Add settings gui plugin (#65)

* Appropriately merged config hashes.
* indentguide: use indent size from doc instead of config
* added settings gui plugin
* added new animation/transition settings
* overwrite ToolbarView settings command
* Introduced new button type
* Added button to open user module on General section
* settings: partially implemented keybindings
* initial support for settings.type.LIST_STRINGS
* added on_apply, prettify settings file and other fixes
* added ability to save keybinds and apply at startup
* dropped custom prettify in favor of new common.serialize support
* handle plugins enable/disable
* added priority:0
* added color theme chooser pane
* do not remove duplicated colors
* properly list all shortcuts assigned to a command
* handle multiple bindings per command
* custom drawing of colors preview
* added video preview to readme
* removed unused settings.type.LIST_NUMBERS

4 files changed, 1463 insertions, 1 deletions

diff --git a/README.md b/README.md
index 20468b7..0ae6c1f 100644
--- a/README.md
+++ b/README.md
@@ -153,6 +153,7 @@ to something other than a raw file it should be marked with an asterisk.*
 | [`scalestatus`](plugins/scalestatus.lua?raw=1)                                                                 | Displays current scale (zoom) in status view (depends on scale plugin)                                                                                                                                                                                                                          |
 | [`select_colorscheme`](plugins/select_colorscheme.lua?raw=1)                                                   | Select a color theme, like VScode, Sublime Text.(plugin saves changes)                                                                                                                                                                                                                          |
 | [`selectionhighlight`](plugins/selectionhighlight.lua?raw=1)                                                   | Highlights regions of code that match the current selection *([screenshot](https://user-images.githubusercontent.com/3920290/80710883-5f597c80-8ae7-11ea-97f0-76dfacc08439.png))*                                                                                                               |
+| [`settings`](plugins/settings.lua?raw=1)                                                                       | Provides a GUI to manage core and plugin settings, bindings and select color theme *([video](https://user-images.githubusercontent.com/1702572/169743674-ececae24-f6b7-4ff2-bfa2-c4762cd327d9.mp4))*. (depends on [`widget`](https://github.com/lite-xl/lite-xl-widgets))                       |
 | [`smallclock`](plugins/smallclock.lua?raw=1)                                                                   | Displays the current time in the corner of the status view                                                                                                                                                                                                                                      |
 | [`smoothcaret`](plugins/smoothcaret.lua?raw=1)                                                                 | Smooth caret animation *([gif](https://user-images.githubusercontent.com/20792268/139006049-a0ba6559-88cb-49a7-8077-4822445b4a1f.gif))*                                                                                                                                                         |
 | [`sort`](plugins/sort.lua?raw=1)                                                                               | Sorts selected lines alphabetically                                                                                                                                                                                                                                                             |
diff --git a/plugins/indentguide.lua b/plugins/indentguide.lua
index c66d825..8d78ee3 100644
--- a/plugins/indentguide.lua
+++ b/plugins/indentguide.lua
@@ -1,4 +1,4 @@
--- mod-version:3 --lite-xl 2.1
+--- mod-version:3 --lite-xl 2.1
 local style = require "core.style"
 local config = require "core.config"
 local DocView = require "core.docview"
diff --git a/plugins/openselected.lua b/plugins/openselected.lua
index 4522fe9..c2cb3a4 100644
--- a/plugins/openselected.lua
+++ b/plugins/openselected.lua
@@ -2,6 +2,7 @@
 local core = require "core"
 local command = require "core.command"
 local keymap = require "core.keymap"
+local common = require "core.common"
 local config = require "core.config"
 local contextmenu = require "plugins.contextmenu"
 
diff --git a/plugins/settings.lua b/plugins/settings.lua
new file mode 100644
index 0000000..f304f9a
--- /dev/null
+++ b/plugins/settings.lua
@@ -0,0 +1,1460 @@
+-- mod-version:3 --lite-xl 2.1 --priority:0
+local core = require "core"
+local config = require "core.config"
+local common = require "core.common"
+local command = require "core.command"
+local keymap = require "core.keymap"
+local style = require "core.style"
+local Widget = require "widget"
+local Label = require "widget.label"
+local Line = require "widget.line"
+local NoteBook = require "widget.notebook"
+local Button = require "widget.button"
+local TextBox = require "widget.textbox"
+local SelectBox = require "widget.selectbox"
+local NumberBox = require "widget.numberbox"
+local Toggle = require "widget.toggle"
+local ListBox = require "widget.listbox"
+local FoldingBook = require "widget.foldingbook"
+local ItemsList = require "widget.itemslist"
+local ToolbarView = require "plugins.toolbarview"
+local KeybindingDialog = require "widget.keybinddialog"
+
+local settings = {}
+
+settings.core = {}
+settings.plugins = {}
+settings.sections = {}
+settings.plugin_sections = {}
+settings.config = {}
+settings.default_keybindings = {}
+
+---Enumeration for the different types of settings.
+---@type table<string, integer>
+settings.type = {
+  STRING = 1,
+  NUMBER = 2,
+  TOGGLE = 3,
+  SELECTION = 4,
+  LIST_STRINGS = 5,
+  BUTTON = 6
+}
+
+---@alias settings.types
+---|>'settings.type.STRING'
+---| 'settings.type.NUMBER'
+---| 'settings.type.TOGGLE'
+---| 'settings.type.SELECTION'
+---| 'settings.type.LIST_STRINGS'
+---| 'settings.type.BUTTON'
+
+---Represents a setting to render on a settings pane.
