module CsvImportAnalyzer
  module DatatypeValidator

    def validate_field(content)
      get_datatype(content)
    end

    private

    ###
    # Date.parse("12/31/20145234", "%m/%d/%Y") => true, which is not supposed to be true (although technically its true)
    # Validate year part has only 4 numbers in it
    ###
    def validate_year_date(field)
      date = nil
      formats = ["%d/%m/%Y","%d-%m-%Y","%d %m %Y","%m/%d/%Y","%m-%d-%Y","%m %d %Y"]
      formats.each do |format|
        if(Date.strptime(field, format) rescue false)
          date = Date.strptime(field, format)
          break
        end
      end
      unless date.nil?
        field = date.to_s.scan(/\d*/) # Return an array with patterns matching with only numbers in it
        if field[0].length == 4
          return true
        else
          return false
        end
      else
        return false
      end
    end

    ###
    # To check for pattern of Date format after Date.parse is successfull
    # Date.parse(3000) => true which is not supposed to be true
    ###
    def datetime_pattern(field)
      pattern1 = field.scan(/[0-9]\//)
      pattern2 = field.scan(/[0-9]\-/)
      pattern3 = field.scan(/[0-9] /)
      pattern4 = field.scan(/[0-9] [A-Z][a-z][a-z] [0-9]|[0-9]-[A-Z][a-z][a-z]-[0-9]|[0-9] [a-z][a-z][a-z] [0-9]|[0-9]-[a-z][a-z][a-z]-[0-9]/)
      if(pattern1.size == 2||pattern2.size == 2||pattern3.size == 2||pattern4.size != 0)
        if(validate_year_date(field))
          return true
        else
          return false
        end
      else
        return false
      end
    end
    
    ###
    # To determine the data-type of an input field
    # Returns a field is either int, float, string, date, datetime type
    ###
    def get_datatype(field)
      #Remove if field has any comma's for int and float rep
      if field != nil && field.class == String
        num = field.gsub(/,/,'')
      else
        num = field
      end
      if(Integer(num) rescue false)
        if num.class == Float
          return "float"
        end
        return "int"
      elsif(Float(num) rescue false)
        return "float"
      elsif(Date.parse(field) rescue false || Date.strptime(field, '%m/%d/%Y') rescue false || Date.strptime(field, '%m-%d-%Y') rescue false || Date.strptime(field, '%m %d %Y') rescue false)
        if datetime_pattern(field)
          if field =~ /:/ # To check if the field contains any pattern for Hours:minutes
            return "datetime"
          else
            return "date"
          end
        end
      end
      return "string"
    end
  end
end