#pragma once

#include <deque>
#include <functional>
#include <map>
#include <optional>
#include <random>
#include <string>
#include <utility>
#include <vector>

#include <QPoint>
#include <QVector2D>

#include "BeltSystem.h"
#include "Building.h"
#include "BuildingType.h"
#include "EntityId.h"
#include "GameConfig.h"
#include "Rotation.h"
#include "Tick.h"

// Manages building placement, construction queuing, and the per-tick
// production loop (belt→building pull, production, building→belt push).
// Belt and Splitter types are forwarded to BeltSystem rather than stored
// as Building instances.
class BuildingSystem
{
public:
    BuildingSystem(const GameConfig& config,
                   BeltSystem& belts,
                   std::function<EntityId()> allocateId,
                   std::function<void(int)> addBuildingBlocks,
                   std::mt19937& rng);

    // -- Placement / demolish ------------------------------------------------
    // Returns the new entity id.  Belt and Splitter register with BeltSystem
    // directly; other types enter the construction queue.
    EntityId place(BuildingType type, QPoint anchor, Rotation rotation,
                   Tick currentTick);

    // Remove a building or construction site by id.  Returns the refund in
    // building blocks (floor(cost * refundPercentage / 100)).  Returns 0 for
    // unknown ids.
    int demolish(EntityId id);

    // Set the recipe (or blueprint id for shipyard) on a building or queued
    // construction site.  Clears both buffers on an operational building.
    void setRecipe(EntityId id, const std::string& recipeId);

    // -- Tick hooks (called from Simulation::tick in the documented order) ---
    void tickConstruction(Tick currentTick);
    void tickBeltPull();
    void tickProduction(Tick currentTick);
    void tickBeltPush();

    // -- Queries -------------------------------------------------------------
    struct BeltTileInfo
    {
        EntityId     id;
        QPoint       tile;
        BuildingType type;  // Belt or Splitter
    };

    const Building*           findBuilding(EntityId id)  const;
    const ConstructionSite*   findSite(EntityId id)      const;
    std::vector<Building>     allBuildings()             const;
    std::vector<ConstructionSite> allSites()             const;
    std::vector<BeltTileInfo> allBeltTiles()             const;
    bool                      isTileOccupied(QPoint tile) const;

    // Find nearest operational building of the given type; nullptr if none.
    const Building* findNearestBuilding(QVector2D worldPos, BuildingType type) const;

    // Place one "scrap" item into a SalvageBay's output buffer.
    // Returns false if bay not found, wrong type, or output buffer is full.
    bool deliverScrapToSalvageBay(EntityId bayId);

    // Increase a building's HP by amount, clamped to maxHp.
    void healBuilding(EntityId id, float amount);

    // Reduce a building's HP by amount; hp may go below 0 (step 9 processes deaths).
    void damageBuilding(EntityId id, float amount);

    // Bypass the construction queue and create a fully-operational Building
    // immediately. Used for pre-placed structures (HQ, defence stations).
    // surfaceMask comes from the relevant config struct.
    EntityId placeImmediate(BuildingType type,
                            const std::vector<std::string>& surfaceMask,
                            QPoint anchor, Rotation rotation,
                            float hp, float maxHp);

    // Remove an operational building by id without refund (used for deaths).
    // Returns true if found and removed.
    bool removeBuilding(EntityId id);

    // Set the weapon component on an already-placed defence station.
    void initStationWeapon(EntityId id, const StationWeapon& weapon);

    // Mutable iteration over all operational buildings (used by CombatSystem).
    void forEachBuilding(std::function<void(Building&)> fn);

private:
    struct BeltEntry
    {
        QPoint       tile;
        BuildingType type;  // Belt or Splitter
    };

    const BuildingDef*  findBuildingDef(BuildingType type) const;
    const RecipeDef*    findRecipe(const std::string& id, BuildingType type) const;
    void                initBuffers(Building& b, const RecipeDef& recipe) const;
    std::vector<Port>   computeInputPorts(const Building& b) const;
    std::vector<Item>   rollReprocessingOutput(const RecipeDef& recipe);

    const GameConfig&           m_config;
    BeltSystem&                 m_belts;
    std::function<EntityId()>   m_allocateId;
    std::function<void(int)>    m_addBuildingBlocks;
    std::mt19937&               m_rng;

    std::vector<Building>           m_buildings;
    std::deque<ConstructionSite>    m_constructionQueue;
    std::map<EntityId, BeltEntry>   m_beltEntities;

    // Maps every occupied body-cell coordinate to the entity that owns it.
    std::map<std::pair<int, int>, EntityId> m_tileOccupancy;
};