+---@class settings.option
+---@field public label string
+---@field public description string
+---@field public path string
+---@field public type settings.types
+---@field public default string | number | table<integer, string> | table<integer, integer>
+---@field public min number
+---@field public max number
+---@field public step number
+---@field public values table
+---@field public get_value nil | fun(value:any):any
+---@field public set_value nil | fun(value:any):any
+---@field public icon string
+---@field public on_click nil | string | fun(button:string, x:integer, y:integer)
+---@field public on_apply nil | fun(value:any)
+settings.option = {
+  ---Title displayed to the user eg: "My Option"
+  label = "",
+  ---Description of the option eg: "Modifies the document indentation"
+  description = "",
+  ---Config path in the config table, eg: section.myoption, myoption, etc...
+  path = "",
+  ---Type of option that will be used to render an appropriate control
+  type = "",
+  ---Default value of the option
+  default = "",
+  ---Used for NUMBER to indiciate the minimum number allowed
+  min = 0,
+  ---Used for NUMBER to indiciate the maximum number allowed
+  max = 0,
+  ---Used for NUMBER to indiciate the increment/decrement amount
+  step = 0,
+  ---Used in a SELECTION to provide the list of valid options
+  values = {},
+  ---Optional function that is used to manipulate the current value on retrieval.
+  get_value = nil,
+  ---Optional function that is used to manipulate the saved value on save.
+  set_value = nil,
+  ---The icon set for a BUTTON
+  icon = "",
+  ---Command or function executed when a BUTTON is clicked
+  on_click = nil,
+  ---Optional function executed when the option value is applied.
+  on_apply = nil
+}
+
+---Add a new settings section to the settings UI
+---@param section string
+---@param options settings.option[]
+---@param plugin_name? string Optional name of plugin
+function settings.add(section, options, plugin_name)
+  local category = ""
+  if plugin_name ~= nil then
+    category = "plugins"
+  else
+    category = "core"
+  end
+
+  if not settings[category][section] then
+    settings[category][section] = {}
+    if category ~= "plugins" then
+      table.insert(settings.sections, section)
+    else
+      table.insert(settings.plugin_sections, section)
+    end
+  end
+
+  if plugin_name ~= nil then
+    if not settings[category][section][plugin_name] then
+      settings[category][section][plugin_name] = {}
+    end
+    for _, option in ipairs(options) do
+      table.insert(settings[category][section][plugin_name], option)
+    end
+  else
+    for _, option in ipairs(options) do
+      table.insert(settings[category][section], option)
+    end
+  end
+end
+
+--------------------------------------------------------------------------------
+-- Add Core Settings
+--------------------------------------------------------------------------------
+
+settings.add("General",
+  {
+    {
+      label = "User Module",
+      description = "Open your init.lua for customizations.",
+      type = settings.type.BUTTON,
+      icon = "P",
+      on_click = "core:open-user-module"
+    },
+    {
+      label = "Maximum Project Files",
+      description = "The maximum amount of project files to register.",
+      path = "max_project_files",
+      type = settings.type.NUMBER,
+      default = 2000,
+      min = 1,
+      max = 100000,
+      on_apply = function()
+        core.rescan_project_directories()
+      end
+    },
+    {
+      label = "File Size Limit",
+      description = "The maximum file size in megabytes allowed for editing.",
+      path = "file_size_limit",
+      type = settings.type.NUMBER,
+      default = 10,
+      min = 1,
+      max = 50
+    },
+    {
+      label = "Ignore Files",
+      description = "List of lua patterns matching files to be ignored by the editor.",
+      path = "ignore_files",
+      type = settings.type.LIST_STRINGS,
+      default = { "^%." },
+      on_apply = function()
+        core.rescan_project_directories()
+      end
+    },
+    {
+      label = "Maximum Clicks",
+      description = "The maximum amount of consecutive clicks that are registered by the editor.",
+      path = "max_clicks",
+      type = settings.type.NUMBER,
+      default = 3,
+      min = 1,
+      max = 10
+    },
+  }
+)
+
+settings.add("Graphics",
+  {
+    {
+      label = "Frames Per Second",
+      description = "Lower value for low end machines and higher for a smoother experience.",
+      path = "fps",
+      type = settings.type.NUMBER,
+      default = 60,
+      min = 10,
+      max = 300
+    },
+    {
+      label = "Transitions",
+      description = "If disabled turns off all transitions but improves rendering performance.",
+      path = "transitions",
+      type = settings.type.TOGGLE,
+      default = true
+    },
+    {
+      label = "Animation Rate",
+      description = "The amount of time it takes for a transition to finish.",
+      path = "animation_rate",
+      type = settings.type.NUMBER,
+      default = 1.0,
+      min = 0.5,
+      max = 3.0,
+      step = 0.1
+    },
+    {
+      label = "Animate Mouse Drag Scroll",
+      description = "Causes higher cpu usage but smoother scroll transition.",
+      path = "animate_drag_scroll",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Disable Scrolling Transitions",
+      path = "disabled_transitions.scroll",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Disable Command View Transitions",
+      path = "disabled_transitions.commandview",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Disable Context Menu Transitions",
+      path = "disabled_transitions.contextmenu",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Disable Log View Transitions",
+      path = "disabled_transitions.logview",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Disable Nag Bar Transitions",
+      path = "disabled_transitions.nagbar",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Disable Tab Transitions",
