/* This file is part of Machina.
 * Copyright 2007-2011 David Robillard <http://drobilla.net>
 *
 * Machina is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Machina is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Machina.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <cstdlib>
#include <map>

#include "raul/Atom.hpp"
#include "raul/SharedPtr.hpp"

#include "sord/sordmm.hpp"

#include "machina/Machine.hpp"
#include "machina/Updates.hpp"
#include "machina/URIs.hpp"
#include "machina/Context.hpp"

#include "Edge.hpp"
#include "Node.hpp"
#include "LearnRequest.hpp"
#include "MidiAction.hpp"

using namespace std;
using namespace Raul;

namespace Machina {

Machine::Machine(TimeUnit unit)
	: _active_nodes(MAX_ACTIVE_NODES, SharedPtr<Node>())
	, _time(unit, 0, 0)
	, _is_activated(false)
	, _is_finished(false)
{}

/** Copy a Machine.
 *
 * Creates a deep copy which is the 'same' machine, but with
 * fresh state (deactivated, rewound)
 */
Machine::Machine(const Machine& copy)
	: Stateful() // don't copy RDF ID
	, _active_nodes(MAX_ACTIVE_NODES, SharedPtr<Node>())
	, _time(copy.time())
	, _is_activated(false)
	, _is_finished(false)
{
	std::map< SharedPtr<Node>, SharedPtr<Node> > replacements;

	for (Nodes::const_iterator n = copy._nodes.begin(); n != copy._nodes.end();
	     ++n) {
		SharedPtr<Machina::Node> node(new Machina::Node(*n->get()));
		_nodes.push_back(node);
		replacements[*n] = node;
	}

	for (Nodes::const_iterator n = _nodes.begin(); n != _nodes.end(); ++n) {
		for (Node::Edges::const_iterator e = (*n)->edges().begin();
		     e != (*n)->edges().end(); ++e) {
			(*e)->set_tail(*n);
			(*e)->set_head(replacements[(*e)->head()]);
			assert((*e)->head());
		}
	}
}

Machine&
Machine::operator=(const Machine& other)
{
	_active_nodes  = std::vector< SharedPtr<Node> >(MAX_ACTIVE_NODES,
	                                                SharedPtr<Node>());
	_is_activated  = false;
	_is_finished   = false;
	_time          = other._time;
	_pending_learn = SharedPtr<LearnRequest>();
	_nodes.clear();

	map< SharedPtr<Node>, SharedPtr<Node> > replacements;

	for (Nodes::const_iterator n = other._nodes.begin(); n != other._nodes.end();
	     ++n) {
		SharedPtr<Machina::Node> node(new Machina::Node(*n->get()));
		_nodes.push_back(node);
		replacements[*n] = node;
	}

	for (Nodes::const_iterator n = _nodes.begin(); n != _nodes.end(); ++n) {
		for (Node::Edges::const_iterator e = (*n)->edges().begin();
		     e != (*n)->edges().end(); ++e) {
			(*e)->set_tail(*n);
			(*e)->set_head(replacements[(*e)->head()]);
			assert((*e)->head());
		}
	}

	return *this;
}

/** Always returns a node, unless there are none */
SharedPtr<Node>
Machine::random_node()
{
	if (_nodes.empty()) {
		return SharedPtr<Node>();
	}

	size_t i = rand() % _nodes.size();

	// FIXME: O(n) worst case :(
	for (Nodes::const_iterator n = _nodes.begin(); n != _nodes.end(); ++n,
		     --i) {
		if (i == 0) {
			return *n;
		}
	}

	return SharedPtr<Node>();
}

/** May return NULL even if edges exist (with low probability) */
SharedPtr<Edge>
Machine::random_edge()
{
	SharedPtr<Node> tail = random_node();

	for (size_t i = 0; i < _nodes.size() && tail->edges().empty(); ++i) {
		tail = random_node();
	}

	return tail ? tail->random_edge() : SharedPtr<Edge>();
}

void
Machine::add_node(SharedPtr<Node> node)
{
	assert(std::find(_nodes.begin(), _nodes.end(), node) == _nodes.end());
	_nodes.push_back(node);
}

void
Machine::remove_node(SharedPtr<Node> node)
{
	_nodes.erase(std::find(_nodes.begin(), _nodes.end(), node));

	for (Nodes::const_iterator n = _nodes.begin(); n != _nodes.end(); ++n) {
		(*n)->remove_edge_to(node);
	}
}

