#include "Internal.h"
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#define INITIAL_CAPACITY 4

static int wsaToErrorCode(int value) {
    switch (value) {
    case 0:
        return CGE_NET_EOK;

    case WSAEINVAL:
        return CGE_NET_EINVAL;

    case WSAENOBUFS:
    case WSA_NOT_ENOUGH_MEMORY:
        return CGE_NET_ENOMEM;

    case WSAEWOULDBLOCK:
        return CGE_NET_EWOULDBLOCK;

    default:
        return CGE_NET_EUNKNOWN;
    }
}

CgeNetPoll *CgeNetPollCreate(int *result) {
    CgeNetPoll *poll;

    if (!(poll = malloc(sizeof(CgeNetPoll)))) {
        if (result)
            *result = CGE_NET_ENOMEM;
        return NULL;
    }

    poll->data = malloc(INITIAL_CAPACITY * sizeof(struct PollData));
    poll->pfd = malloc(INITIAL_CAPACITY * sizeof(WSAPOLLFD));
    if (!poll->data || !poll->pfd) {
        free(poll->data);
        free(poll->pfd);
        free(poll);

        if (result)
            *result = CGE_NET_ENOMEM;
        return NULL;
    }

    poll->size = 0;
    poll->capacity = INITIAL_CAPACITY;
    poll->lastError = CGE_NET_EOK;

    if (result)
        *result = CGE_NET_EOK;
    return poll;
}

void CgeNetPollFree(CgeNetPoll *poll) {
    if (!poll)
        return;

    free(poll->pfd);
    free(poll->data);
    free(poll);
}

int CgeNetPollErrorCode(CgeNetPoll *poll) {
    assert(poll != NULL);
    return poll->lastError;
}

static int ensureCapacity(CgeNetPoll *poll) {
    struct PollData *newData;
    WSAPOLLFD *newPfd;
    size_t newCapacity;

    assert(poll != NULL);
    assert(poll->capacity > 0);

    if (poll->size < poll->capacity)
        return 1;

    newCapacity = poll->capacity * 2;
    newData = malloc(newCapacity * sizeof(struct PollData));
    newPfd = malloc(newCapacity * sizeof(WSAPOLLFD));

    if (!newData || !newPfd) {
        free(newData);
        free(newPfd);
        poll->lastError = CGE_NET_ENOMEM;
        return 0;
    } else {
        memcpy(newData, poll->data, poll->size * sizeof(struct PollData));
        memcpy(newPfd, poll->pfd, poll->size * sizeof(WSAPOLLFD));
        free(poll->data);
        free(poll->pfd);
    }

    poll->data = newData;
    poll->pfd = newPfd;
    poll->capacity = newCapacity;
    return 1;
}

int CgeNetPollAdd(CgeNetPoll *poll, CgeNetSocket *socket,
                  CgeNetCallback callback, int events) {
    assert(poll != NULL);
    assert(socket != NULL);
    assert(socket->handle != INVALID_SOCKET);
    assert(callback != NULL);
    assert(events & CGE_NET_READABLE || events & CGE_NET_WRITABLE);

    if (socket->pollObject) {
        poll->lastError = CGE_NET_EINVAL;
        return 0;
    }

    if (!ensureCapacity(poll))
        return 0;

    assert(poll->size + 1 <= poll->capacity);

    socket->pollObject = poll;
    socket->pollIndex = poll->size;

    poll->data[poll->size].socket = socket;
    poll->data[poll->size].callback = callback;
    poll->data[poll->size].events = events;
    poll->pfd[poll->size].fd = socket->handle;
    poll->pfd[poll->size].events = 0;
    poll->pfd[poll->size].revents = 0;

    if (events & CGE_NET_READABLE)
        poll->pfd[poll->size].events |= POLLIN;
    if (events & CGE_NET_WRITABLE)
        poll->pfd[poll->size].events |= POLLOUT;

    poll->size++;
    return 1;
}

static void processEvent(CgeNetPoll *poll, struct PollData *data) {
    size_t index;
    int events, revents;

    assert(poll != NULL);
    assert(data != NULL);
    assert(data >= poll->data && data < poll->data + poll->size);

    index = data - poll->data;
    revents = poll->pfd[index].revents;
    events = poll->pfd[index].revents = 0;

    poll->pfd[index].events = 0;
    if (data->events & CGE_NET_READABLE)
        poll->pfd[index].events |= POLLIN;
    if (data->events & CGE_NET_WRITABLE)
        poll->pfd[index].events |= POLLOUT;

    if (revents & (POLLIN | POLLERR | POLLHUP))
        events |= CGE_NET_READABLE;
    if (revents & POLLOUT)
        events |= CGE_NET_WRITABLE;

    if (events)
        data->callback(data->socket, events);
}

int CgeNetPollRemove(CgeNetPoll *poll, CgeNetSocket *socket) {
    size_t index;

    assert(poll != NULL);
    assert(socket != NULL);
    assert(socket->handle != INVALID_SOCKET);

    if (socket->pollObject != poll) {
        poll->lastError = CGE_NET_EINVAL;
        return 0;
    }

    assert(poll->size > 0);
    index = socket->pollIndex;
    socket->pollObject = NULL;
    socket->pollIndex = 0;
    poll->size--;

    if (index < poll->size) {
        poll->data[poll->size].socket->pollIndex = index;
        poll->data[index] = poll->data[poll->size];
        poll->pfd[index] = poll->pfd[poll->size];
        processEvent(poll, poll->data + index);
    }

    return 1;
}

int CgeNetPollWait(CgeNetPoll *p, int timeout) {
    int ready;
    size_t i;

    assert(p != NULL);

    if (p->size == 0)
        return 1;

    if ((ready = WSAPoll(p->pfd, (ULONG)p->size, timeout)) == SOCKET_ERROR) {
        p->lastError = wsaToErrorCode(WSAGetLastError());
        return 0;
    }

    for (i = 0; i < p->size && ready > 0; i++) {
        processEvent(p, p->data + i);
    }

    return 1;
}