(* (c) 2017, 2018 Hannes Mehnert, all rights reserved *)

open Vmm_core
open Vmm_commands

open Rresult
open Astring

let oid = Asn.OID.(base 1 3 <| 6 <| 1 <| 4 <| 1 <| 49836 <| 42)

open Rresult.R.Infix

let guard p err = if p then Ok () else Error err

let decode_strict codec cs =
  match Asn.decode codec cs with
  | Ok (a, cs) ->
    guard (Cstruct.len cs = 0) (`Msg "trailing bytes") >>= fun () ->
    Ok a
  | Error (`Parse msg) -> Error (`Msg msg)

let projections_of asn =
  let c = Asn.codec Asn.der asn in
  (decode_strict c, Asn.encode c)

let ipv4 =
  let f cs = Ipaddr.V4.of_octets_exn (Cstruct.to_string cs)
  and g ip = Cstruct.of_string (Ipaddr.V4.to_octets ip)
  in
  Asn.S.map f g Asn.S.octet_string

let policy =
  let f (cpuids, vms, memory, block, bridges) =
    let bridges = String.Set.of_list bridges
    and cpuids = IS.of_list cpuids
    in
    Policy.{ vms ; cpuids ; memory ; block ; bridges }
  and g policy =
    (IS.elements policy.Policy.cpuids,
     policy.Policy.vms,
     policy.Policy.memory,
     policy.Policy.block,
     String.Set.elements policy.Policy.bridges)
  in
  Asn.S.map f g @@
  Asn.S.(sequence5
           (required ~label:"cpuids" Asn.S.(sequence_of int))
           (required ~label:"vms" int)
           (required ~label:"memory" int)
           (optional ~label:"block" int)
           (required ~label:"bridges" Asn.S.(sequence_of utf8_string)))

let console_cmd =
  let f = function
    | `C1 () -> `Console_add
    | `C2 `C1 ts -> `Console_subscribe (`Since ts)
    | `C2 `C2 c -> `Console_subscribe (`Count c)
  and g = function
    | `Console_add -> `C1 ()
    | `Console_subscribe `Since ts -> `C2 (`C1 ts)
    | `Console_subscribe `Count c -> `C2 (`C2 c)
  in
  Asn.S.map f g @@
  Asn.S.(choice2
           (explicit 0 null)
           (explicit 1 (choice2 (explicit 0 utc_time) (explicit 1 int))))

(* TODO is this good? *)
let int64 =
  let f cs = Cstruct.BE.get_uint64 cs 0
  and g data =
    let buf = Cstruct.create 8 in
    Cstruct.BE.set_uint64 buf 0 data ;
    buf
  in
  Asn.S.map f g Asn.S.octet_string

let timeval =
  Asn.S.(sequence2
           (required ~label:"seconds" int64)
           (required ~label:"microseconds" int))

let ru =
  let open Stats in
  let f (utime, (stime, (maxrss, (ixrss, (idrss, (isrss, (minflt, (majflt, (nswap, (inblock, (outblock, (msgsnd, (msgrcv, (nsignals, (nvcsw, nivcsw))))))))))))))) =
    { utime ; stime ; maxrss ; ixrss ; idrss ; isrss ; minflt ; majflt ; nswap ; inblock ; outblock ; msgsnd ; msgrcv ; nsignals ; nvcsw ; nivcsw }
  and g ru =
    (ru.utime, (ru.stime, (ru.maxrss, (ru.ixrss, (ru.idrss, (ru.isrss, (ru.minflt, (ru.majflt, (ru.nswap, (ru.inblock, (ru.outblock, (ru.msgsnd, (ru.msgrcv, (ru.nsignals, (ru.nvcsw, ru.nivcsw)))))))))))))))
  in
  Asn.S.map f g @@
  Asn.S.(sequence @@
           (required ~label:"utime" timeval)
         @ (required ~label:"stime" timeval)
         @ (required ~label:"maxrss" int64)
         @ (required ~label:"ixrss" int64)
         @ (required ~label:"idrss" int64)
         @ (required ~label:"isrss" int64)
         @ (required ~label:"minflt" int64)
         @ (required ~label:"majflt" int64)
         @ (required ~label:"nswap" int64)
         @ (required ~label:"inblock" int64)
         @ (required ~label:"outblock" int64)
         @ (required ~label:"msgsnd" int64)
         @ (required ~label:"msgrcv" int64)
         @ (required ~label:"nsignals" int64)
         @ (required ~label:"nvcsw" int64)
        -@ (required ~label:"nivcsw" int64))

