/*
 *  Baltisot
 *  Copyright (C) 1999-2007 Nicolas "Pixel" Noble
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

/* $Id: TaskMan.cc,v 1.46 2007-05-30 11:57:10 pixel Exp $ */

#ifndef _WIN32
#include <signal.h>
#include <sys/wait.h>
#include <sys/poll.h>
#include <sys/time.h>
#include <unistd.h>
#endif
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <vector>
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include "TaskMan.h"
#include "gettext.h"

TaskMan::TaskList_t TaskMan::TaskList;
TaskMan::TaskList_t TaskMan::Zombies;
std::vector<TaskMan::w4ha_t> TaskMan::w4ha;
std::vector<TaskMan::w4pr_t> TaskMan::w4pr;
std::vector<TaskMan::w4to_t> TaskMan::w4to;
bool TaskMan::stopped = false;

int TaskMan::number = 0;
int TaskMan::got_sigchild = 0;
bool TaskMan::inited = false;

int TaskMan::event, TaskMan::eprocess, TaskMan::estatus;
Task * TaskMan::etask;
Handle * TaskMan::ehandle;

sigset_t TaskMan::sigchildset;

#ifndef _WIN32
void taskman_sigchild(int sig) {
    TaskMan::SigChild();
    signal(SIGCHLD, taskman_sigchild);
}

void taskman_sigpipe(int sig) {
    signal(sig, taskman_sigpipe);
}
void taskman_sighup(int sig) {
    signal(sig, taskman_sighup);
}
#endif

void TaskMan::SigChild() {
    int status;
    pid_t pid;
    
    pid = wait(&status);
    if (GotChild(pid, status)) {
	got_sigchild++;
    } else {
	WaitFor(pid, 0, status);
    }
    
//    cerr << "Got SIGCHILD, pid = " << pid << " and status = " << status << endl;
}

// Windows implementations of poll and gettimeofday.
#ifdef _WIN32
#define POLLIN  1       /* Set if data to read. */
#define POLLPRI 2       /* Set if urgent data to read. */
#define POLLOUT 4       /* Set if writing data wouldn't block. */
#define POLLERR   8     /* An error occured. */
#define POLLHUP  16     /* Shutdown or close happened. */
#define POLLNVAL 32     /* Invalid file descriptor. */

#define NPOLLFILE 64    /* Number of canonical fd's in one call to poll(). */

/* The following values are defined by XPG4. */
#define POLLRDNORM POLLIN
#define POLLRDBAND POLLPRI
#define POLLWRNORM POLLOUT
#define POLLWRBAND POLLOUT

struct pollfd {
  int fd;
  short events;
  short revents;
};

static int poll (struct pollfd *fds, unsigned int nfds, int timeout) {
    fd_set read_fds, write_fds, except_fds;
    struct timeval tv = { timeout / 1000, (timeout % 1000) * 1000 };
    int max_fd = 0, retval, changedfds;
    unsigned int i;
    int n_non_socket = 0;

    FD_ZERO(&read_fds);
    FD_ZERO(&write_fds);
    FD_ZERO(&except_fds);

    for (int i = 0; i < nfds; i++) {
        if (!fds[i].fd && !fds[i].events)
            continue;

        BOOL dummy;
        int dummy_s = sizeof(dummy);

        if (getsockopt(fds[i].fd, SOL_SOCKET, SO_ACCEPTCONN, (char *) &dummy, &dummy_s) == SOCKET_ERROR) {
            if (WSAGetLastError() == WSAENOTSOCK) {
                if (fds[i].events & POLLIN) {
                    n_non_socket++;
                    fds[i].revents |= POLLIN;
                }
                continue;
            }
        }

        if (fds[i].fd > max_fd)
            max_fd = fds[i].fd;

        if (fds[i].events & POLLIN)
            FD_SET(fds[i].fd, &read_fds);

        if (fds[i].events & POLLOUT)
            FD_SET(fds[i].fd, &write_fds);

