Script to switch between light and dark themes for Cinammon running on Mint

lightswitch

#!/bin/bash
# lightswitch - Switch themes between light and dark mode
# This is intended for Linux hosts using the Cinnamon desktop e.g. Mint.

export prog_name="${0##*/}"
export app_filename="/usr/share/applications/${prog_name}.desktop"

# Set our times to switch between light and dark themes (24hr time)
lights_on="${lights_on:-0900}"
lights_off="${lights_off:-2000}"
current_time=$(date +%H%M)

# Force these variables into decimal mode to prevent octal interpretation
lights_on=$(( 10#${lights_on} ))
lights_off=$(( 10#${lights_off} ))
current_time=$(( 10#${current_time} ))

# We set these here for consumption by set_theme_light|dark() and flip_theme()
dark_wmborders="${dark_wmborders:-CBlack}"
dark_icons="${dark_icons:-Papirus-Dark}"
dark_controls="${dark_controls:-CBlack}"
dark_mouse="${dark_mouse:-DMZ-White}"
dark_desktop="${dark_desktop:-CBlack}"

light_wmborders="${light_wmborders:-Cinnamox-Heather}"
light_icons="${light_icons:-Papirus-Light}"
light_controls="${light_controls:-ChromeOS}"
light_mouse="${light_mouse:-DMZ-White}"
light_desktop="${light_desktop:-Chinvat}"

# Define a full set of var validation functions
var_is_set() { [ "${1+x}" = "x" ] && [ "${#1}" -gt "0" ]; }     # set and not null
var_is_unset() { [ -z "${1+x}" ]; }                             # unset
var_is_empty() { [ "${1+x}" = "x" ] && [ "${#1}" -eq "0" ]; }   # set and null
var_is_blank() { var_is_unset "${1}" || var_is_empty "${1}"; }  # unset, or set and null

create_desktop_shortcuts() {
cat << EOF > "${HOME}/Desktop/Light Mode.desktop"
[Desktop Entry]
Name=Light Mode
Exec=lightswitch -t light
Comment=
Terminal=false
Icon=sunny
Type=Application
EOF

cat << EOF > "${HOME}/Desktop/Dark Mode.desktop"
[Desktop Entry]
Name=Dark Mode
Exec=lightswitch -t dark
Comment=
Terminal=false
Icon=night-light-symbolic
Type=Application
EOF

  chmod 755 "${HOME}/Desktop/Light Mode.desktop"
  chmod 755 "${HOME}/Desktop/Dark Mode.desktop"
}

create_panel_shortcut() {
  if [[ ! -f "${app_filename}" ]]; then
cat << EOF > "${app_filename}"
[Desktop Entry]
Name=${prog_name}
Comment=Switch between light and dark themes
GenericName=Theme changer
Exec=lightswitch -f
Terminal=false
Icon=sunny
Type=Application
EOF
  fi

  chown 0:"$(whoami)" "${app_filename}"
  chmod 664 "${app_filename}"
}

add_panel_shortcut() {
  (
    cd "${HOME}/.cinnamon/configs/[email protected]" || return 1
    # Google and my own system tells me this should be 3.json, but just in case
    # TO-DO: Build in some smarts for ensuring the correct file is edited
    local json_file="3.json"

    # Ensure we don't already have an entry
    if grep -q "${prog_name}.desktop" "${json_file}"; then
      return 0
    fi

    # Back up the json file
    cp "${json_file}" "${json_file}.bak.$(date +%Y%m%d)"

    if command -v jq >/dev/null 2>&1; then
      jq \
        --arg prog_name "${prog_name}.desktop" \
        -e \
        '."pinned-apps".value=[$prog_name]+."pinned-apps".value' \
        "${json_file}" > "${json_file}".tmp
      mv "${json_file}".tmp "${json_file}"
    # This 'sed' invocation will match the shortcut to nemo and insert it to the left
    # TO-DO: make this match only the second instance of 'nemo.desktop'
    else
      sed -i "/\"nemo.desktop\",/i \            \"${prog_name}.desktop\",/" "${json_file}"
    fi

    printf -- '%s\n' \
      "${prog_name}: Added shortcut to panel.  To restore, run the following:" \
      "mv ${PWD}/${json_file}.bak.$(date +%Y%m%d) ${PWD}/${json_file}"
  )
}

get_cinnamon_spice() {
  if ! command -v git >/dev/null 2>&1; then
    printf -- '%s\n' "${prog_name} ERROR: 'git' is required to perform this"
    exit 1
  fi
  
