definition module TaskTree
/**
* This module contains data types and utility functions for
* creating and manipulating task trees. The actual construction of
* task tree data structures is performed by the basic tasks and
* task combinators.
*/
import StdMaybe, Either
import Types
import Html, Time
import RPC

from JSON 				import :: JSONNode
from TUIDefinition		import :: TUIDef, :: TUIUpdate
from InteractionTasks	import :: Action

:: TaskTree
	//NODE CONSTRUCTORS
	
	//A task that is treated as a main chunk of work
	= TTMainTask		TaskInfo TaskProperties !(Maybe TaskParallelType) TaskTree
	//A task that is composed of a number of sequentially executed subtasks
	| TTSequenceTask	TaskInfo [TaskTree]	
	//A task that is composed of a number of parallel executed main tasks (a division of big chunks of work)
	| TTParallelTask	TaskInfo TaskParallelType [TaskTree]													 
	//A task that is composed of a number of grouped subtasks
	| TTGroupedTask		TaskInfo [TaskTree] ![(Action, (Either Bool (*TSt -> *(!Bool,!*TSt))))] !(Maybe String)
	
	//LEAF CONSTRUCTORS
	
	//A task which displays an (offline) instruction to the user
	| TTInstructionTask TaskInfo (TaskOutput (Maybe [HtmlTag]))										
	//A task that can be worked on through a gui
	| TTInteractiveTask	TaskInfo (TaskOutput InteractiveTask)													
	//A task that upon evaluation monitors a condition and may give status output
	| TTMonitorTask		TaskInfo (TaskOutput [HtmlTag])																
	//A completed task
	| TTFinishedTask	TaskInfo (TaskOutput [HtmlTag])															
	//A task that represents an rpc invocation
	| TTRpcTask			TaskInfo RPCExecute																		


// Different trees can be constructed.
:: TreeType			= SpineTree		//Only construct the the spine, with minimal output
					| UITree		//Generate user interfaces for the leaf nodes
					| JSONTree		//Generate the JSON representation of the current value at leaf nodes

// Output is generated by the basictasks and combinators while building the task tree.
// Depending on the purpose of evaluating the task tree, different output is generated.
:: TaskOutput ui	= NoOutput																	//No output is generated
					| UIOutput ui																//Output for a user interface is generated
					| JSONOutput JSONNode														//A JSON representation of the task value is generated
							
:: TaskInfo	=		{ taskId				:: TaskId											//Task number in string format
					, subject				:: String											//Short subject of the task
					, description			:: String											//Description of the task (html)
					, context				:: Maybe String										//Optional context information for the task
					, tags					:: [String]
					, groupedBehaviour		:: GroupedBehaviour
					, groupActionsBehaviour	:: GroupActionsBehaviour
					, menus					:: !(Maybe TaskInfoMenus)
					}
					
:: TaskInfoMenus = Menus !Menus | GenFunc !MenuGenFunc

:: TaskParallelType = Open 				//Everybody to whom a subtask is assigned can see the full status of this parallel, including the results of others
					| Closed			//Only the manager can see the overview. For assigned users, it just looks like an ordinary task.


// give definition/updates or determine it after entire tree is build, needed for updateShared, ...
:: InteractiveTask	= Definition	[TUIDef]	[(Action,Bool)]				//Definition for rendering a user interface
					| Updates		[TUIUpdate]	[(Action,Bool)]				//Update an already rendered user interface
					| Message		[TUIDef]	[(Action,Bool)]				//Just show a message
					| Func 			(*TSt -> *(!InteractiveTask, !*TSt))	//Function for delayed generation of an interface definition.
																			//These functions are evaluated after the full tree has been built.
					
:: GroupedBehaviour = Fixed 		//The editor is fixed in the main canvas of the parent task
					| Floating		//The editor is shown in a floating window
					| Modal			//The editor is shown in a modal dialog

// Determines if group-actions are added to actions of interactive task
:: GroupActionsBehaviour	= IncludeGroupActions
							| ExcludeGroupActions