#compdef top

local curcontext="$curcontext" state state_descr line ret=1
local -A opt_args
local -a specs fields order opts

opts=( -s -w -C )

case $OSTYPE in
  *linux*)
    # based on procps-ng-3.3.15
    fields=(
      '%CPU:CPU usage' '%MEM:memory usage (res)' 'CGROUPS:control groups'
      'CODE:code size' 'COMMAND:Command name/line' 'DATA:data + stack size'
      'ENVIRON:environment variables' 'Flags:task flags' 'GID:group id'
      'GROUP:group name' 'NI:nice value' 'P:last used CPU (SMP)'
      'PGRP:process group id' 'PID:process id' 'PPID:parent pid' 'PR:priority'
      'RES:resident memory size' 'RUID:real user id' 'RUSER:real uid'
      'S:process status' 'SHR:shared memory size' 'SID:session id'
      'SUID:saved uid' 'SUPGIDS:supplementary gids'
      'SUPGRPS:supplementary group names' 'SUSER:saved username'
      'SWAP:swapped sized' 'TGID:thread gid' 'TIME:CPU time'
      'TIME+:CPU time (hundredths)' 'TPGID:TTY gid' 'TTY:controlling TTY'
      'UID:user id' 'USED:memory in use' 'USER:user name'
      'VIRT:virtual memory size' 'WCHAN:sleeping in function'
      'nDRT:dirty pages count' 'nMaj:major page count' 'nMin:minor page count'
      'nTH:number of threads' 'nsIPC:IPC namespace' 'nsMNT:MNT namespace'
      'nsNET:NET namespace' 'nsPID:PID namespace' 'nsUSER:USER namespace'
      'nsUTS:UTS namespace' 'vMj:major page fault count delta'
      'vMn:minor page fault count delta' 'LXC:lxc container name'
      'OOMa:out of memory adjustment factor' 'OOMs:out of memory source'
      'Rsan:resident anonymous memory size'
      'RSfd:resident file-backed memory size' 'RSlk:resident locked memory size'
      'RSsh:resident shared memory size' 'CGNAME:control group name'
      'NU:last known NUMA node'
    )
    order=( '+:descending (default)' '-:ascending' )
    local -a units=( 'k:KiB' 'm:MiB' 'g:GiB' 't:TiB' 'p:PiB' 'e:EiB' )
    specs=(
      '(-)-'{h,v}'[show version and usage]'
      '-b[batch mode]'
      '-c[command line/program name toggle]'
      '-d+[delay time interval]:interval'
      '-E+[specify the memory scaling unit]: : _describe -V -t units unit units'
      '-H[threads mode operation]'
      '-i[idle process toggle]'
      '-n+[number of iterations]:number of iterations'
      '-o+[override sort field]:fieldname:->sortkey'
      '-O[output field names]'
      '(-u -U)*-p+[monitor pids]: :_sequence -s , _pids'
      '-s[secure mode operation]'
      '-S[cumulative time toggle]'
      '(-U -p)-u+[effective user filter mode]: :_users'
      '(-u -p)-U+[user filter mode]: :_users'
      '-w+[output width override]::number'
      '-1[single/separate cpu states toggle]'
    );;
  freebsd*|openbsd*)
    fields=( cpu size res time pri pid )
    specs=(
      '-b[batch mode]'
      '-d+[show only specified number of displays then exit]:count:'
      '-H[display individual threads]'
      '-I[do not display idle processes]'
      '-i[interactive mode]'
      '-n[non-interactive mode (identical to batch mode)]'
      '-p+[filter by the specified pid]: :_pids'
      '-q[renice top to -20]'
      '-S[show system processes]'
      '-s+[specify delay interval]:seconds:'
      '-u[do not translate uid to name]'
      '1: :_guard "^-*" "number of processes to display"'
    );|
  freebsd*)
    fields+=( threads total read write fault vcsw ivcsw jid swap )
    specs+=(
      '-C[CPU display mode]'
      '-a[display command names via argv]'
      '-j[display the jail ID]'
      '-t[do not display the top process]'
      '-m+[specify statistic type]:type:(( cpu\:default io ))'
      '-o+[sort process display by the specified field]:field:( $fields )'
      '-P[per-cpu CPU usage statistics]'
      '(1 -)-v[write version number and exit]'
      '-w[display approximate swap usage]'
      "-z[don't display system idle process]"
      '-J+[show processes owned by the specified jail]:jail:_jails -0'
      '-T[display thread ID instead of process ID]'
      '-U+[show processes owned by the specified username]: :_users'