        FD_SET(fds[i].fd, &except_fds);

        fds[i].revents = 0;
    }

    if (n_non_socket) {
        tv.tv_sec = 0;
        tv.tv_usec = 0;
        timeout = 0;
    }

    changedfds = retval = select(max_fd + 1, &read_fds, &write_fds, &except_fds, timeout < 0 ? NULL : &tv);

    if (retval <= 0) {
        if (retval < 0) {
            int err = WSAGetLastError();
            // got timeout or error
            switch (err) {
                case WSANOTINITIALISED:
                    Base::printm(M_INFO, "WSANOTINITIALISED\n");
                    break;
                case WSAEFAULT:
                    Base::printm(M_INFO, "WSAEFAULT\n");
                    break;
                case WSAENETDOWN:
                    Base::printm(M_INFO, "WSAENETDOWN\n");
                    break;
                case WSAEINVAL:
                    Base::printm(M_INFO, "WSAEINVAL\n");
                    break;
                case WSAEINTR:
                    Base::printm(M_INFO, "WSAEINTR\n");
                    break;
                case WSAEINPROGRESS:
                    Base::printm(M_INFO, "WSAEINPROGRESS\n");
                    break;
                case WSAENOTSOCK:
                    Base::printm(M_INFO, "WSAENOTSOCK\n");
                    break;
                default:
                    Base::printm(M_INFO, "Unknown error\n");
            }
            return retval;
        } else {
            return n_non_socket;
        }
    }

    for (i = 0; i < nfds; i++) {
        if (FD_ISSET(fds[i].fd, &read_fds)) {
            fds[i].revents |= POLLIN;
            changedfds--;
        }
        
        if (FD_ISSET(fds[i].fd, &write_fds)) {
            fds[i].revents |= POLLOUT;
            changedfds--;
        }

        if (FD_ISSET(fds[i].fd, &except_fds)) {
            fds[i].revents |= POLLERR;
            changedfds--;
        }

        if (changedfds <= 0)
            break;
    }

    return retval + n_non_socket;
}

#define EPOCHFILETIME (116444736000000000i64)

// special version without timezone support...
static int gettimeofday(struct timeval *tv, struct timezone *tz)
{
    FILETIME        ft;
    LARGE_INTEGER   li;
    __int64         t;

    if (tv)
    {
        GetSystemTimeAsFileTime(&ft);
        li.LowPart  = ft.dwLowDateTime;
        li.HighPart = ft.dwHighDateTime;
        t  = li.QuadPart;       /* In 100-nanosecond intervals */
        t -= EPOCHFILETIME;     /* Offset to the Epoch time */
        t /= 10;                /* In microseconds */
        tv->tv_sec  = (long)(t / 1000000);
        tv->tv_usec = (long)(t % 1000000);
    }

    return 0;
}
#endif

// Static class to handle operations on the timeval structure.
class TimeOps : public Base {
  public:
    static timeval Add(const timeval & t1, const timeval & t2) {
        struct timeval r;

        r.tv_usec = t1.tv_usec + t2.tv_usec;
        r.tv_sec = t1.tv_sec + t2.tv_sec;

        if (r.tv_usec >= 1000000) {
            r.tv_usec %= 1000000;
            r.tv_sec++;
        }

        return r;
    }
    static long Diff(const timeval & t1, const timeval & t2) {
        return (t2.tv_sec - t1.tv_sec) * 1000 + (t2.tv_usec - t1.tv_usec) / 1000;
    }
    static bool IsLE(const timeval & t1, const timeval & t2) {
        return (t1.tv_sec <= t2.tv_sec) || ((t1.tv_sec == t2.tv_sec) && (t1.tv_usec <= t2.tv_usec));
    }
    static long ToMS(const timeval & t) {
        return t.tv_usec / 1000 + t.tv_sec * 1000;
    }
    static void Sleep(const timeval & t) {
        Sleep(ToMS(t));
    }
    static void Sleep(Uint32 t) {
#ifdef _WIN32
        ::Sleep(t);
#else
        usleep(t * 1000);
#endif
    }
};

int TaskMan::GotChild(pid_t pid, int status) {
    int r = 0;
    unsigned int i;

    for (i = 0; i < w4pr.size(); i++) {
	if (w4pr[i].pr == pid) {
	    w4pr[i].flag = true;
	    w4pr[i].status = status;
	    r = 1;
	}
    }
    
    return r;
}

void TaskMan::Init() throw (GeneralException) {
    if (inited) {
	throw GeneralException(_("Task Manager already initialised."));
    }
    
#ifndef _WIN32
    signal(SIGCHLD, taskman_sigchild);
    signal(SIGPIPE, taskman_sigpipe);
    signal(SIGHUP, taskman_sighup);
    
    sigemptyset(&sigchildset);
    sigaddset(&sigchildset, SIGCHLD);
    sigprocmask(SIG_BLOCK, &sigchildset, 0);
#endif    

    inited = true;
    number = 0;
}

void TaskMan::Stop() {
    stopped = true;
}

// Accessor of the current processed event.
int TaskMan::Event() {
    return event;
}

// Accessor of the current task triggering the EVT_TASK event.
Task * TaskMan::Etask() {
    return etask;
}