/** Exit all active states and reset time to 0.
 */
void
Machine::reset(MIDISink* sink, Raul::TimeStamp time)
{
	if (!_is_finished) {
		for (Nodes::const_iterator n = _nodes.begin(); n != _nodes.end();
		     ++n) {
			SharedPtr<Node> node = (*n);

			if (node->is_active()) {
				node->exit(sink, time);
			}

			assert(!node->is_active());
		}

		for (size_t i = 0; i < MAX_ACTIVE_NODES; ++i) {
			_active_nodes.at(i).reset();
		}
	}

	_time        = TimeStamp(_time.unit(), 0, 0);
	_is_finished = false;
}

/** Return the active Node with the earliest exit time.
 */
SharedPtr<Node>
Machine::earliest_node() const
{
	SharedPtr<Node> earliest;

	for (size_t i = 0; i < MAX_ACTIVE_NODES; ++i) {
		SharedPtr<Node> node = _active_nodes.at(i);

		if (node) {
			if (!node->is_active()) {
				std::cerr << "Inactive node in active node list" << std::endl;
				continue;
			}
			if (!earliest || (node->exit_time() < earliest->exit_time()) ) {
				earliest = node;
			}
		}
	}

	return earliest;
}

/** Enter a state at the current _time.
 *
 * Returns true if node was entered, or false if the maximum active nodes has been reached.
 */
bool
Machine::enter_node(Context&                context,
                    SharedPtr<Node>         node,
                    SharedPtr<UpdateBuffer> updates)
{
	assert(!node->is_active());

	/* FIXME: Would be best to use the MIDI note here as a hash key, at least
	 * while all actions are still MIDI notes... */
	size_t index = (rand() % MAX_ACTIVE_NODES);
	for (size_t i = 0; i < MAX_ACTIVE_NODES; ++i) {
		if (_active_nodes.at(index) == NULL) {
			node->enter(context.sink(), _time);
			assert(node->is_active());
			_active_nodes.at(index) = node;

			write_set(updates,
			          node->id(),
			          URIs::instance().machina_active,
			          context.forge().make(true));
			return true;
		}
		index = (index + 1) % MAX_ACTIVE_NODES;
	}

	// If we get here, ran out of active node spots.  Don't enter node
	return false;
}

/** Exit an active node at the current _time.
 */
void
Machine::exit_node(Context&                context,
                   SharedPtr<Node>         node,
                   SharedPtr<UpdateBuffer> updates)
{
	node->exit(context.sink(), _time);
	write_set(updates,
	          node->id(),
	          URIs::instance().machina_active,
	          context.forge().make(false));

	assert(!node->is_active());

	for (size_t i = 0; i < MAX_ACTIVE_NODES; ++i) {
		if (_active_nodes.at(i) == node) {
			_active_nodes.at(i).reset();
		}
	}

	// Activate successors to this node
	// (that aren't aready active right now)

	if (node->is_selector()) {

		const double rand_normal = rand() / (double)RAND_MAX; // [0, 1]
		double       range_min   = 0;

		for (Node::Edges::const_iterator s = node->edges().begin();
		     s != node->edges().end(); ++s) {

			if (!(*s)->head()->is_active()
			    && ( rand_normal > range_min)
			    && ( rand_normal < range_min + (*s)->probability()) ) {

				enter_node(context, (*s)->head(), updates);
				break;

