Refactor HISTFILE setting

Co-authored-by: WATANABE Yuki <magicant@wonderwand.net>

share/initialization/common

@@ -183,21 +183,18 @@ fi
 
 # variables needed for command history
 
-HISTFILE=${XDG_STATE_HOME:-~/.local/state}/yash/history
-HISTSIZE=5000
-
-
-# handle old yash history directory
-if [ -f "$HOME/.yash_history" ] && [ -z "$HISTFILE" ]; then
-  echo 'warning: Yash does not read $HOME/.yash_history by default, please set
-  $HISTFILE to $XDG_STATE_HOME/yash/history'
-  HISTFILE="$HOME/.yash_history"
+if ! [ "${HISTFILE-}" ]; then
+    HISTFILE=${XDG_STATE_HOME:-~/.local/state}/yash/history
+
+    # handle old default history path
+    if [ -f ~/.yash_history ]; then
+        printf 'Note: The default history file location has been changed to "%s".\n' "$HISTFILE" >&2
+        HISTFILE=~/.yash_history
+        printf 'Please consider moving the existing file from the current location "%s".\n' "$HISTFILE" >&2
+    fi
 fi
 
-# create HISTFILE directory if it doesn't exist
-if [ ! -d  "$(dirname "$HISTFILE")" ]; then
-  mkdir -p "$(dirname "$HISTFILE")"
-fi
+HISTSIZE=5000
 
 # HISTRMDUP makes prediction less accurate
 # HISTRMDUP=500