#include "world.h"

#include <stdlib.h>
#include <string.h>

float tc_block_vertices[108] =
{
    // Front
    -0.5f, -0.5f, -0.5f,
    -0.5f, 0.5f, -0.5f,
    0.5f, -0.5f, -0.5f,
    
    0.5f, 0.5f, -0.5f,
    0.5f, -0.5f, -0.5f,
    -0.5f, 0.5f, -0.5f,
    
    // Back
    -0.5f, -0.5f, 0.5f,
    -0.5f, 0.5f, 0.5f,
    0.5f, -0.5f, 0.5f,
    
    0.5f, 0.5f, 0.5f,
    0.5f, -0.5f, 0.5f,
    -0.5f, 0.5f, 0.5f,
    
    // Left
    -0.5f, 0.5f, -0.5f,
    -0.5f, -0.5f, -0.5f,
    -0.5f, -0.5f, 0.5f,
    
    -0.5f, -0.5f, -0.5f,
    -0.5f, 0.5f, 0.5f,
    -0.5f, -0.5f, 0.5f,
    
    // Right
    0.5f, 0.5f, -0.5f,
    0.5f, -0.5f, -0.5f,
    0.5f, -0.5f, 0.5f,
    
    0.5f, -0.5f, -0.5f,
    0.5f, 0.5f, 0.5f,
    0.5f, -0.5f, 0.5f,
    
    // Top
    -0.5f, 0.5f, -0.5f,
    -0.5f, 0.5f, 0.5f,
    0.5f, 0.5f, -0.5f,
    
    0.5f, 0.5f, 0.5f,
    -0.5f, 0.5f, 0.5f,
    0.5f, 0.5f, -0.5f,
    
    // Bottom
    -0.5f, -0.5f, -0.5f,
    -0.5f, -0.5f, 0.5f,
    0.5f, -0.5f, -0.5f,
    
    0.5f, -0.5f, 0.5f,
    -0.5f, -0.5f, 0.5f,
    0.5f, -0.5f, -0.5f
};

uint32_t tc_count_chunk_vertices(tc_chunk_s *chunk)
{
    uint32_t                    num_vertices            = 0;
    
    uint32_t                    x_in_chunk              = 0;
    uint32_t                    y_in_chunk              = 0;
    uint32_t                    z_in_chunk              = 0;
    while(x_in_chunk < 32)
    {
        y_in_chunk                      = 0;
        while(y_in_chunk < 32)
        {
            z_in_chunk                      = 0;
            while(z_in_chunk < 32)
            {
                if(chunk->blocks[x_in_chunk][y_in_chunk][z_in_chunk].type_identifier > 0)
                {
                    num_vertices                                   += 36;
                }
                ++z_in_chunk;
            }
            ++y_in_chunk;
        }
        ++x_in_chunk;
    }
    return num_vertices;
}

void tc_meshize_chunk(tc_chunk_s *chunk)
{
    chunk->num_vertices             = tc_count_chunk_vertices(chunk);
    chunk->vertex_positions         = malloc(sizeof(float) * 3 * chunk->num_vertices);
    
    uint32_t                    vertex_index            = 0;
    float                       block_positions[36*3];
    
    uint32_t                    x_in_chunk              = 0;
    uint32_t                    y_in_chunk              = 0;
    uint32_t                    z_in_chunk              = 0;
    while(x_in_chunk < 32)
    {
        y_in_chunk                      = 0;
        while(y_in_chunk < 32)
        {
            z_in_chunk                      = 0;
            while(z_in_chunk < 32)
            {
                if(chunk->blocks[x_in_chunk][y_in_chunk][z_in_chunk].type_identifier > 0)
                {
                    memcpy(
                        block_positions,
                        tc_block_vertices,
                        sizeof(float) * 36 * 3
                    );
                    
                    // Move the current block to where it is supposed to be
                    
                    uint32_t vertex_of_block = 0;
                    while(vertex_of_block < 36)
                    {
                        uint32_t        vertex_start     = vertex_of_block * 3;
                        block_positions[vertex_start] +=
                            x_in_chunk;
                        block_positions[vertex_start + 1] +=
                            y_in_chunk;
                        block_positions[vertex_start + 2] +=
                            z_in_chunk;
                        ++vertex_of_block;
                    }
                    
                    memcpy(
                        &chunk->vertex_positions[vertex_index],
                        block_positions,
                        sizeof(float) * 36 * 3
                    );
                    vertex_index                                   += 36;
                }
                ++z_in_chunk;
            }
            ++y_in_chunk;
        }
        ++x_in_chunk;
    }
}