// Accessor of the current handle triggering the EVT_HANDLE event.
Handle * TaskMan::Ehandle() {
    return ehandle;
}

// accessor of the current pid_t triggering the EVT_PROCESS event.
int TaskMan::Eprocess() {
    return eprocess;
}

// Accessor of the status of the processus triggering the EVT_PROCESS event.
int TaskMan::Estatus() {
    return estatus;
}

// Should be only called by the constructor of a Task()
void TaskMan::AddTask(Task * t) {
    if (!inited) {
	Init();
    }
    
    if (t) {
	TaskList.push_back(t);
	number++;
    }
}

std::vector<Task *>::iterator TaskMan::FindTask(Task * t) throw (GeneralException) {
    if (!inited) {
	Init();
    }
    
    if (TaskList.empty())
	throw TaskNotFound();
    
    for (std::vector<Task *>::iterator p = TaskList.begin(); p != TaskList.end(); p++) {
	if (*p == t) {
	    return p;
	}
    }
    
    throw TaskNotFound();
}

// Should only be called by the destructor of a task.
void TaskMan::RemoveFromWatches(Task * t) {
    if (!w4ha.empty()) {
	for (std::vector<w4ha_t>::iterator p = w4ha.begin(); p != w4ha.end(); p++) {
	    if (p->T == t) {
		w4ha.erase(p);
		p = w4ha.begin();
                if (w4ha.empty())
                    break;
	    }
	}
    }

    if (!w4pr.empty()) {
	for (std::vector<w4pr_t>::iterator p = w4pr.begin(); p != w4pr.end(); p++) {
	    if (p->T == t) {
		w4pr.erase(p);
		p = w4pr.begin();
                if (w4pr.empty())
                    break;
	    }
	}
    }

    if (!w4to.empty()) {
	for (std::vector<w4to_t>::iterator p = w4to.begin(); p != w4to.end(); p++) {
	    if (p->T == t) {
		w4to.erase(p);
		p = w4to.begin();
                if (w4to.empty())
                    break;
	    }
	}
    }
    
    if (!TaskList.empty()) {
	for (TaskList_t::iterator p = TaskList.begin(); p != TaskList.end(); p++) {
	    if ((*p)->WaitedBy() == t) {
		Zombies.push_back(*p);
	        (*p)->RemoveFromWatches();
		TaskList.erase(p);
		number--;
	        p = TaskList.begin();
                if (TaskList.empty())
                    break;
	    } else if ((*p) == t) {
		TaskList.erase(p);
	        number--;
		p = TaskList.begin();
                if (TaskList.empty())
                    break;
	    }
	}
    }
}

// Possibility to cancel a timeout.
void TaskMan::RemoveTimeout(Task * t) {
    if (!w4to.empty()) {
	for (std::vector<w4to_t>::iterator p = w4to.begin(); p != w4to.end(); p++) {
	    if (p->T == t) {
		w4to.erase(p);
		p = w4to.begin();
                if (w4to.empty())
                    break;
	    }
	}
    }
}

void TaskMan::WaitFor(Handle * h, Task * t, int flags) {
    h->SetNonBlock();
    w4ha.push_back(w4ha_t(h, flags, t));
}

void TaskMan::WaitFor(pid_t pid, Task * t, int status) {
    if (status == -1) {
	if (!w4pr.empty()) {
	    for (std::vector<w4pr_t>::iterator p = w4pr.begin(); p != w4pr.end(); p++) {
		if (p->pr == pid) {
		    p->T = t;
		    p->flag = true;
		    got_sigchild++;
		    return;
		}
	    }
	}
    }
    w4pr.push_back(w4pr_t(pid, t));
    w4pr[w4pr.size() - 1].status = status;
}

void TaskMan::WaitFor(const timeval & t, Task * T, int flags) {
    struct timeval tod;
    gettimeofday(&tod, 0);
    w4to.push_back(w4to_t(TimeOps::Add(tod, t), flags, T));
}

// The big ugly mainloop.
void TaskMan::MainLoop() throw (GeneralException) {
    struct pollfd * ufsd;
    unsigned int nfds;
    
    int no_burst;
    
    if (!inited) {
	Init();
    }

    while (1) {
	if (number == 0) {
	    throw GeneralException(_("TaskMan: No more task to manage."));
	}
	
	if (stopped) return;

        // We should have a small fuse here, and check if there is no 'dead' task,
        // that is, a task which doesn't have anything to wait for, but which is
        // not a zombie.
	
