#include "BaseBattle.h"

#include <algorithm>

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

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

#include "Builder.h"


namespace kurator
{
namespace sim
{


BaseBattle::BaseBattle(const campaign::Scenario& scenario) :
	_registry {},
	spawner {scenario.last_team(), scenario.radius, 0.1}
{
	Builder build {_registry, spawner};
	for (const auto& ship : scenario.ships) {
		const auto entity = build(ship.loadout.type, ship.team);
		_registry.emplace<universe::UniqueIdentifier>(entity, ship.identifier);
		auto& state = _registry.get<AIState>(entity);
		for (const auto& turret_type : ship.loadout.turrets) {
			build(turret_type, entity);
			state.keep_at_range = std::min(state.keep_at_range, turret_type.optimal_range);
		}
		manager.add(ship.team, entity);  // registry supports on construction events
	}
}


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


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


static void keep_at_range(engine::Context& ctx);
static void kill_off_dead(engine::Context& ctx);


void
BaseBattle::update(engine::Context& ctx)
{
	pick_random_targets();
	keep_at_range(ctx);
	FloatingMovement::update(ctx);
	TurretControl::update(ctx);
	kill_off_dead(ctx);
	manager.update(ctx);
}


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


void
kill_off_dead(engine::Context& ctx)
{
	auto view = ctx.registry.view<HitPoints>();
	for (auto&& [entity, points] : view.each()) {
		if (points.is_alive())
			continue;
		if (ctx.registry.all_of<universe::UniqueIdentifier, Team>(entity)) {
			const auto& [identifier, team] = ctx.registry.get<universe::UniqueIdentifier, Team>(entity);
			ctx.dispatcher.trigger(stats::ShipLeft{ctx.clock.game, identifier, team.id, true});
			ctx.dispatcher.trigger(Destroyed{entity});
		}
		ctx.registry.destroy(entity);
	}
}


}  // namespace sim
}  // namespace kurator