+      path = "disabled_transitions.tabs",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Disable Tab Drag Transitions",
+      path = "disabled_transitions.tab_drag",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Disable Status Bar Transitions",
+      path = "disabled_transitions.statusbar",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+  }
+)
+
+settings.add("User Interface",
+  {
+    {
+      label = "Borderless",
+      description = "Use built-in window decorations.",
+      path = "borderless",
+      type = settings.type.TOGGLE,
+      default = false,
+      on_apply = function()
+        core.configure_borderless_window()
+      end
+    },
+    {
+      label = "Messages Timeout",
+      description = "The amount in seconds before a notification dissapears.",
+      path = "message_timeout",
+      type = settings.type.NUMBER,
+      default = 5,
+      min = 1,
+      max = 30
+    },
+    {
+      label = "Always Show Tabs",
+      description = "Shows tabs even if a single document is opened.",
+      path = "always_show_tabs",
+      type = settings.type.TOGGLE,
+      default = true
+    },
+    {
+      label = "Maximum Tabs",
+      description = "The maximum amount of visible document tabs.",
+      path = "max_tabs",
+      type = settings.type.NUMBER,
+      default = 8,
+      min = 1,
+      max = 100
+    },
+    {
+      label = "Close Button on Tabs",
+      description = "Display the close button on tabs.",
+      path = "tab_close_button",
+      type = settings.type.TOGGLE,
+      default = true
+    },
+    {
+      label = "Mouse wheel scroll rate",
+      description = "The amount to scroll when using the mouse wheel.",
+      path = "mouse_wheel_scroll",
+      type = settings.type.NUMBER,
+      default = 50,
+      min = 10,
+      max = 200,
+      get_value = function(value)
+        return value / SCALE
+      end,
+      set_value = function(value)
+        return value * SCALE
+      end
+    },
+    {
+      label = "Disable Cursor Blinking",
+      description = "Disables cursor blinking on text input elements.",
+      path = "disable_blink",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Cursor Blinking Period",
+      description = "Interval in seconds in which the cursor blinks.",
+      path = "blink_period",
+      type = settings.type.NUMBER,
+      default = 0.8,
+      min = 0.3,
+      max = 2.0,
+      step = 0.1
+    }
+  }
+)
+
+settings.add("Editor",
+  {
+    {
+      label = "Indentation Type",
+      description = "The character inserted when pressing the tab key.",
+      path = "tab_type",
+      type = settings.type.SELECTION,
+      default = "soft",
+      values = {
+        {"Space", "soft"},
+        {"Tab", "hard"}
+      }
+    },
+    {
+      label = "Indentation Size",
+      description = "Amount of spaces shown per indentation.",
+      path = "indent_size",
+      type = settings.type.NUMBER,
+      default = 2,
+      min = 1,
+      max = 10
+    },
+    {
+      label = "Line Limit",
+      description = "Amount of characters at which the line breaking column will be drawn.",
+      path = "line_limit",
+      type = settings.type.NUMBER,
+      default = 80,
+      min = 1
+    },
+    {
+      label = "Line Height",
+      description = "The amount of spacing between lines.",
+      path = "line_height",
+      type = settings.type.NUMBER,
+      default = 1.2,
+      min = 1.0,
+      max = 3.0,
+      step = 0.1
+    },
+    {
+      label = "Highlight Line",
+      description = "Highlight the current line.",
+      path = "highlight_current_line",
+      type = settings.type.SELECTION,
+      default = true,
+      values = {
+        {"Yes", true},
+        {"No", false},
+        {"No Selection", "no_selection"}
+      },
+      set_value = function(value)
+        if type(value) == "nil" then return false end
+        return value
+      end
+    },
+    {
+      label = "Maximum Undo History",
+      description = "The amount of undo elements to keep.",
+      path = "max_undos",
+      type = settings.type.NUMBER,
+      default = 10000,
+      min = 100,
+      max = 100000
+    },
+    {
+      label = "Undo Merge Timeout",
+      description = "Time in seconds before applying an undo action.",
+      path = "undo_merge_timeout",
+      type = settings.type.NUMBER,
+      default = 0.3,
+      min = 0.1,
+      max = 1.0,
+      step = 0.1
+    },
+    {
+      label = "Show Spaces",
+      description = "Draw another character in place of invisble spaces.",
+      path = "draw_whitespace",
+      type = settings.type.TOGGLE,
+      default = false
+    },
+    {
+      label = "Symbol Pattern",
+      description = "A lua pattern used to match symbols in the document.",
+      path = "symbol_pattern",
+      type = settings.type.STRING,
+      default = "[%a_][%w_]*"
+    },
+    {
+      label = "Non Word Characters",
+      description = "A string of characters that do not belong to a word.",
+      path = "non_word_chars",
+      type = settings.type.STRING,
+      default = " \\t\\n/\\()\"':,.;<>~!@#$%^&*|+=[]{}`?-",
+      get_value = function(value)
+        return value:gsub("\n", "\\n"):gsub("\t", "\\t")
+      end,
+      set_value = function(value)
+        return value:gsub("\\n", "\n"):gsub("\\t", "\t")
+      end
+    },
+    {
+      label = "Scroll Past the End",
+      description = "Allow scrolling beyond the document ending.",
+      path = "scroll_past_end",
+      type = settings.type.TOGGLE,
+      default = true
+    }
+  }
+)
+
+settings.add("Development",
+  {
+    {
+      label = "Log Items",
+      description = "The maximum amount of entries to keep on the log UI.",
+      path = "max_log_items",
+      type = settings.type.NUMBER,
+      default = 80,
+      min = 50,
+      max = 2000
+    },
+    {
+      label = "Skip Plugins Version",
+      description = "Do not verify the plugins required versions at startup.",
+      path = "skip_plugins_version",
+      type = settings.type.TOGGLE,
+      default = false
+    }
+  }
+)
+
+---Retrieve from given config the associated value using the given path.
