# 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
  # The ff module provides a way to find files.
  module FF
    # Represents a query cursor.
    class Cursor
      # Represents a directory context.
      Context = Struct.new(:path, :components, :entries)
      # @return [Integer]
      attr_reader :index
      # @param config [TermUtils::FF::Config]
      # @param path [String]
      def initialize(config, path)
        @config = config
        @path = path
        @contexts = []
        push_context(path)
        @index = 0
      end
      # Starts the query.
      # @return [TermUtils::FF::Cursor, nil]
      def bootstrap
        res = self
        if @config.min_depth
          while depth < @config.min_depth
            res = following0
            break unless res
          end
        end
        res
      end
      # Returns the next cursor.
      # @return [TermUtils::FF::Cursor, nil]
      def following
        res = nil
        loop do
          res = following0
          break unless res
          if @config.min_depth
            next if depth < @config.min_depth
          end
          if @config.max_depth
            next if depth > @config.max_depth
          end
          @index += 1
          break
        end
        res
      end
      # Returns the result associated to this one.
      # @return [String]
      def result
        @contexts.last.path
      end
      # @return [Integer]
      def depth
        @contexts.last.components.length
      end
      # @return [String]
      def relative_path
        @contexts.last.components.join("/")
      end
      # @return [String]
      def name
        @contexts.last.components[-1]
      end
      # Returns the path components.
      # @return [Array<String>]
      def components
        @contexts.last.components.dup
      end
      private
      # Returns the next cursor.
      # @return [TermUtils::FF::Cursor, nil]
      def following0
        ctx = @contexts.last
        if ctx
          if ctx.entries
            # Directory.
            until ctx.entries.empty?
              name = ctx.entries.first
              break if accept_name(name)
              ctx.entries.shift
            end
            if ctx.entries.empty?
              # Walked through every entry of directory.
              @contexts.pop
              following0
            else
              # Directory entry.
              new_path = StringIO.new
              new_path << ctx.path
              new_path << "/" if ctx.path[-1] != "/"
              new_path << ctx.entries.first
              new_components = ctx.components.dup
              new_components << ctx.entries.first
              push_context(new_path.string, new_components)
              ctx.entries.shift
              self
            end
          else
            # Not directory.
            @contexts.pop
            following0
          end
        end
      end
      # Pushes a new context on the stask.
      # @param path [String]
      def push_context(path, components = [])
        entries = nil
        if File.directory? path
          entries = Dir.entries(path)
          entries.sort! if @config.sorted
        end
        @contexts.push(Context.new(path, components, entries))
      end
      # Tests whether a given name shall be accepted.
      # @param name [String]
      # @return [Boolean]
      def accept_name(name)
        if (name != ".") and (name != "..")
          ret = true
          @config.ignore_list.each do |i|
            if i.match? name
              ret = false
              break
            end
          end
          ret
        else
          false
        end
      end
    end
  end
end