Feature: Add vi-mode plugin

functions/geometry_vi

@@ -0,0 +1,77 @@
+# geometry_vi - A geometry plugin to display the ZLE vi-mode state.
+
+geometry_vi() {
+    # Required for RPROMPT to render properly after submitting a command.
+    geometry::vi-get-mode
+}
+
+# Re-render the prompt.
+function geometry::vi-update-prompt() {
+    imode=$(geometry::vi-insert-mode)
+    nmode=$(geometry::vi-normal-mode)
+    if [[ $KEYMAP == vicmd ]]; then
+        PROMPT=${PROMPT//$imode/$nmode}
+        RPROMPT=${RPROMPT//$imode/$nmode}
+    else
+        PROMPT=${PROMPT//$nmode/$imode}
+        RPROMPT=${RPROMPT//$nmode/$imode}
+    fi
+}
+
+# Render normal mode.
+function geometry::vi-normal-mode() {
+    ansi ${GEOMETRY_VI_NORMAL_COLOR:-white} ${GEOMETRY_VI_NORMAL_MODE:-"<NORMAL>"}
+}
+
+# Render insert mode.
+function geometry::vi-insert-mode() {
+    ansi ${GEOMETRY_VI_INSERT_COLOR:-yellow} ${GEOMETRY_VI_INSERT_MODE:-"<INSERT>"}
+}
+
+# Return the currently active mode.
+function geometry::vi-get-mode() {
+    imode=$(geometry::vi-insert-mode)
+    nmode=$(geometry::vi-normal-mode)
+    [[ $KEYMAP == vicmd ]] && echo $nmode || echo $imode
+}
+
+# ZLE widget to trigger prompt updates.
+function geometry::vi-draw-mode {
+    keymap=$(geometry::vi-get-mode)
+    geometry::vi-update-prompt
+    zle reset-prompt
+}
+
+
+# Initialization: Bind the widgets required to perform proper prompt updates.
+# Adapted from https://github.com/zsh-users/zsh-syntax-highlighting/blob/master/zsh-syntax-highlighting.zsh#L295-L359
+local prefix="geometry_vi"
+for w (zle-keymap-select zle-line-pre-redraw zle-line-init zle-line-finish); do
+    case ${widgets[$w]:-""} in
+    # Already Bound to geometry: Do nothing.
+    user:geometry-vi-draw) ;;
+
+    # Existing user widget: Chain a call to it.
+    user:*) zle -N $prefix-$w ${widgets[$w]#*:}
+        # Dynamically create a function to call the previous widget.
+        eval "geometry::${(q)prefix}-${(q)w}() { geometry::vi-draw-mode; builtin zle ${(q)prefix}-${(q)w} -- \"\$@\" }"
+        zle -N $w geometry::$prefix-$w;;
+
+    # Completion widgets: Ignore.
+    completion:*) ;;
+
+    # Builtin widget: Chain a call to ".widget".
+    # Eval is required to get a closure (
+    builtin) eval "geometry::${(q)prefix}-${(q)w}() { geometry::vi-draw-mode; builtin zle .${(q)w} -- \"\$@\" }"
+         zle -N $cur_widget _zsh_highlight_widget_$prefix-$cur_widget;;
+
+    # Unbound widget: Bind directly.
+    *) 
+        if [[ $w == zle-* ]] && (( ! ${+widgets[$w]} )); then
+        zle -N $w geometry::vi-draw-mode
+        else
+        # Default: unhandled case.
+        print -r -- >&2 "geometry::geometry_vi: unhandled ZLE widget ${(qq)w}"
+        fi
+    esac
+done