#--
# BibTeX-Ruby
# Copyright (C) 2010-2012  Sylvester Keil <sylvester.keil.or.at>
#
# This program 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 BibTeX

  #
  # The Bibliography class models a BibTeX bibliography;
  # typically, it corresponds to a `.bib' file.
  #
  class Bibliography
    extend Forwardable

    include Enumerable
    include Comparable

    @defaults = { :parse_names => true, :parse_months => true }.freeze

    class << self

      attr_reader :defaults

      # Opens and parses the `.bib' file at the given +path+. Returns
      # a new Bibliography instance corresponding to the file, or, if a block
      # is given, yields the instance to the block, ensuring that the file
      # is saved after the block's execution (use the :out option if you want
      # to specify a save path other than the path from where the file is
      # loaded).
      #
      # The options argument is passed on to BibTeX::Parser.new. Additional
      # option parameters are:
      #
      # -:parse_names: set to false to disable automatic name parsing
      # -:parse_months: set to false to disable automatic month conversion
      # -:filter: convert all entries using the sepcified filter (not set by default)
      #
      def open(path, options = {})
        b = parse(Kernel.open(path, 'r:UTF-8').read, options)
        b.path = path
        return b unless block_given?

        begin
          yield b
        ensure
          b.save_to(options[:out] || path)
        end
      end

      # Parses the given string and returns a corresponding Bibliography instance.
      def parse(input, options = {})
        case input
        when Array, Hash, Element
          Bibliography.new(options).add(input)
        when ::String
          Parser.new(options).parse(input) || Bibliography.new(options)
        else
          raise ArgumentError, "failed to parse #{input.inspect}"
        end
      end

      # Defines a new accessor that selects elements by type.
      def attr_by_type(*arguments)
        arguments.each do |type|
          method_id = "#{type}s"
          define_method(method_id) { find_by_type(type) } unless respond_to?(method_id)
        end
      end
    end

    attr_accessor :path

    attr_reader :data, :strings, :entries, :errors, :options

    attr_by_type :article, :book, :journal, :collection, :preamble,
      :comment, :meta_content

    def_delegators :@data, :length, :size, :empty?
    def_delegators :@entries, :key?, :has_key?, :values_at

    alias entries_at values_at

    # Creates a new bibliography.
    def initialize(options = {})
      @options = Bibliography.defaults.merge(options)
      @data, @strings, @errors = [], {}, []
      @entries = Hash.new { |h,k| h.fetch(k.to_s, nil) }

      yield self if block_given?
    end

    def initialize_copy(other)
      @options = other.options.dup
      @errors = other.errors.dup
      @data, @strings = [], {}
      @entries = Hash.new { |h,k| h.fetch(k.to_s, nil) }
      add(other.data)
    end

    # Adds a new element, or a list of new elements to the bibliography.
    # Returns the Bibliography for chainability.
    def add(*arguments)
      Element.parse(arguments.flatten).each do |element|
        data << element.added_to_bibliography(self)
      end
      self
    end

    alias << add
    alias push add


    # Saves the bibliography to the current path.
    def save(options = {})
      save_to(@path, options)
    end

    # Saves the bibliography to a file at the given path. Returns the bibliography.
    def save_to(path, options = {})
      options[:quotes] ||= %w({ })

      File.open(path, 'w:UTF-8') do |f|
        f.write(to_s(options))
      end

      self
    end


    def each
      if block_given?
        data.each(&Proc.new)
        self
      else
        to_enum
      end
    end


    def parse_names
      entries.each_value { |e| e.parse_names }
      self
    end

    def parse_months
      entries.each_value { |e| e.parse_month }
      self
    end


    # Converts all enties using the given filter(s). If an optional block is given
    # the block is used as a condition (the block will be called with each
    # entry). @see Entry#convert!
    def convert(*filters)
      filters = filters.flatten.map { |f| Filters.resolve!(f) }

      entries.each_value do |entry|
        entry.convert!(*filters) if !block_given? || yield(entry)
      end

      self
    end


    # Deletes an object, or a list of objects from the bibliography.
    # If a list of objects is to be deleted, you can either supply the list
    # of objects or use a query or block to define the list.
    #
    # Returns the object (or the list of objects) that were deleted; nil
    # if the object was not part of the bibliography.
    def delete(*arguments, &block)
      objects = q(*arguments, &block).map { |o| o.removed_from_bibliography(self) }
      @data = @data - objects
      objects.length == 1 ? objects[0] : objects
    end