//	cerr << "-=- TaskMan: begin main loop with " << number << " task to manage.\n";
	if (!TaskList.empty()) {
	    for (TaskList_t::iterator p = TaskList.begin(); p != TaskList.end(); p++) {
		Task * t = *p;
//	 	   cerr << "-=- TaskMan: task " << t->GetName() << endl;
	    }
	}
	
//	cerr << "-=- TaskMan: processing burning tasks.\n";
	
	no_burst = 0;
	while (!no_burst) {
	    no_burst = 1;
            /* First, we will check for any burning task and run 'em */
            event = Task::EVT_BURST;
	    if (!TaskList.empty()) {
		for (TaskList_t::iterator p = TaskList.begin(); p != TaskList.end(); p++) {
		    Task * t = *p;
		
		    if (t->IsStopped()) {
			continue;
		    }
		
                    if (t->GetState() == Task::TASK_BURST) {
//		    	cerr << "-=- TaskMan: running burning task " << t->GetName() << endl;
                        if (t->BurstHandle) {
                            // This task got the burst status from
                            // a non-watchable handle. Let's fake the handle event.
                            event = Task::EVT_HANDLE;
                            ehandle = t->BurstHandle;
                        }
			t->Run();
                        if (t->BurstHandle) {
                            event = Task::EVT_BURST;
                            t->BurstHandle = 0;
                        }
		        /* if the task added some new tasks, we have to rerun the loop */
			no_burst = 0;
		        break;
		    }
		
                    // Additionnally, if the task died, let's put it in the zombies list.
                    // This check is done on the whole TaskList at each loop.
                    if (CheckDead(t))
                        p = TaskList.begin();
		}
	    }
	}

	/* Let's compute the nearest timeout, and run a round trip for expired timeouts. */
	int timeout = -1;
	event = Task::EVT_TIMEOUT;
        bool got_timeout = true, ran_on_timeout = false;

	while (!w4to.empty() && got_timeout) {
            got_timeout = false;
	    struct timeval current;
            gettimeofday(&current, 0);
            timeout = -1;
	    for (std::vector<w4to_t>::iterator p = w4to.begin(); p != w4to.end(); p++) {
                if (TimeOps::IsLE(p->to, current)) {
                    // This timeout expired; run the task.
                    w4to_t w4 = *p;
		    w4to.erase(p);
                    w4.T->Run();
                    ran_on_timeout = true;
                    got_timeout = true;
                    CheckDead(w4.T);
                    break;
                } else {
                    // Otherwise, let's keep track of the smallest timeout value.
                    long diff = TimeOps::Diff(current, p->to);
                    if ((timeout == -1) || (timeout > diff)) {
                        timeout = diff;
                    }
                }
	    }
	}

//	cerr << "-=- TaskMan: processing handle-waiting tasks.\n";

        if ((w4ha.size() == 0) && !ran_on_timeout && (timeout != -1) && (Zombies.size() == 0)) {
            // In order to avoid the engine to run full speed without anything real to do,
            // let's eat the timeout here.
            TimeOps::Sleep(timeout);
        }
	
	/* Now is time to check all the handle and enter into a wait state. */

	event = Task::EVT_HANDLE;
	nfds = w4ha.size();
	no_burst = 1;

        if (nfds != 0) {
	    int r;
	    std::vector<w4ha_t>::iterator p;
	    struct pollfd * q;

	    ufsd = (struct pollfd *) malloc(nfds * sizeof(struct pollfd));
            // Let's build the pollfd structure.
	    for (q = ufsd, p = w4ha.begin(); p != w4ha.end(); p++, q++) {
	        p->dirty = false;
                // A stopped task doesn't get cookies.
	        if (p->T->IsStopped()) {
		    q->fd = 0;
		    q->events = 0;
	        } else {
		    if (p->ha->CanWatch()) {
                        // If that handle can be watched, then let's fill in the pollfd structure.
	    	        q->fd = p->ha->GetHandle();
		        q->events = (p->flags & Task::W4_READING ? POLLIN : 0) | (p->flags & Task::W4_WRITING ? POLLOUT : 0);
		    } else {
                        // Otherwise, let's put the task in burst mode, and set its status to dirty,
                        // considering it already processed for this handle loop.
                        // It'll be run immediately next cycle.
		        p->T->SetBurst();
		        no_burst = 0;
		        p->dirty = true;
		        q->fd = 0;
		        q->events = 0;
		    }
	        }
	    }
            // Now the list is done, let's clean up the w4ha list from the non watchable handles.
	    for (p = w4ha.begin(); p != w4ha.end(); p++) {
                if (!p->T->IsStopped() && !p->ha->CanWatch() && !(p->flags & Task::W4_STICKY)) {
		    w4ha.erase(p);
		    p = w4ha.begin();
                }
            }

