definition module iTasks._Framework.TaskState

import iTasks.API.Core.Types

from iTasks._Framework.Task	import :: TaskTime, :: TaskResult, :: TaskRep, :: EventNo, :: TonicOpts
from iTasks._Framework.Task	import :: TaskException

derive JSONEncode TIMeta, TIReduct, TaskTree
derive JSONDecode TIMeta, TIReduct, TaskTree

//Persistent context of active tasks
//Split up version of task instance information

:: TIMeta =
    //Static information
	{ instanceNo	:: !InstanceNo			//Unique global identification
    , instanceKey   :: !InstanceKey         //Random string that a client needs to provide to access the task instance
	, listId        :: !TaskId              //Reference to parent tasklist
    , session       :: !Bool                //Is this a session
    , build         :: !String              //Application build version when the instance was created
    , issuedAt      :: !DateTime
    //Evaluation information
	, progress		:: !InstanceProgress
    //Identification and classification information
	, attributes    :: !TaskAttributes      //Arbitrary meta-data
	}

:: TIReduct =
	{ task			:: !Task JSONNode                   //Main task definition
    , tree          :: !TaskTree                        //Main task state
    , tonicRedOpts  :: !TonicOpts                       //Tonic data
	, nextTaskNo	:: !TaskNo                          //Local task number counter
	, nextTaskTime	:: !TaskTime                        //Local task time (incremented at every evaluation)
    , lastEventNo   :: !EventNo                         //Last event number received from a client
    // TODO Remove from reduct!
	, tasks			:: !Map TaskId Dynamic				//Task functions of embedded parallel tasks
	}

:: TIValue
   = TIValue !(TaskValue JSONNode)
   | TIException !Dynamic !String

:: TaskTree
	= TCInit		            !TaskId !TaskTime													//Initial state for all tasks
	| TCBasic		            !TaskId !TaskTime !JSONNode !Bool 									//Encoded value and stable indicator
	| TCInteract	            !TaskId !TaskTime !JSONNode !JSONNode !JSONNode !InteractionMask
	| TCInteractLocal	        !TaskId !TaskTime !JSONNode !JSONNode !InteractionMask
	| TCInteractViewOnly	    !TaskId !TaskTime !JSONNode !JSONNode !InteractionMask
	| TCInteractLocalViewOnly   !TaskId !TaskTime !JSONNode !InteractionMask
	| TCInteract1				!TaskId !TaskTime !JSONNode !InteractionMask
	| TCInteract2				!TaskId !TaskTime !JSONNode !JSONNode !InteractionMask
	| TCProject					!TaskId !JSONNode !TaskTree
	| TCStep					!TaskId !TaskTime !(Either TaskTree (DeferredJSON,Int,TaskTree))
	| TCParallel				!TaskId !TaskTime ![(!TaskId,!TaskTree)] //Subtrees of embedded tasks
	| TCShared					!TaskId !TaskTime !TaskTree
	| TCExposedShared			!TaskId !TaskTime !String !TaskTree	// +URL
	| TCStable					!TaskId !TaskTime !DeferredJSON
	| TCNop			
	| TCDestroy					!TaskTree															//Marks a task state as garbage that must be destroyed
	| TCTasklet			

taskIdFromTaskTree :: TaskTree -> MaybeError TaskException TaskId

:: DeferredJSON
	= E. a:	DeferredJSON !a & TC a & JSONEncode{|*|} a
	|		DeferredJSONNode !JSONNode

derive JSONEncode DeferredJSON
derive JSONDecode DeferredJSON
	
:: ParallelTaskState =
	{ taskId			:: !TaskId					//Identification
    , index             :: !Int                     //Explicit index (when shares filter the list, you want to keep access to the index in the full list)
    , detached          :: !Bool
    , attributes        :: !TaskAttributes
    , value             :: !TaskValue JSONNode      //Value (only for embedded tasks)
	, createdAt			:: !TaskTime				//Time the entry was added to the set (used by layouts to highlight new items)
    , lastFocus         :: !Maybe TaskTime          //Time the entry was last explicitly focused
	, lastEvent			:: !TaskTime				//Last modified time
	, change            :: !Maybe ParallelTaskChange //Changes like removing or replacing a parallel task are only done when the
	}                                                //parallel is evaluated. This field is used to schedule such changes.

:: ParallelTaskChange
    = RemoveParallelTask                            //Mark for removal from the set on the next evaluation
    | ReplaceParallelTask !Dynamic                  //Replace the task on the next evaluation