#define _GNU_SOURCE
#define _XOPEN_SOURCE 600

#include "config.h"

#include <stdio.h>
#include <string.h>
#include <stdint.h>
#include <assert.h>
#include <pthread.h>
#include <stdint.h>

#ifdef HAVE_STDATOMIC_H
# include <stdatomic.h>
#endif /* HAVE_STDATOMIC_H */

#include "error.h"
#include "lock.h"
#include "pci.h"


struct pcilib_lock_s {
    pthread_mutex_t mutex;
    pcilib_lock_flags_t flags;
#ifdef HAVE_STDATOMIC_H
    volatile atomic_uint refs;
#else /* HAVE_STDATOMIC_H */
    volatile uint32_t refs;
#endif /* HAVE_STDATOMIC_H */
    char name[];
};


/**
 * this function initialize a new semaphore in the kernel if it's not already initialized given the key that permits to differentiate semaphores, and then return the integer that points to the semaphore that have been initialized or to a previously already initialized semaphore
 */
int pcilib_init_lock(pcilib_lock_t *lock, pcilib_lock_flags_t flags, const char *lock_id) {
    int err;
    pthread_mutexattr_t attr;

    assert(lock);
    assert(lock_id);

    memset(lock, 0, PCILIB_LOCK_SIZE);

    if (strlen(lock_id) >= (PCILIB_LOCK_SIZE - offsetof(struct pcilib_lock_s, name))) {
	pcilib_error("The supplied lock id (%s) is too long...", lock_id);
	return PCILIB_ERROR_INVALID_ARGUMENT;
    }

    if ((err = pthread_mutexattr_init(&attr))!=0) {
	pcilib_error("Can't initialize mutex attribute, errno %i", errno);
	return PCILIB_ERROR_FAILED;
    }

    if ((err = pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED))!=0) {
	pcilib_error("Can't configure a shared mutex attribute, errno %i", errno);
	return PCILIB_ERROR_FAILED;
    }

    if ((flags&PCILIB_LOCK_FLAG_PERSISTENT)==0) {
	if ((err = pthread_mutexattr_setrobust(&attr, PTHREAD_MUTEX_ROBUST))!=0) {
	    pcilib_error("Can't configure a robust mutex attribute, errno: %i", errno);
	    return PCILIB_ERROR_FAILED;
	}
    }

    if ((err = pthread_mutex_init(&lock->mutex, &attr))!=0) {
	pcilib_error("Can't create mutex, errno : %i",errno);
	return PCILIB_ERROR_FAILED;
    }

    strcpy(lock->name, lock_id);
    lock->refs = 1;
    lock->flags = flags;

    return 0;
}


/*
 * we uninitialize a mutex and set its name to 0 pointed by lock_ctx with this function. setting name to is the real destroying operation, but we need to unitialize the lock to initialize it again after
 */
void pcilib_free_lock(pcilib_lock_t *lock) {
    int err;

    assert(lock);

//    if (lock->refs)
//	pcilib_error("Forbidding to destroy the referenced mutex...");

    if ((err = pthread_mutex_destroy(&lock->mutex))==-1)
	pcilib_warning("Can't destroy POSIX mutex, errno %i",errno);
}


void pcilib_lock_ref(pcilib_lock_t *lock) {
    assert(lock);
    
#ifdef HAVE_STDATOMIC_H
    atomic_fetch_add_explicit(&lock->refs, 1, memory_order_relaxed);
#else /* HAVE_STDATOMIC_H */
    lock->refs++;
#endif  /* HAVE_STDATOMIC_H */
}

void pcilib_lock_unref(pcilib_lock_t *lock) {
    assert(lock);

    if (!lock->refs) {
	pcilib_warning("Lock is not referenced");
	return;
    }

#ifdef HAVE_STDATOMIC_H
    atomic_fetch_sub_explicit(&lock->refs, 1, memory_order_relaxed);
#else /* HAVE_STDATOMIC_H */
    lock->refs--;
#endif  /* HAVE_STDATOMIC_H */
}

size_t pcilib_lock_get_refs(pcilib_lock_t *lock) {
    return lock->refs;
}

pcilib_lock_flags_t pcilib_lock_get_flags(pcilib_lock_t *lock) {
    return lock->flags;
}

const char *pcilib_lock_get_name(pcilib_lock_t *lock) {
    assert(lock);

    if (lock->name[0]) return lock->name;
    return NULL;
}

/*
 * this function will take the lock for the semaphore pointed by semId
 */
int pcilib_lock_custom(pcilib_lock_t *lock, pcilib_lock_flags_t flags, pcilib_timeout_t timeout) {
    int err;

    if (!lock) {
	pcilib_error("The null lock pointer is passed to lock function");
	return PCILIB_ERROR_INVALID_ARGUMENT;
    }

    struct timespec tm;

    switch (timeout) {
     case PCILIB_TIMEOUT_INFINITE:
        err = pthread_mutex_lock(&lock->mutex);
	break;
     case PCILIB_TIMEOUT_IMMEDIATE:
        err = pthread_mutex_trylock(&lock->mutex);
	break;
     default:
        clock_gettime(CLOCK_REALTIME, &tm);
        tm.tv_nsec += 1000 * (timeout%1000000);
        if (tm.tv_nsec < 1000000000)
	    tm.tv_sec += timeout/1000000;
	else {
	    tm.tv_sec += 1 + timeout/1000000;
	    tm.tv_nsec -= 1000000000;
        } 
        err = pthread_mutex_timedlock(&lock->mutex, &tm);
    }

    if (!err)
	return 0;

    switch (err) {
     case EOWNERDEAD:
        err = pthread_mutex_consistent(&lock->mutex);
        if (err) {
	    pcilib_error("Failed to mark mutex as consistent, errno %i", err);
        }
        break;
     case ETIMEDOUT:
     case EBUSY:
        return PCILIB_ERROR_TIMEOUT;
     default:
        pcilib_error("Failed to obtain mutex, errno %i", err);
    }

    return PCILIB_ERROR_FAILED;
}

int pcilib_lock(pcilib_lock_t* lock) {
    return pcilib_lock_custom(lock, PCILIB_LOCK_FLAGS_DEFAULT, PCILIB_TIMEOUT_INFINITE);
}

int pcilib_try_lock(pcilib_lock_t* lock) {
    return pcilib_lock_custom(lock, PCILIB_LOCK_FLAGS_DEFAULT, PCILIB_TIMEOUT_IMMEDIATE);
}

/**
 * this function will unlock the semaphore pointed by lock_ctx.
 */
void pcilib_unlock(pcilib_lock_t *lock) {
    int err;

    if (!lock)
	return;

    if ((err = pthread_mutex_unlock(&lock->mutex)) != 0)
	pcilib_error("Can't unlock mutex, errno %i", err);
}