# -*- coding: utf-8; frozen_string_literal: true -*-
#
#--
# Copyright (C) 2009-2019 Thomas Leitner <t_leitner@gmx.at>
#
# This file is part of kramdown which is licensed under the MIT.
#++
#

require 'yaml'

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)
      name = name.to_sym
      raise ArgumentError, "Option name #{name} is already used" if @options.key?(name)
      raise ArgumentError, "Invalid option type #{type} specified" unless 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.key?(name.to_sym)
    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|
        k = k.to_sym
        temp[k] = @options.key?(k) ? parse(k, v) : 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)
      name = name.to_sym
      raise ArgumentError, "No option named #{name} defined" unless @options.key?(name)
      unless @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
                 str_to_sym(data)
               elsif @options[name].type == Boolean
                 data.downcase.strip != 'false' && !data.empty?
               end
      end
      data = @options[name].validator[data] if @options[name].validator
      data
    end

    # Converts the given String +data+ into a Symbol or +nil+ with the
    # following provisions:
    #
    # - A leading colon is stripped from the string.
    # - An empty value or a value equal to "nil" results in +nil+.
    def self.str_to_sym(data)
      data = data.strip
      data = data[1..-1] if data[0] == ':'
      (data.empty? || data == 'nil' ? nil : data.to_sym)
    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.
    #
    # Optionally, the array is checked for the correct size.
    def self.simple_array_validator(val, name, size = nil)
      if String === val
        val = val.split(/,/)
      elsif !(Array === val)
        raise Kramdown::Error, "Invalid type #{val.class} for option #{name}"
      end
      if size && val.size != size
        raise Kramdown::Error, "Option #{name} needs exactly #{size} values"
      end
      val
    end

    # Ensures that the option value +val+ for the option called +name+ is a valid hash. The
    # parameter +val+ can be
    #
    # - a hash in YAML format
    # - or a Ruby Hash object.
    def self.simple_hash_validator(val, name)
      if String === val
        begin
          val = YAML.safe_load(val)
        rescue RuntimeError, ArgumentError, SyntaxError
          raise Kramdown::Error, "Invalid YAML value for option #{name}"
        end
      end
      raise Kramdown::Error, "Invalid type #{val.class} for option #{name}" unless Hash === val
      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
      or the ERB template itself.

      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 (the same as the
      converter name) 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). If the file is still not
      found, the template name is checked if it starts with 'string://' and if
      it does, this prefix is removed and the rest is used as template
      content.

      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_stripping, Boolean, false, <<~EOF)
      Strip all formatting from header text for automatic ID generation

      If this option is `true`, only the text elements of a header are used
      for generating the ID later (in contrast to just using the raw header
      text line).

      This option will be removed in version 2.0 because this will be the
      default then.

      Default: false
      Used by: kramdown parser
    EOF

    define(:auto_id_prefix, String, '', <<~EOF)
      Prefix used for automatically generated header 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(:transliterated_header_ids, Boolean, false, <<~EOF)
      Transliterate the header text before generating the ID

      Only ASCII characters are used in headers IDs. This is not good for
      languages with many non-ASCII characters. By enabling this option
      the header text is transliterated to ASCII as good as possible so that
      the resulting header ID is more useful.

      The stringex library needs to be installed for this feature to work!

      Default: false
      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(:link_defs, Object, {}, <<~EOF) do |val|
      Pre-defines link definitions

      This option can be used to pre-define link definitions. The value needs
      to be a Hash where the keys are the link identifiers and the values are
      two element Arrays with the link URL and the link title.

      If the value is a String, it has to contain a valid YAML hash and the
      hash has to follow the above guidelines.

      Default: {}
      Used by: kramdown parser
    EOF
      val = simple_hash_validator(val, :link_defs)
      val.each do |_k, v|
        if !(Array === v) || v.size > 2 || v.empty?
          raise Kramdown::Error, "Invalid structure for hash value of option #{name}"
        end
        v << nil if v.size == 1
      end
      val
    end

    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(: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
      case val
      when String
        if val =~ /^(\d)\.\.(\d)$/
          val = Range.new($1.to_i, $2.to_i).to_a
        elsif val =~ /^\d(?:,\d)*$/
          val = val.split(/,/).map(&:to_i).uniq
        else
          raise Kramdown::Error, "Invalid syntax for option toc_levels"
        end
      when Array, Range
        val = val.map(&:to_i).uniq
      else
        raise Kramdown::Error, "Invalid type #{val.class} for option toc_levels"
      end
      if val.any? {|i| !(1..6).cover?(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,subparagraph
      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

    define(:typographic_symbols, Object, {}, <<~EOF) do |val|
      Defines a mapping from typographical symbol to output characters

      Typographical symbols are normally output using their equivalent Unicode
      codepoint. However, sometimes one wants to change the output, mostly to
      fallback to a sequence of ASCII characters.

