#pragma once

#include <queue>
#include <mutex>
#include <stack>
#include <map>
#include <thread>

#include "DataCell.hh"
#include "tree.hh"

namespace cadabra {

	class ActionBase;
	class ActionAddCell;
	class ActionPositionCursor;
	class ActionRemoveCell;
	class ActionSetRunStatus;
	class ActionSplitCell;
	class ActionInsertText;
	class ActionCompleteText;
	class ActionEraseText;
	class ComputeThread;
	class GUIBase;

	/// \ingroup clientserver
	///
	/// A base class with all the logic to manipulate a Cadabra
	/// notebook document. Relies on the various objects derived from
	/// ActionBase in order to get actual work done. All methods here
	/// will always run on the GUI thread.
	///
	/// In order to implement a GUI, derive from both DocumentThread
	/// and GUIBase and then implement the virtual functions of the
	/// latter (those implement basic insertion/removal of notebook
	/// cells; the logic to figure out which ones and to implement the
	/// undo/redo stack is all in the GUI-agnostic DocumentThread).


	class DocumentThread {
		public:
			DocumentThread(GUIBase *);

			/// It is not possible to copy-construct a DocumentThread as
			/// it holds on to resources which are not easily copied
			/// (such as GUI elements).

			DocumentThread(const DocumentThread&)=delete;

			/// Let the notebook know about the ComputeThread so that it
			/// can send cells for evaluation. Notebook does NOT own this
			/// pointer.

			virtual void set_compute_thread(ComputeThread *);

			/// Ensure that the gui has an up-to-date representation of the
			/// dtree. Traverses the entire tree so is expensive to run and
			/// should only be used when loading new documents or creating
			/// a new canvas view.

			void build_visual_representation();

			/// All changes to the document should be made by submitting
			/// ActionBase derived objects to the 'queue_action' function,
			/// so that an undo stack can be kept. They are then processed
			/// by calling the 'process_action_queue' method (only
			/// available from this thread).

			void queue_action(std::shared_ptr<ActionBase>);

			/// Setup an empty new document with a single Python input cell.

			void new_document();

			/// Load a new notebook from a JSON string. Should only be called
			/// from the GUI thread. Will cancel any pending operations on the
			/// existing notebook (if present) first.

			void load_from_string(const std::string&);

			virtual void on_interactive_output(const nlohmann::json& msg);

			virtual void set_progress(const std::string& msg, int cur_step, int total_steps);

			/// One undo step.
			void undo();

			/// One redo step.
			void redo();

			/// Find string, return match, or a (doc.end(), std::string::npos).
			std::pair<DTree::iterator, size_t> find_string(DTree::iterator start_it, size_t start_pos, const std::string& f, bool case_ins) const;
			
			friend ActionBase;
			friend ActionAddCell;
			friend ActionPositionCursor;
			friend ActionRemoveCell;
			friend ActionSplitCell;
			friend ActionSetRunStatus;
			friend ActionInsertText;
			friend ActionCompleteText;			
			friend ActionEraseText;

			class Prefs {
				public:
					using ColorMap = std::map<std::string, std::string>;
					Prefs(bool use_defaults = false);
					void save();
					int font_step;
					bool highlight;
					bool is_registered;
					bool is_anonymous;
					std::map<std::string, ColorMap> colours;
					std::string git_path;
					std::string python_path;
					bool move_into_new_cell;
					bool tab_completion;
					bool microtex;
				private:
					nlohmann::json data;
					std::string    config_path;
				};
			Prefs prefs;

			/// Set user details which will be sent to the Cadabra log
			/// server.

			void set_user_details(const std::string& name, const std::string& email, const std::string& affiliation);

			/// For debugging purposes we store the main thread idea here (the
			/// main Cadabra class sets it).
			std::thread::id main_thread_id;
			
		protected:
			GUIBase       *gui;
			ComputeThread *compute;

			/// The actual document tree. This object is only modified on
			/// the GUI thread, either directly by code in
			/// DocumentThread, or by code in the various objects derived
			/// from ActionBase. In particular, ComputeThread cannot
			/// access this tree directly.

			DTree          doc;

			/// The action undo/redo/todo stacks and logic to execute
			/// them. These stacks can be accessed from both the
			/// DocumentThread as well as the ComputeThread (the latter
			/// does it through the DocumentThread::queue_action method),
			/// so they need a mutex to access them.

			std::mutex                                       stack_mutex;
			typedef std::stack<std::shared_ptr<ActionBase> > ActionStack;
			ActionStack                                      undo_stack, redo_stack;
			std::queue<std::shared_ptr<ActionBase> >         pending_actions;
			bool                                             disable_stacks;

			/// Process the action queue. It is allowed to call queue_action() above
			/// while this is running. So a running action can add more actions.
			/// Needs to be called on the GUI thread!

			void         process_action_queue();
			virtual bool on_unhandled_error(const std::exception& err);



			/// Help system
			enum class help_t { algorithm, property, latex, none };
			bool help_type_and_topic(const std::string& before, const std::string& after,
			                         help_t& help_type, std::string& help_topic) const;

		};

	}