module ActiveScaffold
  module Finder
    module ClassMethods
      # Takes a collection of search terms (the tokens) and creates SQL that
      # searches all specified ActiveScaffold columns. A row will match if each
      # token is found in at least one of the columns.
      def create_conditions_for_columns(tokens, columns, text_search = :full)
        # if there aren't any columns, then just return a nil condition
        return unless columns.length > 0
        like_pattern = like_pattern(text_search)
        tokens = [tokens] if tokens.is_a? String
        obj = active_scaffold_config.model.new  # for typecasting purposes

        tokens.collect do |token|
          pattern = like_pattern.sub('?', token)
          columns.collect do |column|
            if column.column.nil? or column.column[:type] == :string
              column.search_sql.ilike(pattern)
            else
              begin
                {column.search_sql => obj.send(:typecast_value, column.name, token)}
              rescue Sequel::InvalidValue
              end
            end
          end.compact.inject {|a,b| (a | b)}
        end.inject {|a,b| (a & b)}
      end

      # Generates an SQL condition for the given ActiveScaffold column based on
      # that column's database type (or form_ui ... for virtual columns?).
      # TODO: this should reside on the column, not the controller
      def condition_for_column(column, value, text_search = :full)
        like_pattern = like_pattern(text_search)
        if self.respond_to?("condition_for_#{column.name}_column")
          return self.send("condition_for_#{column.name}_column", column, value, like_pattern)
        end
        return unless column and column.search_sql and not value.blank?
        search_ui = column.search_ui || (column.column and column.column[:type])
        begin
          if search_ui && self.respond_to?("condition_for_#{search_ui}_type")
            self.send("condition_for_#{search_ui}_type", column, value, like_pattern)
          else
            unless column.search_sql.instance_of? Proc
              case search_ui
                when :boolean, :checkbox
                  {column.search_sql => active_scaffold_config.model.db.send(:typecast_value_boolean, value)}
                when :integer, :decimal, :float
                  condition_for_numeric(column, value)
                when :string, :range
                  condition_for_range(column, value, like_pattern)
                when :date, :time, :datetime, :timestamp
                  condition_for_datetime(column, value)
                when :select, :multi_select, :country, :usa_state
                  {column.search_sql => Array(value)}
                else
                  if column.column.nil? || column.column[:type] == :string
                    column.search_sql.ilike(like_pattern.sub('?', value))
                  else
                    {column.search_sql => active_scaffold_config.model.new.send(:typecast_value, column.name, value)}
                  end
              end
            else
              column.search_sql.call(value)
            end
          end
        rescue Exception => e
          logger.error Time.now.to_s + "#{e.inspect} -- on the ActiveScaffold column :#{column.name}, search_ui = #{search_ui} in #{self.name}"
          raise e
        end
      end

      def condition_for_numeric(column, value)
        if !value.is_a?(Hash)
          {column.search_sql => condition_value_for_numeric(column, value)}
        elsif value[:from].blank? or not ActiveScaffold::Finder::NumericComparators.include?(value[:opt])
          nil
        elsif value[:opt] == 'BETWEEN'
          {column.search_sql => condition_value_for_numeric(column, value[:from])..condition_value_for_numeric(column, value[:to])}
        else
          Sequel::SQL::PlaceholderLiteralString.new("? #{value[:opt]} ?", [column.search_sql, condition_value_for_numeric(column, value[:from])])
        end
      end

      def condition_for_range(column, value, like_pattern = nil)
        if !value.is_a?(Hash)
          if column.column.nil? || column.column[:type] == :string
            column.search_sql.ilike(like_pattern.sub('?', value))
          else
            {column.search_sql => active_scaffold_config.model.new.send(:typecast_value, column.name, value)}
          end
        elsif ActiveScaffold::Finder::NullComparators.include?(value[:opt])
          condition_for_null_type(column, value[:opt], like_pattern)
        elsif value[:from].blank?
          nil
        elsif ActiveScaffold::Finder::StringComparators.values.include?(value[:opt])
          column.search_sql.ilike(value[:opt].sub('?', value[:from]))
        elsif value[:opt] == 'BETWEEN'
          {column.search_sql => value[:from]..value[:to]}
        elsif ActiveScaffold::Finder::NumericComparators.include?(value[:opt])
          Sequel::SQL::PlaceholderLiteralString.new("? #{value[:opt]} ?", [column.search_sql, value[:from]])
        else
          nil
        end
      end
      
