#include "BaseBattle.h"

#include <entt/entity/registry.hpp>
#include <entt/signal/dispatcher.hpp>

#include <kurator/campaign/Scenario.h>
#include <kurator/campaign/UniqueIdentifier.h>
#include <kurator/sim/components.h>
#include <kurator/sim/events.h>
#include <kurator/sim/FloatingMovement.h>
#include <kurator/stats/events.h>
#include <kurator/universe.h>

#include "Builder.h"


namespace kurator
{
namespace sim
{


BaseBattle::BaseBattle(const campaign::Scenario& scenario) :
	time {0.0},
	_registry {},
	spawner {scenario.last_team(), scenario.radius, 0.1}
{
	const auto repo = universe::load_sample();
	Builder build {_registry, spawner};
	for (const auto& ship : scenario.ships) {
		const auto entity = build(repo->ship_type(ship.type), ship.team);
		_registry.emplace<campaign::UniqueIdentifier>(entity, ship.identifier);
		for (const auto& turret_type : ship.turrets)
			build(repo->turret_type(turret_type), entity);
		manager.add(ship.team, entity);  // registry supports on construction events
	}
}


entt::registry&
BaseBattle::registry()
{
	return _registry;
}


entt::dispatcher&
BaseBattle::dispatcher()
{
	return _dispatcher;
}


void
BaseBattle::update(const float dt)
{
	time += dt;
	pick_random_targets();
	keep_at_range();
	FloatingMovement::update(_registry, _dispatcher, dt);
	turrets(dt);
	kill_off_dead();
	manager.clear(_registry);  // registry supports on destructions events
	manager.update(_dispatcher);
}


void
BaseBattle::pick_random_targets()
{
	auto view = _registry.view<Team, AIState>();
	for (auto&& [entity, team, ai] : view.each()) {
		if (!_registry.valid(ai.target))
			ai.target = manager.random(team.id);
	}
}


void
BaseBattle::keep_at_range()
{
	auto view = _registry.view<Transform, AIState>();
	for (auto&& [entity, self, ai] : view.each()) {
		if (!_registry.valid(ai.target))
			continue;
		const auto target = _registry.get<Transform>(ai.target);
		const Point offset = target.position - self.position;
		ai.destination = target.position - offset.normalized().scale(ai.keep_at_range);
	}
}


void
BaseBattle::turrets(const float dt)
{
	auto view = _registry.view<TurretControl, universe::TurretType>();
	for (auto&& [entity, control, def] : view.each()) {
		if (!_registry.valid(control.owner)) {
			_registry.destroy(entity);
			continue;
		}
		const auto& [state, transform] = _registry.get<AIState, Transform>(control.owner);  // no checks
		if (!_registry.valid(state.target))
			continue;
		if (control.reload > 0.0)
			control.reload -= dt;
		if (control.reload <= 0.0) {
			auto& target_points = _registry.get<HitPoints>(state.target);
			const auto& target = _registry.get<Transform>(state.target);
			const auto distance = transform.position - target.position;
			if (distance.magnitude() > def.optimal_range * 2.5)
				continue;
			const auto damage = def.effective_damage(distance.magnitude());
			if (damage > 0.0) {
				target_points.health -= damage;
				_dispatcher.trigger(Hit{damage, control.owner, state.target});
			}
			control.reload = def.rate_of_fire;
		}
	}
}


void
BaseBattle::kill_off_dead()
{
	auto view = _registry.view<HitPoints>();
	for (auto&& [entity, points] : view.each()) {
		if (points.health > 0.0)
			continue;
		if (_registry.all_of<campaign::UniqueIdentifier, Team>(entity)) {
			const auto& [identifier, team] = _registry.get<campaign::UniqueIdentifier, Team>(entity);
			_dispatcher.trigger(stats::ShipLeft{time, identifier, team.id, true});
		}
		_registry.destroy(entity);
	}
}


}  // namespace sim
}  // namespace kurator