/* Copyright (c) 2001, Stanford University
 * All rights reserved
 *
 * See the file LICENSE.txt for information on redistributing this software.
 */

#include "server.h"
#include "cr_unpack.h"
#include "cr_error.h"
#include "cr_mem.h"
#include "server_dispatch.h"


/**
 * Accept a new client connection, create a new CRClient and add to run queue.
 */
void
crServerAddNewClient(void)
{
    CRClient *newClient = (CRClient *) crCalloc(sizeof(CRClient));

    if (newClient) {
        newClient->spu_id = cr_server.client_spu_id;
        newClient->conn = crNetAcceptClient( cr_server.protocol, NULL,
                                                                                 cr_server.tcpip_port,
                                                                                 cr_server.mtu, 1 );
        newClient->currentCtx = cr_server.DummyContext;

        /* add to array */
        cr_server.clients[cr_server.numClients++] = newClient;

        crServerAddToRunQueue( newClient );
    }
}


/**
 * Check if client is in the run queue.
 */
static GLboolean
FindClientInQueue(CRClient *client)
{
    RunQueue *q = cr_server.run_queue;
    while (q) {
        if (q->client == client) {
            return 1;
        }
        q = q->next;
        if (q == cr_server.run_queue)
            return 0; /* back head */
    }
    return 0;
}


#if 0
static int
PrintQueue(void)
{
    RunQueue *q = cr_server.run_queue;
    int count = 0;
    crDebug("Queue entries:");
    while (q) {
        count++;
        crDebug("Entry: %p  client: %p", q, q->client);
        q = q->next;
        if (q == cr_server.run_queue)
            return count;
    }
    return count;
}
#endif


void crServerAddToRunQueue( CRClient *client )
{
    RunQueue *q = (RunQueue *) crAlloc( sizeof( *q ) );

    /* give this client a unique number if needed */
    if (!client->number) {
        client->number = crServerGenerateID(&cr_server.idsPool.freeClientID);
    }

    crDebug("Adding client %p to the run queue", client);

    if (FindClientInQueue(client)) {
        crError("CRServer: client %p already in the queue!", client);
    }

    q->client = client;
    q->blocked = 0;

    if (!cr_server.run_queue)
    {
        /* adding to empty queue */
        cr_server.run_queue = q;
        q->next = q;
        q->prev = q;
    }
    else
    {
        /* insert in doubly-linked list */
        q->next = cr_server.run_queue->next;
        cr_server.run_queue->next->prev = q;

        q->prev = cr_server.run_queue;
        cr_server.run_queue->next = q;
    }
}



void
crServerDeleteClient( CRClient *client )
{
    int i, j;
    int32_t pos;

    crDebug("Deleting client %p (%d msgs left)", client,
                    crNetNumMessages(client->conn));

#if 0
    if (crNetNumMessages(client->conn) > 0) {
        crDebug("Delay destroying client: message still pending");
        return;
    }
#endif

    if (!FindClientInQueue(client)) {
        /* this should never happen */
        crError("CRServer: client %p not found in the queue!", client);
    }

    /* remove from clients[] array */
    for (i = 0; i < cr_server.numClients; i++) {
        if (cr_server.clients[i] == client) {
            /* found it */
            for (j = i; j < cr_server.numClients - 1; j++)
                cr_server.clients[j] = cr_server.clients[j + 1];
            cr_server.numClients--;
            break;
        }
    }

    /* remove from the run queue */
    if (cr_server.run_queue)
    {
        RunQueue *q = cr_server.run_queue;
        RunQueue *qStart = cr_server.run_queue; 
        do {
            if (q->client == client)
            {
                /* this test seems a bit excessive */
                if ((q->next == q->prev) && (q->next == q) && (cr_server.run_queue == q))
                {
                    /* We're removing/deleting the only client */
                    CRASSERT(cr_server.numClients == 0);
                    crFree(q);
                    cr_server.run_queue = NULL;
                    cr_server.curClient = NULL;
                    crDebug("Last client deleted - empty run queue.");
                } 
                else
                {
                    /* remove from doubly linked list and free the node */
                    if (cr_server.curClient == q->client)
                        cr_server.curClient = NULL;
                    if (cr_server.run_queue == q)
                        cr_server.run_queue = q->next;
                    q->prev->next = q->next;
                    q->next->prev = q->prev;
                    crFree(q);
                }
                break;
            }
            q = q->next;
        } while (q != qStart);
    }

    crNetFreeConnection(client->conn);