      def condition_value_for_datetime(value, conversion = :to_time)
        if value.is_a? Hash
          Time.zone.local(*[:year, :month, :day, :hour, :minute, :second].collect {|part| value[part].to_i}) rescue nil
        elsif value.respond_to?(:strftime)
          value.send(conversion)
        elsif conversion == :to_date
          Date.strptime(value, I18n.t('date.formats.default')) rescue nil
        else
          parts = Date._parse(value)
          time_parts = [[:hour, '%H'], [:min, '%M'], [:sec, '%S']].collect {|part, format_part| format_part if parts[part].present?}.compact
          format = "#{I18n.t('date.formats.default')} #{time_parts.join(':')} #{'%z' if parts[:offset].present?}"
          time = DateTime.strptime(value, format)
          time = Time.zone.local_to_utc(time) unless parts[:offset]
          time.in_time_zone.send(conversion) rescue nil
        end unless value.nil? || value.blank?
      end

      def condition_value_for_numeric(column, value)
        return value if value.nil?
        value = i18n_number_to_native_format(value) if [:i18n_number, :currency].include?(column.options[:format])
        case (column.search_ui || column.column[:type])
        when :integer   then value.to_i rescue value ? 1 : 0
        when :float     then value.to_f
        when :decimal   then active_scaffold_config.model.db.send(:typecast_value_decimal, value)
        else
          value
        end
      end

      def i18n_number_to_native_format(value)
        native = '.'
        delimiter = I18n.t('number.format.delimiter')
        separator = I18n.t('number.format.separator')
        return value if value.blank? || !value.is_a?(String)
        unless delimiter == native && !value.include?(separator) && value !~ /\.\d{3}$/
          value.gsub(/[^0-9\-#{I18n.t('number.format.separator')}]/, '').gsub(I18n.t('number.format.separator'), native)
        else
          value
        end
      end
            
      def condition_for_datetime(column, value, like_pattern = nil)
        conversion = column.column[:type] == :date ? :to_date : :to_time
        from_value = condition_value_for_datetime(value[:from], conversion)
        to_value = condition_value_for_datetime(value[:to], conversion)

        if from_value.nil? and to_value.nil?
          nil
        elsif !from_value
          column.search_sql.sql_expr <= to_value.to_s(:db)
        elsif !to_value
          column.search_sql.sql_expr >= from_value.to_s(:db)
        else
          {column.search_sql => from_value.to_s(:db)..to_value.to_s(:db)}
        end
      end

      def condition_for_record_select_type(column, value, like_pattern = nil)
        {column.search_sql => value}
      end
      
      def condition_for_null_type(column, value, like_pattern = nil)
        case value.to_sym
        when :null
          {column.search_sql => nil}
        when :not_null
          ~{column.search_sql => nil}
        else
          nil
        end
      end

      def like_pattern(text_search)
        case text_search
          when :full then '%?%'
          when :start then '?%'
          when :end then '%?'
          else '?'
        end
      end
    end

    NumericComparators = [
      '=',
      '>=',
      '<=',
      '>',
      '<',
      '!=',
      'BETWEEN'
    ]
    StringComparators = {
      :contains    => '%?%',
      :begins_with => '?%',
      :ends_with   => '%?'
    }
    NullComparators = [
      :null,
      :not_null
    ]
    
    

    def self.included(klass)
      klass.extend ClassMethods
    end

    protected

    attr_writer :active_scaffold_conditions
    def active_scaffold_conditions
      @active_scaffold_conditions ||= []
    end

    attr_writer :active_scaffold_includes
    def active_scaffold_includes
      @active_scaffold_includes ||= []
    end

    attr_writer :active_scaffold_habtm_joins
    def active_scaffold_habtm_joins
      @active_scaffold_habtm_joins ||= []
    end
    
    def all_conditions
      merge_conditions(
        active_scaffold_conditions,                   # from the search modules
        conditions_for_collection,                    # from the dev
        conditions_from_params,                       # from the parameters (e.g. /users/list?first_name=Fred)
        conditions_from_constraints,                  # from any constraints (embedded scaffolds)
        active_scaffold_session_storage[:conditions] # embedding conditions (weaker constraints)
      )
    end
    
    # returns a single record (the given id) but only if it's allowed for the specified action.
    # accomplishes this by checking model.#{action}_authorized?
    # TODO: this should reside on the model, not the controller
    def find_if_allowed(id, crud_type, klass = origin_class)
      record = klass[id]
      raise ActiveScaffold::RecordNotAllowed, "#{klass} with id = #{id}" unless record.authorized_for?(:crud_type => crud_type.to_sym)
      return record
    end

