/* Copyright (C) 2001-2004 Bart Massey and Jamey Sharp.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 * 
 * Except as contained in this notice, the names of the authors or their
 * institutions shall not be used in advertising or otherwise to promote the
 * sale, use or other dealings in this Software without prior written
 * authorization from the authors.
 */

/* Stuff that reads stuff from the server. */

#include <assert.h>
#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <errno.h>

#include "xcb.h"
#include "xcbext.h"
#include "xcbint.h"

typedef struct XCBReplyData {
    unsigned int request;
    void *data;
    XCBGenericError **error;
} XCBReplyData;

static int match_request_error(const void *request, const void *data)
{
    const XCBGenericError *e = data;
    return e->response_type == 0 && e->sequence == ((*(unsigned int *) request) & 0xffff);
}

static int match_reply(const void *request, const void *data)
{
    return ((XCBReplyData *) data)->request == *(unsigned int *) request;
}

static void wake_up_next_reader(XCBConnection *c)
{
    XCBReplyData *cur = _xcb_list_peek_head(c->in.readers);
    int pthreadret;
    if(cur)
        pthreadret = pthread_cond_signal(cur->data);
    else
        pthreadret = pthread_cond_signal(&c->in.event_cond);
    assert(pthreadret == 0);
}

/* Public interface */

void *XCBWaitForReply(XCBConnection *c, unsigned int request, XCBGenericError **e)
{
    pthread_cond_t cond = PTHREAD_COND_INITIALIZER;
    XCBReplyData reader;
    void *ret = 0;
    if(e)
        *e = 0;

    pthread_mutex_lock(&c->iolock);

    /* If this request has not been written yet, write it. */
    if((signed int) (c->out.request_written - request) < 0)
        if(_xcb_out_flush(c) <= 0)
            goto done; /* error */

    if(_xcb_list_find(c->in.readers, match_reply, &request))
        goto done; /* error */

    if(e)
    {
        *e = _xcb_list_remove(c->in.events, match_request_error, &request);
        if(*e)
            goto done;
    }

    reader.request = request;
    reader.data = &cond;
    reader.error = e;
    _xcb_list_append(c->in.readers, &reader);

    /* If this request has not been read yet, wait for it. */
    while(!(e && *e) && ((signed int) (c->in.request_read - request) < 0 ||
            (c->in.request_read == request &&
	     _xcb_queue_is_empty(c->in.current_reply))))
        if(_xcb_conn_wait(c, /*should_write*/ 0, &cond) <= 0)
            goto done;

    if(c->in.request_read != request)
    {
        _xcb_queue *q = _xcb_map_get(c->in.replies, request);
        if(q)
        {
            ret = _xcb_queue_dequeue(q);
            if(_xcb_queue_is_empty(q))
                _xcb_queue_delete(_xcb_map_remove(c->in.replies, request), free);
        }
    }
    else
        ret = _xcb_queue_dequeue(c->in.current_reply);

done:
    _xcb_list_remove(c->in.readers, match_reply, &request);
    pthread_cond_destroy(&cond);

    wake_up_next_reader(c);
    pthread_mutex_unlock(&c->iolock);
    return ret;
}

XCBGenericEvent *XCBWaitEvent(XCBConnection *c)
{
    return XCBWaitForEvent(c);
}

XCBGenericEvent *XCBWaitForEvent(XCBConnection *c)
{
    XCBGenericEvent *ret;

#if XCBTRACEEVENT
    fprintf(stderr, "Entering XCBWaitEvent\n");
#endif

    pthread_mutex_lock(&c->iolock);
    /* _xcb_list_remove_head returns 0 on empty list. */
    while(!(ret = _xcb_queue_dequeue(c->in.events)))
        if(_xcb_conn_wait(c, /*should_write*/ 0, &c->in.event_cond) <= 0)
            break;

    wake_up_next_reader(c);
    pthread_mutex_unlock(&c->iolock);

#if XCBTRACEEVENT
    fprintf(stderr, "Leaving XCBWaitEvent, event type %d\n", ret ? ret->response_type : -1);
#endif

    return ret;
}

XCBGenericEvent *XCBPollForEvent(XCBConnection *c, int *error)
{
    XCBGenericEvent *ret = 0;
    pthread_mutex_lock(&c->iolock);
    if(error)
        *error = 0;
    /* FIXME: follow X meets Z architecture changes. */
    if(_xcb_in_read(c) >= 0)
        ret = _xcb_queue_dequeue(c->in.events);
    else if(error)
        *error = -1;
    else
    {
        fprintf(stderr, "XCBPollForEvent: I/O error occured, but no handler provided.\n");
        abort();
    }
    pthread_mutex_unlock(&c->iolock);
    return ret;
}

unsigned int XCBGetRequestRead(XCBConnection *c)
{
    unsigned int ret;
    pthread_mutex_lock(&c->iolock);
    /* FIXME: follow X meets Z architecture changes. */
    _xcb_in_read(c);
    ret = c->in.request_read;
    pthread_mutex_unlock(&c->iolock);
    return ret;
}