+---@param conf table
+---@param path string
+---@param default any
+---@return any | nil
+local function get_config_value(conf, path, default)
+  local sections = {};
+  for match in (path.."."):gmatch("(.-)%.") do
+    table.insert(sections, match);
+  end
+
+  local element = conf
+  for _, section in ipairs(sections) do
+    if type(element[section]) ~= "nil" then
+      element = element[section]
+    else
+      return default
+    end
+  end
+
+  if type(element) == "nil" then
+    return default
+  end
+
+  return element
+end
+
+---Loops the given config table using the given path and store the value.
+---@param conf table
+---@param path string
+---@param value any
+local function set_config_value(conf, path, value)
+  local sections = {};
+  for match in (path.."."):gmatch("(.-)%.") do
+    table.insert(sections, match);
+  end
+
+  local sections_count = #sections
+
+  if sections_count == 1 then
+    conf[sections[1]] = value
+    return
+  elseif type(conf[sections[1]]) ~= "table" then
+    conf[sections[1]] = {}
+  end
+
+  local element = conf
+  for idx, section in ipairs(sections) do
+    if type(element[section]) ~= "table" then
+      element[section] = {}
+      element = element[section]
+    else
+      element = element[section]
+    end
+    if idx + 1 == sections_count then break end
+  end
+
+  element[sections[sections_count]] = value
+end
+
+---Get a list of system and user installed plugins.
+---@return table<integer, string>
+local function get_installed_plugins()
+  local files, ordered = {}, {}
+
+  for _, root_dir in ipairs {DATADIR, USERDIR} do
+    local plugin_dir = root_dir .. "/plugins"
+    for _, filename in ipairs(system.list_dir(plugin_dir) or {}) do
+      local valid = false
+      local file_info = system.get_file_info(plugin_dir .. "/" .. filename)
+      if
+        file_info.type == "file"
+        and
+        filename:match("%.lua$")
+        and
+        not filename:match("^language_")
+      then
+        valid = true
+        filename = filename:gsub("%.lua$", "")
+      elseif file_info.type == "dir" then
+        if system.get_file_info(plugin_dir .. "/" .. filename .. "/init.lua") then
+          valid = true
+        end
+      end
+      if valid then
+        if not files[filename] then table.insert(ordered, filename) end
+        files[filename] = true
+      end
+    end
+  end
+
+  table.sort(ordered)
+
+  return ordered
+end
+
+---Get a list of system and user installed colors.
+---@return table<integer, table>
+local function get_installed_colors()
+  local files, ordered = {}, {}
+
+  for _, root_dir in ipairs {DATADIR, USERDIR} do
+    local dir = root_dir .. "/colors"
+    for _, filename in ipairs(system.list_dir(dir) or {}) do
+      local file_info = system.get_file_info(dir .. "/" .. filename)
+      if
+        file_info.type == "file"
+        and
+        filename:match("%.lua$")
+      then
+        -- read colors
+        local contents = io.open(dir .. "/" .. filename):read("*a")
+        local colors = {}
+        for r, g, b in contents:gmatch("#(%x%x)(%x%x)(%x%x)") do
+          r = tonumber(r, 16)
+          g = tonumber(g, 16)
+          b = tonumber(b, 16)
+          table.insert(colors, { r, g, b, 0xff })
+        end
+        -- sort colors from darker to lighter
+        table.sort(colors, function(a, b)
+          return a[1] + a[2] + a[3] < b[1] + b[2] + b[3]
+        end)
+        -- remove duplicate colors
+        local b = {}
+        for i = #colors, 1, -1 do
+          local a = colors[i]
+          if a[1] == b[1] and a[2] == b[2] and a[3] == b[3] then
+            table.remove(colors, i)
+          else
+            b = colors[i]
+          end
+        end
+        -- insert color to ordered table if not duplicate
+        filename = filename:gsub("%.lua$", "")
+        if not files[filename] then
+          table.insert(ordered, {name = filename, colors = colors})
+        end
+        files[filename] = true
+      end
+    end
+  end
+
+  table.sort(ordered, function(a, b) return a.name < b.name end)
+
+  return ordered
+end
+
+---Capitalize first letter of every word.
+---Taken from core.command.
+---@param words string
+---@return string
+local function capitalize_first(words)
+  return words:sub(1, 1):upper() .. words:sub(2)
+end
+
+---Similar to command prettify_name but also takes care of underscores.
+---@param name string
+---@return string
+local function prettify_name(name)
+  return name:gsub("[%-_]", " "):gsub("%S+", capitalize_first)
+end
+
+---Load config options from the USERDIR user_settings.lua and store them on
+---settings.config for later usage.
+local function load_settings()
+  local ok, t = pcall(dofile, USERDIR .. "/user_settings.lua")
+  settings.config = ok and t.config or {}
+end
+
+---Save current config options into the USERDIR user_settings.lua
+local function save_settings()
+  local fp = io.open(USERDIR .. "/user_settings.lua", "w")
+  if fp then
+    local output = "{\n  [\"config\"] = "
+      .. common.serialize(
+        settings.config,
+        { pretty = true, escape = true, sort = true, initial_indent = 1 }
+      ):gsub("^%s+", "")
+      .. "\n}\n"
+    fp:write("return ", output)
+    fp:close()
+  end
+end
+
+---Apply a keybinding and optionally save it.
