-- ocv_get.lua — скачивает видео OCV5 с HTTP-сервера на диск OpenComputers.
--
-- Использование:  ocv_get <url_папки> [локальная_папка]
-- Пример:         ocv_get http://192.168.1.103/video/ video

local component = require("component")
local computer  = require("computer")
local fs        = require("filesystem")
local shell     = require("shell")
local term      = require("term")

if not component.isAvailable("internet") then
  io.stderr:write("ocv_get: нужна интернет-карта\n")
  return
end
local internet = require("internet")

local args = shell.parse(...)
local base, dir = args[1], args[2] or "video"
if not base then
  print("usage: ocv_get <url> [folder]")
  return
end
if base:sub(-1) ~= "/" then base = base .. "/" end
dir = shell.resolve(dir)

local function human(n)
  if n >= 1048576 then return string.format("%.2f MB", n / 1048576) end
  if n >= 1024 then return string.format("%.1f KB", n / 1024) end
  return n .. " B"
end

local function status(text)
  local _, y = term.getCursor()
  term.setCursor(1, y)
  term.clearLine()
  io.write(text)
end

local function download(name, label)
  local path = fs.concat(dir, name)
  local file = assert(io.open(path, "wb"))
  local size, t0, lastDraw = 0, computer.uptime(), 0

  local ok, err = pcall(function()
    for chunk in internet.request(base .. name) do
      file:write(chunk)
      size = size + #chunk
      local now = computer.uptime()
      if now - lastDraw >= 0.25 then
        lastDraw = now
        status(label .. "  " .. human(size))
      end
    end
  end)
  file:close()

  if not ok or size == 0 then
    fs.remove(path)
    error(name .. ": " .. tostring(err or "пустой ответ"), 0)
  end
  status(string.format("%s  %s  %.1fs\n", label, human(size), computer.uptime() - t0))
end

local ok, err = pcall(function()
  fs.makeDirectory(dir)
  download("index.ocv", "index.ocv")

  local f = assert(io.open(fs.concat(dir, "index.ocv"), "rb"))
  local h = f:read(64)
  f:close()
  if not h or #h < 64 or h:sub(1, 4) ~= "OCV5" then error("index.ocv: не OCV5", 0) end

  local parts = h:byte(15) * 256 + h:byte(16)
  for i = 1, parts do
    download(string.format("part%04d.ocv", i), string.format("[%d/%d]", i, parts))
  end
  print("Готово: ocv " .. dir)
end)

if not ok then io.stderr:write("\nocv_get: " .. tostring(err) .. "\n") end