-- Copyright (C) 2018-2021 by KittenOS NEO contributors
--
-- Permission to use, copy, modify, and/or distribute this software for any purpose with or without fee is hereby granted.
--
-- THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
-- THIS SOFTWARE.

-- svc-app-claw-worker: Who stays stays. Who goes goes.

local callerPkg, _, destProx, packageId, downloadSrc, checked, primaryINet = ...
if callerPkg ~= "app-claw" then error("Internal process for app-claw's bidding.") end
-- This 'mutex' remains active as long as the process does.
neo.requireAccess("r.svc.app-claw-worker", "CLAW mutex")

local function wrapLines(ocb)
 local buf = ""
 return function (data)
  if not data then
   ocb(buf)
  else
   buf = buf .. data
   buf = buf:gsub("[^\n]*\n", function (t)
    ocb(t:sub(1, -2))
    return ""
   end)
  end
 end
end

local function download(url, cb, src)
 if type(src) == "string" then
  assert(primaryINet, "no internet")
  local req, err = primaryINet.request(src .. url)
  assert(req, err)
  -- OpenComputers#535
  req.finishConnect()
  while true do
   local n, n2 = req.read(neo.readBufSize)
   cb(n)
   if not n then
    req.close()
    if n2 then
     error(n2)
    else
     cb(nil)
     break
    end
   else
    if n == "" then
     neo.scheduleTimer(os.uptime() + 0.05)
     while true do
      local res = coroutine.yield()
      if res == "k.timer" then break end
     end
    end
   end
  end
 else
  local h, e = src.open(url, "rb")
  assert(h, e)
  repeat
   local c = src.read(h, neo.readBufSize)
   cb(c)
  until not c
  src.close(h)
 end
end

local opInstall, opRemove

function opInstall(packageId, checked)
 local gback = {} -- the ultimate strategy
 local gdir = {}
 local preinstall = {}
 download("data/app-claw/" .. packageId .. ".c2x", wrapLines(function (l)
  if l:sub(1, 1) == "?" and checked then
   preinstall[l:sub(2)] = true
  elseif l:sub(1, 1) == "+" then
   table.insert(gback, l:sub(2))
  elseif l:sub(1, 1) == "/" then
   table.insert(gdir, l:sub(2))
  end
 end), downloadSrc)
 for _, v in ipairs(gdir) do
  destProx.makeDirectory(v)
  assert(destProx.isDirectory(v), "unable to create dir " .. v)
 end
 gdir = nil
 for k, _ in pairs(preinstall) do
  if not destProx.exists("data/app-claw/" .. k .. ".c2x") then
   opInstall(k, true)
  end
 end
 preinstall = nil
 for _, v in ipairs(gback) do
  local f = destProx.open(v .. ".C2T", "wb")
  assert(f, "unable to create download file")
  local ok, e = pcall(download, v, function (b)
   assert(destProx.write(f, b or ""), "unable to save data")
  end, downloadSrc)
  destProx.close(f)
  if not ok then error(e) end
 end
 -- CRITICAL SECTION --
 if destProx.exists("data/app-claw/" .. packageId .. ".c2x") then
  opRemove(packageId, false)
 end
 for _, v in ipairs(gback) do
  if destProx.exists(v) then
   for _, v in ipairs(gback) do
    destProx.remove(v .. ".C2T")
   end
   error("file conflict: " .. v)
  end
 end
 for _, v in ipairs(gback) do
  destProx.rename(v .. ".C2T", v)
 end
end

function opRemove(packageId, checked)
 if checked then
  local dependents = {}
  for _, pidf in ipairs(destProx.list("data/app-claw/")) do
   if pidf:sub(-4) == ".c2x" then
    local pid = pidf:sub(1, -5)
    download("data/app-claw/" .. pidf, wrapLines(function (l)
     if l == "?" .. packageId then
      table.insert(dependents, pid)
     end
    end), destProx)
   end
  end
  assert(not dependents[1], "Cannot remove " .. packageId .. ", required by:\n" .. table.concat(dependents, ", "))
 end
 local rmSchedule = {}
 download("data/app-claw/" .. packageId .. ".c2x", wrapLines(function (l)
  if l:sub(1, 1) == "+" then
   table.insert(rmSchedule, l:sub(2))
  end
 end), destProx)
 for _, v in ipairs(rmSchedule) do
  destProx.remove(v)
 end
end

local ok, e
if downloadSrc then
 ok, e = pcall(opInstall, packageId, checked)
else
 ok, e = pcall(opRemove, packageId, checked)
end
destProx = nil
downloadSrc = nil
primaryINet = nil
neo.executeAsync("app-claw", packageId)
if not ok then
 error(e)
end