ruby sql_manager

class SQLManager

	@params = nil
	@record = nil	
	@columns = nil
	@orders = nil
	@groups = nil
	@conditions = nil
	@joins = nil
	@havings = nil
	@firsts = nil
	@lasts = nil
	@limit = nil
	@offset = nil
	@table_name = nil
	
	def initialize(record)
		@record = record
		@table_name = record.class.table_name
		@params = {}
		@params.merge(record.attributes)
		@columns = []
		@orders = []
		@groups = []
		@conditions = []
		@joins = []
		@havings = []
		@firsts = []
		@lasts = []
	end
	
	def self.clone(sm)
		c_sm = sm.clone
		new_sm = SQLManager.new(c_sm.record)
		new_sm.columns + Marshal.load(Marshal.dump(sm.columns))
		new_sm.orders + Marshal.load(Marshal.dump(sm.orders))
		new_sm.groups + Marshal.load(Marshal.dump(sm.groups))
		new_sm.conditions + Marshal.load(Marshal.dump(sm.conditions))
		new_sm.joins + Marshal.load(Marshal.dump(sm.joins))
		new_sm.havings + Marshal.load(Marshal.dump(sm.havings))
		new_sm.firsts + Marshal.load(Marshal.dump(sm.firsts))
		new_sm.lasts + Marshal.load(Marshal.dump(sm.lasts))
		new_sm.limit = c_sm.limit
		new_sm.offset = c_sm.offset
		new_sm
	end
	
	def self.union(*unions)
		u_sql = unions[0].to_query
		a = *unions
		a.each do |u|
			 u_sql << " UNION " << u.to_query
		end
		u_sql
	end
	
	def self.union_all(*unions)
		u_sql = unions[0].to_query
		a = *unions
		a.each do |u|
			 u_sql << " UNION ALL " << u.to_query
		end
		u_sql
	end
	
	def record
	    @record
	end
	
	def params
	    @params
	end
	
	def merge_param(param)
		@params = @params.merge(param)	
	end

	def columns
		@columns
	end

	def orders
		@orders
	end
	
	def groups
		@groups	
	end
	
	def conditions
		@conditions	
	end
	
	def joins
		@joins
	end
	
	def havings
		@havings	
	end
	
	def firsts
		@firsts		
	end
	
	def lasts
		@lasts		
	end

	def limit
		@limit	
	end
	
	def limit=(att)
		@limit = att
	end
	
	def offset
		@offset	
	end
	
	def offset=(att)
		@offset = att
	end

	def table_name
		@table_name
	end
	
	def to_columns
		str = ""
		@columns.each do |item|
			str << item + ','
		end
		str = str.chop
		(str << @table_name  << ".*") if columns.size == 0	
		str
	end
	
	def to_orders
		str = ""
		@orders.each do |item|
			str << item + ','
		end
		str.chop
	end
	
	def to_groups
		str = ""
		@groups.each do |item|
			str << item + ','
		end
		str.chop
	end
	
	def to_conditions
		str = ""
		@conditions.each do |item|
			str << item + ' '
		end
		str.chop
	end
	
	def to_havings
		str = ""
		@havings.each do |item|
			str << item + ' '
		end
		str.chop
	end
	
	def to_firsts
		str = ""
		@firsts.each do |item|
			str << item + ' '
		end
		str.chop
	end
	
	def to_lasts
		str = ""
		@lasts.each do |item|
			str << item + ' '
		end
		str.chop
	end
	
	def to_joins
		str = ""
		@joins.each do |item|
			str << item + ' '
		end
		str.chop
	end
	
	def to_query
		first = to_firsts
		condition = to_conditions
		join = to_joins
		column = to_columns
		group = to_groups
		having = to_havings
		order = to_orders
		last = to_lasts
		sql = "SELECT "		
		sql << column if !column.empty?
		sql << " FORM "
		sql << @table_name 	
		sql << " " << join if !join.empty?
		sql << " WHERE " << condition if !condition.empty?
		sql << group if !group.empty?
		sql << having if !having.empty?
		sql << order if !order.empty?
		sql << " LIMIT " << @limit.to_s if !@limit.nil?
		
		if !@limit.nil?
			sql << "," << @offset.to_s if !@offset.nil?
		else
			sql << "0," << @offset.to_s if !@offset.nil?
		end
		
		(sql << " " << last) if !last.empty?
		
		(sql.insert 0,(first << " ")) if !first.empty?
		 sql
	end
	
end