feat: Make all themes easily user-customizable

This is achieved by using custom @-prefixed tmux options which are set
with the `-o` option, meaning, the theme will only set the value if it
is not already set.

This allows users to override any of the options in the theme by simply
setting them before loading the theme.

Additionally all themes are now generated using a custom theme builder,
that allows sharing various parts of themes between them easily.

basic.tmuxtheme

@@ -1,54 +1,73 @@
-# Status update interval
-set -g status-interval 1
+#
+# Basic theme
+#
 
-# Basic status bar colors
-set -g status-style bg=black,fg=cyan
+# Themepack format options
+set -goq @themepack-status-left-area-left-format "#S"
+set -goq @themepack-status-left-area-middle-format "#I"
+set -goq @themepack-status-left-area-right-format "#P"
+set -goq @themepack-status-right-area-left-format "#H"
+set -goq @themepack-status-right-area-middle-format "%H:%M:%S"
+set -goq @themepack-status-right-area-right-format "%d-%b-%y"
+set -goq @themepack-window-status-current-format "#I:#W#F"
+set -goq @themepack-window-status-format "#I:#W#F"
 
-# Left side of status bar
-set -g status-left-style bg=black,fg=green
-set -g status-left-length 40
-set -g status-left "#S #[fg=white]» #[fg=yellow]#I #[fg=cyan]#P"
+# Theme options
+set -goq  @theme-clock-mode-colour red
+set -goq  @theme-clock-mode-style 24
+set -goq  @theme-display-panes-active-colour default
+set -goq  @theme-display-panes-colour default
+set -goq  @theme-message-bg default
+set -goq  @theme-message-command-bg default
+set -goq  @theme-message-command-fg default
+set -goq  @theme-message-fg default
+set -goq  @theme-mode-bg red
+set -goq  @theme-mode-fg default
+set -goq  @theme-pane-active-border-bg default
+set -goq  @theme-pane-active-border-fg green
+set -goq  @theme-pane-border-bg default
+set -goq  @theme-pane-border-fg default
+set -goq  @theme-status-bg black
+set -goq  @theme-status-fg cyan
+set -goq  @theme-status-interval 1
+set -goq  @theme-status-justify centre
+set -goqF @theme-status-left "#{@themepack-status-left-area-left-format} #[fg=white]» #[fg=yellow]#{@themepack-status-left-area-middle-format} #[fg=cyan]#{@themepack-status-left-area-right-format}"
+set -goq  @theme-status-left-bg black
+set -goq  @theme-status-left-fg green
+set -goq  @theme-status-left-length 40
+set -goqF @theme-status-right "#{@themepack-status-right-area-left-format} #[fg=white]« #[fg=yellow]#{@themepack-status-right-area-middle-format} #[fg=green]#{@themepack-status-right-area-right-format}"
+set -goq  @theme-status-right-bg black
+set -goq  @theme-status-right-fg cyan
+set -goq  @theme-status-right-length 40
+set -goq  @theme-window-status-activity-bg black
+set -goq  @theme-window-status-activity-fg yellow
+set -goq  @theme-window-status-current-bg red
+set -goq  @theme-window-status-current-fg black
+set -goqF @theme-window-status-current-format " #{@themepack-window-status-current-format} "
+set -goqF @theme-window-status-format " #{@themepack-window-status-format} "
+set -goq  @theme-window-status-separator ""
 
-# Right side of status bar
-set -g status-right-style bg=black,fg=cyan
-set -g status-right-length 40
-set -g status-right "#H #[fg=white]« #[fg=yellow]%H:%M:%S #[fg=green]%d-%b-%y"
-
-# Window status
-set -g window-status-format " #I:#W#F "
-set -g window-status-current-format " #I:#W#F "
-
-# Current window status
-set -g window-status-current-style bg=red,fg=black
-
-# Window with activity status
-set -g window-status-activity-style bg=black,fg=yellow
-
-# Window separator
-set -g window-status-separator ""
-
-# Window status alignment
-set -g status-justify centre
-
-# Pane border
-set -g pane-border-style bg=default,fg=default
-
-# Active pane border
-set -g pane-active-border-style bg=default,fg=green
-
-# Pane number indicator
-set -g display-panes-colour default
-set -g display-panes-active-colour default
-
-# Clock mode
-set -g clock-mode-colour red
-set -g clock-mode-style 24
-
-# Message
-set -g message-style bg=default,fg=default
-
-# Command message
-set -g message-command-style bg=default,fg=default
-
-# Mode
-set -g mode-style bg=red,fg=default
+# Apply theme options
+set -gF display-panes-active-colour "#{@theme-display-panes-active-colour}"
+set -gF display-panes-colour "#{@theme-display-panes-colour}"
+set -gF message-command-style "fg=#{@theme-message-command-fg},bg=#{@theme-message-command-bg}"
+set -gF message-style "fg=#{@theme-message-fg},bg=#{@theme-message-bg}"
+set -gF status-interval "#{@theme-status-interval}"
+set -gF status-justify "#{@theme-status-justify}"
+set -gF status-left "#{@theme-status-left}"
+set -gF status-left-length "#{@theme-status-left-length}"
+set -gF status-left-style "fg=#{@theme-status-left-fg},bg=#{@theme-status-left-bg}"
+set -gF status-right "#{@theme-status-right}"
+set -gF status-right-length "#{@theme-status-right-length}"
+set -gF status-right-style "fg=#{@theme-status-right-fg},bg=#{@theme-status-right-bg}"
+set -gF status-style "fg=#{@theme-status-fg},bg=#{@theme-status-bg}"
+set -gwF clock-mode-colour "#{@theme-clock-mode-colour}"
+set -gwF clock-mode-style "#{@theme-clock-mode-style}"
+set -gwF mode-style "fg=#{@theme-mode-fg},bg=#{@theme-mode-bg}"
+set -gwF pane-active-border-style "fg=#{@theme-pane-active-border-fg},bg=#{@theme-pane-active-border-bg}"
+set -gwF pane-border-style "fg=#{@theme-pane-border-fg},bg=#{@theme-pane-border-bg}"
+set -gwF window-status-activity-style "fg=#{@theme-window-status-activity-fg},bg=#{@theme-window-status-activity-bg}"
+set -gwF window-status-current-format "#{@theme-window-status-current-format}"
+set -gwF window-status-current-style "fg=#{@theme-window-status-current-fg},bg=#{@theme-window-status-current-bg}"
+set -gwF window-status-format "#{@theme-window-status-format}"
+set -gwF window-status-separator "#{@theme-window-status-separator}"