#include "world.h"
#include "state.h"
#include <linmath.h>

#include <stdlib.h>

tc_worldgen_s tc_default_terrain_generator_g;

void tc_draw_chunk(tc_chunk_s *chunk)
{
    mat4x4              model_matrix;
    mat4x4_identity(model_matrix);
    mat4x4_translate_in_place(model_matrix, chunk->position.x*32, chunk->position.y*32, -chunk->position.z*32);
    
    int                 model_matrix_uniform_location =
    glGetUniformLocation(tc_game_state_g.renderer.draw_shader.program_id, "model_matrix");
    glUniformMatrix4fv(model_matrix_uniform_location, 1, GL_FALSE, &model_matrix[0][0]);
    
    // glBindVertexArray(chunk->vao);
    glBindBuffer(GL_ARRAY_BUFFER, chunk->vertex_data);
    glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(float), (void *) 0);
    glEnableVertexAttribArray(0);
    
    glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE,
        2 * sizeof(float),
        (void *) (sizeof(float) * 3 * chunk->num_vertices)
    );
    
    glEnableVertexAttribArray(1);
    
    glActiveTexture(GL_TEXTURE0);
    glUniform1i(
        glGetUniformLocation(tc_game_state_g.renderer.draw_shader.program_id, "block_atlas"),
        0
    );
    glBindTexture(GL_TEXTURE_2D, tc_game_state_g.block_texture_atlas->gl_identifier);
    
    glDrawArrays(GL_TRIANGLES, 0, chunk->num_vertices);
    
    glBindVertexArray(0);
}

void tc_init_world_generators()
{
    tc_default_terrain_generator_g.name                 = "Default Terrain Generator";
    tc_default_terrain_generator_g.fn_generate_chunk    = &tc_generate_default_terrain_chunk;
}
 
tc_world_s tc_init_worlds()
{
    tc_init_world_generators();
    
    tc_world_s              world;
    world.chunks_capacity       = 256;
    world.num_chunks            = 0;
    world.chunks                = calloc(sizeof(tc_chunk_s *), world.chunks_capacity);
    world.worldgen              = &tc_default_terrain_generator_g;
    
    return world;
}



void tc_set_block_in_chunk(
    tc_chunk_s *chunk,
    uint32_t x, uint32_t y, uint32_t z,
    tc_block_s block
) {
    chunk->blocks[x][y][z]      = block.type_identifier;
}



void tc_draw_world(tc_world_s *world)
{
    uint32_t                chunk_index         = 0;
    while(chunk_index < world->num_chunks)
    {
        tc_draw_chunk(world->chunks[chunk_index]);
        ++chunk_index;
    }
}

void tc_add_chunk(tc_world_s *world, tc_chunk_s *chunk)
{
    if(world->num_chunks >= world->chunks_capacity)
    {
        world->chunks_capacity                 *= 2;
        world->chunks                           = realloc(world->chunks, sizeof(tc_chunk_s *) * world->chunks_capacity);
    }
    world->chunks[world->num_chunks]        = chunk;
    ++world->num_chunks;
}

// Creates & Generates a chunk and provides a pointer to it
tc_chunk_s * tc_new_chunk(tc_world_s *world, float x, float y, float z)
{
    tc_chunk_s             *chunk               = malloc(sizeof(tc_chunk_s));
    chunk->position.x           = x;
    chunk->position.y           = y;
    chunk->position.z           = z;
    world->worldgen->fn_generate_chunk(world->worldgen, chunk);
    tc_meshize_chunk(chunk);
    
    glGenVertexArrays(1, &chunk->vao);
    glBindVertexArray(chunk->vao);
    
    glGenBuffers(1, &chunk->vertex_data);
    glBindBuffer(GL_ARRAY_BUFFER, chunk->vertex_data);
    
    glBufferData(GL_ARRAY_BUFFER, chunk->num_vertices * 5 * sizeof(float), NULL, GL_STATIC_DRAW);
    glBufferSubData(GL_ARRAY_BUFFER, 0,
        chunk->num_vertices * 3 * sizeof(float),
        chunk->vertex_positions
    );
    glBufferSubData(GL_ARRAY_BUFFER, 
        chunk->num_vertices * 3 * sizeof(float),
        chunk->num_vertices * 2 * sizeof(float),
        chunk->vertex_uvs
    );
    
    glBindVertexArray(0);
    
    tc_add_chunk(world, chunk);
    
    return chunk;
}