+---@param cmd string
+---@param bindings table<integer, string>
+---@param skip_save? boolean
+---@return table | nil
+local function apply_keybinding(cmd, bindings, skip_save)
+  local row_value = nil
+  local changed = false
+
+  local original_bindings = { keymap.get_binding(cmd) }
+  for _, binding in ipairs(original_bindings) do
+    keymap.unbind(binding, cmd)
+  end
+
+  if #bindings > 0 then
+    local shortcuts = ""
+    for _, binding in ipairs(bindings) do
+      if not binding:match("%+$") and binding ~= "" and binding ~= "none" then
+        keymap.add({[binding] = cmd})
+        shortcuts = shortcuts .. binding .. "\n"
+        if not skip_save then
+          if not settings.config.custom_keybindings then
+            settings.config.custom_keybindings = {}
+            settings.config.custom_keybindings[cmd] = {}
+          elseif not settings.config.custom_keybindings[cmd] then
+            settings.config.custom_keybindings[cmd] = {}
+          end
+          table.insert(settings.config.custom_keybindings[cmd], binding)
+          changed = true
+        end
+      end
+    end
+    if shortcuts ~= "" then
+      local bindings_list = shortcuts:gsub("\n$", "")
+      row_value = {
+        style.text, cmd, ListBox.COLEND, style.dim, bindings_list
+      }
+    end
+  elseif
+    not skip_save
+    and
+    settings.config.custom_keybindings
+    and
+    settings.config.custom_keybindings[cmd]
+  then
+    settings.config.custom_keybindings[cmd] = nil
+    changed = true
+  end
+
+  if changed then
+    save_settings()
+  end
+
+  if not row_value then
+    row_value = {
+      style.text, cmd, ListBox.COLEND, style.dim, "none"
+    }
+  end
+
+  return row_value
+end
+
+---Merge previously saved settings without destroying the config table.
+local function merge_settings()
+  if type(settings.config) ~= "table" then return end
+
+  -- merge core settings
+  for _, section in ipairs(settings.sections) do
+    local options = settings.core[section]
+    for _, option in ipairs(options) do
+      if type(option.path) == "string" then
+        local saved_value = get_config_value(settings.config, option.path)
+        if type(saved_value) ~= "nil" then
+          set_config_value(config, option.path, saved_value)
+          if option.on_apply then
+            option.on_apply(saved_value)
+          end
+        end
+      end
+    end
+  end
+
+  -- merge plugin settings
+  table.sort(settings.plugin_sections)
+  for _, section in ipairs(settings.plugin_sections) do
+    local plugins = settings.plugins[section]
+    for plugin_name, options in pairs(plugins) do
+      for _, option in pairs(options) do
+        if type(option.path) == "string" then
+          local path = "plugins." .. plugin_name .. "." .. option.path
+          local saved_value = get_config_value(settings.config, path)
+          if type(saved_value) ~= "nil" then
+            set_config_value(config, path, saved_value)
+            if option.on_apply then
+              option.on_apply(saved_value)
+            end
+          end
+        end
+      end
+    end
+  end
+
+  -- apply custom keybindings
+  if settings.config.custom_keybindings then
+    for cmd, bindings in pairs(settings.config.custom_keybindings) do
+      apply_keybinding(cmd, bindings, true)
+    end
+  end
+end
+
+---Called at core first run to store the default keybindings.
+local function store_default_keybindings()
+  for name, _ in pairs(command.map) do
+    local keys = { keymap.get_binding(name) }
+    if #keys > 0 then
+      settings.default_keybindings[name] = keys
+    end
+  end
+end
+
+---@class settings.ui : widget
+---@field private notebook widget.notebook
+---@field private core widget
+---@field private plugins widget
+---@field private keybinds widget
+---@field private core_sections widget.foldingbook
+---@field private plugin_sections widget.foldingbook
+local Settings = Widget:extend()
+
+---Constructor
+function Settings:new()
+  Settings.super.new(self, false)
+
+  self.name = "Settings"
+  self.defer_draw = false
+  self.border.width = 0
+  self.draggable = false
+  self.scrollable = false
+
+  ---@type widget.notebook
+  self.notebook = NoteBook(self)
+  self.notebook.size.x = 250
+  self.notebook.size.y = 300
+  self.notebook.border.width = 0
+
+  self.core = self.notebook:add_pane("core", "Core")
+  self.colors = self.notebook:add_pane("colors", "Colors")
+  self.plugins = self.notebook:add_pane("plugins", "Plugins")
+  self.keybinds = self.notebook:add_pane("keybindings", "Keybindings")
+
+  self.notebook:set_pane_icon("core", "P")
+  self.notebook:set_pane_icon("colors", "W")
+  self.notebook:set_pane_icon("plugins", "B")
+  self.notebook:set_pane_icon("keybindings", "M")
+
+  self.core_sections = FoldingBook(self.core)
+  self.core_sections.border.width = 0
+  self.core_sections.scrollable = false
+
+  self.plugin_sections = FoldingBook(self.plugins)
+  self.plugin_sections.border.width = 0
+  self.plugin_sections.scrollable = false
+
+  self:load_core_settings()
+  self:load_color_settings()
+  self:load_plugin_settings()
+  self:load_keymap_settings()
+end
+
+---Helper function to add control for both core and plugin settings.
