select_duplicates.lua

--[[

    select_duplicates.lua - select duplicate images from a collection

    Copyright (C) 2026 Bill Ferguson <wpferguson@gmail.com>.

    This program 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.

    This program 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 this program.  If not, see <http://www.gnu.org/licenses/>.
]]
--[[
    select_duplicates - select duplicate images from a collection

    select_duplicates adds a button to the select module to select 
    duplicate images from a collection.  If the selection2collection
    script is also active an option is available to have the selected
    duplicates appear as a temporary collection.

    A shortcut is available to select the duplicates from the collection
    but it is somewhat slower because it doesn't have access to the current
    image cache and therfore has to open each image separately.

    ADDITIONAL SOFTWARE NEEDED FOR THIS SCRIPT
    
    None

    USAGE
    
    * enable in script manager
    * Press the button

    BUGS, COMMENTS, SUGGESTIONS
    Bill Ferguson <wpferguson@gmail.com>

    CHANGES
]]

local dt = require "darktable"
local du = require "lib/dtutils"
-- local df = require "lib/dtutils.file"
-- local ds = require "lib/dtutils.string"
-- local dtsys = require "lib/dtutils.system"
local log = require "lib/dtutils.log"
-- local debug = require "darktable.debug"


-- - - - - - - - - - - - - - - - - - - - - - - - 
-- A P I  C H E C K
-- - - - - - - - - - - - - - - - - - - - - - - - 

du.check_min_api_version("7.0.0", MODULE)   -- choose the minimum version that contains the features you need


-- - - - - - - - - - - - - - - - - - - - - - - - - -
-- I 1 8 N
-- - - - - - - - - - - - - - - - - - - - - - - - - -

local gettext = dt.gettext.gettext

local function _(msgid)
    return gettext(msgid)
end


-- - - - - - - - - - - - - - - - - - - - - - - - - -
-- S C R I P T  M A N A G E R  I N T E G R A T I O N
-- - - - - - - - - - - - - - - - - - - - - - - - - -

local script_data = {}

script_data.destroy = nil           -- function to destory the script
script_data.destroy_method = nil    -- set to hide for libs since we can't destroy them commpletely yet
script_data.restart = nil           -- how to restart the (lib) script after it's been hidden - i.e. make it visible again
script_data.show = nil              -- only required for libs since the destroy_method only hides them

script_data.metadata = {
  name = _("select duplicates"),         -- visible name of script
  purpose = _("select duplicate images from a collection"),   -- purpose of script
  author = "Bill Ferguson <wpferguson@gmail.com>",   -- your name and optionally e-mail address
  help = "https://docs.darktable.org/lua/stable/lua.scripts.manual/scripts/official/select_duplicates/"                   -- URL to help/documentation
}


-- - - - - - - - - - - - - - - - - - - - - - - - 
-- C O N S T A N T S
-- - - - - - - - - - - - - - - - - - - - - - - - 

local MODULE <const> = "select_duplicates"
local DEFAULT_LOG_LEVEL <const> = log.info
local TMP_DIR <const> = dt.configuration.tmp_dir

-- path separator
local PS <const> = dt.configuration.running_os == "windows" and "\\" or "/"

-- command separator
local CS <const> = dt.configuration.running_os == "windows" and "&" or ";"

-- - - - - - - - - - - - - - - - - - - - - - - - 
-- L O G  L E V E L
-- - - - - - - - - - - - - - - - - - - - - - - - 

log.log_level(DEFAULT_LOG_LEVEL)

-- - - - - - - - - - - - - - - - - - - - - - - - 
-- N A M E  S P A C E
-- - - - - - - - - - - - - - - - - - - - - - - - 

local select_duplicates = {}

-- - - - - - - - - - - - - - - - - - - - - - - - 
-- G L O B A L  V A R I A B L E S
-- - - - - - - - - - - - - - - - - - - - - - - - 

select_duplicates.log_level = DEFAULT_LOG_LEVEL
select_duplicates.create_collection = false

