#pragma once
#include "hd2d/GL.h"
#include "hd2d/Texture.h"

#include <array>
#include <cstdint>
#include <glm/glm.hpp>
#include <vector>

namespace hd2d {

// How a material id maps onto layers of the terrain texture array.
struct TerrainMaterial {
    int topFirst = 0, topCount = 1;        // layers picked per tile for top faces
    int accentFirst = 0, accentCount = 0;  // occasional variation layers
    float accentChance = 0.0f;             // probability a tile uses an accent layer
    int sideFirst = 0, sideCount = 1;      // layers for cliff faces below this tile
    int lipLayer = -1;                     // layer for an overhang strip atop cliff faces (-1 = none)
};

// Tile-based diorama terrain: every tile has an integer height level and a
// material. Top faces are drawn with organically jittered material borders
// at pixel granularity; height differences produce textured cliff faces.
class Terrain {
public:
    static constexpr int kMaxMaterials = 8;

    void init(int width, int depth, float levelHeight = 0.5f);
    int width() const { return w_; }
    int depth() const { return d_; }
    float levelHeight() const { return levelHeight_; }

    bool inBounds(int x, int z) const { return x >= 0 && z >= 0 && x < w_ && z < d_; }
    int level(int x, int z) const;
    uint8_t material(int x, int z) const;
    void setLevel(int x, int z, int level);
    void setMaterial(int x, int z, uint8_t mat);
    float heightAt(float x, float z) const;  // top surface height of tile under (x, z)

    // Cliff faces at the map border extend down to this level (diorama base).
    int baseLevel = -6;
    std::array<TerrainMaterial, kMaxMaterials> materials{};

    // (Re)builds GPU mesh + material map after edits.
    void build();
    void draw() const;
    void bindMaterialMap(GLuint unit) const { glBindTextureUnit(unit, matTex_); }

    TextureArray textures;  // pixel-art material layers, all same size

private:
    int w_ = 0, d_ = 0;
    float levelHeight_ = 0.5f;
    std::vector<int> levels_;
    std::vector<uint8_t> mats_;

    GLuint vao_ = 0, vbo_ = 0, ibo_ = 0, matTex_ = 0;
    GLsizei indexCount_ = 0;
};

}  // namespace hd2d