Add install script

Signed-off-by: Nikolaos Karaolidis <nick@karaolidis.com>

hosts/common/configs/system/nix-install/install.completion.zsh

@@ -0,0 +1,30 @@
+_nix-install_completion() {
+  local -a options
+  options=(
+    '1:flake:_directories'
+    '-m[Mode: 'install' or 'repair']:mode:(install repair)'
+    '-h[Host to configure]:host:($(_list_hosts))'
+    '-k[Key file to copy to user config]:key:($(_list_keys))'
+    '-p[LUKS password file to use for encryption]:password_file:_files'
+    '-c[Copy configuration to target]'
+    '-r[Reboot after completion]'
+  )
+
+  _list_hosts() {
+    flake="$(realpath ${words[2]})"
+    if [[ -f "${flake}/flake.nix" ]]; then
+      nix flake show --quiet --json "${flake}" 2>/dev/null | jq -r '.nixosConfigurations | keys[]'
+    fi
+  }
+
+  _list_keys() {
+    flake="$(realpath ${words[2]})"
+    if [[ -d "${flake}/secrets" ]]; then
+      find "${flake}/secrets" -type f -name 'key.txt' | sed -E 's|^.*/secrets/([^/]+)/key.txt$|\1|' | sort -u
+    fi
+  }
+
+  _arguments -s $options
+}
+
+compdef _nix-install_completion nix-install