(* although this changed (+runtime + cow + start) from V3 to V4, since it's not
   persistent, no need to care about it *)
let kinfo_mem =
  let open Stats in
  let f (vsize, (rss, (tsize, (dsize, (ssize, (runtime, (cow, start))))))) =
    { vsize ; rss ; tsize ; dsize ; ssize ; runtime ; cow ; start }
  and g t =
    (t.vsize, (t.rss, (t.tsize, (t.dsize, (t.ssize, (t.runtime, (t.cow, t.start)))))))
  in
  Asn.S.map f g @@
  Asn.S.(sequence @@
           (required ~label:"bsize" int64)
         @ (required ~label:"rss" int64)
         @ (required ~label:"tsize" int64)
         @ (required ~label:"dsize" int64)
         @ (required ~label:"ssize" int64)
         @ (required ~label:"runtime" int64)
         @ (required ~label:"cow" int)
        -@ (required ~label:"start" timeval))

(* TODO is this good? *)
let int32 =
  let f i = Int32.of_int i
  and g i = Int32.to_int i
  in
  Asn.S.map f g Asn.S.int

let ifdata =
  let open Stats in
  let f (bridge, (flags, (send_length, (max_send_length, (send_drops, (mtu, (baudrate, (input_packets, (input_errors, (output_packets, (output_errors, (collisions, (input_bytes, (output_bytes, (input_mcast, (output_mcast, (input_dropped, output_dropped))))))))))))))))) =
    { bridge ; flags; send_length; max_send_length; send_drops; mtu; baudrate; input_packets; input_errors; output_packets; output_errors; collisions; input_bytes; output_bytes; input_mcast; output_mcast; input_dropped; output_dropped }
  and g i =
    (i.bridge, (i.flags, (i.send_length, (i.max_send_length, (i.send_drops, (i.mtu, (i.baudrate, (i.input_packets, (i.input_errors, (i.output_packets, (i.output_errors, (i.collisions, (i.input_bytes, (i.output_bytes, (i.input_mcast, (i.output_mcast, (i.input_dropped, i.output_dropped)))))))))))))))))
  in
  Asn.S.map f g @@
  Asn.S.(sequence @@
         (required ~label:"bridge" utf8_string)
       @ (required ~label:"flags" int32)
       @ (required ~label:"send_length" int32)
       @ (required ~label:"max_send_length" int32)
       @ (required ~label:"send_drops" int32)
       @ (required ~label:"mtu" int32)
       @ (required ~label:"baudrate" int64)
       @ (required ~label:"input_packets" int64)
       @ (required ~label:"input_errors" int64)
       @ (required ~label:"output_packets" int64)
       @ (required ~label:"output_errors" int64)
       @ (required ~label:"collisions" int64)
       @ (required ~label:"input_bytes" int64)
       @ (required ~label:"output_bytes" int64)
       @ (required ~label:"input_mcast" int64)
       @ (required ~label:"output_mcast" int64)
       @ (required ~label:"input_dropped" int64)
      -@ (required ~label:"output_dropped" int64))

let stats_cmd =
  let f = function
    | `C1 (name, pid, taps) -> `Stats_add (name, pid, taps)
    | `C2 () -> `Stats_remove
    | `C3 () -> `Stats_subscribe
  and g = function
    | `Stats_add (name, pid, taps) -> `C1 (name, pid, taps)
    | `Stats_remove -> `C2 ()
    | `Stats_subscribe -> `C3 ()
  in
  Asn.S.map f g @@
  Asn.S.(choice3
           (explicit 0 (sequence3
                          (required ~label:"vmmdev" utf8_string)
                          (required ~label:"pid" int)
                          (required ~label:"network"
                             (sequence_of
                                (sequence2
                                   (required ~label:"bridge" utf8_string)
                                   (required ~label:"tap" utf8_string))))))
           (explicit 1 null)
           (explicit 2 null))

