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

#include <stdlib.h>

tc_worldgen_s tc_default_terrain_generator_g;

void tc_upload_chunk(tc_chunk_s *chunk)
{
    // If the chunk has no mesh yet
    if(chunk->num_vertices == 0)
    {
        // Create one
        tc_meshize_chunk(chunk);
    }
    
    if(chunk->vao != 0) glDeleteVertexArrays(1, &chunk->vao);
    if(chunk->vertex_data != 0) glDeleteBuffers(1, &chunk->vertex_data);
    
    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);
}
void tc_draw_chunk(tc_chunk_s *chunk, tc_world_s *world)
{
    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;
}
 
void tc_init_worlds()
{
    tc_init_world_generators();
}



void tc_set_block_in_chunk(
    tc_chunk_s *chunk,
    uint8_t x, uint8_t y, uint8_t z,
    tc_block_s block
) {
    chunk->blocks[x][y][z]      = block.type_identifier;
}


void tc_draw_world(tc_world_s *world)
{
    for(uint32_t loader_index = 0; loader_index < world->num_loaders; ++loader_index)
        for(uint32_t chunk_index = 0; chunk_index < world->loaders[loader_index].num_chunks; ++chunk_index)
            tc_draw_chunk(world->loaders[loader_index].chunks[chunk_index], world);
}

tc_chunkloader_s tc_create_chunkloader(tc_world_s *world)
{
    tc_chunkloader_s        loader;
    loader.extent.x             = UPDATE_DISTANCE * 2 + 1;
    loader.extent.y             = UPDATE_DISTANCE * 2 + 1;
    loader.extent.z             = UPDATE_DISTANCE * 2 + 1;
    loader.center.x             = 0;
    loader.center.y             = 0;
    loader.center.z             = 0;
    loader.chunks_capacity      = 512;
    loader.chunks               = calloc(sizeof(tc_chunk_s *), loader.chunks_capacity);
    loader.num_chunks           = 0;
    loader.needs_reload         = false;
    
    return loader;
}

tc_chunkloader_s tc_create_spawn_loader(tc_world_s *world)
{
    tc_chunkloader_s        loader              = tc_create_chunkloader(world);
    loader.needs_reload         = true;
    loader.world                = world;
    
    return loader;
}

tc_world_s * tc_new_world(tc_worldgen_s *generator)
{
    tc_world_s             *world               = calloc(sizeof(tc_world_s), 1);
    world->pool                 = tc_new_chunk_pool(512);
    world->worldgen             = &tc_default_terrain_generator_g;
    world->num_loaders          = 1;
    world->loaders              = malloc(sizeof(tc_chunkloader_s) * world->num_loaders);
    world->loaders[0]           = tc_create_spawn_loader(world);
    world->spawn_loader         = &world->loaders[0];
    
    return world;
}