#include "libc.h"
#include <errno.h>
#include <limits.h>
#include <signal.h>
#include <sys/resource.h>
#include <unistd.h>

#include <zircon/syscalls.h>

#define JT(x) (-256 | (x))
#define VER JT(1)
#define JT_ARG_MAX JT(2)
#define JT_MQ_PRIO_MAX JT(3)
#define JT_PAGE_SIZE JT(4)
#define JT_SEM_VALUE_MAX JT(5)
#define JT_NPROCESSORS_CONF JT(6)
#define JT_NPROCESSORS_ONLN JT(7)
#define JT_PHYS_PAGES JT(8)
#define JT_AVPHYS_PAGES JT(9)
#define JT_ZERO JT(10)

#define RLIM(x) (-32768 | (RLIMIT_##x))

long sysconf(int name) {
    static const short values[] = {
            [_SC_ARG_MAX] = JT_ARG_MAX,
            [_SC_CHILD_MAX] = RLIM(NPROC),
            [_SC_CLK_TCK] = 100,
            [_SC_NGROUPS_MAX] = 32,
            [_SC_OPEN_MAX] = RLIM(NOFILE),
            [_SC_STREAM_MAX] = -1,
            [_SC_TZNAME_MAX] = TZNAME_MAX,
            [_SC_JOB_CONTROL] = 1,
            [_SC_SAVED_IDS] = 1,
            [_SC_REALTIME_SIGNALS] = 1,
            [_SC_PRIORITY_SCHEDULING] = -1,
            [_SC_TIMERS] = VER,
            [_SC_ASYNCHRONOUS_IO] = VER,
            [_SC_PRIORITIZED_IO] = -1,
            [_SC_SYNCHRONIZED_IO] = -1,
            [_SC_FSYNC] = VER,
            [_SC_MAPPED_FILES] = VER,
            [_SC_MEMLOCK] = VER,
            [_SC_MEMLOCK_RANGE] = VER,
            [_SC_MEMORY_PROTECTION] = VER,
            [_SC_MESSAGE_PASSING] = VER,
            [_SC_SEMAPHORES] = VER,
            [_SC_SHARED_MEMORY_OBJECTS] = VER,
            [_SC_AIO_LISTIO_MAX] = -1,
            [_SC_AIO_MAX] = -1,
            [_SC_AIO_PRIO_DELTA_MAX] = JT_ZERO, /* ?? */
            [_SC_DELAYTIMER_MAX] = _POSIX_DELAYTIMER_MAX,
            [_SC_MQ_OPEN_MAX] = -1,
            [_SC_MQ_PRIO_MAX] = JT_MQ_PRIO_MAX,
            [_SC_VERSION] = VER,
            [_SC_PAGE_SIZE] = JT_PAGE_SIZE,
            [_SC_RTSIG_MAX] = _NSIG - 1 - 31 - 3,
            [_SC_SEM_NSEMS_MAX] = SEM_NSEMS_MAX,
            [_SC_SEM_VALUE_MAX] = JT_SEM_VALUE_MAX,
            [_SC_SIGQUEUE_MAX] = -1,
            [_SC_TIMER_MAX] = -1,
            [_SC_BC_BASE_MAX] = _POSIX2_BC_BASE_MAX,
            [_SC_BC_DIM_MAX] = _POSIX2_BC_DIM_MAX,
            [_SC_BC_SCALE_MAX] = _POSIX2_BC_SCALE_MAX,
            [_SC_BC_STRING_MAX] = _POSIX2_BC_STRING_MAX,
            [_SC_COLL_WEIGHTS_MAX] = COLL_WEIGHTS_MAX,
            [_SC_EXPR_NEST_MAX] = -1,
            [_SC_LINE_MAX] = -1,
            [_SC_RE_DUP_MAX] = RE_DUP_MAX,
            [_SC_2_VERSION] = VER,
            [_SC_2_C_BIND] = VER,
            [_SC_2_C_DEV] = -1,
            [_SC_2_FORT_DEV] = -1,
            [_SC_2_FORT_RUN] = -1,
            [_SC_2_SW_DEV] = -1,
            [_SC_2_LOCALEDEF] = -1,
            [_SC_IOV_MAX] = IOV_MAX,
            [_SC_THREADS] = VER,
            [_SC_THREAD_SAFE_FUNCTIONS] = VER,
            [_SC_GETGR_R_SIZE_MAX] = -1,
            [_SC_GETPW_R_SIZE_MAX] = -1,
            [_SC_LOGIN_NAME_MAX] = 256,
