// serverbrowser.cpp: eihrul's concurrent resolver, and server browser window management

#include "pch.h"
#include "engine.h"
#include "SDL_thread.h"

struct resolverthread
{
    SDL_Thread *thread;
    const char *query;
    int starttime;
};

struct resolverresult
{
    const char *query;
    ENetAddress address;
};

vector<resolverthread> resolverthreads;
vector<const char *> resolverqueries;
vector<resolverresult> resolverresults;
SDL_mutex *resolvermutex;
SDL_cond *querycond, *resultcond;

#define RESOLVERTHREADS 1
#define RESOLVERLIMIT 3000

int resolverloop(void * data)
{
    resolverthread *rt = (resolverthread *)data;
    SDL_LockMutex(resolvermutex);
    SDL_Thread *thread = rt->thread;
    SDL_UnlockMutex(resolvermutex);
    if(!thread || SDL_GetThreadID(thread) != SDL_ThreadID())
        return 0;
    while(thread == rt->thread)
    {
        SDL_LockMutex(resolvermutex);
        while(resolverqueries.empty()) SDL_CondWait(querycond, resolvermutex);
        rt->query = resolverqueries.pop();
        rt->starttime = totalmillis;
        SDL_UnlockMutex(resolvermutex);

        ENetAddress address = { ENET_HOST_ANY, sv->serverinfoport() };
        enet_address_set_host(&address, rt->query);

        SDL_LockMutex(resolvermutex);
        if(rt->query && thread == rt->thread)
        {
            resolverresult &rr = resolverresults.add();
            rr.query = rt->query;
            rr.address = address;
            rt->query = NULL;
            rt->starttime = 0;
            SDL_CondSignal(resultcond);
        }
        SDL_UnlockMutex(resolvermutex);
    }
    return 0;
}

void resolverinit()
{
    resolvermutex = SDL_CreateMutex();
    querycond = SDL_CreateCond();
    resultcond = SDL_CreateCond();

    SDL_LockMutex(resolvermutex);
    loopi(RESOLVERTHREADS)
    {
        resolverthread &rt = resolverthreads.add();
        rt.query = NULL;
        rt.starttime = 0;
        rt.thread = SDL_CreateThread(resolverloop, &rt);
    }
    SDL_UnlockMutex(resolvermutex);
}

void resolverstop(resolverthread &rt)
{
    SDL_LockMutex(resolvermutex);
    if(rt.query)
    {
#ifndef __APPLE__
        SDL_KillThread(rt.thread);
#endif
        rt.thread = SDL_CreateThread(resolverloop, &rt);
    }
    rt.query = NULL;
    rt.starttime = 0;
    SDL_UnlockMutex(resolvermutex);
} 

void resolverclear()
{
    if(resolverthreads.empty()) return;

    SDL_LockMutex(resolvermutex);
    resolverqueries.setsize(0);
    resolverresults.setsize(0);
    loopv(resolverthreads)
    {
        resolverthread &rt = resolverthreads[i];
        resolverstop(rt);
    }
    SDL_UnlockMutex(resolvermutex);
}

void resolverquery(const char *name)
{
    if(resolverthreads.empty()) resolverinit();

    SDL_LockMutex(resolvermutex);
    resolverqueries.add(name);
    SDL_CondSignal(querycond);
    SDL_UnlockMutex(resolvermutex);
}

bool resolvercheck(const char **name, ENetAddress *address)
{
    bool resolved = false;
    SDL_LockMutex(resolvermutex);
    if(!resolverresults.empty())
    {
        resolverresult &rr = resolverresults.pop();
        *name = rr.query;
        address->host = rr.address.host;
        resolved = true;
    }
    else loopv(resolverthreads)
    {
        resolverthread &rt = resolverthreads[i];
        if(rt.query && totalmillis - rt.starttime > RESOLVERLIMIT)        
        {
            resolverstop(rt);
            *name = rt.query;
            resolved = true;
        }    
    }
    SDL_UnlockMutex(resolvermutex);
    return resolved;
}

bool resolverwait(const char *name, ENetAddress *address)
{
    if(resolverthreads.empty()) resolverinit();

    s_sprintfd(text)("resolving %s... (esc to abort)", name);
    show_out_of_renderloop_progress(0, text);