let of_name, to_name =
  Name.to_list,
  fun list -> match Name.of_list list with
    | Error (`Msg msg) -> Asn.S.error (`Parse msg)
    | Ok name -> name

let log_event =
  (* this is stored on disk persistently -- be aware when changing the grammar
     below to only ever extend it! *)
  let f = function
    | `C1 `C1 () -> `Startup
    | `C1 `C2 (name, ip, port) -> `Login (to_name name, ip, port)
    | `C1 `C3 (name, ip, port) -> `Logout (to_name name, ip, port)
    | `C1 `C4 (name, pid, taps, block) ->
      let name = to_name name in
      let blocks = match block with
        | None -> []
        | Some block -> [ block, Name.block_name name block ]
      and taps = List.map (fun tap -> tap, tap) taps
      in
      `Unikernel_start (name, pid, taps, blocks)
    | `C2 `C1 (name, pid, taps, blocks) ->
      let blocks = List.map (fun (name, dev) ->
          name, match Name.of_string dev with
          | Error `Msg msg -> Asn.S.error (`Parse msg)
          | Ok id -> id) blocks
      in
      `Unikernel_start (to_name name, pid, taps, blocks)
    | `C1 `C5 (name, pid, status) ->
      let status' = match status with
        | `C1 n -> `Exit n
        | `C2 n -> `Signal n
        | `C3 n -> `Stop n
      in
      `Unikernel_stop (to_name name, pid, status')
    | `C1 `C6 () -> `Hup
    | `C2 `C2 () -> assert false (* placeholder *)
  and g = function
    | `Startup -> `C1 (`C1 ())
    | `Login (name, ip, port) -> `C1 (`C2 (of_name name, ip, port))
    | `Logout (name, ip, port) -> `C1 (`C3 (of_name name, ip, port))
    | `Unikernel_start (name, pid, taps, blocks) ->
      let blocks =
        List.map (fun (name, dev) -> name, Name.to_string dev) blocks
      in
      `C2 (`C1 (of_name name, pid, taps, blocks))
    | `Unikernel_stop (name, pid, status) ->
      let status' = match status with
        | `Exit n -> `C1 n
        | `Signal n -> `C2 n
        | `Stop n -> `C3 n
      in
      `C1 (`C5 (of_name name, pid, status'))
    | `Hup -> `C1 (`C6 ())
  in
  let endp =
    Asn.S.(sequence3
            (required ~label:"name" (sequence_of utf8_string))
            (required ~label:"ip" ipv4)
            (required ~label:"port" int))
  in
  Asn.S.map f g @@
  Asn.S.(choice2
           (choice6
              (explicit 0 null)
              (explicit 1 endp)
              (explicit 2 endp)
              (* the old V3 unikernel start *)
              (explicit 3 (sequence4
                             (required ~label:"name" (sequence_of utf8_string))
                             (required ~label:"pid" int)
                             (required ~label:"taps" (sequence_of utf8_string))
                             (optional ~label:"block" utf8_string)))
              (explicit 4 (sequence3
                             (required ~label:"name" (sequence_of utf8_string))
                             (required ~label:"pid" int)
                             (required ~label:"status" (choice3
                                                          (explicit 0 int)
                                                          (explicit 1 int)
                                                          (explicit 2 int)))))
              (explicit 5 null))
           (choice2
              (* the new V4 unikernel start*)
              (explicit 6 (sequence4
                             (required ~label:"name" (sequence_of utf8_string))
                             (required ~label:"pid" int)
                             (required ~label:"taps"
                                (sequence_of
                                   (sequence2
                                      (required ~label:"bridge" utf8_string)
                                      (required ~label:"tap" utf8_string))))
                             (required ~label:"blocks"
                                (sequence_of
                                   (sequence2
                                      (required ~label:"name" utf8_string)
                                      (required ~label:"device" utf8_string))))))
              (explicit 7 null (* placeholder *) )))