            [_SC_TTY_NAME_MAX] = TTY_NAME_MAX,
            [_SC_THREAD_DESTRUCTOR_ITERATIONS] = PTHREAD_DESTRUCTOR_ITERATIONS,
            [_SC_THREAD_KEYS_MAX] = PTHREAD_KEYS_MAX,
            [_SC_THREAD_STACK_MIN] = PTHREAD_STACK_MIN,
            [_SC_THREAD_THREADS_MAX] = -1,
            [_SC_THREAD_ATTR_STACKADDR] = VER,
            [_SC_THREAD_ATTR_STACKSIZE] = VER,
            [_SC_THREAD_PRIORITY_SCHEDULING] = VER,
            [_SC_THREAD_PRIO_INHERIT] = -1,
            [_SC_THREAD_PRIO_PROTECT] = -1,
            [_SC_THREAD_PROCESS_SHARED] = VER,
            [_SC_NPROCESSORS_CONF] = JT_NPROCESSORS_CONF,
            [_SC_NPROCESSORS_ONLN] = JT_NPROCESSORS_ONLN,
            [_SC_PHYS_PAGES] = JT_PHYS_PAGES,
            [_SC_AVPHYS_PAGES] = JT_AVPHYS_PAGES,
            [_SC_ATEXIT_MAX] = -1,
            [_SC_PASS_MAX] = -1,
            [_SC_XOPEN_VERSION] = _XOPEN_VERSION,
            [_SC_XOPEN_XCU_VERSION] = _XOPEN_VERSION,
            [_SC_XOPEN_UNIX] = 1,
            [_SC_XOPEN_CRYPT] = -1,
            [_SC_XOPEN_ENH_I18N] = 1,
            [_SC_XOPEN_SHM] = 1,
            [_SC_2_CHAR_TERM] = -1,
            [_SC_2_UPE] = -1,
            [_SC_XOPEN_XPG2] = -1,
            [_SC_XOPEN_XPG3] = -1,
            [_SC_XOPEN_XPG4] = -1,
            [_SC_NZERO] = NZERO,
            [_SC_XBS5_ILP32_OFF32] = -1,
            [_SC_XBS5_ILP32_OFFBIG] = sizeof(long) == 4 ? 1 : JT_ZERO,
            [_SC_XBS5_LP64_OFF64] = sizeof(long) == 8 ? 1 : JT_ZERO,
            [_SC_XBS5_LPBIG_OFFBIG] = -1,
            [_SC_XOPEN_LEGACY] = -1,
            [_SC_XOPEN_REALTIME] = -1,
            [_SC_XOPEN_REALTIME_THREADS] = -1,
            [_SC_ADVISORY_INFO] = VER,
            [_SC_BARRIERS] = VER,
            [_SC_CLOCK_SELECTION] = VER,
            [_SC_CPUTIME] = VER,
            [_SC_THREAD_CPUTIME] = VER,
            [_SC_MONOTONIC_CLOCK] = VER,
            [_SC_READER_WRITER_LOCKS] = VER,
            [_SC_SPIN_LOCKS] = VER,
            [_SC_REGEXP] = 1,
            [_SC_SHELL] = 1,
            [_SC_SPAWN] = VER,
            [_SC_SPORADIC_SERVER] = -1,
            [_SC_THREAD_SPORADIC_SERVER] = -1,
            [_SC_TIMEOUTS] = VER,
            [_SC_TYPED_MEMORY_OBJECTS] = -1,
            [_SC_2_PBS] = -1,
            [_SC_2_PBS_ACCOUNTING] = -1,
            [_SC_2_PBS_LOCATE] = -1,
            [_SC_2_PBS_MESSAGE] = -1,
            [_SC_2_PBS_TRACK] = -1,
            [_SC_SYMLOOP_MAX] = SYMLOOP_MAX,
            [_SC_STREAMS] = JT_ZERO,
            [_SC_2_PBS_CHECKPOINT] = -1,
            [_SC_V6_ILP32_OFF32] = -1,
            [_SC_V6_ILP32_OFFBIG] = sizeof(long) == 4 ? 1 : JT_ZERO,
            [_SC_V6_LP64_OFF64] = sizeof(long) == 8 ? 1 : JT_ZERO,
            [_SC_V6_LPBIG_OFFBIG] = -1,
            [_SC_HOST_NAME_MAX] = HOST_NAME_MAX,
            [_SC_TRACE] = -1,
            [_SC_TRACE_EVENT_FILTER] = -1,
            [_SC_TRACE_INHERIT] = -1,
            [_SC_TRACE_LOG] = -1,