    /* Destroy any windows created by the client */
    for (pos = 0; pos<CR_MAX_WINDOWS && client->windowList[pos]; pos++) 
    {
        cr_server.dispatch.WindowDestroy(client->windowList[pos]);
    }

    /* Check if we have context(s) made by this client left, could happen if client side code is lazy */
    for (pos = 0; pos<CR_MAX_CONTEXTS && client->contextList[pos]; pos++) 
    {
        cr_server.dispatch.DestroyContext(client->contextList[pos]);
    }

    crFree(client);
}


/**
 * Test if the given client is in the middle of a glBegin/End or
 * glNewList/EndList pair.
 * This is used to test if we can advance to the next client.
 * \return GL_TRUE if so, GL_FALSE otherwise.
 */
GLboolean
crServerClientInBeginEnd(const CRClient *client)
{
    if (client->currentCtx &&
            (client->currentCtx->lists.currentIndex != 0 ||
             client->currentCtx->current.inBeginEnd ||
             client->currentCtx->occlusion.currentQueryObject)) {
        return GL_TRUE;
    }
    else {
        return GL_FALSE;
    }
}


/**
 * Find the next client in the run queue that's not blocked and has a
 * waiting message.
 * Check if all clients are blocked (on barriers, semaphores), if so we've
 * deadlocked!
 * If no clients have a waiting message, call crNetRecv to get something
 * if 'block' is true, else return NULL if 'block' if false.
 */
static RunQueue *
getNextClient(GLboolean block)
{
    while (1)
    {
        if (cr_server.run_queue) 
        {
            GLboolean all_blocked = GL_TRUE;
            GLboolean done_something = GL_FALSE;
            RunQueue *start = cr_server.run_queue;

            /* check if this client's connection has gone away */
            if (!cr_server.run_queue->client->conn
                || (cr_server.run_queue->client->conn->type == CR_NO_CONNECTION
                    && crNetNumMessages(cr_server.run_queue->client->conn) == 0)) 
            {
                crServerDeleteClient( cr_server.run_queue->client );
                start = cr_server.run_queue;
            }
 
            if (cr_server.run_queue == NULL) {
                /* empty queue */
                return NULL;
            }

            if (crServerClientInBeginEnd(cr_server.run_queue->client)) {
                /* We _must_ service this client and no other.
                 * If we've got a message waiting on this client's connection we'll
                 * service it.  Else, return NULL.
                 */
                if (crNetNumMessages(cr_server.run_queue->client->conn) > 0)
                    return cr_server.run_queue;
                else
                    return NULL;
            }

            /* loop over entries in run queue, looking for next one that's ready */
            while (!done_something || cr_server.run_queue != start)
            {
                done_something = GL_TRUE;
                if (!cr_server.run_queue->blocked)
                {
                    all_blocked = GL_FALSE;
                }
                if (!cr_server.run_queue->blocked
                        && cr_server.run_queue->client->conn
                        && crNetNumMessages(cr_server.run_queue->client->conn) > 0)
                {
                    /* OK, this client isn't blocked and has a queued message */
                    return cr_server.run_queue;
                }
                cr_server.run_queue = cr_server.run_queue->next;
            }

            if (all_blocked)
            {
                 /* XXX crError is fatal?  Should this be an info/warning msg? */
                crError( "crserver: DEADLOCK! (numClients=%d, all blocked)",
                                 cr_server.numClients );
                if (cr_server.numClients < (int) cr_server.maxBarrierCount) {
                    crError("Waiting for more clients!!!");
                    while (cr_server.numClients < (int) cr_server.maxBarrierCount) {
                        crNetRecv();
                    }
                }
            }
        }

        if (!block)
             return NULL;