    alias remove delete
    alias rm delete


    # call-seq:
    # >> bib[-1]
    # => Returns the last element of the Bibliography or nil
    # >> bib[1,2]
    # => Returns the second and third elements or nil
    # >> bib[1..2]
    # >> Same as above
    # >> bib[:key]
    # => Returns the first entry with key 'key' or nil
    # >> bib['key']
    # => Same as above
    # >> bib['@article']
    # => Returns all entries of type 'article' or []
    # >> bib['@preamble']
    # => Returns all preamble objects (this is the same as Bibliography#preambles) or []
    # >> bib[/ruby/]
    # => Returns all objects that match 'ruby' anywhere or []
    # >> bib['@book[keywords=ruby]']
    # => Returns all books whose keywords attribute equals 'ruby' or []
    #
    # Returns an element or a list of elements according to the given index,
    # range, or query. Contrary to the Bibliography#query this method does
    # not yield to a block for additional refinement of the query.
    #
    def [](*arguments)
      raise(ArgumentError, "wrong number of arguments (#{arguments.length} for 1..2)") unless arguments.length.between?(1,2)

      case
      when arguments[0].is_a?(Numeric) || arguments[0].is_a?(Range)
        data[*arguments]
      when arguments.length == 1
        case
        when arguments[0].nil?
          nil
        when arguments[0].respond_to?(:empty?) && arguments[0].empty?
          nil
        when arguments[0].is_a?(Symbol)
          entries[arguments[0]]
        when arguments[0].respond_to?(:start_with?) && !arguments[0].start_with?('@', '!@')
          entries[arguments[0]]
        else
          query(*arguments)
        end
      else
        query(*arguments)
      end
    end


    # Returns true if there are object which could not be parsed.
    def errors?
      !errors.empty?
    end

    # Returns true if the +Bibliography+ contains no errors and only
    # valid BibTeX objects (meta content is ignored).
    def valid?
      !errors? && entries.values.all?(&:valid?)
    end

    # Returns a list of the names of all authors, editors and translators in the Bibliography.
    def names
      map(&:names).flatten
    end

    # Replaces all string symbols which are defined in the bibliography.
    #
    # By default symbols in @string, @preamble and entries are replaced; this
    # behaviour can be changed using the optional query parameter.
    #
    # Note that strings are replaced in the order in which they occur in the
    # bibliography.
    #
    # call-seq:
    # bib.replace #=> replaces all symbols
    # bib.replace('@string, @preamble')
    # #=> replaces only symbols in @string and @preamble objects
    #
    def replace(filter = '')
      q(filter) { |e| e.replace(@strings.values) }
      self
    end

    alias :replace_strings :replace

    def join(filter = '')
      q(filter, &:join)
      self
    end

    alias join_strings join

    def rename(*arguments, &block)
      q('@entry') { |e| e.rename(*arguments, &block) }
      self
    end

    # call-seq:
    #   b.extend_initials(['Edgar Allen', 'Poe'], ['Nathaniel', 'Hawthorne'])
    #   #=> Extends the initials in names like 'E.A. Poe' or 'Hawethorne, N.'
    #       in the bibliography.
    #
    # Extends the initials for the given names. Returns the Bibliography.
    def extend_initials(*arguments)
      arguments.each do |with_first, for_last|
        names.each do |name|
          name.extend_initials(with_first, for_last)
        end
      end

      self
    end

    # This method combines all names in the bibliography that look identical
    # when using initials as first names and then tries to extend the first
    # names for all names in each group to the longest available form.
    # Returns the bibliography.
    #
    # If your bibliography contains the names 'Poe, Edgar A.', 'Poe, E.A.',
    # and 'Poe, E. A.' calling this method would convert all three names to
    # 'Poe, Edgar A.'.
    def extend_initials!
      groups = Hash.new do |h,k|
        h[k] = { :prototype => nil, :names => [] }
      end

      # group names together
      names.each do |name|
        group = groups[name.sort_order(:initials => true).downcase]
        group[:names] << name

        if group[:prototype].nil? || group[:prototype].first.to_s.length < name.first.to_s.length
          group[:prototype] = name
        end
      end

      # extend all names in group to prototype
      groups.each_value do |group|
        group[:names].each do |name|
          name.set(group[:prototype])
        end
      end

      self
    end

    # call-seq:
    #   b.unify :publisher, /o'?reilly/i, "O'Reilly"
    #   #=> Unifies the publisher name "O'Reilly" in the bibliography
    #
    # Sets all fields matching the passed-in pattern to the supplied value.
    # If a block is given, each matching entry will be passed to the block
    # instead. Returns the bibliography.
    def unify(field, pattern, value = nil)
      pattern = Regexp.new(pattern) unless pattern.is_a?(Regexp)

      block = if block_given?
        Proc.new
      else
        Proc.new { |e| e[field] = value }
      end

      each_entry do |entry|
        if entry.field?(field) && entry[field].to_s =~ pattern
          block.call(entry)
        end
      end

      self
    end

    def group_by(*arguments, &block)
      groups = Hash.new { |h,k| h[k] = [] }

      entries.values.each do |e|
        groups[e.digest(arguments, &block)] << e
      end

      groups
    end

    def sort(*arguments, &block)
      data.sort(*arguments, &block)
      self
    end