            [_SC_IPV6] = VER,
            [_SC_RAW_SOCKETS] = VER,
            [_SC_V7_ILP32_OFF32] = -1,
            [_SC_V7_ILP32_OFFBIG] = sizeof(long) == 4 ? 1 : JT_ZERO,
            [_SC_V7_LP64_OFF64] = sizeof(long) == 8 ? 1 : JT_ZERO,
            [_SC_V7_LPBIG_OFFBIG] = -1,
            [_SC_SS_REPL_MAX] = -1,
            [_SC_TRACE_EVENT_NAME_MAX] = -1,
            [_SC_TRACE_NAME_MAX] = -1,
            [_SC_TRACE_SYS_MAX] = -1,
            [_SC_TRACE_USER_EVENT_MAX] = -1,
            [_SC_XOPEN_STREAMS] = JT_ZERO,
            [_SC_THREAD_ROBUST_PRIO_INHERIT] = -1,
            [_SC_THREAD_ROBUST_PRIO_PROTECT] = -1,
    };

    if (name >= sizeof(values) / sizeof(values[0]) || !values[name]) {
        errno = EINVAL;
        return -1;
    } else if (values[name] >= -1) {
        return values[name];
    } else if (values[name] < -256) {
        struct rlimit lim;
        getrlimit(values[name] & 16383, &lim);
        return lim.rlim_cur > LONG_MAX ? LONG_MAX : lim.rlim_cur;
    }

    switch ((unsigned char)values[name]) {
    case VER & 255:
        return _POSIX_VERSION;
    case JT_ARG_MAX & 255:
        return ARG_MAX;
    case JT_MQ_PRIO_MAX & 255:
        return MQ_PRIO_MAX;
    case JT_PAGE_SIZE & 255:
        return PAGE_SIZE;
    case JT_SEM_VALUE_MAX & 255:
        return SEM_VALUE_MAX;
    case JT_NPROCESSORS_CONF & 255:
    case JT_NPROCESSORS_ONLN & 255:
        return _zx_system_get_num_cpus();
    case JT_PHYS_PAGES & 255:
        return _zx_system_get_physmem() / PAGE_SIZE;
    case JT_AVPHYS_PAGES & 255:
        // TODO(kulakowski) Ask zircon for physical memory allocation

        // Note that on Linux the calculation looks like this
        // depending on whether _SC_PHYS_PAGES was asked for or not:
        // if (name == _SC_PHYS_PAGES)
        //     mem = si.totalram;
        // else
        //     mem = si.freeram + si.bufferram;
        // mem *= si.mem_unit;
        // mem /= PAGE_SIZE;
        // return (mem > LONG_MAX) ? LONG_MAX : mem;
        errno = EINVAL;
        return -1;
    case JT_ZERO & 255:
        return 0;
    }
    return values[name];
}