# The ASF licenses this file to You under the Apache License, Version 2.0
# (the "License"); you may not use this file except in compliance with
# the License.  You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

class Solr::Util
  # paired_array_each([key1,value1,key2,value2]) yields twice:
  #     |key1,value1|  and |key2,value2|
  def self.paired_array_each(a, &block)
    0.upto(a.size / 2 - 1) do |i|
      n = i * 2
      yield(a[n], a[n+1])
    end
  end

  # paired_array_to_hash([key1,value1,key2,value2]) => {key1 => value1, key2, value2}
  def self.paired_array_to_hash(a)
    Hash[*a]
  end

  # from http://lucene.apache.org/core/old_versioned_docs/versions/3_0_0/queryparsersyntax.html#Escaping Special Characters
  ESCAPES = %w[+ - && || ! ( ) { } \[ \] " ~ * ? \\]
  
  def self.query_parser_escape(string, fields = [])
    string = string.split(' ').map do |str| 
      if /(\w+):(.*)/ =~ str # escape : considering fields
        (!$2.empty? and fields.include?($1.to_sym)) ? "#{$1}:#{$2}" : "#{$1}\\:#{$2}"
      elsif /^\^(.*)/ =~ str # escape ^
        "\\^#{$1}"
      else
        str
      end
    end.join(' ')

    ESCAPES.each { |e| string.gsub! e, "\\#{e}" }
    string
  end

end