    # Returns a string representation of the bibliography.
    def to_s(options = {})
      map { |o| o.to_s(options) }.join
    end

    def inspect
      "#<#{self.class} data=[#{length}]>"
    end

    def to_a(options = {})
      map { |o| o.to_hash(options) }
    end

    # Returns a Ruby hash representation of the bibliography.
    def to_hash(options = {})
      { :bibliography => map { |o| o.to_hash(options) } }
    end

    # Returns a YAML representation of the bibliography.
    def to_yaml(options = {})
      to_a(options).to_yaml
    end

    # Returns a JSON representation of the bibliography.
    def to_json(options = {})
      MultiJson.dump(to_a(options))
    end

    # Returns a CiteProc JSON representation of the bibliography. Only BibTeX enrties are exported.
    def to_citeproc(options = {})
      q('@entry').map { |o| o.to_citeproc(options) }
    end

    # Returns a REXML::Document representation of the bibliography using the
    # BibTeXML format.
    def to_xml(options = {})
      require 'rexml/document'

      xml =  REXML::Document.new
      xml << REXML::XMLDecl.new('1.0','UTF-8')

      root = REXML::Element.new('bibtex:file')
      root.add_namespace('bibtex', 'http://bibtexml.sf.net/')

      each { |e| root.add_element(e.to_xml(options)) if e.is_a?(Entry) }

      xml.add_element(root)
      xml
    end

    # Returns an RDF::Graph representation of the bibliography. The graph
    # can be serialized using any of the RDF serializer plugins.
    def to_rdf(options = {})
      require 'rdf'

      graph = RDF::Graph.new

      q('@entry').each do |entry|
        graph << entry.to_rdf(options)
      end

      graph
    rescue LoadError
      BibTeX.log.error "Please gem install rdf for RDF support."
    end

    # call-seq:
    #   bib.query()          #=> returns all elements
    #   bib.query('@book')   #=> returns all books
    #   bib.query('@entry')  #=> returns all entries (books, articles etc.)
    #   bib.query('@*')      #=> same as above
    #   bib.query(:first, '@book, @article')
    #     #=> returns the first book or article or nil
    #   bib.query('@book[year<=2011], @article)
    #     #=> returns all books published in 2011 or earlier and all articles
    #   bib.query('@book, @article) { |o| o.year == '2011' }
    #     #=> returns all books and articles published in 2011
    #   bib.query('@book[year=2011], @article[year=2011])
    #     #=> same as above without using a block
    #
    # Returns objects in the Bibliography which match the given selector and,
    # optionally, the conditions specified in the given block.
    #
    # Queries offer syntactic sugar for common enumerator invocations:
    #
    #     >> bib.query(:all, '@book')
    #     => same as bib.select { |b| b.has_type?(:book) }
    #     >> bib.query('@book')
    #     => same as above
    #     >> bib.query(:first, '@book')
    #     => same as bib.detect { |b| b.has_type?(:book) }
    #     >> bib.query(:none, '@book')
    #     => same as bib.reject { |b| b.has_type?(:book) }
    #
    def query(*arguments, &block)
      case arguments.length
      when 0
        selector, q = :all, nil
      when 1
        selector, q = :all, arguments[0]
      when 2
        selector, q = arguments
      else
        raise ArgumentError, "wrong number of arguments (#{arguments.length} for 0..2)"
      end

      filter = block ? Proc.new { |e| e.match?(q) && block.call(e) } :
        Proc.new { |e| e.match?(q) }

      send(query_handler(selector), &filter)
    end

    alias q query

    def each_entry
      if block_given?
        q('@entry').each(&Proc.new)
      else
        q('@entry').to_enum
      end
    end

    def find_by_type(*types, &block)
      q(types.flatten.compact.map { |t| "@#{t}" }.join(', '), &block)
    end

    alias find_by_types find_by_type

    def <=>(other)
      other.respond_to?(:to_a) ? to_a <=> other.to_a : nil
    end

    def select_duplicates_by(*arguments)
      arguments = [:year, :title] if arguments.empty?

      group_by(*arguments) { |digest|
        digest.gsub(/\s+/, '').downcase
      }.values.select { |d| d.length > 1 }
    end

    alias duplicates select_duplicates_by

    def duplicates?
      !select_duplicates_by?.empty?
    end


    private

    def query_handler(selector)
      case selector.to_s
      when /first|distinct|detect/i
        :detect
      when /none|reject|not/i
        :reject
      else
        :select
      end
    end

  end
end