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

typedef struct message_t {
    int messageId;
    void* data;
}message;

typedef struct node_t {
    struct node_t* next;
    struct message_t msg;
}*node_ptr;

typedef struct queue_t {
    node_ptr head;
    node_ptr tail;
    CRITICAL_SECTION cs;
}*queue_ptr;

queue_ptr queue_create() {
    queue_ptr p = (queue_ptr)malloc(sizeof(struct queue_t));
    p->head = p->tail = 0;
    InitializeCriticalSection(&p->cs);
    return p;
}

int queue_empty(queue_ptr queue) {
    return !queue->head && !queue->tail;
}

void queue_push(queue_ptr queue, message msg) {
    node_ptr p = (node_ptr)malloc(sizeof(struct node_t));
    p->next = 0;
    p->msg = msg;

    EnterCriticalSection(&queue->cs);
    if(queue_empty(queue)) {
        queue->head = p;
        queue->tail = p;
    } else {
        queue->tail->next = p;
        queue->tail = p;
    }
    LeaveCriticalSection(&queue->cs);
}

int queue_pop(queue_ptr queue, message* outMsg) {
    node_ptr p;
    EnterCriticalSection(&queue->cs);
    if(queue_empty(queue)) {
        LeaveCriticalSection(&queue->cs);
        return 0;
    }

    p = queue->head;
    queue->head = p->next;

    if(!p->next)
        queue->tail = p->next;

    *outMsg = p->msg;
    free(p);
    LeaveCriticalSection(&queue->cs);
    return 1;
}

//warning: ensure queue will not be referenced before calling.
void queue_dump(queue_ptr queue) {
    message msg;
    while(queue_pop(queue, &msg));
    DeleteCriticalSection(&queue->cs);
    free(queue);
}