    );;
  openbsd*)
    fields+=( command )
    order=( '-:reverse order' )
    specs+=(
      '-1[combine CPU statistic into one line]'
      '-t[show the routing table instead of the wait channel]'
      '-C[show command arguments as well as process name]'
      '-g+[filter processes by the specified string]:string'
      '-o+[sort process display by the specified field]:field:->sortkey'
      '-T+[filter processes by the specified routing table]:routing table:_routing_tables'
      '-U+[filter processes by the specified user]: :_users -M "L\:|-="'
    );;
  darwin*)
    local -a modes
    opts=( -C )   # no option stacking
    modes=(
      'a:count events cumulatively'
      'd:count events relative to the previous sample'
      'e:count events using absolute counters'
      'n:non-event mode (default)'
    )
    fields=(
      'pid:process id'
      'command:command name'
      'cpu:CPU usage'
      'cpu_me:CPU time charged to me by other processes'
      'cpu_others:CPU time charged to other processes by me'
      'csw:number of context switches'
      'time:execution time'
      {threads,th}':number of threads'
      {ports,prt}':number of Mach ports'
      {mregion,mreg,reg}':number of memory regions'
      'mem:internal memory size'
      'rprvt:resident private address space size'
      'purg:purgeable memory size'
      'vsize:total memory size'
      'vprvt:private address space size'
      'kprvt:private kernel memory size'
      'kshrd:shared kernel memory size'
      'pgrp:process group id'
      'ppid:parent process id'
      {state,pstate}':process state'
      'uid:user id'
      {wq,'#wq',workqueue}':workqueue total/running'
      {faults,fault}':number of page faults'
      {cow,cow_faults}':copy-on-write faults'
      {user,username}':username'
      'msgsent:total number of Mach messages sent'
      'msgrecv:total number of Mach messages received'
      'sysbsd:total BSD syscalls'
      'sysmach:total Mach syscalls'
      'pageins:total pageins'
      'boosts:number of boosts held by the process'
      'instrs:number of instructions retired by the process'
      'cycles:number of cycles spent in the process'
    )
    order=( '-:descending (default)' '+:ascending' )
    specs=(
      '-a[count events cumulatively]'
      '-c[set event counting mode]:mode:(( $modes ))'
      '-d[count events relative to the previous sample]'
      '-e[count events using absolute counters]'
      '-F[do not calculate statistics on shared libraries]'
      '-f[calculate statistics on shared libraries]'
      '(-)-h[print usage information and exit]'
      '-i+[specify interval between samples for -f option]:interval'
      '-l+[logging mode. output specified number of samples periodically]:number of samples'
      '-ncols[output specified number of columns in logging mode]:number of columns'
      '-n+[only display up to the specified number of processes]:number of processes:'
      '-O+[specify the secondary sort key]:key:->sortkey'
      '-o+[specify the primary sort key]:key:->sortkey'
      '-R[do not traverse and report memory object map for each process]'
      '-r[traverse and report memory object map for each process]'
      '-S[display global statistics for swap and purgeable memory]'
      '-s[set the delay between update]:number of seconds'
      '-stats[only display the specified fields]:list of fields:->fieldlist'
      '*-pid[only display the specified process]:pid:_pids'
      {-user,-U+}'[only display processes owned by the specified user]:user:_users'
      '-u[same as -o cpu -O time]'
    );;
esac

if (( $#specs == 0 )); then
  _default
  return
fi

_arguments $opts : "$specs[@]" && ret=0

case $state in
  (sortkey)
    compset -P '(+|-)' && order=()
    _alternative 'sort-orders:sort order:(( $order ))' \
	'sort-keys:sort key:(( $fields ))' && ret=0
    ;;
  (fieldlist)
    _sequence -s , _describe -t fields 'field' fields && ret=0
    ;;
esac

return ret