let log_cmd =
  let f = function
    | `C1 since -> `Log_subscribe (`Since since)
    | `C2 n -> `Log_subscribe (`Count n)
  and g = function
    | `Log_subscribe `Since since -> `C1 since
    | `Log_subscribe `Count n -> `C2 n
  in
  Asn.S.map f g @@
  Asn.S.(choice2 (explicit 0 utc_time) (explicit 1 int))

let typ =
  let f = function
    | `C1 () -> `Solo5
    | `C2 () -> assert false
  and g = function
    | `Solo5 -> `C1 ()
  in
  Asn.S.map f g @@
  Asn.S.(choice2 (explicit 0 null) (explicit 1 null))

let fail_behaviour =
  let f = function
    | `C1 () -> `Quit
    | `C2 xs ->
      let exit_codes = match xs with
        | [] -> None
        | xs -> Some (IS.of_list xs)
      in
      `Restart exit_codes
  and g = function
    | `Quit -> `C1 ()
    | `Restart xs ->
      let exit_codes = match xs with
        | None -> []
        | Some i -> IS.elements i
      in
      `C2 exit_codes
  in
  Asn.S.map f g @@
  Asn.S.(choice2
           (explicit 0 null)
           (explicit 1 (set_of int)))

(* this is part of the state file! *)
let v0_unikernel_config =
  let image =
    let f = function
      | `C1 x -> `Hvt_amd64, x
      | `C2 x -> `Hvt_arm64, x
      | `C3 x -> `Hvt_amd64_compressed, x
    and g = function
      | `Hvt_amd64, x -> `C1 x
      | `Hvt_arm64, x -> `C2 x
      | `Hvt_amd64_compressed, x -> `C3 x
    in
    Asn.S.map f g @@
    Asn.S.(choice3
             (explicit 0 octet_string)
             (explicit 1 octet_string)
             (explicit 2 octet_string))
  in
  let open Unikernel in
  let f (cpuid, memory, block_device, network_interfaces, image, argv) =
    let bridges = match network_interfaces with None -> [] | Some xs -> List.map (fun n -> n, None) xs
    and block_devices = match block_device with None -> [] | Some b -> [ b ]
    in
    let typ = `Solo5
    and compressed = match fst image with `Hvt_amd64_compressed -> true | _ -> false
    and image = snd image
    and fail_behaviour = `Quit (* TODO maybe set to restart by default :) *)
    in
    { typ ; compressed ; image ; fail_behaviour ; cpuid ; memory ; block_devices ; bridges ; argv }
  and g _vm = failwith "cannot encode v0 unikernel configs"
  in
  Asn.S.map f g @@
  Asn.S.(sequence6
           (required ~label:"cpu" int)
           (required ~label:"memory" int)
           (optional ~label:"block" utf8_string)
           (optional ~label:"network_interfaces" (sequence_of utf8_string))
           (required ~label:"image" image)
           (optional ~label:"arguments" (sequence_of utf8_string)))


(* this is part of the state file (and unikernel_create command)
   be aware if this (or a dependent grammar) is changed! *)
let v1_unikernel_config =
  let open Unikernel in
  let f (typ, (compressed, (image, (fail_behaviour, (cpuid, (memory, (blocks, (bridges, argv)))))))) =
    let bridges = match bridges with None -> [] | Some xs -> List.map (fun b -> b, None) xs
    and block_devices = match blocks with None -> [] | Some xs -> xs
    in
    { typ ; compressed ; image ; fail_behaviour ; cpuid ; memory ; block_devices ; bridges ; argv }
  and g _vm = failwith "cannot encode v1 unikernel configs"
  in
  Asn.S.(map f g @@ sequence @@
           (required ~label:"typ" typ)
         @ (required ~label:"compressed" bool)
         @ (required ~label:"image" octet_string)
         @ (required ~label:"fail behaviour" fail_behaviour)
         @ (required ~label:"cpuid" int)
         @ (required ~label:"memory" int)
         @ (optional ~label:"blocks" (explicit 0 (set_of utf8_string)))
         @ (optional ~label:"bridges" (explicit 1 (set_of utf8_string)))
        -@ (optional ~label:"arguments"(explicit 2 (sequence_of utf8_string))))

