# frozen-string-literal: true
#
# Copyright (C) 2019 Thomas Baron
#
# This file is part of term_utils.
#
# term_utils 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, version 3 of the License.
#
# term_utils 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 term_utils.  If not, see <https://www.gnu.org/licenses/>.
module TermUtils
  module AP
    # Represents an argument parsing Result.
    class Result
      # @return [TermUtils::PropertyTreeNode]
      attr_accessor :value
      # Constructs a new Result.
      # @param syntax [Darn::AP::Syntax] Syntax.
      # @param element [Darn::AP::Element] Optional Element.
      # @param value [Darn::PropertyTreeNode] Optional value.
      def initialize(syntax, element = nil, value = nil)
        @syntax = syntax.dup
        @element = element ? element.dup : nil
        if value
          @value = value.dup
          @value.key = nil
        else
          @value = TermUtils::PropertyTreeNode.new
        end
      end
      # Collects IDs.
      # @param id [Symbol, Array<Symbol>] ID path.
      # @return [Array<Symbol>]
      def collect(id, &block)
        node = @value
        if id
          id = [id] if id.is_a? Symbol
          node = @value.find_node(id)
        end
        res = []
        return res unless node && node.child_nodes
        if block
          node.child_nodes.each do |n|
            res << n.key if block.call(n.key)
          end
        else
          node.child_nodes.each do |n|
            res << n.key
          end
        end
        res
      end
      # Tests whether a given level/parameter/article is present in the result value.
      # @param id [Symbol, Array<Symbol>] ID path.
      # @return [Boolean]
      def present?(id)
        if id.is_a? Symbol
          !!@value.child_node(id)
        elsif id.is_a? Array
          @value.node_exists?(id)
        end
      end
      # Evaluates the number of occurrences of a given level, parameter or article.
      # @param id [Symbol, Array<Symbol>]
      # @return [Integer]
      def eval_occurs(id)
        id = [id] if id.is_a? Symbol
        obj = fetch_syntax_object(id)
        raise TermUtils::AP::NoSuchValueError, "no such syntax object" unless obj
        node = @value.find_node(id)
        return 0 unless node
        return 1 if obj.occur_bounded? && (obj.max_occurs == 1)
        # Parameter is multiple.
        node.child_nodes ? node.child_nodes.length : 0
      end
      # Fetches a value.
      # @param id [Symbol, Array<Symbol>, nil]
      # @param opts [Hash] `:index`, `:multi`.
      # @option opts [Integer] :index The index of a multiple-occurrence level/parameter/article.
      # @option opts [Boolean] :multi Whether an array of values shall be returned instead of a single value.
      # @return [Object]
      # @raise [TermUtils::AP::NoSuchValueError]
      def fetch_value(id, opts = {})
        index = opts.fetch(:index, nil)
        multi = opts.fetch(:multi, false)
        unless id
          node = @value
          if node && node.child_nodes && index
            node = node.child_node(index)
          end
          raise TermUtils::AP::NoSuchValueError, "no such value" unless node
          vals = node.collect_values
          raise TermUtils::AP::NoSuchValueError, "no such value" if vals.empty?
          return multi ? vals : vals.first
        end
        id = [id] if id.is_a? Symbol
        obj = fetch_syntax_object(id)
        raise TermUtils::AP::NoSuchValueError, "no such syntax object" unless obj
        node = @value.find_node(id)
        if node && node.child_nodes && index
          node = node.child_node(index)
        end
        raise TermUtils::AP::NoSuchValueError, "no such value" unless node
        catch :value do
          if obj.is_a? TermUtils::AP::Parameter
            raise TermUtils::AP::NoSuchValueError, "parameter has no article" if obj.articles.empty?
            raise TermUtils::AP::NoSuchValueError, "no such value" if node.leaf?
            vals = node.collect_values
            raise TermUtils::AP::NoSuchValueError, "no such value" if vals.empty?
            if multi
              throw :value, vals
            else
              throw :value, vals.first
            end
          elsif obj.is_a? TermUtils::AP::Article
            # raise TermUtils::AP::NoSuchValueError, "no such value" if node.leaf?
            vals = node.collect_values
            raise TermUtils::AP::NoSuchValueError, "no such value" if vals.empty?
            if multi
              throw :value, vals
            else
              throw :value, vals.first
            end
          end
          raise  TermUtils::AP::NoSuchValueError, "wrong id"
        end
      end
      # Shifts this one.
      # @param id [Symbol, Array<Symbol>]
      # @param opts [Hash] `:index`, `:multi`.
      # @option opts [Integer] :index The index of a multiple-occurrence level/parameter/article.
      # @return [TermUtils::AP::Result]
      # @raise [TermUtils::AP::NoSuchValueError]
      def shift(id, opts = {})
        index = opts.fetch(:index, nil)
        id = [id] if id.is_a? Symbol
        obj = fetch_syntax_object(id)
        raise TermUtils::AP::NoSuchValueError, "no such syntax object" unless obj
        node = @value.find_node(id)
        if node && node.child_nodes && index
          node = node.child_node(index)
        end
        raise TermUtils::AP::NoSuchValueError, "no such value" unless node
        catch :value do
          if obj.is_a? TermUtils::AP::Level
            throw :value, TermUtils::AP::Result.new(obj.syntax, nil, node)
          elsif obj.is_a? TermUtils::AP::Parameter
            throw :value, TermUtils::AP::Result.new(@syntax, obj, node)
          elsif obj.is_a? TermUtils::AP::Article
            throw :value, TermUtils::AP::Result.new(@syntax, obj, node)
          end
          raise  TermUtils::AP::NoSuchValueError, "wrong id"
        end
      end
      private
      # Fetches a given syntax object.
      # @param id_path [Array<Symbol>]
      # @return [TermUtils::AP::Level, TermUtils::AP::Parameter, TermUtils::AP::Article, nil]
      def fetch_syntax_object(id_path)
        id = id_path.dup
        id = [@element.id].concat(id) if @element
        catch :done do
          fetch_syntax_object0(@syntax, id)
        end
      end
      # Fetches a given syntax object.
      # @param syntax [TermUtils::AP::Syntax]
      # @param id_path [Array<Symbol>]
      # @return [TermUtils::AP::Level, TermUtils::AP::Parameter, TermUtils::AP::Article, nil]
      def fetch_syntax_object0(syntax, id_path)
        id = id_path.shift
        syntax.elements.each do |e|
          next unless e.id == id
          throw :done, e if id_path.empty?
          if e.is_a? TermUtils::AP::Level
            fetch_syntax_object0(e.syntax, id_path)
          elsif e.is_a? TermUtils::AP::Parameter
            throw :done if id_path.empty?
            id = id_path.shift
            throw :done unless id_path.empty?
            e.articles.each do |a|
              throw :done, a if a.id = id
            end
            throw :done
          end
        end
      end
    end
  end
end