/* Private interface */

int _xcb_in_init(_xcb_in *in)
{
    if(pthread_cond_init(&in->event_cond, 0))
        return 0;
    in->reading = 0;

    in->queue_len = 0;

    in->request_read = 0;
    in->current_reply = _xcb_queue_new();

    in->replies = _xcb_map_new();
    in->events = _xcb_queue_new();
    in->readers = _xcb_list_new();
    if(!in->current_reply || !in->replies || !in->events || !in->readers)
        return 0;

    return 1;
}

void _xcb_in_destroy(_xcb_in *in)
{
    pthread_cond_destroy(&in->event_cond);
    _xcb_queue_delete(in->current_reply, free);
    _xcb_map_delete(in->replies, free);
    _xcb_queue_delete(in->events, free);
    _xcb_list_delete(in->readers, 0);
}

int _xcb_in_expect_reply(XCBConnection *c, unsigned int request)
{
    /* XXX: currently a no-op */
    return 1;
}

int _xcb_in_read_packet(XCBConnection *c)
{
    XCBGenericRep genrep;
    int length = 32;
    unsigned char *buf;

    /* Wait for there to be enough data for us to read a whole packet */
    if(c->in.queue_len < length)
        return 0;

    /* Get the response type, length, and sequence number. */
    memcpy(&genrep, c->in.queue, sizeof(genrep));

    /* For reply packets, check that the entire packet is available. */
    if(genrep.response_type == 1)
        length += genrep.length * 4;

    buf = malloc(length);
    if(!buf)
        return 0;
    if(_xcb_in_read_block(c, buf, length) <= 0)
    {
        free(buf);
        return 0;
    }

    /* Compute 32-bit sequence number of this packet. */
    /* XXX: do "sequence lost" check here */
    if((genrep.response_type & 0x7f) != KeymapNotify)
    {
        int lastread = c->in.request_read;
        c->in.request_read = (lastread & 0xffff0000) | genrep.sequence;
        if(c->in.request_read != lastread && !_xcb_queue_is_empty(c->in.current_reply))
        {
            _xcb_map_put(c->in.replies, lastread, c->in.current_reply);
            c->in.current_reply = _xcb_queue_new();
        }
        if(c->in.request_read < lastread)
            c->in.request_read += 0x10000;
    }

    if(buf[0] == 1) /* response is a reply */
    {
        XCBReplyData *reader = _xcb_list_find(c->in.readers, match_reply, &c->in.request_read);
        _xcb_queue_enqueue(c->in.current_reply, buf);
        if(reader)
            pthread_cond_signal(reader->data);
        return 1;
    }

    if(buf[0] == 0) /* response is an error */
    {
        XCBReplyData *reader = _xcb_list_find(c->in.readers, match_reply, &c->in.request_read);
        if(reader && reader->error)
        {
            *reader->error = (XCBGenericError *) buf;
            pthread_cond_signal(reader->data);
            return 1;
        }
    }

    /* event, or error without a waiting reader */
    _xcb_queue_enqueue(c->in.events, buf);
    pthread_cond_signal(&c->in.event_cond);
    return 1; /* I have something for you... */
}

int _xcb_in_read(XCBConnection *c)
{
    int n = _xcb_readn(c->fd, c->in.queue, sizeof(c->in.queue), &c->in.queue_len);
    if(n < 0 && errno == EAGAIN)
        n = 1;
    while(_xcb_in_read_packet(c) > 0)
        /* empty */;
    return n;
}

int _xcb_in_read_block(XCBConnection *c, void *buf, int len)
{
    int done = c->in.queue_len;
    if(len < done)
        done = len;

    memcpy(buf, c->in.queue, done);
    c->in.queue_len -= done;
    memmove(c->in.queue, c->in.queue + done, c->in.queue_len);

    if(len > done)
    {
        int ret = _xcb_read_block(c->fd, (char *) buf + done, len - done);
        if(ret <= 0)
            return ret;
    }

    return len;
}