+---@oaram pane widget
+---@param option settings.option
+---@param plugin_name? string | nil
+local function add_control(pane, option, plugin_name)
+  local found = false
+  local path = type(plugin_name) ~= "nil" and
+    "plugins." .. plugin_name .. "." .. option.path or option.path
+  local option_value = nil
+  if type(path) ~= "nil" then
+    option_value = get_config_value(config, path, option.default)
+  end
+
+  if option.get_value then
+    option_value = option.get_value(option_value)
+  end
+
+  ---@type widget
+  local widget = nil
+
+  if option.type == settings.type.NUMBER then
+    ---@type widget.label
+    Label(pane, option.label .. ":")
+    ---@type widget.numberbox
+    local number = NumberBox(pane, option_value, option.min, option.max, option.step)
+    widget = number
+    found = true
+
+  elseif option.type == settings.type.TOGGLE then
+    ---@type widget.toggle
+    local toggle = Toggle(pane, option.label, option_value)
+    widget = toggle
+    found = true
+
+  elseif option.type == settings.type.STRING then
+    ---@type widget.label
+    Label(pane, option.label .. ":")
+    ---@type widget.textbox
+    local string = TextBox(pane, option_value)
+    widget = string
+    found = true
+
+  elseif option.type == settings.type.SELECTION then
+    ---@type widget.label
+    Label(pane, option.label .. ":")
+    ---@type widget.selectbox
+    local select = SelectBox(pane)
+    for _, data in pairs(option.values) do
+      select:add_option(data[1], data[2])
+    end
+    for idx, _ in ipairs(select.list.rows) do
+      if select.list:get_row_data(idx) == option_value then
+        select:set_selected(idx-1)
+        break
+      end
+    end
+    widget = select
+    found = true
+
+  elseif option.type == settings.type.BUTTON then
+    ---@type widget.button
+    local button = Button(pane, option.label)
+    if option.icon then
+      button:set_icon(option.icon)
+    end
+    if option.on_click then
+      local command_type = type(option.on_click)
+      if command_type == "string" then
+        function button:on_click()
+          command.perform(option.on_click)
+        end
+      elseif command_type == "function" then
+        button.on_click = option.on_click
+      end
+    end
+    widget = button
+    found = true
+
+  elseif option.type == settings.type.LIST_STRINGS then
+     ---@type widget.label
+    Label(pane, option.label .. ":")
+    ---@type widget.itemslist
+    local list = ItemsList(pane)
+    if type(option_value) == "table" then
+      for _, value in ipairs(option_value) do
+        list:add_item(value)
+      end
+    end
+    widget = list
+    found = true
+  end
+
+  if widget and type(path) ~= "nil" then
+    function widget:on_change(value)
+      if self:is(SelectBox) then
+        value = self:get_selected_data()
+      elseif self:is(ItemsList) then
+        value = self:get_items()
+      end
+      if option.set_value then
+        value = option.set_value(value)
+      end
+      set_config_value(config, path, value)
+      set_config_value(settings.config, path, value)
+      save_settings()
+      if option.on_apply then
+        option.on_apply(value)
+      end
+    end
+  end
+
+  if option.description and found then
+    local default = ""
+    local default_type = type(option.default)
+    if default_type ~= "table" and default_type ~= "nil" then
+      default = string.format(" (default: %s)", option.default)
+    end
+     ---@type widget.label
+    local description = Label(pane, option.description .. default)
+    description.desc = true
+  end
+end
+
+---Generate all the widgets for core settings.
+function Settings:load_core_settings()
+  for _, section in ipairs(settings.sections) do
+    local options = settings.core[section]
+
+    ---@type widget
+    local pane = self.core_sections:get_pane(section)
+    if not pane then
+      pane = self.core_sections:add_pane(section, section)
+    else
+      pane = pane.container
+    end
+
+    for _, opt in ipairs(options) do
+      ---@type settings.option
+      local option = opt
+      add_control(pane, option)
+    end
+  end
+end
+
+---Function in charge of rendering the colors column of the color pane.
+---@param self widget.listbox
+---@oaram row integer
+---@param x integer
+---@param y integer
+---@param font renderer.font
+---@param color renderer.color
+---@param only_calc boolean
+---@return number width
+---@return number height
+local function on_color_draw(self, row, x, y, font, color, only_calc)
+  local w = self:get_width() - (x - self.position.x) - style.padding.x
+  local h = font:get_height()
+
+  if not only_calc then
+    local row_data = self:get_row_data(row)
+    local width = w/#row_data.colors
+
+    for i = 1, #row_data.colors do
+      renderer.draw_rect(x + ((i - 1) * width), y, width, h, row_data.colors[i])
+    end
+  end
+
+  return w, h
+end
+
+---Generate the list of all available colors with preview
+function Settings:load_color_settings()
+  self.colors.scrollable = false
+
+  local colors = get_installed_colors()
+
+  ---@type widget.listbox
+  local listbox = ListBox(self.colors)
+
+  listbox.border.width = 0
+  listbox:enable_expand(true)
+
+  listbox:add_column("Theme")
+  listbox:add_column("Colors")
+
+  for idx, details in ipairs(colors) do
+    local name = details.name
+    if settings.config.theme and settings.config.theme == name then
+      listbox:set_selected(idx)
+    end
+    listbox:add_row({
+      style.text, name, ListBox.COLEND, on_color_draw
+    }, {name = name, colors = details.colors})
+  end
+
+  function listbox:on_row_click(idx, data)
+    core.reload_module("colors." .. data.name)
+    settings.config.theme = data.name
+  end
+end
+
+---Unload a plugin settings from plugins section.
+---@param plugin string
+function Settings:disable_plugin(plugin)
+  for _, section in ipairs(settings.plugin_sections) do
+    local plugins = settings.plugins[section]
+
+    for plugin_name, options in pairs(plugins) do
+      if plugin_name == plugin then
+        self.plugin_sections:delete_pane(section)
+      end
+    end
+  end
+
+  if
+    type(settings.config.enabled_plugins) == "table"
+    and
+    settings.config.enabled_plugins[plugin]
+  then
+    settings.config.enabled_plugins[plugin] = nil
+  end
+  if type(settings.config.disabled_plugins) ~= "table" then
+    settings.config.disabled_plugins = {}
+  end
+
+  settings.config.disabled_plugins[plugin] = true
+  save_settings()
+end
+
+---Load plugin and append its settings to the plugins section.
