-- CMC.lua — Command Controller (AtlasOS Shell/CPU v2.0)
-- in[1]  = cmd_rx  ← IOC.out[4] (IN|command)
-- in[2]  = mem_rx  ← MMC.out[1] (FS response)
-- out[1] = text_tx → IOC.in[2] (OUT|text)
-- out[2] = clear_tx → IOC.in[3] (1 = clear)
-- out[3] = color_tx → IOC.in[4] (R,G,B)
-- out[4] = mem_tx  → MMC.in[1] (FS request)

local state = 0
local ST_IDLE = 0
local ST_WAIT_FS = 1

local uid, gid, cwd, curUser = 0, 0, "/", "root"

local pendingCmd = nil
local lastRespSeq = 0

local function parseMsg(msg)
  local p = msg:find("|")
  return p and msg:sub(1, p - 1) or msg, p and msg:sub(p + 1) or nil
end

local function printOut(t)
  out[1] = "OUT|" .. tostring(t)
end

local function printErr(t)
  out[1] = "OUT|" .. tostring(t)
end

local function doClear()
  out[2] = 1
end

local function doColor(r, g, b)
  out[3] = r .. "," .. g .. "," .. b
end

local function fsReq(op, arg)
  local msg = op
  if arg then msg = msg .. "|" .. arg end
  out[4] = msg
end

local cmds = {}

local function reg(name, fn, desc)
  cmds[name] = { fn = fn, desc = desc }
end

reg("help", function(a)
  local t = "AtlasOS v2.0 commands:\n"
  for n, e in pairs(cmds) do
    t = t .. "  " .. n .. "  " .. e.desc .. "\n"
  end
  return t
end, "Show help")

reg("echo", function(a)
  if #a == 0 then error("echo: missing text") end
  return table.concat(a, " ")
end, "Echo text")

reg("clear", function(a)
  doClear()
end, "Clear screen")

reg("color", function(a)
  if #a < 3 then error("color: need R G B") end
  local r, g, b = tonumber(a[1]), tonumber(a[2]), tonumber(a[3])
  if not (r and g and b) then error("color: invalid values") end
  r = math.floor(math.max(0, math.min(255, r)))
  g = math.floor(math.max(0, math.min(255, g)))
  b = math.floor(math.max(0, math.min(255, b)))
  doColor(r, g, b)
  printOut("Color set to " .. r .. "," .. g .. "," .. b)
end, "Set color R G B")

reg("status", function(a)
  return "AtlasOS v2.0 | User: " .. curUser .. "(" .. uid .. ") | CWD: " .. cwd
end, "System status")

reg("ls", function(a)
  local path = cwd
  local opts = {}
  for i = 1, #a do
    if a[i]:sub(1, 1) == "-" then
      opts[a[i]] = true
    else
      path = a[i]
    end
  end
  pendingCmd = { name = "ls", path = path, opts = opts }
  state = ST_WAIT_FS
  fsReq("LS", path)
end, "List directory [path]")

reg("cat", function(a)
  if #a == 0 then error("cat: missing path") end
  pendingCmd = { name = "cat", path = a[1] }
  state = ST_WAIT_FS
  fsReq("READ", a[1] .. "|0|8192")
end, "Show file content")

reg("cd", function(a)
  local path = a[1]
  if not path then path = "/" end
  pendingCmd = { name = "cd", path = path }
  state = ST_WAIT_FS
  fsReq("CHDIR", path)
end, "Change directory [path]")

reg("stat", function(a)
  if #a == 0 then error("stat: missing path") end
  pendingCmd = { name = "stat", path = a[1] }
  state = ST_WAIT_FS
  fsReq("STAT", a[1])
end, "Show file metadata")

local function execCmd(cmdStr)
  local parts = {}
  for t in cmdStr:gmatch("%S+") do
    parts[#parts + 1] = t
  end
  if #parts == 0 then return end

  local name = parts[1]
  local args = {}
  for i = 2, #parts do
    args[#args + 1] = parts[i]
  end

  local entry = cmds[name]
  if not entry then
    printErr("Unknown: " .. name .. ". Try 'help'.")
    return
  end

  local ok, result = pcall(entry.fn, args)
  if not ok then
    printErr(tostring(result))
  elseif result ~= nil then
    printOut(result)
  end
end

local function handleFSResponse(op, data)
  if not pendingCmd then return end
  local cmd = pendingCmd

  if op == "ERR" then
    local code = data or "EIO"
    if code == "ENOENT" then
      printErr(cmd.path .. ": No such file or directory")
    elseif code == "EACCES" then
      printErr(cmd.path .. ": Permission denied")
    elseif code == "ENOTDIR" then
      printErr(cmd.path .. ": Not a directory")
    elseif code == "EISDIR" then
      printErr(cmd.path .. ": Is a directory")
    else
      printErr(cmd.path .. ": " .. code)
    end
    pendingCmd = nil
    state = ST_IDLE
    return
  end

  if cmd.name == "ls" then
    local showAll = (cmd.opts["-la"] or cmd.opts["-a"])
    local names = {}
    for n in data:gmatch("([^|]+)") do
      names[#names + 1] = n
    end
    local outLines = {}
    for _, n in ipairs(names) do
      if n ~= "." and n ~= ".." or showAll then
        outLines[#outLines + 1] = n
      end
    end
    if #outLines == 0 then outLines[1] = "(empty)" end
    printOut(table.concat(outLines, "\n"))
  elseif cmd.name == "cat" then
    printOut(data)
  elseif cmd.name == "cd" then
    cwd = data
    printOut(cwd)
  elseif cmd.name == "stat" then
    local parts = {}
    for s in data:gmatch("([^|]+)") do
      parts[#parts + 1] = s
    end
    if #parts >= 6 then
      local typ = parts[2] == "d" and "directory" or "file"
      local out = "Inode: " .. parts[1] .. "  Type: " .. typ .. "\n"
      out = out .. "Mode: " .. parts[3] .. "  UID: " .. parts[4] .. "  GID: " .. parts[5] .. "\n"
      out = out .. "Size: " .. parts[6] .. "  Modified: " .. (parts[7] or "?")
      printOut(out)
    else
      printOut(data)
    end
  end

  pendingCmd = nil
  state = ST_IDLE
end

inp = {}

function upd()
  if state == ST_IDLE then
    if inp[1] ~= nil then
      local op, cmd = parseMsg(tostring(inp[1]))
      if op == "IN" and cmd and #cmd > 0 then
        execCmd(cmd)
      end
    end
  end

  if state == ST_WAIT_FS and inp[2] ~= nil then
    local resp = tostring(inp[2])
    if #resp > 0 then
      local op, rest = parseMsg(resp)
      if op and rest then
        local seqStr, data = parseMsg(rest)
        local seq = tonumber(seqStr) or 0
        if seq > lastRespSeq then
          lastRespSeq = seq
          handleFSResponse(op, data)
        end
      end
    end
  end

  table.clear(inp)
end