-- - - - - - - - - - - - - - - - - - - - - - - - 
-- P R E F E R E N C E S
-- - - - - - - - - - - - - - - - - - - - - - - - 

dt.preferences.register(MODULE, "create_collection", "bool", 
  script_data.metadata.name .. _(" create collection from selection"), 
  _("create collection of selected duplicates"), false)

-- - - - - - - - - - - - - - - - - - - - - - - - 
-- A L I A S E S
-- - - - - - - - - - - - - - - - - - - - - - - - 

local namespace = select_duplicates
local sd = select_duplicates

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

-------------------
-- helper functions
-------------------

local function set_log_level(level)
  if not level then
    level = namespace.log_level
  end

  local old_log_level = log.log_level()
  log.log_level(level)

  return old_log_level
end

local function restore_log_level(level)
  if not level then
    level = namespace.log_level
  end
  log.log_level(level)
end

local function reset_log_level()
  log.log_level(DEFAULT_LOG_LEVEL)
  namespace.log_level = DEFAULT_LOG_LEVEL
end

local function pref_read(name, pref_type)
  local old_log_level = set_log_level(namespace.log_level)

  log.msg(log.debug, "name is " .. name .. " and type is " .. pref_type)

  local val = dt.preferences.read(MODULE, name, pref_type)

  log.msg(log.debug, "read value " .. tostring(val))

  restore_log_level(old_log_level)
  return val
end

local function pref_write(name, pref_type, value)
  local old_log_level = set_log_level(namespace.log_level)

  log.msg(log.debug, "writing value " .. tostring(value) .. " for name " .. name)

  dt.preferences.write(MODULE, name, pref_type, value)

  restore_log_level(old_log_level)
end

local function select_duplicate_files(event, images)
  local duplicates = {}
  local sorted_files = {}
  sd.create_collection = pref_read("create_collection", "bool")

  for _, img in ipairs(images) do
    local rawname = img.path .. PS .. img.filename
    if not sorted_files[rawname] then
      sorted_files[rawname] = {}
    end
    table.insert(sorted_files[rawname], img)
  end
  for k,v in pairs(sorted_files) do
    if #v > 1 then
      local old_image = nil
      for _,i in ipairs(v) do
        if not old_image then
          old_image = i
        else
          if i.duplicate_index > old_image.duplicate_index then
            table.insert(duplicates, i)
          else
            table.insert(duplicates, old_image)
            old_image = i
          end
        end
      end
    end
  end
  if sd.create_collection then
    dt.util.message(MODULE, "selection2collection", "create")
  end
  return duplicates
end

-- - - - - - - - - - - - - - - - - - - - - - - - 
-- M A I N  P R O G R A M
-- - - - - - - - - - - - - - - - - - - - - - - - 

-- - - - - - - - - - - - - - - - - - - - - - - - 
-- U S E R  I N T E R F A C E
-- - - - - - - - - - - - - - - - - - - - - - - - 

dt.gui.libs.select.register_selection(MODULE, _("select duplicates"), select_duplicate_files,  
                                      _("select duplicated images"))

-- - - - - - - - - - - - - - - - - - - - - - - - 
-- D A R K T A B L E  I N T E G R A T I O N 
-- - - - - - - - - - - - - - - - - - - - - - - - 

local function destroy()
  dt.gui.libs.select.destroy_selection(MODULE)
end

script_data.destroy = destroy

-- - - - - - - - - - - - - - - - - - - - - - - - 
-- E V E N T S
-- - - - - - - - - - - - - - - - - - - - - - - - 

if not dt.query_event(MODULE, "shortcut") then  -- skip if shortcut already registered
  dt.register_event(MODULE, "shortcut",
    function(event, shortcut)
      local duplicates = select_duplicate_files(event, dt.collection)
      if duplicates then
        dt.gui.selection(duplicates)
      end
    end, _("select duplicates")
  )
end

return script_data