  [[ ! -d "${HOME}"/.cinnamon_spices_themes ]] && mkdir -p "${HOME}"/.cinnamon_spices_themes

  if [[ ! -f "${HOME}"/.cinnamon_spices_themes/README.md ]]; then
    git clone https://github.com/linuxmint/cinnamon-spices-themes.git "${HOME}"/.cinnamon_spices_themes/
  fi

  (
    cd "${HOME}"/.cinnamon_spices_themes || return 1
    git pull
    for theme in *; do
      case "${theme}" in
        (README.md|.git|.github) : ;;
        (*)
          cp -R "${theme}/files/${theme}/" "${HOME}/.themes/"
        ;;
      esac
    done
  )
}

get_desktop() { gsettings get org.cinnamon.theme name; }
get_icons() { gsettings get org.cinnamon.desktop.interface icon-theme; }
get_mouse() { gsettings get org.cinnamon.desktop.interface cursor-theme; }
get_controls() { gsettings get org.cinnamon.desktop.interface gtk-theme; }
get_wallpaper() { gsettings get org.cinnamon.desktop.background picture-uri; }
get_wmborders() { gsettings get org.cinnamon.desktop.wm.preferences theme; }

list_themes() {
  printf -- '>>>> %s\n' "Current settings:"
  printf -- '%s\n' \
    "Window Borders: $(get_wmborders)" \
    "Icons: $(get_icons)" \
    "Controls: $(get_controls)" \
    "Mouse Pointer: $(get_mouse)" \
    "Desktop: $(get_desktop)" \
    "Wallpaper: $(get_wallpaper)"

  printf -- '>>>> %s\n' "Available themes:"
  find /usr/share/themes/ "${HOME}"/.themes/ -maxdepth 1 -printf '%P\n' | 
    grep . | 
    sort |
    column
}

set_desktop() {
  gsettings set org.cinnamon.theme name "${1:?No theme declared}"
}

set_icons() {
  gsettings set org.cinnamon.desktop.interface icon-theme "${1:?No theme declared}"
}

set_mouse() {
  gsettings set org.cinnamon.desktop.interface cursor-theme "${1:?No theme declared}"
}

set_controls() {
  gsettings set org.cinnamon.desktop.interface gtk-theme "${1:?No theme declared}"
}

set_wallpaper() {
  if [[ ! -r "${1:?No wallpaper declared}" ]]; then
    printf -- '%s\n' "${prog_name} ERROR:  Could not find or read '${1}'" >&2
    exit 1
  fi
  gsettings set org.cinnamon.desktop.background picture-uri "file://${1}"
}

set_wmborders() {
  gsettings set org.cinnamon.desktop.wm.preferences theme "${1:?No theme declared}"
}

set_dark_theme_vars() {
  var_is_set "${dark_wmborders}"  && wmborders="${dark_wmborders}"
  var_is_set "${dark_icons}"      && icons="${dark_icons}"
  var_is_set "${dark_controls}"   && controls="${dark_controls}"
  var_is_set "${dark_mouse}"      && mouse="${dark_mouse}"
  var_is_set "${dark_desktop}"    && desktop="${dark_desktop}"
}

set_light_theme_vars() {
  var_is_set "${light_wmborders}" && wmborders="${light_wmborders}"
  var_is_set "${light_icons}"     && icons="${light_icons}"
  var_is_set "${light_controls}"  && controls="${light_controls}"
  var_is_set "${light_mouse}"     && mouse="${light_mouse}"
  var_is_set "${light_desktop}"   && desktop="${light_desktop}"
}