    SDL_LockMutex(resolvermutex);
    resolverqueries.add(name);
    SDL_CondSignal(querycond);
    int starttime = SDL_GetTicks(), timeout = 0;
    bool resolved = false;
    for(;;) 
    {
        SDL_CondWaitTimeout(resultcond, resolvermutex, 250);
        loopv(resolverresults) if(resolverresults[i].query == name) 
        {
            address->host = resolverresults[i].address.host;
            resolverresults.remove(i);
            resolved = true;
            break;
        }
        if(resolved) break;
    
        timeout = SDL_GetTicks() - starttime;
        show_out_of_renderloop_progress(min(float(timeout)/RESOLVERLIMIT, 1.0f), text);
        if(interceptkey(SDLK_ESCAPE)) timeout = RESOLVERLIMIT + 1;
        if(timeout > RESOLVERLIMIT) break;    
    }
    if(!resolved && timeout > RESOLVERLIMIT)
    {
        loopv(resolverthreads)
        {
            resolverthread &rt = resolverthreads[i];
            if(rt.query == name) { resolverstop(rt); break; }
        }
    }
    SDL_UnlockMutex(resolvermutex);
    return resolved;
}

SDL_Thread *connthread = NULL;
SDL_mutex *connmutex = NULL;
SDL_cond *conncond = NULL;

struct connectdata
{
    ENetSocket sock;
    ENetAddress address;
    int result;
};

// do this in a thread to prevent timeouts
// could set timeouts on sockets, but this is more reliable and gives more control
int connectthread(void *data)
{
    SDL_LockMutex(connmutex);
    if(!connthread || SDL_GetThreadID(connthread) != SDL_ThreadID())
    {
        SDL_UnlockMutex(connmutex);
        return 0;
    }
    connectdata cd = *(connectdata *)data;
    SDL_UnlockMutex(connmutex);

    int result = enet_socket_connect(cd.sock, &cd.address);

    SDL_LockMutex(connmutex);
    if(!connthread || SDL_GetThreadID(connthread) != SDL_ThreadID())
    {
        enet_socket_destroy(cd.sock);
        SDL_UnlockMutex(connmutex);
        return 0;
    }
    ((connectdata *)data)->result = result;
    SDL_CondSignal(conncond);
    SDL_UnlockMutex(connmutex);

    return 0;
}

#define CONNLIMIT 20000

int connectwithtimeout(ENetSocket sock, const char *hostname, ENetAddress &address)
{
    s_sprintfd(text)("connecting to %s... (esc to abort)", hostname);
    show_out_of_renderloop_progress(0, text);

    if(!connmutex) connmutex = SDL_CreateMutex();
    if(!conncond) conncond = SDL_CreateCond();
    SDL_LockMutex(connmutex);
    connectdata cd = { sock, address, -1 };
    connthread = SDL_CreateThread(connectthread, &cd);

    int starttime = SDL_GetTicks(), timeout = 0;
    for(;;)
    {
        if(!SDL_CondWaitTimeout(conncond, connmutex, 250))
        {
            if(cd.result<0) enet_socket_destroy(sock);
            break;
        }      
        timeout = SDL_GetTicks() - starttime;
        show_out_of_renderloop_progress(min(float(timeout)/CONNLIMIT, 1.0f), text);
        if(interceptkey(SDLK_ESCAPE)) timeout = CONNLIMIT + 1;
        if(timeout > CONNLIMIT) break;
    }