			} else {
				range_min += (*s)->probability();
			}
		}

	} else {

		for (Node::Edges::const_iterator e = node->edges().begin();
		     e != node->edges().end(); ++e) {

			const double rand_normal = rand() / (double)RAND_MAX; // [0, 1]

			if (rand_normal <= (*e)->probability()) {
				SharedPtr<Node> head = (*e)->head();

				if (!head->is_active()) {
					enter_node(context, head, updates);
				}
			}
		}

	}
}

/** Run the machine for a (real) time slice.
 *
 * Returns the duration of time the machine actually ran.
 *
 * Caller can check is_finished() to determine if the machine still has any
 * active states.  If not, time() will return the exact time stamp the
 * machine actually finished on (so it can be restarted immediately
 * with sample accuracy if necessary).
 */
uint32_t
Machine::run(Context& context, SharedPtr<UpdateBuffer> updates)
{
	if (_is_finished) {
		return 0;
	}

	const TimeStamp cycle_end_frames = context.time().start_ticks()
		+ context.time().length_ticks();
	const TimeStamp cycle_end = context.time().ticks_to_beats(
		cycle_end_frames);

	assert(_is_activated);

	// Initial run, enter all initial states
	if (_time.is_zero()) {
		bool entered = false;
		if (!_nodes.empty()) {
			for (Nodes::const_iterator n = _nodes.begin(); n != _nodes.end();
			     ++n) {
				if ((*n)->is_active()) {
					(*n)->exit(context.sink(), _time);
					write_set(updates,
					          (*n)->id(),
					          URIs::instance().machina_active,
					          context.forge().make(false));
				}

				if ((*n)->is_initial()) {
					if (enter_node(context, (*n), updates)) {
						entered = true;
					}
				}
			}
		}
		if (!entered) {
			_is_finished = true;
			return 0;
		}
	}

	while (true) {

		SharedPtr<Node> earliest = earliest_node();

		if (!earliest) {
			// No more active states, machine is finished
#ifndef NDEBUG
			for (Nodes::const_iterator n = _nodes.begin(); n != _nodes.end();
			     ++n) {
				assert(!(*n)->is_active());
			}
#endif
			_is_finished = true;
			break;

		} else if (context.time().beats_to_ticks(earliest->exit_time()) <
		           cycle_end_frames) {
			// Earliest active state ends this cycle
			_time = earliest->exit_time();
			exit_node(context, earliest, updates);

		} else {
			// Earliest active state ends in the future, done this cycle
			_time = cycle_end;
			break;
		}

	}

	return context.time().beats_to_ticks(_time).ticks()
		- context.time().start_ticks().ticks();
}

/** Push a node onto the learn stack.
 *
 * NOT realtime (actions are allocated here).
 */
void
Machine::learn(SharedPtr<Raul::Maid> maid, SharedPtr<Node> node)
{
	_pending_learn = LearnRequest::create(maid, node);
}

void
Machine::write_state(Sord::Model& model)
{
	using namespace Raul;

	model.world().add_prefix("machina", "http://drobilla.net/ns/machina#");

	model.add_statement(model.base_uri(),
	                    Sord::Curie(model.world(), "rdf:type"),
	                    Sord::Curie(model.world(), "machina:Machine"));

	for (Nodes::const_iterator n = _nodes.begin(); n != _nodes.end(); ++n) {

		(*n)->write_state(model);

		if ((*n)->is_initial()) {
			model.add_statement(model.base_uri(),
			                    Sord::Curie(model.world(), "machina:initialNode"),
			                    (*n)->rdf_id(model.world()));
		} else {
			model.add_statement(model.base_uri(),
			                    Sord::Curie(model.world(), "machina:node"),
			                    (*n)->rdf_id(model.world()));
		}
	}

	for (Nodes::const_iterator n = _nodes.begin(); n != _nodes.end(); ++n) {

		for (Node::Edges::const_iterator e = (*n)->edges().begin();
		     e != (*n)->edges().end(); ++e) {

			(*e)->write_state(model);

			model.add_statement(model.base_uri(),
			                    Sord::Curie(model.world(), "machina:edge"),
			                    (*e)->rdf_id(model.world()));
		}

	}
}

} // namespace Machina