set_theme_vars_by_time() {
  if (( current_time > lights_off ))||(( current_time < lights_on )); then
    set_dark_theme_vars
  else
    set_light_theme_vars
  fi
}

set_theme() {
  [[ "$(get_wmborders)" != "${wmborders}" ]]   && set_wmborders "${wmborders}"
  [[ "$(get_icons)" != "${icons}" ]]           && set_icons "${icons}"
  [[ "$(get_controls)" != "${controls}" ]]     && set_controls "${controls}"
  [[ "$(get_mouse)" != "${mouse}" ]]           && set_mouse "${mouse}"
  [[ "$(get_desktop)" != "${desktop}" ]]       && set_desktop "${desktop}"
  if var_is_set "${wallpaper}"; then
    [[ "$(get_wallpaper)" != "${wallpaper}" ]] && set_wallpaper "${wallpaper}"
  fi
}

set_theme_light() {
  set_light_theme_vars

  if [ -f "${app_filename}" ]; then
    sed 's/^Icon.*/Icon=sunny/' "${app_filename}" > /tmp/.lightswitch.light
    cp /tmp/.lightswitch.light "${app_filename}"
  fi

  set_theme
}

set_theme_dark() {
  set_dark_theme_vars

  if [ -f "${app_filename}" ]; then
    if dpkg -l | grep -q -- "papirus-icon-theme"; then
      sed 's|^Icon.*|Icon=palemoon|' "${app_filename}" > /tmp/.lightswitch.dark
    else
      sed 's/^Icon.*/Icon=night-light-symbolic/' "${app_filename}" > /tmp/.lightswitch.dark
    fi
    cp /tmp/.lightswitch.dark "${app_filename}"
  fi

  set_theme
}

set_theme_auto() {
  if (( current_time > lights_off ))||(( current_time < lights_on )); then
    set_theme_dark
  else
    set_theme_light
  fi
}

flip_theme() {
  found_theme=$(get_controls | tr -d "\'")
  if [[ "${found_theme}" = "${dark_controls}" ]]; then
    set_theme_light
    exit 0
  elif [[ "${found_theme}" = "${light_controls}" ]]; then
    set_theme_dark
    exit 0
  else
    set_theme_auto
  fi
}

setup_papirus() {
  add-apt-repository ppa:papirus/papirus
  apt-get update
  apt-get install papirus-icon-theme
}

validate_config() {
  local conf_file conf_errcount
  conf_file="${1:?No config file defined}"
  [[ -r "${conf_file}" ]] || {
    printf -- '%s\n' "Could not read ${conf_file}" >&2
    exit 1
  }
  [[ -s "${conf_file}" ]] || {
    printf -- '%s\n' "${conf_file} appears to be empty" >&2
    exit 1
  }
  # TO-DO: Update the filter to cater for configs that don't use dark_ or light_ vars
  conf_errcount="$(grep -Evc '^dark_.*=|^light_.*=|^lights_.*=|^$|^#' "${conf_file}")"
  (( conf_errcount > 0 )) && {
    printf -- '%s\n' "Invalid config found in ${conf_file}" >&2
    exit 1
  }
}

write_var() {
  printf -- '%s="%s"\n' "${1:?No key supplied}" "${2:?No value supplied}"
}