    /* thread will actually timeout eventually if its still trying to connect
     * so just leave it (and let it destroy socket) instead of causing problems on some platforms by killing it 
     */
    connthread = NULL;
    SDL_UnlockMutex(connmutex);

    return cd.result;
}
 
enum { UNRESOLVED = 0, RESOLVING, RESOLVED };

struct serverinfo
{
    string name;
    string map;
    string sdesc;
    int numplayers, ping, resolved;
    vector<int> attr;
    ENetAddress address;

    serverinfo()
     : numplayers(0), ping(999), resolved(UNRESOLVED)
    {
        name[0] = map[0] = sdesc[0] = '\0';
    }
};

vector<serverinfo *> servers;
ENetSocket pingsock = ENET_SOCKET_NULL;
int lastinfo = 0;

char *getservername(int n) { return servers[n]->name; }

static serverinfo *newserver(const char *name, uint ip = ENET_HOST_ANY, uint port = sv->serverinfoport())
{
    serverinfo *si = new serverinfo;
    si->address.host = ip;
    si->address.port = port;
    if(ip!=ENET_HOST_ANY) si->resolved = RESOLVED;

    if(name) s_strcpy(si->name, name);
    else if(ip==ENET_HOST_ANY || enet_address_get_host_ip(&si->address, si->name, sizeof(si->name)) < 0)
    {
        delete si;
        return NULL;

    }

    servers.add(si);

    return si;
}

void addserver(char *servername)
{
    loopv(servers) if(!strcmp(servers[i]->name, servername)) return;
    newserver(servername);
}

VAR(searchlan, 0, 0, 1);
VAR(servpingrate, 0, 5000, 60000);
VAR(maxservpings, 0, 0, 1000);

void pingservers()
{
    if(pingsock == ENET_SOCKET_NULL) 
    {
        pingsock = enet_socket_create(ENET_SOCKET_TYPE_DATAGRAM, NULL);
        if(pingsock == ENET_SOCKET_NULL)
        {
            lastinfo = totalmillis;
            return;
        }
        enet_socket_set_option(pingsock, ENET_SOCKOPT_NONBLOCK, 1);
        enet_socket_set_option(pingsock, ENET_SOCKOPT_BROADCAST, 1);
    }
    ENetBuffer buf;
    uchar ping[MAXTRANS];
    ucharbuf p(ping, sizeof(ping));
    putint(p, totalmillis);

    static int lastping = 0;
    if(lastping >= servers.length()) lastping = 0;
    loopi(maxservpings ? min(servers.length(), maxservpings) : servers.length())
    {
        serverinfo &si = *servers[lastping];
        if(++lastping >= servers.length()) lastping = 0;
        if(si.address.host == ENET_HOST_ANY) continue;
        buf.data = ping;
        buf.dataLength = p.length();
        enet_socket_send(pingsock, &si.address, &buf, 1);
    }
    if(searchlan)
    {
        ENetAddress address;
        address.host = ENET_HOST_BROADCAST;
        address.port = sv->serverinfoport();
        buf.data = ping;
        buf.dataLength = p.length();
        enet_socket_send(pingsock, &address, &buf, 1);
    }
    lastinfo = totalmillis;
}
  
void checkresolver()
{
    int resolving = 0;
    loopv(servers)
    {
        serverinfo &si = *servers[i];
        if(si.resolved == RESOLVED) continue;
        if(si.address.host == ENET_HOST_ANY)
        {
            if(si.resolved == UNRESOLVED) { si.resolved = RESOLVING; resolverquery(si.name); }
            resolving++;
        }
    }
    if(!resolving) return;

    const char *name = NULL;
    ENetAddress addr = { ENET_HOST_ANY, sv->serverinfoport() };
    while(resolvercheck(&name, &addr))
    {
        loopv(servers)
        {
            serverinfo &si = *servers[i];
            if(name == si.name)
            {
                si.resolved = RESOLVED; 
                si.address = addr;
                addr.host = ENET_HOST_ANY;
                break;
            }
        }
    }
}

