#if __linux__
// pull in RUSAGE_THREAD
#define _GNU_SOURCE
#include <sys/resource.h>
#elif __APPLE__
// pull in thread_info and friends
#include <mach/mach.h>
#else
#error
#endif

#include <limits.h>
#include <string.h>
#include "kernel/calls.h"

static bool resource_valid(int resource) {
    return resource >= 0 && resource < RLIMIT_NLIMITS_;
}

static int rlimit_get(struct task *task, int resource, struct rlimit_ *limit) {
    if (!resource_valid(resource))
        return _EINVAL;
    struct tgroup *group = task->group;
    lock(&group->lock);
    *limit = group->limits[resource];
    unlock(&group->lock);
    return 0;
}

static int rlimit_set(struct task *task, int resource, struct rlimit_ limit) {
    if (!resource_valid(resource))
        return _EINVAL;
    struct tgroup *group = task->group;
    lock(&group->lock);
    group->limits[resource] = limit;
    unlock(&group->lock);
    return 0;
}

rlim_t_ rlimit(int resource) {
    struct rlimit_ limit;
    if (rlimit_get(current, resource, &limit) != 0)
        die("invalid resource %d", resource);
    return limit.cur;
}

static int do_getrlimit32(int resource, struct rlimit32_ *rlimit32) {
    STRACE("getlimit(%d)", resource);
    struct rlimit_ rlimit;
    int err = rlimit_get(current, resource, &rlimit);
    if (err < 0)
        return err;
    STRACE(" {cur=%#x, max=%#x}", rlimit.cur, rlimit.max);

    rlimit32->max = rlimit.max;
    rlimit32->cur = rlimit.cur;
    return 0;
}

dword_t sys_getrlimit32(dword_t resource, addr_t rlim_addr) {
    struct rlimit32_ rlimit;
    int err = do_getrlimit32(resource, &rlimit);
    if (err < 0)
        return err;
    if (user_put(rlim_addr, rlimit))
        return _EFAULT;
    return 0;
}

dword_t sys_old_getrlimit32(dword_t resource, addr_t rlim_addr) {
    struct rlimit32_ rlimit;
    int err = do_getrlimit32(resource, &rlimit);
    if (err < 0)
        return err;

    // This version of the call is for programs that aren't aware of rlim_t
    // being 64 bit. RLIM_INFINITY looks like -1 when truncated to 32 bits.
    if (rlimit.cur > INT_MAX)
        rlimit.cur = INT_MAX;
    if (rlimit.max > INT_MAX)
        rlimit.max = INT_MAX;

    if (user_put(rlim_addr, rlimit))
        return _EFAULT;
    return 0;
}

static int check_setrlimit(int resource, struct rlimit_ new_limit) {
    if (superuser())
        return 0;
    struct rlimit_ old_limit;
    int err = rlimit_get(current, resource, &old_limit);
    if (err < 0)
        return err;
    if (new_limit.max > old_limit.max)
        return _EPERM;
    return 0;
}

dword_t sys_setrlimit32(dword_t resource, addr_t rlim_addr) {
    struct rlimit_ rlimit;
    if (user_get(rlim_addr, rlimit))
        return _EFAULT;
    STRACE("setrlimit(%d, {cur=%#x, max=%#x})", resource, rlimit.cur, rlimit.max);
    int err = check_setrlimit(resource, rlimit);
    if (err < 0)
        return err;
    return rlimit_set(current, resource, rlimit);
}

dword_t sys_prlimit64(pid_t_ pid, dword_t resource, addr_t new_limit_addr, addr_t old_limit_addr) {
    STRACE("prlimit64(%d, %d)", pid, resource);
    if (pid != 0)
        return _EINVAL;

    if (old_limit_addr != 0) {
        struct rlimit_ rlimit;
        int err = rlimit_get(current, resource, &rlimit);
        if (err < 0)
            return err;
        STRACE(" old={cur=%#x, max=%#x}", rlimit.cur, rlimit.max);
        if (user_put(old_limit_addr, rlimit))
            return _EFAULT;
    }

    if (new_limit_addr != 0) {
        struct rlimit_ rlimit;
        if (user_get(new_limit_addr, rlimit))
            return _EFAULT;
        STRACE(" new={cur=%#x, max=%#x}", rlimit.cur, rlimit.max);
        int err = check_setrlimit(resource, rlimit);
        if (err < 0)
            return err;
        return rlimit_set(current, resource, rlimit);
    }
    return 0;
}

