Add auto-update functionality

Fixes marlonrichert#102

README.md

@@ -48,6 +48,11 @@ To run `znap pull` on specific repos only, including ones you have set to be exc
 % znap pull <repo> ...
 ```
 
+To be prompted to automatically update with `znap pull` every 30 days, add the following to your `.zshrc` file:
+```sh
+zstyle ':znap:pull' auto-update 30
+```
+
 ## `.zshrc` optimization
 Using Znap to optimize your Zsh config can be as simple as this:
 ```sh

functions/.znap.auto-update

@@ -0,0 +1,25 @@
+#!/bin/zsh
+
+zmodload zsh/datetime
+
+.znap.autoupdate() {
+  local update_file=${XDG_STATE_HOME}/znap/last-update
+  if [[ ! -f "${update_file}" ]] ; then
+    echo $EPOCHSECONDS > "${update_file}"
+    return 0
+  fi
+
+  local -F interval
+  zstyle -s ':znap:pull' auto-update interval
+
+  local last_update=$(< "${update_file}")
+  (( last_update + (interval * 86400) < EPOCHSECONDS )) || return 0
+
+  read -q "?Update znap? [y/N] " _ || return 0
+  echo
+
+  .znap.pull
+  echo $EPOCHSECONDS > "${update_file}"
+}
+
+.znap.autoupdate "$@"

scripts/init.zsh

@@ -58,6 +58,10 @@ zstyle -T :znap: auto-compile &&
     add-zsh-hook preexec ..znap.auto-compile
 add-zsh-hook zsh_directory_name ..znap.dirname
 
+if zstyle -s ':znap:pull' auto-update _ ; then
+    .znap.auto-update
+fi
+
 typeset -gH _comp_dumpfile=${_comp_dumpfile:-$XDG_CACHE_HOME/zsh/compdump}
 [[ -f $_comp_dumpfile && ${${:-${ZDOTDIR:-$HOME}/.zshrc}:P} -nt $_comp_dumpfile ]] &&
     zf_rm -f $_comp_dumpfile