/**
 * Chunk class, 32x32x32 section of blocks
 */

#ifndef __chunk_h__
#define __chunk_h__

#include "Block.h"
#include <vector>
#include <iostream>

#define CHUNK_SIZE 16
#define C_SURFACE_AREA 256
#define stp(val) GLfloat(val) - CHUNK_SIZE/2.0f - B_HALF_SIZE

/// A pair of indices, makes up a row of non-null blocks
typedef struct _indicePair {
    int start, end;
} IndicePair;

/// A quad of indices, makes up a quad of non-null blocks
/// which will then be used to construct the merged face
typedef struct _indiceQuad {
    int startX, startY;
    int endX, endY;
} IndiceQuad;

/// Test whether one pair ascends from the next.
/// eg. If chunk size is 16, then the pair (18, 24)
/// is an ascension of (2, 8).
#define IPAIR_Ascension(p1, p2) ( p1.start == p2.start + CHUNK_SIZE &&  \
                                  p1.end == p2.end + CHUNK_SIZE )

/// Helper class for face merging
class CPoint {
public:
    CPoint() { }

    CPoint(GLfloat x, GLfloat y, GLfloat z) {
        pts[0] = x;
        pts[1] = y;
        pts[2] = z;
    }

    GLfloat* arr(void) { return pts; }

private:
    GLfloat pts[3];
};

/// Merges adjacent blocks
/// on the same level into one large face for
/// performance improvements.
typedef struct _mgFace {
    CPoint pointList[4];
    int xr, yr; // num times to repeat texture
} MergedFace;

class Chunk {
public:
    Chunk();

    /// Build the chunk
    void buildChunk(void);
    /// Draw all blocks in the chunk
    void drawAll(void);
    /// Cleans up all blocks within the chunk
    void destroyChunk(void);
    /// Build merged faces
    void buildMergedFaces(void);

private:
    /// Draws a single block in the chunk
    void draw(Block* block, int i, int j, int k);
    /// Determines whether a block is on the edge of a chunk
    bool isEdgeBlock(int x, int y, int z);
    /// Construct merged face
    void constructMergedFace(int startA, int sizeA, int startB, int sizeB, int orientation, int depth);
    /// Split off a row into a list of paired indices (start and end)
    std::vector<IndicePair> getSplitRow(std::vector<int> values);

    Block* blocks[CHUNK_SIZE][CHUNK_SIZE][CHUNK_SIZE];
    std::vector<MergedFace> mergeList;
};

#endif