# TO-DO: plug this into getopts
write_config() {
  local output_file
  output_file="${1:?No output path defined}"

  {
    printf -- '%s\n' "# Set our times to switch between light and dark themes (24hr time)"
    write_var "lights_on" "${lights_on:-0900}" 
    write_var "lights_off" "${lights_off:-2000}"
    printf -- '%s\n' "" "# Define our theme settings"
    var_is_set "${wmborders}" && write_var "wmborders" "${wmborders}"
    var_is_set "${icons}"     && write_var "icons" "${icons}"
    var_is_set "${controls}"  && write_var "controls" "${controls}"
    var_is_set "${mouse}"     && write_var "mouse" "${mouse}"
    var_is_set "${desktop}"   && write_var "desktop" "${desktop}"
    var_is_set "${wallpaper}" && write_var "desktop" "${wallpaper}"
  } > "${output_file}"
}

usage() {
  printf '%s\n' "${prog_name} - Switch themes between light and dark themes" \
    "Also includes ability to set individual theme elements" ""
  
  printf '\t%s\n' "Options:" \
    " -b set window borders to the given theme" \
    " -c clone https://github.com/linuxmint/cinnamon-spices-themes into ~/.themes/" \
    " -C read supplied config file" \
    " -d set desktop panels to the given theme" \
    " -f flip between light and dark themes" \
    " -g get papirus icon themes" \
    " -h usage" \
    " -i set icons to the given theme" \
    " -l list current theme, set elements and available themes" \
    " -m set mouse pointer to the given theme" \
    " -p add a shortcut for the flip mode to the panel" \
    " -s create desktop shortcuts for light and dark modes" \
    " -t set theme.  Can be one of the following arguments:" \
    "    a|auto - selects the '${prog_name}' light/dark theme based on the time" \
    "    dark|Dark - the '${prog_name}' dark theme" \
    "    light|Light - the '${prog_name}' light theme" \
    "    [anything else] - will attempt to load a gtk theme.  See '-l'." \
    " -w set wallpaper to the given file" 
  exit 0
}

main() {
  # If no args are given, assume auto mode
  if (( "${#}" == 0 )); then
    set_theme_auto
    exit 0
  fi

  # Otherwise, we process our args using getopts
  while getopts ":b:cC:d:fghi:lm:pst:w:" optFlags; do
    case "${optFlags}" in
      (b) wmborders="${OPTARG}" ;;
      (c) get_cinnamon_spice ;;
      (C)
        read_config=true
        config_file="${OPTARG}"
      ;;
      (d) desktop="${OPTARG}" ;;
      (f) flip_theme ;;
      (g)
        sudo -E bash -c "$(declare -f setup_papirus); setup_papirus"
        sudo -k
      ;;
      (h) usage ;;
      (i) icons="${OPTARG}" ;;
      (l) list_themes ;;
      (m) mouse="${OPTARG}" ;;
      (p)
        sudo -E bash -c "$(declare -f create_panel_shortcut); create_panel_shortcut"
        sudo -k
        add_panel_shortcut
        flip_theme
      ;;
      (s) create_desktop_shortcuts ;;
      (t)
        case "${OPTARG}" in
          (a|auto)    set_theme_auto ;;
          ([dD]ark)   set_theme_dark ;;
          ([lL]ight)  set_theme_light ;;
          (*)
            wmborders="${OPTARG}"
            icons="${OPTARG}"
            controls="${OPTARG}"
            mouse="${OPTARG}"
            desktop="${OPTARG}"
          ;;
        esac
      ;;
      (w) wallpaper="${OPTARG}" ;;
      (\?)
        printf -- '%s\n' "${prog_name} ERROR: Invalid option: '-${OPTARG}'" >&2
        exit 1
      (:)
        printf -- '%s\n' "${prog_name} ERROR: Option '-${OPTARG}' requires an argument" >&2
        exit 1
      ;;
    esac
  done
  # If we have a config file, read it now to ensure that its settings take precedence
  if [[ "${read_config}" = "true" ]]; then
    validate_config "${config_file}"
    # shellcheck disable=SC1090
    source "${config_file}"
    # If the config file contains dark_* and/or light_* vars
    # This function will map them relative to the current time
    set_theme_vars_by_time
    # Force these variables into decimal mode to prevent octal interpretation
    lights_on=$(( 10#${lights_on} ))
    lights_off=$(( 10#${lights_off} ))
  fi
  set_theme
}

main "${@}"