#include <signal.h>
#include <wait.h>
#include <sys/poll.h>
#include <errno.h>
#include <string.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#include <vector.h>
#include "TaskMan.h"
#include "config.h"

#define USE_POLL 1

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

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

static int got_sigchild = 0;

void taskman_sigchild(int sig) {
    int status;
    pid_t pid;
    
    pid = wait(&status);
    if (TaskMan::GotChild(pid, status)) {
	got_sigchild = 1;
    }
    signal(SIGCHLD, taskman_sigchild);
}

void taskman_sigpipe(int sig) {
    signal(SIGPIPE, taskman_sigpipe);
}

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

    for (vector<w4pr_t>::iterator p = w4pr.begin(); p && (p != w4pr.end()); p++) {
	if (p->pr == pid) {
	    p->flag = true;
	    p->status = status;
	    r = 1;
	}
    }
    
    return r;
}

void TaskMan::Init() throw (GeneralException) {
    if (inited) {
	throw GeneralException("Task Manager already initialised.");
    }
    
    signal(SIGCHLD, taskman_sigchild);
    signal(SIGPIPE, taskman_sigpipe);
    
    inited = true;
    number = 0;
}

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

void TaskMan::AddTask(Task * t) {
    if (!inited) {
	Init();
    }
    
    if (t) {
	TaskList.push_back(t);
	number++;
    }
}

vector<Task *>::iterator TaskMan::FindTask(Task * t) {
    if (!inited) {
	Init();
    }
    
    for (TaskList_t::iterator p = TaskList.begin(); p && (p != TaskList.end()); p++) {
	if (*p == t) {
	    return p;
	}
    }
    
    return NULL;
}

void TaskMan::RemoveFromWatches(Task * t) {
    for (vector<w4ha_t>::iterator p = w4ha.begin(); p && (p != w4ha.end()); p++) {
	if (p->T == t) {
	    w4ha.erase(p);
	    p--;
	}
    }

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

    for (vector<w4to_t>::iterator p = w4to.begin(); p && (p != w4to.end()); p++) {
	if (p->T == t) {
	    w4to.erase(p);
	    p--;
	}
    }
}

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

void TaskMan::WaitFor(pid_t p, Task * t) {
    w4pr.push_back(w4pr_t(p, t));
}

void TaskMan::WaitFor(timeval t, Task * T, int flags) {
    w4to.push_back(w4to_t(t, flags, T));
}

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;
	
	cerr << "-=- TaskMan: begin main loop with " << number << " task to manage.\n";
	
	no_burst = 0;
	while (!no_burst) {
	    no_burst = 1;
            /* First, we will check for any burning task and run 'em */
	    for (TaskList_t::iterator p = TaskList.begin(); p && (p != TaskList.end()); p++) {
		Task * t = *p;

		if (t->GetState() == TASK_BURST) {
		    cerr << "-=- TaskMan: running burning task " << t->GetName() << endl;
		    t->Run();
		    /* if the task added some new tasks, we have to rerun the loop */
		    no_burst = 0;
		    break;
		}
	    
		if (t->GetState() == TASK_BURST) {
		    no_burst = 0;
		} else if (t->GetState() == TASK_DONE) {
		    TaskList.erase(p);
		    number--;
		    p--;
		    Zombies.push_back(t);
		}
	    }
	}

	nfds = w4ha.size();
	no_burst = 1;
	
	if (nfds != 0) {
	    int r;
	    vector<w4ha_t>::iterator p;
#ifdef USE_POLL
	    struct pollfd * q;
#else
	    int highest;
	    fd_set readfds, writefds, exceptfds;
#endif