#ifndef _WIN32
	    sigprocmask(SIG_UNBLOCK, &sigchildset, 0);
#endif
	    r = poll(ufsd, nfds, (no_burst) && !(Zombies.size()) && !(got_sigchild) ? timeout: 0);
#ifndef _WIN32
            sigprocmask(SIG_BLOCK, &sigchildset, 0);
#endif
	    if (r < 0) {
		if (errno != EINTR) {
		    throw GeneralException(String(_("Error during poll: ")) + strerror(errno));
		}
	    } else if (r == 0) {
		// timeout.
		// We shouldn't do anything here, since the next loop should catch
                // the expired timeouts.
	    } else {
		int fd;
		struct pollfd * q;
		unsigned int i;
		for (q = ufsd, i = 0; i < nfds; i++, q++) {
		    if (q->revents & POLLNVAL) {
			throw GeneralException(String(_("Error with poll, handle ")) + q->fd + _(" invalid."));
		    }
		    
//		    if (q->revents & POLLERR) {
//			cerr << _("Error condition with poll, handle ") << q->fd << endl;
//		    }
		    
//		    if (q->revents & POLLHUP) {
//			cerr << _("Handle ") << q->fd << _(" hung up.\n");
//		    }
		    
		    fd = q->fd;
		    if (q->revents & (POLLIN | POLLOUT | POLLERR | POLLHUP)) {
			// We have to look into the handle structure now...
			bool touched;
			if (!w4ha.empty()) {
			    for (std::vector<w4ha_t>::iterator p = w4ha.begin(); p != w4ha.end(); p = touched ? w4ha.begin() : p + 1) {
				touched = false;
			        if ((p->ha->GetHandle() == fd) && (!p->T->IsStopped()) && (p->T->GetState() != Task::TASK_DONE) && (!p->dirty)) {
			    	    // We've got one, launch it.
//				    cerr << "-=- TaskMan: launching task " << p->T->GetName() << " for handle " << p->ha->GetHandle() << endl;
				    w4ha_t w4 = *p;
				    p->dirty = true;
				    ehandle = p->ha;

				    if (!(p->flags & Task::W4_STICKY)) {
					w4ha.erase(p);
				    }

				    touched = true;

				    w4.T->Run();
                                    CheckDead(w4.T);
				}
			    }
			}
		    }
		}
	    }
	    free(ufsd);
	}
	
	/* And finally, let's clean-up all the zombies around here. */
	
	int no_zombies;
	no_zombies = 0;
	
	event = Task::EVT_TASK;
//	cerr << "-=- TaskMan: processing zombies loop.\n";
	
	while (!no_zombies) {
	    no_zombies = 1;
	    while (Zombies.size()) {
		Task * t = Zombies[0], * o;
		
		if (!t) {
//		    cerr << "!?!?!? We have t = NULL ?!?!?! WTF\n";
		    break;
		}
		
		if ((o = t->WaitedBy())) {
//		    cerr << "-=- TaskMan: running task " << o->GetName() << " for task " << t->GetName() << endl;
		    etask = t;
		    o->Run();
                    if (CheckDead(o))
                        no_zombies = 0;
		} else {
		    delete t;
		}
		Zombies.erase(Zombies.begin());
	    }
	}
	
	/* To end up the loop, let's recall tasks waiting for processes */
	
	event = Task::EVT_PROCESS;
//	cerr << "-=- TaskMan: processing child-waiting tasks.\n";
	
	if (got_sigchild) {
	    if (!w4pr.empty()) {
		for (std::vector<w4pr_t>::iterator p = w4pr.begin(); p != w4pr.end(); p++) {
		    if (p->flag) {
			Task * t;
		        if (p->T->IsStopped()) {
		    	    continue;
			}
			eprocess = p->pr;
			estatus = p->status;
//		        cerr << "-=- TaskMan: running task " << p->T->GetName() << " for process " << p->pr << " (" << p->status << ")\n";
			t = p->T;
			w4pr.erase(p);
			got_sigchild--;
			t->Run();
		        break;
		    }
		}
	    }
	}
    }
}

bool TaskMan::CheckDead(Task * t) {
    if (t->GetState() == Task::TASK_DONE) {
	TaskList_t::iterator f = FindTask(t);
	TaskList.erase(f);
	number--;
	Zombies.push_back(t);
        return true;
    }
    return false;
}