#include <world/update/internal.h>

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

tc_world_updater_queue_s tc_new_world_updater_queue(u32_t capacity)
{
    tc_world_updater_queue_s queue;
    queue.capacity              = capacity;
    queue.commands              = calloc(sizeof(tc_world_updater_command_s), capacity);
    queue.first                 = NULL;
    queue.last                  = NULL;
    queue.in_action             = FALSE;
    
    return queue;
}

// tc_allocate_world_updater_command: Returns a pointer to a command-slot in the given queue.
//  Sub-function of tc_issue_world_updater_command
tc_world_updater_command_s * tc_allocate_world_updater_command(tc_world_updater_queue_s *queue)
{
    u32_t                           command_index       = 0;
    while(command_index < queue->capacity)
    {
        if(!queue->commands[command_index].is_used)
            return &queue->commands[command_index];
        
        ++command_index;
    }
    return NULL;
}

bool_t tc_issue_world_updater_command(tc_world_updater_queue_s *queue, tc_world_updater_command_s command)
{
    while(queue->in_action) continue;
    queue->in_action            = TRUE;
    
    tc_world_updater_command_s     *queue_command       = tc_allocate_world_updater_command(queue);
    if(queue_command == NULL) return FALSE;
    
    command.is_used             = TRUE;
    (*queue_command)            = command;
    queue_command->previous     = queue->last;
    queue_command->next         = NULL;
    
    if(queue->last != NULL) queue->last->next = queue_command;
    if(queue->first == NULL) queue->first = queue_command;
    queue->last                 = queue_command;
    
    queue->in_action            = FALSE;
    
    return TRUE;
}

tc_world_updater_command_s tc_world_updater_query_next_command(tc_world_updater_queue_s *queue)
{
    while(queue->in_action) continue;
    queue->in_action            = TRUE;
    
    tc_world_updater_command_s     *queue_command       = queue->first;
    tc_world_updater_command_s      command;
    memset(&command, 0x00, sizeof(tc_world_updater_command_s));
    
    if(queue_command != NULL)
    {
        command              = *queue_command;
        
        queue_command->is_used      = FALSE;
    }
    queue->in_action            = FALSE;
    
    return command;
}