let unikernel_config =
  let open Unikernel in
  let f (typ, (compressed, (image, (fail_behaviour, (cpuid, (memory, (blocks, (bridges, argv)))))))) =
    let bridges = match bridges with None -> [] | Some xs -> xs
    and block_devices = match blocks with None -> [] | Some xs -> xs
    in
    { typ ; compressed ; image ; fail_behaviour ; cpuid ; memory ; block_devices ; bridges ; argv }
  and g vm =
    let bridges = match vm.bridges with [] -> None | xs -> Some xs
    and blocks = match vm.block_devices with [] -> None | xs -> Some xs
    in
    (vm.typ, (vm.compressed, (vm.image, (vm.fail_behaviour, (vm.cpuid, (vm.memory, (blocks, (bridges, vm.argv))))))))
  in
  Asn.S.(map f g @@ sequence @@
           (required ~label:"typ" typ)
         @ (required ~label:"compressed" bool)
         @ (required ~label:"image" octet_string)
         @ (required ~label:"fail behaviour" fail_behaviour)
         @ (required ~label:"cpuid" int)
         @ (required ~label:"memory" int)
         @ (optional ~label:"blocks" (explicit 0 (set_of utf8_string)))
         @ (optional ~label:"bridges"
              (explicit 1 (sequence_of
                             (sequence2
                                (required ~label:"netif" utf8_string)
                                (optional ~label:"bridge" utf8_string)))))
        -@ (optional ~label:"arguments"(explicit 2 (sequence_of utf8_string))))

let unikernel_cmd =
  let f = function
    | `C1 `C1 () -> `Unikernel_info
    | `C1 `C2 vm -> `Unikernel_create vm
    | `C1 `C3 vm -> `Unikernel_force_create vm
    | `C1 `C4 () -> `Unikernel_destroy
    | `C1 `C5 vm -> `Unikernel_create vm
    | `C1 `C6 vm -> `Unikernel_force_create vm
    | `C2 `C1 () -> `Unikernel_get
    | `C2 `C2 () -> assert false (* placeholder *)
  and g = function
    | `Unikernel_info -> `C1 (`C1 ())
    | `Unikernel_create vm -> `C1 (`C5 vm)
    | `Unikernel_force_create vm -> `C1 (`C6 vm)
    | `Unikernel_destroy -> `C1 (`C4 ())
    | `Unikernel_get -> `C2 (`C1 ())
  in
  Asn.S.map f g @@
  Asn.S.(choice2
          (choice6
             (explicit 0 null)
             (explicit 1 v1_unikernel_config)
             (explicit 2 v1_unikernel_config)
             (explicit 3 null)
             (explicit 4 unikernel_config)
             (explicit 5 unikernel_config))
          (choice2
             (explicit 6 null)
             (explicit 7 null (* placeholder *) )))

let policy_cmd =
  let f = function
    | `C1 () -> `Policy_info
    | `C2 policy -> `Policy_add policy
    | `C3 () -> `Policy_remove
  and g = function
    | `Policy_info -> `C1 ()
    | `Policy_add policy -> `C2 policy
    | `Policy_remove -> `C3 ()
  in
  Asn.S.map f g @@
  Asn.S.(choice3
           (explicit 0 null)
           (explicit 1 policy)
           (explicit 2 null))

let block_cmd =
  let f = function
    | `C1 () -> `Block_info
    | `C2 size -> `Block_add size
    | `C3 () -> `Block_remove
  and g = function
    | `Block_info -> `C1 ()
    | `Block_add size -> `C2 size
    | `Block_remove -> `C3 ()
  in
  Asn.S.map f g @@
  Asn.S.(choice3
           (explicit 0 null)
           (explicit 1 int)
           (explicit 2 null))