+---@param plugin string
+function Settings:enable_plugin(plugin)
+  local loaded = false
+  local config_type = type(config.plugins[plugin])
+  if config_type == "boolean" or config_type == "nil" then
+    config.plugins[plugin] = {}
+    loaded = true
+  end
+
+  require("plugins." .. plugin)
+
+  for _, section in ipairs(settings.plugin_sections) do
+    local plugins = settings.plugins[section]
+
+    for plugin_name, options in pairs(plugins) do
+      if plugin_name == plugin then
+        ---@type widget
+        local pane = self.plugin_sections:get_pane(section)
+        if not pane then
+          pane = self.plugin_sections:add_pane(section, section)
+        else
+          pane = pane.container
+        end
+
+        for _, opt in ipairs(options) do
+          ---@type settings.option
+          local option = opt
+          add_control(pane, option, plugin_name)
+        end
+      end
+    end
+  end
+
+  if
+    type(settings.config.disabled_plugins) == "table"
+    and
+    settings.config.disabled_plugins[plugin]
+  then
+    settings.config.disabled_plugins[plugin] = nil
+  end
+  if type(settings.config.enabled_plugins) ~= "table" then
+    settings.config.enabled_plugins = {}
+  end
+
+  settings.config.enabled_plugins[plugin] = true
+  save_settings()
+
+  if loaded then
+    core.log("Loaded '%s' plugin", plugin)
+  end
+end
+
+---Generate all the widgets for plugin settings.
+function Settings:load_plugin_settings()
+  ---@type widget
+  local pane = self.plugin_sections:get_pane("enable_disable")
+  if not pane then
+    pane = self.plugin_sections:add_pane("enable_disable", "Installed")
+  else
+    pane = pane.container
+  end
+
+  -- requires earlier access to startup process
+  Label(
+    pane,
+    "Notice: disabling plugins will not take effect until next restart"
+  )
+
+  Line(pane, 2, 10)
+
+  local plugins = get_installed_plugins()
+  for _, plugin in ipairs(plugins) do
+    if plugin ~= "settings" then
+      local enabled = false
+
+      if
+        (
+          type(config.plugins[plugin]) ~= "nil"
+          and
+          config.plugins[plugin] ~= false
+        )
+        or
+        (
+          settings.config.enabled_plugins
+          and
+          settings.config.enabled_plugins[plugin]
+        )
+      then
+        enabled = true
+      end
+
+      local this = self
+
+      ---@type widget.toggle
+      local toggle = Toggle(pane, prettify_name(plugin), enabled)
+      function toggle:on_change(value)
+        if value then
+          this:enable_plugin(plugin)
+        else
+          this:disable_plugin(plugin)
+        end
+      end
+    end
+  end
+
+  table.sort(settings.plugin_sections)
+
+  for _, section in ipairs(settings.plugin_sections) do
+    local plugins = settings.plugins[section]
+
+    for plugin_name, options in pairs(plugins) do
+      ---@type widget
+      local pane = self.plugin_sections:get_pane(section)
+      if not pane then
+        pane = self.plugin_sections:add_pane(section, section)
+      else
+        pane = pane.container
+      end
+
+      for _, opt in ipairs(options) do
+        ---@type settings.option
+        local option = opt
+        add_control(pane, option, plugin_name)
+      end
+    end
+  end
+end
+
+---@type widget.keybinddialog
+local keymap_dialog = KeybindingDialog()
+
+function keymap_dialog:on_save(bindings)
+  local row_value = apply_keybinding(self.command, bindings)
+  if row_value then
+    self.listbox:set_row(self.row_id, row_value)
+  end
+end
+
+function keymap_dialog:on_reset()
+  local default_keys = settings.default_keybindings[self.command]
+  local current_keys = { keymap.get_binding(self.command) }
+
+  for _, binding in ipairs(current_keys) do
+    keymap.unbind(binding, self.command)
+  end
+
+  if default_keys and #default_keys > 0 then
+    local cmd = self.command
+    if not settings.config.custom_keybindings then
+      settings.config.custom_keybindings = {}
+      settings.config.custom_keybindings[cmd] = {}
+    elseif not settings.config.custom_keybindings[cmd] then
+      settings.config.custom_keybindings[cmd] = {}
+    end
+    local shortcuts = ""
+    for _, binding in ipairs(default_keys) do
+      keymap.add({[binding] = cmd})
+      shortcuts = shortcuts .. binding .. "\n"
+      table.insert(settings.config.custom_keybindings[cmd], binding)
+    end
+    local bindings_list = shortcuts:gsub("\n$", "")
+    self.listbox:set_row(self.row_id, {
+      style.text, cmd, ListBox.COLEND, style.dim, bindings_list
+    })
+  else
+    self.listbox:set_row(self.row_id, {
+      style.text, self.command, ListBox.COLEND, style.dim, "none"
+    })
+  end
+  if
+    settings.config.custom_keybindings
+    and
+    settings.config.custom_keybindings[self.command]
+  then
+    settings.config.custom_keybindings[self.command] = nil
+    save_settings()
+  end
+end
+
+---Generate the list of all available commands and allow editing their keymaps.