struct rusage_ rusage_get_current() {
    // only the time fields are currently implemented
    struct rusage_ rusage;
#if __linux__
    struct rusage usage;
    int err = getrusage(RUSAGE_THREAD, &usage);
    assert(err == 0);
    rusage.utime.sec = usage.ru_utime.tv_sec;
    rusage.utime.usec = usage.ru_utime.tv_usec;
    rusage.stime.sec = usage.ru_stime.tv_sec;
    rusage.stime.usec = usage.ru_stime.tv_usec;
#elif __APPLE__
    thread_basic_info_data_t info;
    mach_msg_type_number_t count = THREAD_BASIC_INFO_COUNT;
    thread_info(mach_thread_self(), THREAD_BASIC_INFO, (thread_info_t) &info, &count);
    rusage.utime.sec = info.user_time.seconds;
    rusage.utime.usec = info.user_time.microseconds;
    rusage.stime.sec = info.system_time.seconds;
    rusage.stime.usec = info.system_time.microseconds;
#endif
    return rusage;
}

static void timeval_add(struct timeval_ *dst, struct timeval_ *src) {
    dst->sec += src->sec;
    dst->usec += src->usec;
    if (dst->usec >= 1000000) {
        dst->usec -= 1000000;
        dst->sec++;
    }
}

void rusage_add(struct rusage_ *dst, struct rusage_ *src) {
    timeval_add(&dst->utime, &src->utime);
    timeval_add(&dst->stime, &src->stime);
}

dword_t sys_getrusage(dword_t who, addr_t rusage_addr) {
    struct rusage_ rusage;
    switch (who) {
        case RUSAGE_SELF_:
            rusage = rusage_get_current();
            break;
        case RUSAGE_CHILDREN_:
            lock(&current->group->lock);
            rusage = current->group->children_rusage;
            unlock(&current->group->lock);
            break;
        default:
            return _EINVAL;
    }
    if (user_put(rusage_addr, rusage))
        return _EFAULT;
    return 0;
}

int_t sys_sched_getaffinity(pid_t_ pid, dword_t cpusetsize, addr_t cpuset_addr) {
    STRACE("sched_getaffinity(%d, %d, %#x)", pid, cpusetsize, cpuset_addr);
    if (pid != 0) {
        lock(&pids_lock);
        struct task *task = pid_get_task(pid);
        unlock(&pids_lock);
        if (task == NULL)
            return _ESRCH;
    }

    unsigned cpus = sysconf(_SC_NPROCESSORS_ONLN);
    if (cpus > cpusetsize * 8)
        cpus = cpusetsize * 8;
    char cpuset[cpusetsize];
    memset(cpuset, 0, sizeof(cpuset));
    for (unsigned i = 0; i < cpus; i++)
        bit_set(i, cpuset);
    if (user_write(cpuset_addr, cpuset, cpusetsize))
        return _EFAULT;
    return 0;
}
int_t sys_sched_setaffinity(pid_t_ UNUSED(pid), dword_t UNUSED(cpusetsize), addr_t UNUSED(cpuset_addr)) {
    // meh
    return 0;
}

int_t sys_getpriority(int_t which, pid_t_ who) {
    STRACE("getpriority(%d, %d)", which, who);
    return 20;
}
int_t sys_setpriority(int_t which, pid_t_ who, int_t prio) {
    STRACE("setpriority(%d, %d, %d)", which, who, prio);
    return 0;
}

// realtime scheduling stubs
int_t sys_sched_getparam(pid_t_ UNUSED(pid), addr_t param_addr) {
    int_t sched_priority = 0;
    if (user_put(param_addr, sched_priority))
        return _EFAULT;
    return 0;
}
#define SCHED_OTHER_ 0
int_t sys_sched_getscheduler(pid_t_ UNUSED(pid)) {
    return SCHED_OTHER_;
}
int_t sys_sched_setscheduler(pid_t_ UNUSED(pid), int_t policy, addr_t param_addr) {
    if (policy != SCHED_OTHER_)
        return _EINVAL;
    int_t sched_priority;
    if (user_get(param_addr, sched_priority))
        return _EFAULT;
    if (sched_priority != 0)
        return _EINVAL;
    return 0;
}

int_t sys_sched_get_priority_max(int_t policy) {
    STRACE("sched_get_priority_max(%d)", policy);
    if (policy == 0)
        return 0;
    return _EINVAL;
}