let version =
  let f data = match data with
    | 4 -> `AV4
    | 3 -> `AV3
    | x -> Asn.S.error (`Parse (Printf.sprintf "unknown version number 0x%X" x))
  and g = function
    | `AV4 -> 4
    | `AV3 -> 3
  in
  Asn.S.map f g Asn.S.int

let wire_command =
  let f = function
    | `C1 console -> `Console_cmd console
    | `C2 stats -> `Stats_cmd stats
    | `C3 log -> `Log_cmd log
    | `C4 vm -> `Unikernel_cmd vm
    | `C5 policy -> `Policy_cmd policy
    | `C6 block -> `Block_cmd block
  and g = function
    | `Console_cmd c -> `C1 c
    | `Stats_cmd c -> `C2 c
    | `Log_cmd c -> `C3 c
    | `Unikernel_cmd c -> `C4 c
    | `Policy_cmd c -> `C5 c
    | `Block_cmd c -> `C6 c
  in
  Asn.S.map f g @@
  Asn.S.(choice6
           (explicit 0 console_cmd)
           (explicit 1 stats_cmd)
           (explicit 2 log_cmd)
           (explicit 3 unikernel_cmd)
           (explicit 4 policy_cmd)
           (explicit 5 block_cmd))

let data =
  let f = function
    | `C1 (timestamp, data) -> `Console_data (timestamp, data)
    | `C2 (ru, ifs, vmm, mem) -> `Stats_data (ru, mem, vmm, ifs)
    | `C3 (timestamp, event) -> `Log_data (timestamp, event)
  and g = function
    | `Console_data (timestamp, data) -> `C1 (timestamp, data)
    | `Stats_data (ru, mem, ifs, vmm) -> `C2 (ru, vmm, ifs, mem)
    | `Log_data (timestamp, event) -> `C3 (timestamp, event)
  in
  Asn.S.map f g @@
  Asn.S.(choice3
           (explicit 0 (sequence2
                          (required ~label:"timestamp" utc_time)
                          (required ~label:"data" utf8_string)))
           (explicit 1 (sequence4
                          (required ~label:"resource_usage" ru)
                          (required ~label:"ifdata" (sequence_of ifdata))
                          (optional ~label:"vmm_stats" @@ explicit 0
                             (sequence_of (sequence2
                                             (required ~label:"key" utf8_string)
                                             (required ~label:"value" int64))))
                          (optional ~label:"kinfo_mem" @@ implicit 1 kinfo_mem)))
           (explicit 2 (sequence2
                          (required ~label:"timestamp" utc_time)
                          (required ~label:"event" log_event))))

let header =
  let f (version, sequence, name) = { version ; sequence ; name = to_name name }
  and g h = h.version, h.sequence, of_name h.name
  in
  Asn.S.map f g @@
  Asn.S.(sequence3
           (required ~label:"version" version)
           (required ~label:"sequence" int64)
           (required ~label:"name" (sequence_of utf8_string)))

let success =
  let f = function
    | `C1 () -> `Empty
    | `C2 str -> `String str
    | `C3 policies -> `Policies (List.map (fun (name, p) -> to_name name, p) policies)
    | `C4 vms -> `Unikernels (List.map (fun (name, vm) -> to_name name, vm) vms)
    | `C5 blocks -> `Block_devices (List.map (fun (name, s, a) -> to_name name, s, a) blocks)
  and g = function
    | `Empty -> `C1 ()
    | `String s -> `C2 s
    | `Policies ps -> `C3 (List.map (fun (name, p) -> of_name name, p) ps)
    | `Unikernels vms -> `C4 (List.map (fun (name, v) -> of_name name, v) vms)
    | `Block_devices blocks -> `C5 (List.map (fun (name, s, a) -> of_name name, s, a) blocks)
  in
  Asn.S.map f g @@
  Asn.S.(choice5
           (explicit 0 null)
           (explicit 1 utf8_string)
           (explicit 2 (sequence_of
                          (sequence2
                             (required ~label:"name" (sequence_of utf8_string))
                             (required ~label:"policy" policy))))
           (explicit 3 (sequence_of
                          (sequence2
                             (required ~label:"name" (sequence_of utf8_string))
                             (required ~label:"config" unikernel_config))))
           (explicit 4 (sequence_of
                          (sequence3
                             (required ~label:"name" (sequence_of utf8_string))
                             (required ~label:"size" int)
                             (required ~label:"active" bool)))))