void checkpings()
{
    if(pingsock==ENET_SOCKET_NULL) return;
    enet_uint32 events = ENET_SOCKET_WAIT_RECEIVE;
    ENetBuffer buf;
    ENetAddress addr;
    uchar ping[MAXTRANS];
    char text[MAXTRANS];
    buf.data = ping; 
    buf.dataLength = sizeof(ping);
    while(enet_socket_wait(pingsock, &events, 0) >= 0 && events)
    {
        int len = enet_socket_receive(pingsock, &addr, &buf, 1);
        if(len <= 0) return;  
        serverinfo *si = NULL;
        loopv(servers) if(addr.host == servers[i]->address.host) { si = servers[i]; break; }
        if(!si && searchlan) si = newserver(NULL, addr.host); 
        if(!si) continue;
        ucharbuf p(ping, len);
        si->ping = totalmillis - getint(p);
        si->numplayers = getint(p);
        int numattr = getint(p);
        si->attr.setsize(0);
        loopj(numattr) si->attr.add(getint(p));
        getstring(text, p);
        filtertext(si->map, text);
        getstring(text, p);
        filtertext(si->sdesc, text);
    }
}

int sicompare(serverinfo **ap, serverinfo **bp)
{
    serverinfo *a = *ap, *b = *bp;
    bool ac = sv->servercompatible(a->name, a->sdesc, a->map, a->ping, a->attr, a->numplayers),
         bc = sv->servercompatible(b->name, b->sdesc, b->map, b->ping, b->attr, b->numplayers);
    if(ac>bc) return -1;
    if(bc>ac) return 1;   
    if(a->numplayers<b->numplayers) return 1;
    if(a->numplayers>b->numplayers) return -1;
    if(a->ping>b->ping) return 1;
    if(a->ping<b->ping) return -1;
    return strcmp(a->name, b->name);
}

void refreshservers()
{
    static int lastrefresh = 0;
    if(lastrefresh==totalmillis) return;
    lastrefresh = totalmillis;

    checkresolver();
    checkpings();
    if(totalmillis - lastinfo >= servpingrate/(maxservpings ? (servers.length() + maxservpings - 1) / maxservpings : 1)) pingservers();
    servers.sort(sicompare);
}

const char *showservers(g3d_gui *cgui)
{
    refreshservers();
    const char *name = NULL;
    for(int start = 0; start < servers.length();)
    {
        if(start > 0) cgui->tab();
        int end = servers.length();
        cgui->pushlist();
        loopi(10)
        {
            if(!cl->serverinfostartcolumn(cgui, i)) break;
            for(int j = start; j < end; j++)
            {
                if(!i && cgui->shouldtab()) { end = j; break; }
                serverinfo &si = *servers[j];
                const char *sdesc = si.sdesc;
                if(si.address.host == ENET_HOST_ANY) sdesc = "[unknown host]";
                else if(si.ping == 999) sdesc = "[waiting for response]";
                if(cl->serverinfoentry(cgui, i, si.name, sdesc, si.map, sdesc == si.sdesc ? si.ping : -1, si.attr, si.numplayers))
                    name = si.name;
            }
            cl->serverinfoendcolumn(cgui, i);
        }
        cgui->poplist();
        start = end;
    }
    return name;
}

void clearservers()
{
    resolverclear();
    servers.deletecontentsp();
}

void updatefrommaster()
{
    uchar buf[32000];
    uchar *reply = retrieveservers(buf, sizeof(buf));
    if(!*reply || strstr((char *)reply, "<html>") || strstr((char *)reply, "<HTML>")) conoutf("master server not replying");
    else
    {
        clearservers();
        execute((char *)reply);
    }
    refreshservers();
}

COMMAND(addserver, "s");
COMMAND(clearservers, "");
COMMAND(updatefrommaster, "");

void writeservercfg()
{
    if(!cl->savedservers()) return;
    FILE *f = openfile(path(cl->savedservers(), true), "w");
    if(!f) return;
    fprintf(f, "// servers connected to are added here automatically\n\n");
    loopvrev(servers) fprintf(f, "addserver %s\n", servers[i]->name);
    fclose(f);
}