/**
 * This was something I explored today.
 * The approach is fundamentally flawed for a couple of reasons.
 * 
 * 1. play JSON serializes dates to strings,
 * but they are better represented as timestamps or ISODates in mongo.
 * 
 * 2. ObjectId's cannot be round-tripped, since they turn into JSON
 * strings on the way out.
 * 
 * There are probably further issues as well...
 */
package dao.mongodb

import play.api.libs.json._
import com.mongodb.casbah.Implicits._
import com.mongodb.BasicDBList
import com.mongodb.DBObject
import com.mongodb.casbah.commons.MongoDBObject
import com.mongodb.casbah.commons.MongoDBList
import org.bson.types.ObjectId

object JsonUtil {
  def toMongoDBObject(obj: JsObject): DBObject = {
    MongoDBObject {
      obj.fields.toList.map { case (key, value) =>
        key -> toMongo(value)
      }
    }
  }
  
  def toMongoDBList(list: JsArray): BasicDBList = {
    MongoDBList.concat {
      list.value.map { value => toMongo(value) }
    }
  }
  
  def toMongo(json: JsValue): Any = json match {
    case list: JsArray => toMongoDBList(list) 
    case JsBoolean(value) => value    
    case JsNull => null
    case JsNumber(value) => value.toDouble
    case obj: JsObject => toMongoDBObject(obj) 
    case JsString(value) => value
    case undefined: JsUndefined => sys.error(undefined.toString) 
  }
  
  def fromMongoDBObject(obj: MongoDBObject): JsObject = {
    JsObject(obj.toSeq.map { case (key, value) =>
      key -> fromMongo(value)      
    })  
  }
  
  def fromMongoDBList(list: MongoDBList): JsArray = {
    JsArray(list.map(fromMongo))
  }
  
  private def fromMongo(a: Any): JsValue = a match {
    case id: ObjectId => JsString(id.toString)
    case list: BasicDBList => fromMongoDBList(list)
    case obj: DBObject => fromMongoDBObject(obj)
    case long: Long => JsNumber(long)
    case int: Int => JsNumber(int)
    case float: Float => JsNumber(float)
    case double: Double => JsNumber(double)
    case decimal: java.math.BigDecimal => JsNumber(decimal)
    case decimal: scala.BigDecimal => JsNumber(decimal)
    case string: String => JsString(string)
    case boolean: Boolean => JsBoolean(boolean)
    case null => JsNull
  }
}