#include <world/world.h>
#include <entity/entity.h>
#include <state.h>

#include <stdlib.h>
#include <stdio.h>

tc_chunklist_s tc_create_chunklist(u32_t capacity)
{
    tc_chunklist_s          list;
    list.capacity               = capacity;
    list.entries                = calloc(sizeof(tc_chunklist_entry_s), capacity);
    list.first_free             = list.entries;
    list.first                  = NULL;
    
    return list;
}

void tc_delete_chunklist(tc_chunklist_s list)
{
    
    for(tc_chunklist_entry_s *current = list.first; current != NULL; current = current->next)
        tc_chunklist_remove_item(&list, list.first->entity);
    
    free(list.entries);
}

tc_chunklist_entry_s * tc_chunklist_find_first_free(tc_chunklist_s *list)
{
    for(u32_t index = 0; index < list->capacity; ++index)
        if(list->entries[index].entity == NULL) return &list->entries[index];
    
    return NULL;
}

tc_chunklist_entry_s * tc_chunklist_find_corresponding_entry(tc_chunklist_s *list, tc_entity_s *chunk)
{
    for(u32_t index = 0; index < list->capacity; ++index)
    {
        if(list->entries[index].entity == chunk) return &list->entries[index];
    }
    return NULL;
}

bool_t tc_chunklist_contains(tc_chunklist_s *list, tc_chunk_location_s location)
{
    for(tc_chunklist_entry_s *current = list->first; current != NULL; current = current->next)
    {
        if(current->entity == NULL) continue;
        
        tc_vec3i_s          chunk_coords;
        chunk_coords.x = tc_get_integer_from_entity(current->entity, "grid_x");
        chunk_coords.y = tc_get_integer_from_entity(current->entity, "grid_y");
        chunk_coords.z = tc_get_integer_from_entity(current->entity, "grid_z");
        
        if(tc_vec3i_equ(chunk_coords, location.grid_coords))
        {
            return TRUE;
        }
    }
    return FALSE;
}

tc_entity_s * tc_chunklist_find_chunk_at(tc_chunklist_s *list, tc_chunk_location_s location)
{
    u32_t       num_searched            = 0;
    for(tc_chunklist_entry_s *current = list->first; current != NULL; current = current->next)
    {
        ++num_searched;
        
        if(current->entity == NULL) continue;
        
        tc_vec3i_s          chunk_coords;
        chunk_coords.x = tc_get_integer_from_entity(current->entity, "grid_x");
        chunk_coords.y = tc_get_integer_from_entity(current->entity, "grid_y");
        chunk_coords.z = tc_get_integer_from_entity(current->entity, "grid_z");
        
        if(tc_vec3i_equ(chunk_coords, location.grid_coords))
        {
            return current->entity;
        }
    }
    return NULL;
}

void tc_chunklist_add_item(tc_chunklist_s *list, tc_entity_s *chunk)
{
    if(list->first_free == NULL)
    {
        puts("Chunk List overflow!");
        return;
    }
    
    tc_chunklist_entry_s            new_entry;
    
    new_entry.entity                    = chunk;
    new_entry.next                      = list->first;
    (*list->first_free)                 = new_entry;
    
    // Link everything together
    
    if(list->first_free->next != NULL)
        list->first_free->next->previous    = list->first_free;
    list->first_free->previous          = NULL;
    
    // Finally assign it
    list->first                         = list->first_free;
    list->first_free                    = tc_chunklist_find_first_free(list);
}

void tc_chunklist_remove_item(tc_chunklist_s *list, tc_entity_s *chunk)
{
    tc_chunklist_entry_s       *entry           = tc_chunklist_find_corresponding_entry(list, chunk);
    
    if(list->first == entry)
        list->first = entry->next;
    
    if(entry->previous != NULL)
        entry->previous->next           = entry->next;
    
    if(entry->next != NULL)
        entry->next->previous           = entry->previous;
    
    entry->entity               = NULL;
    list->first_free            = entry;
}



tc_chunkloader_s tc_create_chunkloader(tc_chunk_location_s location)
{
    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               = location;
    loader.chunklist            = tc_create_chunklist(512);
    loader.needs_reload         = FALSE;
    
    return loader;
}

void tc_delete_chunkloader(tc_chunkloader_s loader)
{
    for(tc_chunklist_entry_s *current = loader.chunklist.first;
        current != NULL; current = current->next)
    {
        tc_chunk_s     *current_chunk       = current->entity->specific;
        tc_unload_chunk_at(&loader, current_chunk->location);
    }
    tc_delete_chunklist(loader.chunklist);
}

bool_t tc_coord_is_within_loaders_range(tc_chunkloader_s *loader, tc_vec3i_s coord)
{
    if(coord.x < ((loader->center.grid_coords.x - loader->extent.x / 2)-1))     return FALSE;
    if(coord.y < ((loader->center.grid_coords.y - loader->extent.y / 2)-1))     return FALSE;
    if(coord.z < ((loader->center.grid_coords.z - loader->extent.z / 2)-1))     return FALSE;
    
