#This class handels various MySQL-column-specific operations.
class KnjDB_mysql::Columns
  #Constructor. Should not be called manually.
  def initialize(args)
    @args = args
  end
  
  #Returns the SQL for this column.
  def data_sql(data)
    raise "No type given." if !data["type"]
    
    data["maxlength"] = 255 if data["type"] == "varchar" and !data.key?("maxlength")
    
    sql = "`#{data["name"]}` #{data["type"]}"
    sql << "(#{data["maxlength"]})" if data["maxlength"]
    sql << " PRIMARY KEY" if data["primarykey"]
    sql << " AUTO_INCREMENT" if data["autoincr"]
    sql << " NOT NULL" if !data["null"]
    
    if data.key?("default_func")
      sql << " DEFAULT #{data["default_func"]}"
    elsif data.key?("default") and data["default"] != false
      sql << " DEFAULT '#{@args[:db].escape(data["default"])}'"
    end
    
    sql << " COMMENT '#{@args[:db].escape(data["comment"])}'" if data.key?("comment")
    sql << " AFTER `#{@args[:db].esc_col(data["after"])}`" if data["after"] and !data["first"]
    sql << " FIRST" if data["first"]
    
    return sql
  end
end

#This class handels every MySQL-column, that can be returned from a table-object.
class KnjDB_mysql::Columns::Column
  attr_reader :args
  
  #Constructor. Should not be called manually.
  def initialize(args)
    @args = args
  end
  
  #Used to validate in Knj::Wrap_map.
  def __object_unique_id__
    return @args[:data][:Field]
  end
  
  #Returns the name of the column.
  def name
    return @args[:data][:Field]
  end
  
  #Returns the table-object that this column belongs to.
  def table
    return @args[:db].tables[@args[:table_name]]
  end
  
  #Returns all data of the column in the knjdb-format.
  def data
    return {
      "type" => self.type,
      "name" => self.name,
      "null" => self.null?,
      "maxlength" => self.maxlength,
      "default" => self.default,
      "primarykey" => self.primarykey?,
      "autoincr" => self.autoincr?
    }
  end
  
  #Returns the type of the column (integer, varchar etc.).
  def type
    if !@type
      if match = @args[:data][:Type].match(/^([A-z]+)$/)
        @maxlength = false
        @type = match[0].to_sym
      elsif match = @args[:data][:Type].match(/^decimal\((\d+),(\d+)\)$/)
        @maxlength = "#{match[1]},#{match[2]}"
        @type = :decimal
      elsif match = @args[:data][:Type].match(/^enum\((.+)\)$/)
        @maxlength = match[1]
        @type = :enum
      elsif match = @args[:data][:Type].match(/^(.+)\((\d+)\)/)
        @maxlength = match[2].to_i
        @type = match[1].to_sym
      end
      
      raise "Still not type from: '#{@args[:data][:Type]}'." if @type.to_s.strip.length <= 0
    end
    
    return @type
  end
  
  #Return true if the columns allows null. Otherwise false.
  def null?
    return false if @args[:data][:Null] == "NO"
    return true
  end
  
  #Returns the maxlength.
  def maxlength
    self.type if !@maxlength
    return @maxlength if @maxlength
    return false
  end
  
  #Returns the default value for the column.
  def default
    return false if (self.type == "datetime" or self.type == "date") and @args[:data][:Default].to_s.strip.length <= 0
    return false if (self.type == "int" or self.type == "bigint") and @args[:data][:Default].to_s.strip.length <= 0
    return false if !@args[:data][:Default]
    return @args[:data][:Default]
  end
  
  #Returns true if the column is the primary key. Otherwise false.
  def primarykey?
    return true if @args[:data][:Key] == "PRI"
    return false
  end
  
  #Returns true if the column is auto-increasing. Otherwise false.
  def autoincr?
    return true if @args[:data][:Extra].index("auto_increment") != nil
    return false
  end
  
  #Returns the comment for the column.
  def comment
    return @args[:data][:Comment]
  end
  
  #Drops the column from the table.
  def drop
    @args[:db].query("ALTER TABLE `#{@args[:table_name]}` DROP COLUMN `#{self.name}`")
    return nil
  end
  
  #Changes the column properties by the given hash.
  def change(data)
    col_escaped = "`#{@args[:db].esc_col(self.name)}`"
    table_escape = "`#{@args[:db].esc_table(self.table.name)}`"
    newdata = data.clone
    
    newdata["name"] = self.name if !newdata.key?("name")
    newdata["type"] = self.type if !newdata.key?("type")
    newdata["maxlength"] = self.maxlength if !newdata.key?("maxlength") and self.maxlength
    newdata["null"] = self.null? if !newdata.key?("null")
    newdata["default"] = self.default if !newdata.key?("default") and self.default
    newdata.delete("primarykey") if newdata.key?("primarykey")
    
    type_s = newdata["type"].to_s
    @args[:db].query("ALTER TABLE #{table_escape} CHANGE #{col_escaped} #{@args[:db].cols.data_sql(newdata)}")
  end
end