#pragma once

#include <optional>
#include <vector>

#include <QVector2D>

#include "Building.h"
#include "EntityId.h"
#include "FireEvent.h"
#include "GameConfig.h"
#include "Ship.h"
#include "Tick.h"

class BuildingSystem;
class ShipSystem;

// Resolves all weapon fire for ships and defence stations (tick-order step 8).
// REQ-SHP-FIRING, REQ-DEF-PLAYER-FIRE, REQ-DEF-ENEMY-FIRE.
class CombatSystem
{
public:
    explicit CombatSystem(const GameConfig& config);

    // Advance weapon cooldowns, acquire targets for stations, fire when ready,
    // apply damage, and append FireEvents. Damage is applied immediately via
    // ShipSystem::damageShip and BuildingSystem::damageBuilding; step 9
    // removes entities whose HP dropped to zero or below.
    void tick(Tick currentTick,
              ShipSystem& ships,
              BuildingSystem& buildings,
              std::vector<FireEvent>& outFireEvents);

private:
    // Process one ship's weapon for this tick.
    void resolveShipWeapon(Ship& ship, Tick currentTick,
                           ShipSystem& ships,
                           BuildingSystem& buildings,
                           std::vector<FireEvent>& out);

    // Process one defence-station's weapon for this tick.
    void resolveStationWeapon(Building& station, Tick currentTick,
                              ShipSystem& ships,
                              BuildingSystem& buildings,
                              std::vector<FireEvent>& out);

    // Find the nearest valid target for a defence station within its range.
    // Both enemy and player stations target ships of the opposing faction only.
    std::optional<EntityId> acquireStationTarget(
        const Building& station, bool stationIsEnemy,
        const ShipSystem& ships) const;

    // Return the world position of the entity, or nullopt if it no longer exists.
    std::optional<QVector2D> targetPosition(EntityId id,
                                            const ShipSystem& ships,
                                            const BuildingSystem& buildings) const;

    const GameConfig& m_config;
};