    # returns a hash with options to find records
    # valid options may include:
    # * :sorting - a Sorting DataStructure (basically an array of hashes of field => direction, e.g. [{:field1 => 'asc'}, {:field2 => 'desc'}]). please note that multi-column sorting has some limitations: if any column in a multi-field sort uses method-based sorting, it will be ignored. method sorting only works for single-column sorting.
    # * :per_page
    # * :page
    def finder_options(options = {})
      options.assert_valid_keys :sorting, :per_page, :page, :count_includes, :pagination, :select

      search_conditions = all_conditions
      full_includes = (active_scaffold_includes.blank? ? nil : active_scaffold_includes)

      # create a general-use options array that's compatible with Rails finders
      finder_options = { :order => options[:sorting].try(:clause),
                         :where => search_conditions,
                         :joins => joins_for_finder,
                         :includes => full_includes}
                         
      finder_options.merge! custom_finder_options
      finder_options
    end

    # Returns a hash with options to count records, rejecting select and order options
    # See finder_options for valid options
    def count_options(find_options = {}, count_includes = nil)
      count_includes ||= find_options[:includes] unless find_options[:where].nil?
      options = find_options.reject{|k,v| [:select, :order].include? k}
      options[:includes] = count_includes
      options
    end

    # returns a Paginator::Page (not from ActiveRecord::Paginator) for the given parameters
    # See finder_options for valid options
    # TODO: this should reside on the model, not the controller
    def find_page(options = {})
      options[:per_page] ||= 999999999
      options[:page] ||= 1

      find_options = finder_options(options)
      klass = beginning_of_chain
      
      # NOTE: we must use :include in the count query, because some conditions may reference other tables
      if options[:pagination] && options[:pagination] != :infinite
        count_query = append_to_query(klass, count_options(find_options, options[:count_includes]))
        count = count_query.count unless options[:pagination] == :infinite
      end
  
      # Converts count to an integer if ActiveRecord returned an OrderedHash
      # that happens when find_options contains a :group key
      count = count.length if count.is_a? ActiveSupport::OrderedHash

      # we build the paginator differently for method- and sql-based sorting
      if options[:sorting] and options[:sorting].sorts_by_method?
        pager = ActiveScaffold::Paginator.new(count, options[:per_page]) do |offset, per_page|
          sorted_collection = sort_collection_by_column(append_to_query(klass, find_options).all, *options[:sorting].first)
          sorted_collection = sorted_collection.slice(offset, per_page) if options[:pagination]
          sorted_collection
        end
      else
        pager = ActiveScaffold::Paginator.new(count, options[:per_page]) do |offset, per_page|
          find_options.merge!(:offset => offset, :limit => per_page) if options[:pagination]
          append_to_query(klass, find_options).all
        end
      end
      pager.page(options[:page])
    end
    
    def append_to_query(query, options)
      options.assert_valid_keys :where, :select, :group, :order, :limit, :offset, :joins, :includes, :lock, :readonly, :from
      offset = options.delete(:offset)
      options.delete(:readonly)
      options.reject{|k, v| v.blank?}.inject(query) do |query, (k, v)|
        if k == :order
          # default ordering of model has a higher priority than current queries ordering
          # fix this by removing existing ordering from arel
          query = query.unordered
          query.send(:order, *v)
        elsif k == :limit
          val = [v]
          val << offset if offset
          query.send(:limit, *val)
        elsif k == :includes
          query.send(:eager, v)
        elsif k == :joins
          v.each do |j|
            query = query.send(:join, *j)
          end
          query
        elsif k == :lock
          query.send(:lock_style, (v == true ? :update : v))
        else
          query.send(k, v)
        end
      end
    end

    def joins_for_finder
      case joins_for_collection
        when String
          [ joins_for_collection ]
        when Array
          joins_for_collection
        else
          []
      end + active_scaffold_habtm_joins
    end

    def merge_conditions(*conditions)
      segments = conditions.collect {|c| c unless c.blank?}.compact
      segments.inject {|a,b| (a & b)}
    end

    # TODO: this should reside on the column, not the controller
    def sort_collection_by_column(collection, column, order)
      sorter = column.sort[:method]
      collection = collection.sort_by { |record|
        value = (sorter.is_a? Proc) ? record.instance_eval(&sorter) : record.instance_eval(sorter)
        value = '' if value.nil?
        value
      }
      collection.reverse! if order[:descending]
      collection
    end
  end
end