let payload =
  let f = function
    | `C1 cmd -> `Command cmd
    | `C2 s -> `Success s
    | `C3 str -> `Failure str
    | `C4 data -> `Data data
  and g = function
    | `Command cmd -> `C1 cmd
    | `Success s -> `C2 s
    | `Failure str -> `C3 str
    | `Data d -> `C4 d
  in
  Asn.S.map f g @@
  Asn.S.(choice4
           (explicit 0 wire_command)
           (explicit 1 success)
           (explicit 2 utf8_string)
           (explicit 3 data))

let wire =
  Asn.S.(sequence2
           (required ~label:"header" header)
           (required ~label:"payload" payload))

let wire_of_cstruct, wire_to_cstruct = projections_of wire

let log_entry =
  Asn.S.(sequence2
           (required ~label:"timestamp" utc_time)
           (required ~label:"event" log_event))

let log_entry_of_cstruct, log_entry_to_cstruct = projections_of log_entry

(* data is persisted to disk, we need to ensure to be able to decode (and
   encode) properly without conflicts! *)
let log_disk =
  Asn.S.(sequence2
           (required ~label:"version" version)
           (required ~label:"entry" log_entry))

let log_disk_of_cstruct, log_disk_to_cstruct =
  let c = Asn.codec Asn.der log_disk in
  (Asn.decode c, Asn.encode c)

let log_to_disk entry = log_disk_to_cstruct (current, entry)

let logs_of_disk buf =
  let rec next acc buf =
    match log_disk_of_cstruct buf with
    | Ok ((version, entry), cs) ->
      Logs.info (fun m -> m "read a log entry version %a" pp_version version) ;
      next (entry :: acc) cs
    | Error (`Parse msg) ->
      Logs.warn (fun m -> m "parse error %s while parsing log" msg) ;
      acc (* ignore *)
  in
  next [] buf

let trie e =
  let f elts =
    List.fold_left (fun trie (key, value) ->
        match Name.of_string key with
        | Error (`Msg m) -> invalid_arg m
        | Ok name ->
          let trie, ret = Vmm_trie.insert name value trie in
          assert (ret = None);
          trie) Vmm_trie.empty elts
  and g trie =
    List.map (fun (k, v) -> Name.to_string k, v) (Vmm_trie.all trie)
  in
  Asn.S.map f g @@
  Asn.S.(sequence_of
           (sequence2
              (required ~label:"name" utf8_string)
              (required ~label:"value" e)))

let version0_unikernels = trie v0_unikernel_config

let version1_unikernels = trie v1_unikernel_config

let version2_unikernels = trie unikernel_config

let unikernels =
   (* the choice is the implicit version + migration... be aware when
     any dependent data layout changes .oO(/o\) *)
  let f = function
    | `C1 data -> data
    | `C2 data -> data
    | `C3 data -> data
  and g data =
    `C3 data
  in
  Asn.S.map f g @@
  Asn.S.(choice3
           (explicit 0 version1_unikernels)
           (explicit 1 version0_unikernels)
           (explicit 2 version2_unikernels))

let unikernels_of_cstruct, unikernels_to_cstruct = projections_of unikernels

let cert_extension =
  Asn.S.(sequence2
           (required ~label:"version" version)
           (required ~label:"command" wire_command))

let of_cert_extension, to_cert_extension =
  let a, b = projections_of cert_extension in
  a, (fun d -> b (current, d))