module Ransack
  module Constants
    TRUE_VALUES = [true, 1, '1', 't', 'T', 'true', 'TRUE'].to_set
    FALSE_VALUES = [false, 0, '0', 'f', 'F', 'false', 'FALSE'].to_set
    BOOLEAN_VALUES = TRUE_VALUES + FALSE_VALUES

    AREL_PREDICATES = %w(
      eq not_eq matches does_not_match lt lteq gt gteq in not_in
    ).freeze

    EQ         = 'eq'.freeze
    NOT_EQ     = 'not_eq'.freeze
    EQ_ANY     = 'eq_any'.freeze
    NOT_EQ_ALL = 'not_eq_all'.freeze

    DERIVED_PREDICATES = [
      ['cont'.freeze, {
        :arel_predicate => 'matches'.freeze,
        :formatter => proc { |v| "%#{escape_wildcards(v)}%" }
        }
      ],
      ['i_cont'.freeze, {
        :arel_predicate => 'i_matches'.freeze,
        :formatter => proc { |v| "%#{escape_wildcards(v)}%" }
      }
      ],
      ['not_cont'.freeze, {
        :arel_predicate => 'does_not_match'.freeze,
        :formatter => proc { |v| "%#{escape_wildcards(v)}%" }
        }
      ],
      ['i_not_cont'.freeze, {
        :arel_predicate => 'i_does_not_match'.freeze,
        :formatter => proc { |v| "%#{escape_wildcards(v)}%" }
      }
      ],
      ['start'.freeze, {
        :arel_predicate => 'matches'.freeze,
        :formatter => proc { |v| "#{escape_wildcards(v)}%" }
        }
      ],
      ['not_start'.freeze, {
        :arel_predicate => 'does_not_match'.freeze,
        :formatter => proc { |v| "#{escape_wildcards(v)}%" }
        }
      ],
      ['end'.freeze, {
        :arel_predicate => 'matches'.freeze,
        :formatter => proc { |v| "%#{escape_wildcards(v)}" }
        }
      ],
      ['not_end'.freeze, {
        :arel_predicate => 'does_not_match'.freeze,
        :formatter => proc { |v| "%#{escape_wildcards(v)}" }
        }
      ],
      ['true'.freeze, {
        :arel_predicate => proc { |v| v ? EQ : NOT_EQ },
        :compounds => false,
        :type => :boolean,
        :validator => proc { |v| BOOLEAN_VALUES.include?(v) },
        :formatter => proc { |v| true }
        }
      ],
      ['not_true'.freeze, {
        :arel_predicate => proc { |v| v ? NOT_EQ : EQ },
        :compounds => false,
        :type => :boolean,
        :validator => proc { |v| BOOLEAN_VALUES.include?(v) },
        :formatter => proc { |v| true }
        }
      ],
      ['false'.freeze, {
        :arel_predicate => proc { |v| v ? EQ : NOT_EQ },
        :compounds => false,
        :type => :boolean,
        :validator => proc { |v| BOOLEAN_VALUES.include?(v) },
        :formatter => proc { |v| false }
        }
      ],
      ['not_false'.freeze, {
        :arel_predicate => proc { |v| v ? NOT_EQ : EQ },
        :compounds => false,
        :type => :boolean,
        :validator => proc { |v| BOOLEAN_VALUES.include?(v) },
        :formatter => proc { |v| false }
        }
      ],
      ['present'.freeze, {
        :arel_predicate => proc { |v| v ? NOT_EQ_ALL : EQ_ANY },
        :compounds => false,
        :type => :boolean,
        :validator => proc { |v| BOOLEAN_VALUES.include?(v) },
        :formatter => proc { |v| [nil, EMPTY_STRING] }
        }
      ],
      ['blank'.freeze, {
        :arel_predicate => proc { |v| v ? EQ_ANY : NOT_EQ_ALL },
        :compounds => false,
        :type => :boolean,
        :validator => proc { |v| BOOLEAN_VALUES.include?(v) },
        :formatter => proc { |v| [nil, EMPTY_STRING] }
        }
      ],
      ['null'.freeze, {
        :arel_predicate => proc { |v| v ? EQ : NOT_EQ },
        :compounds => false,
        :type => :boolean,
        :validator => proc { |v| BOOLEAN_VALUES.include?(v)},
        :formatter => proc { |v| nil }
        }
      ],
      ['not_null'.freeze, {
        :arel_predicate => proc { |v| v ? NOT_EQ : EQ },
        :compounds => false,
        :type => :boolean,
        :validator => proc { |v| BOOLEAN_VALUES.include?(v) },
        :formatter => proc { |v| nil } }
      ]
    ].freeze

  module_function
    # replace % \ to \% \\
    def escape_wildcards(unescaped)
      case ActiveRecord::Base.connection.adapter_name
      when "Mysql2".freeze, "PostgreSQL".freeze
        # Necessary for PostgreSQL and MySQL
        unescaped.to_s.gsub(/([\\|\%|.])/, '\\\\\\1')
      else
        unescaped
      end
    end
  end
end