        /* no one had any work, get some! */
        crNetRecv();

    } /* while */

    /* UNREACHED */
    /* return NULL; */
}


/**
 * This function takes the given message (which should be a buffer of
 * rendering commands) and executes it.
 */
static void
crServerDispatchMessage(CRMessage *msg)
{
    const CRMessageOpcodes *msg_opcodes;
    int opcodeBytes;
    const char *data_ptr;

    if (msg->header.type == CR_MESSAGE_REDIR_PTR)
    {
        msg = (CRMessage *) msg->redirptr.pMessage;
    }

    CRASSERT(msg->header.type == CR_MESSAGE_OPCODES);

    msg_opcodes = (const CRMessageOpcodes *) msg;
    opcodeBytes = (msg_opcodes->numOpcodes + 3) & ~0x03;

    data_ptr = (const char *) msg_opcodes + sizeof(CRMessageOpcodes) + opcodeBytes;
    crUnpack(data_ptr,                 /* first command's operands */
             data_ptr - 1,             /* first command's opcode */
             msg_opcodes->numOpcodes,  /* how many opcodes */
             &(cr_server.dispatch));   /* the CR dispatch table */
}


typedef enum
{
  CLIENT_GONE = 1, /* the client has disconnected */
  CLIENT_NEXT = 2, /* we can advance to next client */
  CLIENT_MORE = 3  /* we need to keep servicing current client */
} ClientStatus;


/**
 * Process incoming/pending message for the given client (queue entry).
 * \return CLIENT_GONE if this client has gone away/exited,
 *         CLIENT_NEXT if we can advance to the next client
 *         CLIENT_MORE if we have to process more messages for this client. 
 */
static ClientStatus
crServerServiceClient(const RunQueue *qEntry)
{
    CRMessage *msg;
    CRConnection *conn;

    /* set current client pointer */
    cr_server.curClient = qEntry->client;

    conn = cr_server.run_queue->client->conn;

    /* service current client as long as we can */
    while (conn && conn->type != CR_NO_CONNECTION &&
                 crNetNumMessages(conn) > 0) {
        unsigned int len;

        /*
        crDebug("%d messages on %p",
                        crNetNumMessages(conn), (void *) conn);
        */

        /* Don't use GetMessage, because we want to do our own crNetRecv() calls
         * here ourself.
         * Note that crNetPeekMessage() DOES remove the message from the queue
         * if there is one.
         */
        len = crNetPeekMessage( conn, &msg );
        CRASSERT(len > 0);
        if (msg->header.type != CR_MESSAGE_OPCODES
            && msg->header.type != CR_MESSAGE_REDIR_PTR) {
            crError( "SPU %d sent me CRAP (type=0x%x)",
                             cr_server.curClient->spu_id, msg->header.type );
        }

        /* Do the context switch here.  No sense in switching before we
         * really have any work to process.  This is a no-op if we're
         * not really switching contexts.
         *
         * XXX This isn't entirely sound.  The crStateMakeCurrent() call
         * will compute the state difference and dispatch it using
         * the head SPU's dispatch table.
         *
         * This is a problem if this is the first buffer coming in,
         * and the head SPU hasn't had a chance to do a MakeCurrent()
         * yet (likely because the MakeCurrent() command is in the
         * buffer itself).
         *
         * At best, in this case, the functions are no-ops, and
         * are essentially ignored by the SPU.  In the typical
         * case, things aren't too bad; if the SPU just calls
         * crState*() functions to update local state, everything
         * will work just fine.
         *
         * In the worst (but unusual) case where a nontrivial
         * SPU is at the head of a crserver's SPU chain (say,
         * in a multiple-tiered "tilesort" arrangement, as
         * seen in the "multitilesort.conf" configuration), the
         * SPU may rely on state set during the MakeCurrent() that
         * may not be present yet, because no MakeCurrent() has
         * yet been dispatched.
         *
         * This headache will have to be revisited in the future;
         * for now, SPUs that could head a crserver's SPU chain
         * will have to detect the case that their functions are
         * being called outside of a MakeCurrent(), and will have
         * to handle the situation gracefully.  (This is currently
         * the case with the "tilesort" SPU.)
         */

