package cn.orz.pascal.persistance

import com.db4o.{Db4o, ObjectContainer}
import com.db4o.query.Predicate

import scala.collection.jcl.Conversions.convertList

object Db4oDao {
  implicit def toPredicate[E](predicate:(E) => Boolean) = new Predicate[E](){ def `match`(x:E) = predicate(x) }

  var db:ObjectContainer = null
  var path = "sample.db"

  def source() = db

  def open(){
    db = Db4o.openFile(path)
  }
  def close(){
    db.close()
    db = null
  }

  def config = Db4o.configure()

  def isTransaction = db != null

  def $[E](callback: => E):E = {
    if(isTransaction){
      callback
    }else{
      transaction{ callback }.asInstanceOf[E]
    }
  }

  def get[E <: Model](id:Long):E = {
    ${
      val o:E = (db.ext().getByID(id)).asInstanceOf[E]
      db.activate(o, 5)
      o.id = id
      o
    }
  }

  def delete[E <: Model](id:Long) = {
    ${
      db.delete(get[E](id))
      this
    }
  }

  def store(o:Model) = {
    ${
      if(db.query((t:Model) => o == t).length == 0) db.store(o)
      this
    }
  }

  def update[E <: Model](id:Long)(callback:(E)=>Unit) = {
    ${
      val o = get[E](id)
      callback(o)
      store(o)
    }
  }

  def query[E <: Model](predicate:(E) => Boolean):List[E] =  {
    ${
      db.query(predicate).toList.asInstanceOf[List[E]].map{ o => o.id = db.ext.getID(o); o}
    }
  }

  def transaction(callback: => Any) = {
    var r:Any = null
    open()
    try{
      r = callback
      db.commit()
    }catch {
      case e: Exception => {
        db.rollback()
        throw e
      }
    }finally{
      close()
    }
    r
  }
}