#ifdef USE_POLL
	    ufsd = (struct pollfd *) malloc(nfds * sizeof(struct pollfd));
	    for (q = ufsd, p = w4ha.begin(); p && (p != w4ha.end()); p++, q++) {
		p->dirthy = false;
		if (p->T->IsStopped()) {
		    q->fd = 0;
		    q->events = 0;
		} else {
		    if (p->ha->CanWatch()) {
			q->fd = p->ha->GetHandle();
			q->events = (p->flags & W4_READING ? POLLIN : 0) | (p->flags & W4_WRITING ? POLLOUT : 0);
		    } else {
			p->T->SetBurst();
			no_burst = 0;
			if (!(p->flags & W4_STICKY)) {
			    w4ha.erase(p);
			    p--;
			}
			q->fd = 0;
			q->events = 0;
		    }
		}
	    }
	    
	    r = poll(ufsd, nfds, (no_burst) && !(Zombies.size()) ? -1: 1);
#else
	    FD_ZERO(readfds);
	    FD_ZERO(writefds);
	    FD_ZERO(exceptfds);
	    
	    highest = -1;
	    for (p = w4ha.begin(); p && (p != w4ha.end()); p++) {
		if (p->T->IsStopped()) continue;
		if (p->flags & W4_READING) {
		    FD_SET(p->ha->GetHandle(), readfds);
		}
		if (p->flags & W4_WRITING) {
		    FD_SET(p->ha->GetHandle(), writefds);
		}
		FD_SET(p->ha->GetHandle(), exceptfds);
	    }
	    
	    r = select(highest + 1, &readfds, &writefds, &exceptfds, NULL);
#endif
	    if (r == -1) {
		if (errno == EINTR) {
		    // child
		} else {
		    throw GeneralException(String("Error during poll: ") + strerror(errno));
		}
	    } else if (r == 0) {
		// timeout...
	    } else {
		int fd;
#ifdef USE_POLL
		struct pollfd * q;
		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 whith poll, handle " << q->fd << endl;
		    }
		    
		    if (q->revents & POLLHUP) {
			cerr << "Handle " << q->fd << " hung up.\n";
			// What should I do now?
		    }
		    
		    fd = q->fd;
		    if (q->revents & (POLLIN | POLLOUT | POLLERR | POLLHUP)) {
#else
		    /* Later perhaps... Let's use poll for now.
		       The following is independant of the use of select or poll.
		       Just have to set 'fd' to the changed handle. Two '{' to open with
		       the first as the loop through the handles and the second with 
		       the test "if handle has changed" */
#endif
			// We have to look into the handle structure now...
			bool touched;
			for (vector<w4ha_t>::iterator p = w4ha.begin(); p && (p != w4ha.end()); p = touched ? w4ha.begin() : p + 1) {
			    touched = false;
			    if ((p->ha->GetHandle() == fd) && (!p->T->IsStopped()) && (p->T->GetState() != TASK_DONE) && (!p->dirthy)) {
				// We've got one, launch it.
				cerr << "-=- TaskMan: launching task " << p->T->GetName() << " for handle " << p->ha->GetHandle() << endl;
				w4ha_t w4 = *p;
				p->dirthy = true;

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

				touched = true;

				w4.T->Run();
				
				if (w4.T->GetState() == TASK_DONE) {
				    // This task died, remove it.
				    TaskList_t::iterator q = FindTask(w4.T);
				    if (q) {
					TaskList.erase(q);
					number--;
					Zombies.push_back(w4.T);
				    }
				}
				
			    }
			}
		    }
		}
	    }
#ifdef USE_POLL
	    free((void *) ufsd);
#endif
	}
	
	int no_zombies;
	no_zombies = 0;
	
	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;
		    o->Run();
		    
		    if (o->GetState() == TASK_DONE) {
			TaskList_t::iterator f = FindTask(o);
			if (!f) {
			    throw GeneralException("TaskMan: internal error (task not found)");
			}
			TaskList.erase(f);
			number--;
			Zombies.push_back(o);
			no_zombies = 0;
		    }
		} else {
		    delete t;
		}
		Zombies.erase(Zombies.begin());
	    }
	}
    }
}