#if 0
        crStateMakeCurrent( cr_server.curClient->currentCtx );
#else
        crStateMakeCurrent( cr_server.curClient->currentCtx );

        /* Check if the current window is the one that the client wants to
         * draw into.  If not, dispatch a MakeCurrent to activate the proper
         * window.
         */
        if (cr_server.curClient) {
             int clientWindow = cr_server.curClient->currentWindow;
             int clientContext = cr_server.curClient->currentContextNumber;
             if (clientWindow && clientWindow != cr_server.currentWindow) {
                 crServerDispatchMakeCurrent(clientWindow, 0, clientContext);
                 /*
                 CRASSERT(cr_server.currentWindow == clientWindow);
                 */
             }
        }
#endif

        /* Force scissor, viewport and projection matrix update in
         * crServerSetOutputBounds().
         */
        cr_server.currentSerialNo = 0;

        /* Commands get dispatched here */
        crServerDispatchMessage(msg);

        crNetFree( conn, msg );

        if (qEntry->blocked) {
            /* Note/assert: we should not be inside a glBegin/End or glNewList/
             * glEndList pair at this time!
             */
            return CLIENT_NEXT;
        }

    } /* while */

    /*
     * Check if client/connection is gone
     */
    if (!conn || conn->type == CR_NO_CONNECTION) {
        crDebug("Delete client %p at %d", cr_server.run_queue->client, __LINE__);
        crServerDeleteClient( cr_server.run_queue->client );
        return CLIENT_GONE;
    }

    /*
     * Determine if we can advance to next client.
     * If we're currently inside a glBegin/End primitive or building a display
     * list we can't service another client until we're done with the
     * primitive/list.
     */
    if (crServerClientInBeginEnd(cr_server.curClient)) {
        /* The next message has to come from the current client's connection. */
        CRASSERT(!qEntry->blocked);
        return CLIENT_MORE;
    }
    else {
        /* get next client */
        return CLIENT_NEXT;
    }
}



/**
 * Check if any of the clients need servicing.
 * If so, service one client and return.
 * Else, just return.
 */
void
crServerServiceClients(void)
{
    RunQueue *q;

    q = getNextClient(GL_FALSE); /* don't block */
    while (q) 
    {
        ClientStatus stat = crServerServiceClient(q);
        if (stat == CLIENT_NEXT && cr_server.run_queue->next) {
            /* advance to next client */
            cr_server.run_queue = cr_server.run_queue->next;
        }
        q = getNextClient(GL_FALSE);
    }
}




/**
 * Main crserver loop.  Service connections from all connected clients.
 * XXX add a config option to specify whether the crserver
 * should exit when there's no more clients.
 */
void
crServerSerializeRemoteStreams(void)
{
    /*MSG msg;*/

    while (cr_server.run_queue)
    {
        crServerServiceClients();
        /*if (PeekMessage( &msg, 0, 0, 0, PM_REMOVE ))
        {
            if (msg.message == WM_QUIT)
            {
                PostQuitMessage((int)msg.wParam);
                break;
            }
            TranslateMessage( &msg );
            DispatchMessage( &msg );
        }*/
    }
}


/**
 * This will be called by the network layer when it's received a new message.
 */
int
crServerRecv( CRConnection *conn, CRMessage *msg, unsigned int len )
{
    CRMessage *pRealMsg;
    (void) len;

    pRealMsg = (msg->header.type!=CR_MESSAGE_REDIR_PTR) ? msg : (CRMessage*) msg->redirptr.pMessage;

    switch( pRealMsg->header.type )
    {
        /* Called when using multiple threads */
        case CR_MESSAGE_NEWCLIENT:
            crServerAddNewClient();
            return 1; /* msg handled */
        default:
            /*crWarning( "Why is the crserver getting a message of type 0x%x?",
                msg->header.type ); */
            ;
    }
    return 0; /* not handled */
}