      This option allows this by specifying a mapping from typographical
      symbol to its output string. For example, the mapping {hellip: ...} would
      output the standard ASCII representation of an ellipsis.

      The available typographical symbol names are:

      * hellip: ellipsis
      * mdash: em-dash
      * ndash: en-dash
      * laquo: left guillemet
      * raquo: right guillemet
      * laquo_space: left guillemet followed by a space
      * raquo_space: right guillemet preceeded by a space

      Default: {}
      Used by: HTML/Latex converter
    EOF
      val = simple_hash_validator(val, :typographic_symbols)
      val.keys.each do |k|
        val[k.kind_of?(String) ? str_to_sym(k) : k] = val.delete(k).to_s
      end
      val
    end

    define(:remove_block_html_tags, Boolean, true, <<~EOF)
      Remove block HTML tags

      If this option is `true`, the RemoveHtmlTags converter removes
      block HTML tags.

      Default: true
      Used by: RemoveHtmlTags converter
    EOF

    define(:remove_span_html_tags, Boolean, false, <<~EOF)
      Remove span HTML tags

      If this option is `true`, the RemoveHtmlTags converter removes
      span HTML tags.

      Default: false
      Used by: RemoveHtmlTags converter
    EOF

    define(:header_offset, Integer, 0, <<~EOF)
      Sets the output offset for headers

      If this option is c (may also be negative) then a header with level n
      will be output as a header with level c+n. If c+n is lower than 1,
      level 1 will be used. If c+n is greater than 6, level 6 will be used.

      Default: 0
      Used by: HTML converter, Kramdown converter, Latex converter
    EOF

    define(:syntax_highlighter, Symbol, :rouge, <<~EOF)
      Set the syntax highlighter

      Specifies the syntax highlighter that should be used for highlighting
      code blocks and spans. If this option is set to +nil+, no syntax
      highlighting is done.

      Options for the syntax highlighter can be set with the
      syntax_highlighter_opts configuration option.

      Default: rouge
      Used by: HTML/Latex converter
    EOF

    define(:syntax_highlighter_opts, Object, {}, <<~EOF) do |val|
      Set the syntax highlighter options

      Specifies options for the syntax highlighter set via the
      syntax_highlighter configuration option.

      The value needs to be a hash with key-value pairs that are understood by
      the used syntax highlighter.

      Default: {}
      Used by: HTML/Latex converter
    EOF
      val = simple_hash_validator(val, :syntax_highlighter_opts)
      val.keys.each do |k|
        val[k.kind_of?(String) ? str_to_sym(k) : k] = val.delete(k)
      end
      val
    end

    define(:math_engine, Symbol, :mathjax, <<~EOF)
      Set the math engine

      Specifies the math engine that should be used for converting math
      blocks/spans. If this option is set to +nil+, no math engine is used and
      the math blocks/spans are output as is.

      Options for the selected math engine can be set with the
      math_engine_opts configuration option.

      Default: mathjax
      Used by: HTML converter
    EOF

    define(:math_engine_opts, Object, {}, <<~EOF) do |val|
      Set the math engine options

      Specifies options for the math engine set via the math_engine
      configuration option.

      The value needs to be a hash with key-value pairs that are understood by
      the used math engine.

      Default: {}
      Used by: HTML converter
    EOF
      val = simple_hash_validator(val, :math_engine_opts)
      val.keys.each do |k|
        val[k.kind_of?(String) ? str_to_sym(k) : k] = val.delete(k)
      end
      val
    end

    define(:footnote_backlink, String, '&#8617;', <<~EOF)
      Defines the text that should be used for the footnote backlinks

      The footnote backlink is just text, so any special HTML characters will
      be escaped.

      If the footnote backlint text is an empty string, no footnote backlinks
      will be generated.

      Default: '&8617;'
      Used by: HTML converter
    EOF

    define(:footnote_backlink_inline, Boolean, false, <<~EOF)
      Specifies whether the footnote backlink should always be inline

      With the default of false the footnote backlink is placed at the end of
      the last paragraph if there is one, or an extra paragraph with only the
      footnote backlink is created.

      Setting this option to true tries to place the footnote backlink in the
      last, possibly nested paragraph or header. If this fails (e.g. in the
      case of a table), an extra paragraph with only the footnote backlink is
      created.

      Default: false
      Used by: HTML converter
    EOF

    define(:footnote_prefix, String, '', <<~EOF)
      Prefix used for footnote IDs

      This option can be used to set a prefix for footnote IDs. This is useful
      when rendering multiple documents into the same output file to avoid
      duplicate IDs. The prefix should only contain characters that are valid
      in an ID!

      Default: ''
      Used by: HTML
    EOF

  end

end