    if(coord.x > ((loader->center.grid_coords.x + loader->extent.x / 2)+1))     return FALSE;
    if(coord.y > ((loader->center.grid_coords.y + loader->extent.y / 2)+1))     return FALSE;
    if(coord.z > ((loader->center.grid_coords.z + loader->extent.z / 2)+1))     return FALSE;
    
    return TRUE;
}

tc_chunkloader_s * tc_get_corresponding_loader(tc_chunk_location_s location)
{
    tc_vec3i_s          coords          = location.grid_coords;
    tc_world_s         *world           = location.world;
    
    for(uint32_t loader_index = 0; loader_index < world->num_loaders; ++loader_index)
        if(tc_coord_is_within_loaders_range(&world->loaders[loader_index], coords))
            return &world->loaders[loader_index];
    
    return NULL;
}

void tc_unload_chunk_at(tc_chunkloader_s *loader, tc_chunk_location_s location)
{
    tc_entity_s            *entity          = tc_chunklist_find_chunk_at(&loader->chunklist, location);
    if(entity == NULL) return;
    
    tc_chunk_s             *chunk           = entity->specific;
    tc_world_s             *world           = location.world;
    
    tc_run_hooklist(&world->on_chunk_unload, entity);
    --chunk->refcounter;
    
    if(chunk->refcounter < 1)
    {
        tc_delete_entity(entity);
        tc_chunklist_remove_item(&loader->chunklist, entity);
    }
}

tc_entity_s * tc_load_chunk_at(tc_chunk_location_s location)
{
    tc_chunkloader_s *loader = tc_get_corresponding_loader(location);
    if(loader == NULL) return NULL;
    
    tc_entity_s            *entity          = tc_chunklist_find_chunk_at(&loader->chunklist, location);
    tc_chunk_s             *chunk           = entity->specific;
        
    ++chunk->refcounter;
    return entity;
}

void tc_unload_out_of_range_loader_chunks(tc_chunkloader_s *loader)
{
    tc_chunk_location_s         location;
    location.world                  = loader->center.world;
    
    for(tc_chunklist_entry_s *current = loader->chunklist.first; current != NULL; current = current->next)
    {
        tc_entity_s                *entity          = current->entity;
        if(entity == NULL)
        {
            continue;
        }
        tc_chunk_s                 *chunk           = entity->specific;
        
        location.grid_coords = chunk->location.grid_coords;
        location.grid_coords.x = tc_get_integer_from_entity(current->entity, "grid_x");
        location.grid_coords.y = tc_get_integer_from_entity(current->entity, "grid_y");
        location.grid_coords.z = tc_get_integer_from_entity(current->entity, "grid_z");
        
        if(!tc_coord_is_within_loaders_range(loader, location.grid_coords))
        {
            tc_unload_chunk_at(loader, location);
            tc_chunklist_remove_item(&loader->chunklist, current->entity);
        }
    }
}

tc_entity_s * tc_create_chunk_for_loader_at(tc_chunkloader_s *loader, tc_vec3i_s grid_coords)
{
    tc_entity_s         *entity         = tc_create_entity("chunk", loader->center.world);
    tc_chunk_location_s  location;
    location.world          = loader->center.world;
    location.grid_coords    = grid_coords;
    tc_set_integer_for_entity(entity, "grid_x", location.grid_coords.x);
    tc_set_integer_for_entity(entity, "grid_y", location.grid_coords.y);
    tc_set_integer_for_entity(entity, "grid_z", location.grid_coords.z);
    
    tc_world_s         *world           = loader->center.world;
    
    tc_send_integer_to_entity(entity, "generate", 0);
    tc_run_hooklist(&world->after_chunk_generate, entity->specific);
    tc_send_integer_to_entity(entity, "gl_upload", 0);
    
    tc_chunklist_add_item(&loader->chunklist, entity);
    
    return entity;
}

void tc_load_all_chunks_of_chunkloader(tc_chunkloader_s *loader)
{
    for(int32_t x = 0; x < loader->extent.x; ++x)
        for(int32_t y = 0; y < loader->extent.y; ++y)
            for(int32_t z = 0; z < loader->extent.z; ++z)
            {
                tc_chunk_location_s      location;
                location.grid_coords.x = (loader->center.grid_coords.x + x - (((int32_t) loader->extent.x) / 2)+1);
                location.grid_coords.y = (loader->center.grid_coords.y + y - (((int32_t) loader->extent.y) / 2)+1);
                location.grid_coords.z = (loader->center.grid_coords.z + z - (((int32_t) loader->extent.z) / 2)+1);
                
                if(!tc_chunklist_contains(&loader->chunklist, location))
                {
                    tc_create_chunk_for_loader_at(loader, location.grid_coords);
                }
            }
    
}

void tc_reload_chunkloader_zone(tc_chunkloader_s *loader)
{
    tc_unload_out_of_range_loader_chunks(loader);
    tc_load_all_chunks_of_chunkloader(loader);
}

uint64_t world_update_tick = 0;

void tc_update_world(tc_world_s *world)
{
    if((world_update_tick % 256) == 0)
    {
        uint32_t chunkloader_index = 0;
        while(chunkloader_index < world->num_loaders)
        {
            tc_reload_chunkloader_zone(&world->loaders[chunkloader_index]);
            ++chunkloader_index;
        }
    }
    ++world_update_tick;
}