timestamp then "#{f(val.to_date)} #{f(val.to_time)}"
      when :text    then val.present? ? simple_format(h(val)) : EMPTY_STRING
      when :decimal then f(val.to_s.to_f)
      else f(val)
    end
  end

  # Returns the ActiveRecord column type or nil.
  def column_type(obj, attr)
    column_property(obj, attr, :type)
  end

  # Returns an ActiveRecord column property for the passed attr or nil
  def column_property(obj, attr, property)
    if obj.respond_to?(:column_for_attribute)
      column = obj.column_for_attribute(attr)
      column.try(property)
    end
  end

  # Formats an active record association
  def format_assoc(obj, assoc)
    if assoc_val = obj.send(assoc.name)
      link_to_unless(no_assoc_link?(assoc, assoc_val), assoc_val, assoc_val)
    else
      ta(:no_entry, assoc)
    end
  end

  # Returns true if no link should be created when formatting the given association.
  def no_assoc_link?(assoc, val)
    !respond_to?("#{val.class.model_name.underscore}_path".to_sym)
  end

  # Returns the association proxy for the given attribute. The attr parameter
  # may be the _id column or the association name. If a macro (e.g. :belongs_to)
  # is given, the association must be of this type, otherwise, any association
  # is returned. Returns nil if no association (or not of the given macro) was
  # found.
  def association(obj, attr, macro = nil)
    if obj.class.respond_to?(:reflect_on_association)
      name = attr.to_s =~ /_id$/ ? attr.to_s[0..-4].to_sym : attr
      assoc = obj.class.reflect_on_association(name)
      assoc if assoc && (macro.nil? || assoc.macro == macro)
    end
  end

end