#pragma once

#include <map>
#include <memory>
#include <random>
#include <set>
#include <string>
#include <vector>

#include <QPoint>

#include "BeltSystem.h"
#include "EntityAdmin.h"
#include "entt/entity/entity.hpp"
#include "SchematicChoiceOption.h"
#include "BuildingType.h"
#include "BuildingId.h"
#include "EventHandler.h"
#include "WeaponFiredEvent.h"
#include "GameConfig.h"
#include "Rotation.h"
#include "Tick.h"
#include "TracePrintRequestedEvent.h"

class AiSystem;
class BuildingSystem;
class CombatSystem;
class DynamicBodySystem;
class MovementIntentSystem;
class ShipSystem;
class ScrapSystem;
class WaveSystem;

class Simulation: public CombinedEventHandler<TracePrintRequestedEvent>
{
public:
    explicit Simulation(GameConfig config, unsigned int seed = 0);
    ~Simulation();

    const GameConfig& config() const;

    // Reinitializes all simulation state as if constructed fresh.
    void reset(unsigned int seed = 0);

    // Reloads config then reinitializes all simulation state.
    void reset(GameConfig newConfig, unsigned int seed = 0);

    // Advances the simulation by one tick. Tick order per architecture.md §Tick Order.
    void tick();

    // Returns all fire events accumulated since the last drain, clearing the
    // internal queue. Call once per rendered frame (REQ-SHP-FIRING-BEAM).
    std::vector<WeaponFiredEvent> drainWeaponFiredEvents();

    // Returns the pending schematic choices (empty if no drop is pending).
    const std::vector<SchematicChoiceOption>& getPendingSchematicChoices() const;

    // Returns true if there are pending schematic choices waiting for player input.
    bool hasSchematicChoicesPending() const;

    // Applies the player's chosen schematic from the pending choices.
    // choiceIndex must be in [0, pendingChoices.size()).
    // Clears the pending choices after application.
    void applySchematicChoice(int choiceIndex);

    Tick   currentTick()          const;
    int    buildingBlocksStock()  const;
    bool   isGameOver()           const;
    double threatLevel()          const;
    double threatAccumulationRate() const;
    double maxFactoryProductionThreatRate()     const;
    double currentFactoryProductionThreatRate() const;
    int    bossWaveCounter()      const;
    Tick   bossCountdownTicks()         const;
    Tick   normalGapRemainingTicks()    const;

    // Ship schematic state queries.
    int  schematicLevel(const std::string& shipId)    const;
    bool isSchematicUnlocked(const std::string& shipId) const;

    // Module schematic state queries.
    int  moduleSchematicLevel(const std::string& moduleId)    const;
    bool isModuleSchematicUnlocked(const std::string& moduleId) const;

    // Implicit recipe/item unlock queries (REQ-LOCK-IMPLICIT).
    bool isRecipeUnlocked(const std::string& recipeId) const;
    bool isItemUnlocked(const std::string& itemId) const;

    // Checks affordability, deducts building blocks, and places the building.
    // Returns the new entity id, or kInvalidBuildingId if blocks are insufficient.
    BuildingId tryPlaceBuilding(BuildingType type, QPoint anchor, Rotation rotation);

    // Demolishes the building with the given id and refunds building blocks.
    void demolish(BuildingId id);

    BuildingSystem&       buildings();
    const BuildingSystem& buildings() const;
    BeltSystem&           belts();
    const BeltSystem&     belts() const;
    ShipSystem&           ships();
    const ShipSystem&     ships() const;
    ScrapSystem&          scraps();
    const ScrapSystem&    scraps() const;
    EntityAdmin&          admin();
    const EntityAdmin&    admin() const;

private:
	void handleEvent(std::shared_ptr<const TracePrintRequestedEvent> event) override;

    BuildingId allocateBuildingId();  // Strictly increasing; never returns kInvalidBuildingId.

    // Populate HQ, player defence stations, and the first enemy station set.
    void placeInitialStructures();

    // Place two enemy defence stations for the given generation level.
    // Stores their IDs in m_currentEnemyStationIds.
    void placeEnemyStationSet(int generation);

    // Tick step 9: remove dead ships and buildings, drop scrap, handle push.
    void tickDeathsAndLoot();

    // Generate up to 3 schematic choices (REQ-DEF-SCHEMATIC-DROP) for the player.
    void generateSchematicChoices(int destroyedStationLevel);

    GameConfig m_config;
    std::mt19937 m_rng;

    Tick     m_currentTick;
    Tick     m_nextDepartureTick;
    BuildingId m_nextBuildingId;
    int      m_buildingBlocksStock;
    bool     m_gameOver = false;

    // Pre-placed structure IDs.
    BuildingId     m_hqBuildingId;           // Building id (for belt integration)
    entt::entity m_hqProxyEntity;          // ECS entity (HP, targeting)
    entt::entity m_playerStation1Entity;
    entt::entity m_playerStation2Entity;
    entt::entity m_currentEnemyStationEntities[2];

    // Schematic unlock state (REQ-DEF-SCHEMATIC-DROP).
    struct SchematicState
    {
        bool unlocked;
        int  level;
    };
    std::map<std::string, SchematicState> m_schematicLevels;
    std::map<std::string, SchematicState> m_moduleSchematicLevels;

    // Explicitly unlocked assembler recipe schematics (REQ-LOCK-EXPLICIT).
    std::set<std::string> m_unlockedRecipeSchematicIds;

    // Implicit unlock sets derived from schematic state (REQ-LOCK-IMPLICIT).
    std::set<std::string> m_unlockedRecipeIds;
    std::set<std::string> m_unlockedItemIds;

    // Recomputes m_unlockedRecipeIds and m_unlockedItemIds from current schematic state.
    void recomputeUnlocked();

    // Result of the REQ-LOCK-IMPLICIT traversal.
    struct UnlockedSets
    {
        std::set<std::string> itemIds;
        std::set<std::string> recipeIds;
    };

    // Pure REQ-LOCK-IMPLICIT traversal given hypothetical explicit-unlock sets.
    UnlockedSets computeUnlockedSets(const std::set<std::string>& unlockedShipSchematicIds,
                                      const std::set<std::string>& unlockedModuleSchematicIds,
                                      const std::set<std::string>& unlockedRecipeSchematicIds) const;

    // Current explicit-unlock id sets, derived from m_schematicLevels / m_moduleSchematicLevels.
    std::set<std::string> getUnlockedShipSchematicIds() const;
    std::set<std::string> getUnlockedModuleSchematicIds() const;

    // Display names (deduplicated, alphabetical) of output items of recipes in
    // hypothetical.recipeIds that are not yet in m_unlockedRecipeIds.
    std::vector<std::string> computeNewlyUnlockedItemNames(const UnlockedSets& hypothetical) const;

    EntityAdmin                       m_admin;
    BeltSystem                        m_beltSystem;
    std::unique_ptr<BuildingSystem>   m_buildingSystem;
    std::unique_ptr<ShipSystem>       m_shipSystem;
    std::unique_ptr<AiSystem>         m_aiSystem;
    std::unique_ptr<MovementIntentSystem> m_movementIntentSystem;
    std::unique_ptr<DynamicBodySystem>    m_dynamicBodySystem;
    std::unique_ptr<ScrapSystem>      m_scrapSystem;
    std::unique_ptr<WaveSystem>       m_waveSystem;
    std::unique_ptr<CombatSystem>     m_combatSystem;

    std::vector<WeaponFiredEvent>          m_weaponFiredEvents;
    std::vector<SchematicChoiceOption> m_pendingSchematicChoices;
};