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

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

    DERIVED_PREDICATES = [
      ['cont', {
        arel_predicate: 'matches',
        formatter: proc { |v| "%#{escape_wildcards(v)}%" }
        }
      ],
      ['not_cont', {
        arel_predicate: 'does_not_match',
        formatter: proc { |v| "%#{escape_wildcards(v)}%" }
        }
      ],
      ['start', {
        arel_predicate: 'matches',
        formatter: proc { |v| "#{escape_wildcards(v)}%" }
        }
      ],
      ['not_start', {
        arel_predicate: 'does_not_match',
        formatter: proc { |v| "#{escape_wildcards(v)}%" }
        }
      ],
      ['end', {
        arel_predicate: 'matches',
        formatter: proc { |v| "%#{escape_wildcards(v)}" }
        }
      ],
      ['not_end', {
        arel_predicate: 'does_not_match',
        formatter: proc { |v| "%#{escape_wildcards(v)}" }
        }
      ],
      ['true', {
        arel_predicate: 'eq',
        compounds: false,
        type: :boolean,
        validator: proc { |v| TRUE_VALUES.include?(v) }
        }
      ],
      ['false', {
        arel_predicate: 'eq',
        compounds: false,
        type: :boolean,
        validator: proc { |v| TRUE_VALUES.include?(v) },
        formatter: proc { |v| !v }
        }
      ],
      ['present', {
        arel_predicate: 'not_eq_all',
        compounds: false,
        type: :boolean,
        validator: proc { |v| TRUE_VALUES.include?(v) },
        formatter: proc { |v| [nil, ''] }
        }
      ],
      ['blank', {
        arel_predicate: 'eq_any',
        compounds: false,
        type: :boolean,
        validator: proc { |v| TRUE_VALUES.include?(v) },
        formatter: proc { |v| [nil, ''] }
        }
      ],
      ['null', {
        arel_predicate: 'eq',
        compounds: false,
        type: :boolean,
        validator: proc { |v| TRUE_VALUES.include?(v)},
        formatter: proc { |v| nil }
        }
      ],
      ['not_null', {
        arel_predicate: 'not_eq',
        compounds: false,
        type: :boolean,
        validator: proc { |v| TRUE_VALUES.include?(v) },
        formatter: proc { |v| nil } }
      ]
    ]

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