# -*- coding: utf-8 -*-
#
#--
# Copyright (C) 2009-2010 Thomas Leitner <t_leitner@gmx.at>
#
# This file is part of kramdown.
#
# kramdown is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.
#++
#

module Kramdown

  # This module defines all options that are used by parsers and/or converters as well as providing
  # methods to deal with the options.
  module Options

    # Helper class introducing a boolean type for specifying boolean values (+true+ and +false+) as
    # option types.
    class Boolean

      # Return +true+ if +other+ is either +true+ or +false+
      def self.===(other)
        FalseClass === other || TrueClass === other
      end

    end

    # ----------------------------
    # :section: Option definitions
    #
    # This sections describes the methods that can be used on the Options module.
    # ----------------------------

    # Struct class for storing the definition of an option.
    Definition = Struct.new(:name, :type, :default, :desc, :validator)

    # Allowed option types.
    ALLOWED_TYPES = [String, Integer, Float, Symbol, Boolean, Object]

    @options = {}

    # Define a new option called +name+ (a Symbol) with the given +type+ (String, Integer, Float,
    # Symbol, Boolean, Object), default value +default+ and the description +desc+. If a block is
    # specified, it should validate the value and either raise an error or return a valid value.
    #
    # The type 'Object' should only be used for complex types for which none of the other types
    # suffices. A block needs to be specified when using type 'Object' and it has to cope with
    # a value given as string and as the opaque type.
    def self.define(name, type, default, desc, &block)
      raise ArgumentError, "Option name #{name} is already used" if @options.has_key?(name)
      raise ArgumentError, "Invalid option type #{type} specified" if !ALLOWED_TYPES.include?(type)
      raise ArgumentError, "Invalid type for default value" if !(type === default) && !default.nil?
      raise ArgumentError, "Missing validator block" if type == Object && block.nil?
      @options[name] = Definition.new(name, type, default, desc, block)
    end

    # Return all option definitions.
    def self.definitions
      @options
    end

    # Return +true+ if an option called +name+ is defined.
    def self.defined?(name)
      @options.has_key?(name)
    end

    # Return a Hash with the default values for all options.
    def self.defaults
      temp = {}
      @options.each {|n, o| temp[o.name] = o.default}
      temp
    end

    # Merge the #defaults Hash with the *parsed* options from the given Hash, i.e. only valid option
    # names are considered and their value is run through the #parse method.
    def self.merge(hash)
      temp = defaults
      hash.each do |k,v|
        next unless @options.has_key?(k)
        temp[k] = parse(k, v)
      end
      temp
    end

    # Parse the given value +data+ as if it was a value for the option +name+ and return the parsed
    # value with the correct type.
    #
    # If +data+ already has the correct type, it is just returned. Otherwise it is converted to a
    # String and then to the correct type.
    def self.parse(name, data)
      raise ArgumentError, "No option named #{name} defined" if !@options.has_key?(name)
      if !(@options[name].type === data)
        data = data.to_s
        data = if @options[name].type == String
                 data
               elsif @options[name].type == Integer
                 Integer(data) rescue raise Kramdown::Error, "Invalid integer value for option '#{name}': '#{data}'"
               elsif @options[name].type == Float
                 Float(data) rescue raise Kramdown::Error, "Invalid float value for option '#{name}': '#{data}'"
               elsif @options[name].type == Symbol
                 (data.strip.empty? ? nil : data.to_sym)
               elsif @options[name].type == Boolean
                 data.downcase.strip != 'false' && !data.empty?
               end
      end
      data = @options[name].validator[data] if @options[name].validator
      data
    end

    # ----------------------------
    # :section: Option Validators
    #
    # This sections contains all pre-defined option validators.
    # ----------------------------

    # Ensures that the option value +val+ for the option called +name+ is a valid array. The
    # parameter +val+ can be
    #
    # - a comma separated string which is split into an array of values
    # - or an array.
    #
    # Additionally, the array is checked for the correct size.
    def self.simple_array_validator(val, name, size)
      if String === val
        val = val.split(/,/)
      elsif !(Array === val)
        raise Kramdown::Error, "Invalid type #{val.class} for option #{name}"
      end
      if val.size != size
        raise Kramdown::Error, "Option #{name} needs exactly #{size} values"
      end
      val
    end

    # ----------------------------
    # :section: Option Definitions
    #
    # This sections contains all option definitions that are used by the included
    # parsers/converters.
    # ----------------------------

    define(:template, String, '', <<EOF)
The name of an ERB template file that should be used to wrap the output

This is used to wrap the output in an environment so that the output can
be used as a stand-alone document. For example, an HTML template would
provide the needed header and body tags so that the whole output is a
valid HTML file. If no template is specified, the output will be just
the converted text.

When resolving the template file, the given template name is used first.
If such a file is not found, the converter extension is appended. If the
file still cannot be found, the templates name is interpreted as a
template name that is provided by kramdown (without the converter
extension).

kramdown provides a default template named 'document' for each converter.

Default: ''
Used by: all converters
EOF

    define(:auto_ids, Boolean, true, <<EOF)
Use automatic header ID generation

If this option is `true`, ID values for all headers are automatically
generated if no ID is explicitly specified.

