--[[
  This file is part of darktable,
  copyright (c) 2019 Bill Ferguson <wpferguson@gmail.com>
  
  darktable is free software: you can redistribute it and/or modify
  it under the terms of the GNU General Public License as published by
  the Free Software Foundation, either version 3 of the License, or
  (at your option) any later version.
  
  darktable is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU General Public License for more details.
  
  You should have received a copy of the GNU General Public License
  along with darktable.  If not, see <http://www.gnu.org/licenses/>.
]]
--[[
    filetether.lua - poor man's camera tethering using the file system

]]

local dt = require "darktable"
local du = require "lib/dtutils"
local df = require "lib/dtutils.file"

local PS = dt.configuration.running_os == "windows" and "\\" or "/"
local DIR = dt.configuration.running_os == "windows" and "DIR /B/O:-D " or "ls -rt "

local filetether = {
  widgets = {},
}

-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
-- F U N C T I O N S
-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

local function file_closed(file)
  local status = false
  if dt.configuration.running_os == "windows" then
    -- try and rename it so see if it's busy
    -- if you can rename it, rename it back and then return true
    local result = dt.external_command("rename " .. file .. " tmp.part")
    if result == 0 then
      dt.external_command("rename tmp.part " .. file)
      status = true
    end
  else
    local p = io.popen("lsof " .. file .. " 2>&1 || echo ::ERROR::", "r")
    local result = p:read("*a")
    p:close()
    if string.len(result) == 0 or string.match(result, "::ERROR::") then
      -- string length of zero means that the file is closed
      -- ::ERROR:: means that the file didn't exist, so no use returning false and waiting
      status = true
    end
  end
  return status
end

local function stop_polling()
  filetether["run"] = false
end

local function start_polling()
  filetether["run"] = true
  local path = filetether.widgets["path"].value
  dt.preferences.write("filetether", "path", "string", path)
  local view_in_darkroom = filetether.widgets["view_in_darkroom"].value
  dt.preferences.write("filetether", "view_in_darkroom", "bool", view_in_darkroom)
  dt.print_log("view in darkroom is " .. tostring(view_in_darkroom))
  local interval = filetether.widgets["interval"].value * 1000
  dt.preferences.write("filetether", "interval", "integer", math.floor(filetether.widgets["interval"].value))
  if not df.check_if_file_exists(path) then 
    df.mkdir(path) 
  end
  local files = {}
  local f = io.popen(DIR .. path)
  local old_file_list = f:read("*a")
  -- strip out all the chanacters that have meaning in a pattern match
  old_file_list = string.gsub(old_file_list, "%-", "%%-")
  old_file_list = string.gsub(old_file_list, "%(", "%%(")
  old_file_list = string.gsub(old_file_list, "%)", "%%)")
  dt.database.import(path)
  f:close()
  while(filetether["run"]) do
    dt.control.sleep(interval)
    dt.print_log("view in darkroom is " .. tostring(view_in_darkroom))
    -- process the queue of files that was detected last interval
    local save_state
    if #files > 1  and not string.match(old_file_list, "%.xmp") then
      save_state = view_in_darkroom
      dt.print_log("save state is " .. tostring(save_state))
      view_in_darkroom = false
    end
    for _,file in ipairs(files) do 
      dt.print_log(file)
      -- ignore xmp files
      if not string.match(file, "%.xmp$") then
        -- do a reasonable check to determine if it's a filename instead of a directory
        -- on linux and mocos we could ues the file command, but windows doesn't have it
        if string.len(file) > 4 and string.match(file, "%.") then
          if df.check_if_file_exists(path .. PS .. file)  then
            dt.print_log("checking if file is complete")
            while not file_closed(path .. PS .. file) do 
              dt.print_log("not yet complete")
              dt.control.sleep(2000)
            end
            dt.print_log("file is complete")
            dt.print_log("importing " .. path .. PS .. file)
            local result = dt.database.import(path .. PS .. file)
            dt.print_log(result.filename .. " imported with id " .. result.id)
            dt.gui.selection({result})
            if #files > 1 and file == files[#files] and not string.match(old_file_list, "%.xmp") then
              view_in_darkroom = save_state
              dt.print_log("view in darkroom set to " .. tostring(view_in_darkroom))
            end
            if view_in_darkroom then
              if dt.gui.current_view() == dt.gui.views.darkroom then
                dt.gui.current_view(dt.gui.views.lighttable)
                dt.control.sleep(500)
                dt.gui.current_view(dt.gui.views.lighttable)
                --dt.gui.views.darkroom.display_image(result)
              else
                dt.gui.current_view(dt.gui.views.darkroom)
              end
            end
          end
        end
      end
    end
    files = {}
    f = io.popen(DIR .. path)
    local file_list = f:read("*a")
    f:close()
    local diff = string.gsub(file_list, old_file_list, "")
    dt.print_log(diff)
    files = du.split(diff, "\n")
    dt.print_log("number of files is " .. #files)
    old_file_list = file_list
    old_file_list = string.gsub(old_file_list, "%-", "%%-")
    old_file_list = string.gsub(old_file_list, "%(", "%%(")
    old_file_list = string.gsub(old_file_list, "%)", "%%)")
  end
end

-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 
-- W I D G E T S
-- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 

local tmp = dt.preferences.read("filetether", "path", "string")
dt.print_log("path is " .. tmp)

filetether.widgets["path"] = dt.new_widget("file_chooser_button"){
  title = "select directory to watch",
  tooltip = "select directory where files will be loaded to",
  is_directory = true,
  value = tmp,
}

tmp = dt.preferences.read("filetether", "interval", "integer")
dt.print_log("interval is " .. tmp)
if tmp == 0 then
  tmp = 10
end

filetether.widgets["interval"] = dt.new_widget("slider"){
  label = "polling interval",
  tooltip = "select the number of seconds to wait before checking for new images",
  soft_min = 1,
  soft_max = 180,
  hard_min = 1, 
  hard_max = 180,
  digits = 0,
  step = 1,
  value = tmp,
}

tmp = dt.preferences.read("filetether", "view_in_darkroom", "bool")
dt.print_log("view in darkroom preference is " .. tostring(tmp))

filetether.widgets["view_in_darkroom"] = dt.new_widget("check_button"){
  label = "view in darkroom",
  tooltip = "view imported image in darkroom (single image only)",
  value = tmp,
}

filetether.widgets["start_stop"] = dt.new_widget("button"){
  label = "start",
  clicked_callback = function(self)
    if self.label == "start" then
      self.label = "stop"
      start_polling()
    else
      self.label = "start"
      stop_polling()
    end
  end
}

filetether.widgets["filetether"] = dt.new_widget("box"){
  orientation = "vertical",
  dt.new_widget("label"){label = "select directory to monitor"},
  filetether.widgets["path"],
  filetether.widgets["interval"],
  filetether.widgets["view_in_darkroom"],
  filetether.widgets["start_stop"],
}

dt.register_lib(
  "filetether",
  "filetether",
  true,
  false,
  {[dt.gui.views.lighttable] = {"DT_UI_CONTAINER_PANEL_LEFT_CENTER", 100}},
  filetether.widgets["filetether"],
  nil,
  nil
)