# src/npl/nipbox/nipbox.nim

# --- 1. RAW IMPORTS (The Physics) ---
# We talk directly to libc_shim.zig

type
  cint = int32
  csize_t = uint
  cptr = pointer

# Standard POSIX-ish
proc write(fd: cint, buf: cptr, count: csize_t): csize_t {.importc, cdecl.}
proc read(fd: cint, buf: cptr, count: csize_t): csize_t {.importc, cdecl.}
proc open(pathname: cstring, flags: cint): cint {.importc, cdecl.}
proc close(fd: cint): cint {.importc, cdecl.}
proc exit(status: cint) {.importc, cdecl.}
proc list_files(buf: pointer, len: uint64): int64 {.importc, cdecl.}

# Our Custom Syscalls (Defined in libc_shim)
proc nexus_syscall(cmd: cint, arg: uint64): cint {.importc, cdecl.}
proc nexus_yield() {.importc, cdecl.}

const CMD_GPU_MATRIX = 0x100
const CMD_GPU_STATUS = 0x102
const CMD_GET_GPU_STATUS = 0x102
const CMD_SYS_EXEC = 0x400

# --- 2. MINIMAL RUNTIME (The Tools) ---

# Helper: Print to Stdout (FD 1)
proc print(s: string) =
  if s.len > 0:
    discard write(1, unsafeAddr s[0], csize_t(s.len))
  var nl = "\n"
  discard write(1, unsafeAddr nl[0], 1)

proc print_raw(s: string) =
  if s.len > 0:
    discard write(1, unsafeAddr s[0], csize_t(s.len))

# Helper: Read Line from Stdin (FD 0)
# Returns true if line read, false if EOF
var read_buffer: array[256, char]
var read_pos: int = 0
var read_len: int = 0

proc my_readline(buf: var string): bool =
  buf.setLen(0)
  while true:
    # Buffer empty? Fill it.
    if read_pos >= read_len:
      let n = read(0, addr read_buffer[0], 256)
      if n <= 0:
        nexus_yield()
        continue
      read_len = int(n)
      read_pos = 0

    # Process buffer
    while read_pos < read_len:
      let c = read_buffer[read_pos]
      read_pos += 1

      # Handle Backspace
      if c == char(127) or c == char(8):
        if buf.len > 0:
          var seq = "\b \b"
          discard write(1, unsafeAddr seq[0], 3)
          buf.setLen(buf.len - 1)
        continue

      # Echo logic skipped (Host handles it mostly)

      if c == '\n' or c == '\r':
        return true

      buf.add(c)

# --- 3. COMMAND LOGIC ---

proc do_echo(arg: string) =
  print(arg)

proc do_matrix(arg: string) =
  if arg == "on":
    print("[NipBox] Engaging Matrix...")
    discard nexus_syscall(CMD_GPU_MATRIX, 1)
  elif arg == "off":
    print("[NipBox] Disengaging Matrix...")
    discard nexus_syscall(CMD_GPU_MATRIX, 0)
  else:
    print("Usage: matrix on|off")

proc do_cat(filename: string) =
  # 1. Open
  let fd = open(cstring(filename), 0) # O_RDONLY
  if fd < 0:
    print("cat: cannot open file")
    return

  # 2. Read Loop
  const BUF_SIZE = 1024
  var buffer: array[BUF_SIZE, char]

  while true:
    let bytesRead = read(fd, addr buffer[0], BUF_SIZE)
    if bytesRead <= 0: break

    # Write to Stdout
    discard write(1, addr buffer[0], bytesRead)

  # 3. Close
  discard close(fd)
  print("") # Final newline

proc do_ls() =
  var buf: array[2048, char]
  let n = list_files(addr buf[0], 2048)
  if n > 0:
    var s = newString(n)
    copyMem(addr s[0], addr buf[0], n)
    print(s)

proc do_exec(filename: string) =
  if filename.len == 0:
    print("Usage: exec <path>")
    return
  print("[NipBox] Summoning " & filename & "...")
  let result = nexus_syscall(CMD_SYS_EXEC, cast[uint64](cstring(filename)))
  if result != 0:
    print("[NipBox] Syscall failed!")
  else:
    print("[NipBox] Syscall sent successfully")

proc do_help() =
  print("NipBox v0.2 (Sovereign)")
  print("Commands: echo, cat, ls, matrix, exec, help, exit")

# --- 4. MAIN LOOP ---

proc main() =
  var inputBuffer = newStringOfCap(256)

  print("\n[NipBox] Interactive Shell Ready.")

  while true:
    print_raw("root@nexus:# ")

    if not my_readline(inputBuffer):
      break # EOF

    if inputBuffer.len == 0: continue

    # Simple manual parsing

    # Reset manual parsing
    var cmd = newStringOfCap(32)
    var arg = newStringOfCap(128)
    var spaceFound = false

    var i = 0
    while i < inputBuffer.len:
      let c = inputBuffer[i]
      i += 1

      if not spaceFound and c == ' ':
        spaceFound = true
        continue
      if not spaceFound:
        cmd.add(c)
      else:
        arg.add(c)


    if cmd == "exit":
      print("Exiting...")
      exit(0)
    elif cmd == "echo":
      do_echo(arg)
    elif cmd == "cat":
      do_cat(arg)
    elif cmd == "ls":
      do_ls()
    elif cmd == "matrix":
      do_matrix(arg)
    elif cmd == "exec":
      do_exec(arg)
    elif cmd == "help":
      do_help()
    else:
      print_raw("Unknown command: ")
      print(cmd)

when isMainModule:
  main()