+function Settings:load_keymap_settings()
+  self.keybinds.scrollable = false
+
+  local ordered = {}
+  for name, _ in pairs(command.map) do
+    table.insert(ordered, name)
+  end
+  table.sort(ordered)
+
+  ---@type widget.listbox
+  local listbox = ListBox(self.keybinds)
+
+  listbox.border.width = 0
+  listbox:enable_expand(true)
+
+  listbox:add_column("Command")
+  listbox:add_column("Bindings")
+
+  for _, name in ipairs(ordered) do
+    local keys = { keymap.get_binding(name) }
+    local binding = ""
+    if #keys == 1 then
+      binding = keys[1]
+    elseif #keys > 1 then
+      binding = keys[1]
+      for idx, key in ipairs(keys) do
+        if idx ~= 1 then
+          binding = binding .. "\n" .. key
+        end
+      end
+    elseif #keys < 1 then
+      binding = "none"
+    end
+    listbox:add_row({
+      style.text, name, ListBox.COLEND, style.dim, binding
+    }, name)
+  end
+
+  function listbox:on_row_click(idx, data)
+    if not keymap_dialog:is_visible() then
+      local bindings = { keymap.get_binding(data) }
+      keymap_dialog:set_bindings(bindings)
+      keymap_dialog.row_id = idx
+      keymap_dialog.command = data
+      keymap_dialog.listbox = self
+      keymap_dialog:show()
+    end
+  end
+end
+
+---Reposition and resize core and plugin widgets.
+function Settings:update()
+  if not Settings.super.update(self) then return end
+
+  self.notebook:set_size(self.size.x, self.size.y)
+
+  self.core:set_size(
+    self.size.x,
+    self.size.y - self.notebook.active_pane.tab:get_height() - 8
+  )
+
+  self.plugins:set_size(
+    self.size.x,
+    self.size.y - self.notebook.active_pane.tab:get_height() - 8
+  )
+
+  self.core_sections:set_size(
+    self.core.size.x - (style.padding.x),
+    self.core_sections:get_real_height()
+  )
+
+  self.plugin_sections:set_size(
+    self.plugins.size.x - (style.padding.x),
+    self.plugin_sections:get_real_height()
+  )
+
+  self.core_sections:set_position(
+    style.padding.x / 2,
+    0
+  )
+
+  self.plugin_sections:set_position(
+    style.padding.x / 2,
+    0
+  )
+
+  for _, section in ipairs({self.core_sections, self.plugin_sections}) do
+    for _, pane in ipairs(section.panes) do
+      local prev_child = nil
+      for pos=#pane.container.childs, 1, -1 do
+        local child = pane.container.childs[pos]
+        local x, y = 10, 10
+        if prev_child then
+          if
+            (prev_child:is(Label) and not prev_child.desc)
+            or
+            (child:is(Label) and child.desc)
+          then
+            y = prev_child:get_bottom() + 10
+          else
+            y = prev_child:get_bottom() + 40
+          end
+        end
+        if child:is(Line) then
+          x = 0
+        elseif child:is(ItemsList) then
+          child:set_size(pane.container:get_width() - 20, child.size.y)
+        end
+        child:set_position(x, y)
+        prev_child = child
+      end
+    end
+  end
+end
+
+--------------------------------------------------------------------------------
+-- overwrite core run to inject previously saved settings and save at exit
+--------------------------------------------------------------------------------
+local core_run = core.run
+function core.run()
+  store_default_keybindings()
+
+  -- merge custom settings into config
+  merge_settings()
+
+  ---@type settings.ui
+  settings.ui = Settings()
+
+  -- load plugins disabled by default and enabled by user
+  if settings.config.enabled_plugins then
+    for name, _ in pairs(settings.config.enabled_plugins) do
+      if
+        type(config.plugins[name]) == "boolean"
+        and
+        not config.plugins[name]
+      then
+        settings.ui:enable_plugin(name)
+      end
+    end
+  end
+
+  -- apply user chosen color theme
+  if settings.config.theme then
+    core.reload_module("colors." .. settings.config.theme)
+  end
+
+  core_run()
+
+  -- save on a normal exit
+  save_settings()
+end
+
+--------------------------------------------------------------------------------
+-- Disable plugins at startup, only works if this file is the first
+-- required on user module, or priority tag is obeyed by lite-xl.
+--------------------------------------------------------------------------------
+-- load custom user settings that include list of disabled plugins
+load_settings()
+
+-- only disable non already loaded plugins
+if settings.config.disabled_plugins then
+  for name, _ in pairs(settings.config.disabled_plugins) do
+    if type(rawget(config.plugins, name)) == "nil" then
+      config.plugins[name] = false
+    end
+  end
+end
+
+--------------------------------------------------------------------------------
+-- Add command and keymap to load settings view
+--------------------------------------------------------------------------------
+command.add(nil, {
+  ["ui:settings"] = function()
+    settings.ui:show()
+    local node = core.root_view:get_active_node_default()
+    local found = false
+    for _, view in ipairs(node.views) do
+      if view == settings.ui then
+        found = true
+        node:set_active_view(view)
+        break
+      end
+    end
+    if not found then
+      node:add_view(settings.ui)
+    end
+  end,
+})
+
+keymap.add {
+  ["ctrl+alt+p"] = "ui:settings"
+}
+
+--------------------------------------------------------------------------------
+-- Overwrite toolbar preferences command to open the settings gui
+--------------------------------------------------------------------------------
+local toolbarview_on_mouse_moved = ToolbarView.on_mouse_moved
+function ToolbarView:on_mouse_moved(px, py, ...)
+  toolbarview_on_mouse_moved(self, px, py, ...)
+  if
+    self.hovered_item
+    and
+    self.hovered_item.command == "core:open-user-module"
+  then
+    self.hovered_item.command = "ui:settings"
+  end
+end
+
+
+return settings;