Default: true
Used by: HTML/Latex converter
EOF

    define(:auto_id_prefix, String, '', <<EOF)
Prefix used for automatically generated heaer IDs

This option can be used to set a prefix for the automatically generated
header IDs so that there is no conflict when rendering multiple kramdown
documents into one output file separately. The prefix should only
contain characters that are valid in an ID!

Default: ''
Used by: HTML/Latex converter
EOF

    define(:parse_block_html, Boolean, false, <<EOF)
Process kramdown syntax in block HTML tags

If this option is `true`, the kramdown parser processes the content of
block HTML tags as text containing block-level elements. Since this is
not wanted normally, the default is `false`. It is normally better to
selectively enable kramdown processing via the markdown attribute.

Default: false
Used by: kramdown parser
EOF

    define(:parse_span_html, Boolean, true, <<EOF)
Process kramdown syntax in span HTML tags

If this option is `true`, the kramdown parser processes the content of
span HTML tags as text containing span-level elements.

Default: true
Used by: kramdown parser
EOF

    define(:html_to_native, Boolean, false, <<EOF)
Convert HTML elements to native elements

If this option is `true`, the parser converts HTML elements to native
elements. For example, when parsing `<em>hallo</em>` the emphasis tag
would normally be converted to an `:html` element with tag type `:em`.
If `html_to_native` is `true`, then the emphasis would be converted to a
native `:em` element.

This is useful for converters that cannot deal with HTML elements.

Default: false
Used by: kramdown parser
EOF

    define(:footnote_nr, Integer, 1, <<EOF)
The number of the first footnote

This option can be used to specify the number that is used for the first
footnote.

Default: 1
Used by: HTML converter
EOF

    define(:coderay_wrap, Symbol, :div, <<EOF)
Defines how the highlighted code should be wrapped

The possible values are :span, :div or nil.

Default: :div
Used by: HTML converter
EOF

    define(:coderay_line_numbers, Symbol, :inline, <<EOF)
Defines how and if line numbers should be shown

The possible values are :table, :inline, :list or nil. If this option is
nil, no line numbers are shown.

Default: :inline
Used by: HTML converter
EOF

    define(:coderay_line_number_start, Integer, 1, <<EOF)
The start value for the line numbers

Default: 1
Used by: HTML converter
EOF

    define(:coderay_tab_width, Integer, 8, <<EOF)
The tab width used in highlighted code

Used by: HTML converter
EOF

    define(:coderay_bold_every, Integer, 10, <<EOF)
Defines how often a line number should be made bold

Default: 10
Used by: HTML converter
EOF

    define(:coderay_css, Symbol, :style, <<EOF)
Defines how the highlighted code gets styled

Possible values are :class (CSS classes are applied to the code
elements, one must supply the needed CSS file) or :style (default CSS
styles are directly applied to the code elements).

Default: style
Used by: HTML converter
EOF

    define(:entity_output, Symbol, :as_char, <<EOF)
Defines how entities are output

The possible values are :as_input (entities are output in the same
form as found in the input), :numeric (entities are output in numeric
form), :symbolic (entities are output in symbolic form if possible) or
:as_char (entities are output as characters if possible, only available
on Ruby 1.9).

Default: :as_char
Used by: HTML converter, kramdown converter
EOF

    define(:toc_levels, Object, (1..6).to_a, <<EOF) do |val|
Defines the levels that are used for the table of contents

The individual levels can be specified by separating them with commas
(e.g. 1,2,3) or by using the range syntax (e.g. 1..3). Only the
specified levels are used for the table of contents.

Default: 1..6
Used by: HTML/Latex converter
EOF
      if String === val
        if val =~ /^(\d)\.\.(\d)$/
          val = Range.new($1.to_i, $2.to_i).to_a
        elsif val =~ /^\d(?:,\d)*$/
          val = val.split(/,/).map {|s| s.to_i}.uniq
        else
          raise Kramdown::Error, "Invalid syntax for option toc_levels"
        end
      elsif Array === val
        val = val.map {|s| s.to_i}.uniq
      else
        raise Kramdown::Error, "Invalid type #{val.class} for option toc_levels"
      end
      if val.any? {|i| !(1..6).include?(i)}
        raise Kramdown::Error, "Level numbers for option toc_levels have to be integers from 1 to 6"
      end
      val
    end

    define(:line_width, Integer, 72, <<EOF)
Defines the line width to be used when outputting a document

Default: 72
Used by: kramdown converter
EOF

    define(:latex_headers, Object, %w{section subsection subsubsection paragraph subparagraph subparagraph}, <<EOF) do |val|
Defines the LaTeX commands for different header levels

The commands for the header levels one to six can be specified by
separating them with commas.

Default: section,subsection,subsubsection,paragraph,subparagraph,subsubparagraph
Used by: Latex converter
EOF
      simple_array_validator(val, :latex_headers, 6)
    end

    define(:smart_quotes, Object, %w{lsquo rsquo ldquo rdquo}, <<EOF) do |val|
Defines the HTML entity names or code points for smart quote output

The entities identified by entity name or code point that should be
used for, in order, a left single quote, a right single quote, a left
double and a right double quote are specified by separating them with
commas.

Default: lsquo,rsquo,ldquo,rdquo
Used by: HTML/Latex converter
EOF
      val = simple_array_validator(val, :smart_quotes, 4)
      val.map! {|v| Integer(v) rescue v}
      val
    end

  end

end