trim old holidays

update

@@ -8,14 +8,16 @@ EXIT_SUCCESS=0
 EXIT_FAILURE=1
 
 # Verify the required runtime environment
-if ! command -v curl >/dev/null; then
-  echo "This script requires \"curl\" to be installed. Please install it and try again."
-  exit $EXIT_FAILURE
-fi
-if ! command -v nkf >/dev/null; then
-  echo "This script requires \"nkf\" to be installed. Please install it and try again."
-  exit $EXIT_FAILURE
-fi
+verify_command() {
+  if ! command -v $1 >/dev/null; then
+    echo "This script requires \"$1\" to be installed. Please install it and try again."
+    exit $EXIT_FAILURE
+  fi
+}
+
+verify_command "curl"
+verify_command "nkf"
+verify_command "awk"
 
 # Logging
 CURRENT_MONTH=$(date "+%Yw%U%z")
@@ -45,13 +47,16 @@ mkdir -p $LOG_DIR
 # Internal configuration settings
 TMP_CSV_FILE="holidays-jp-tmp.csv"
 RAW_CSV_FILE="holidays-jp-raw.csv"
+ALL_CSV_FILE="holidays-jp-all.csv"
 CSV_FILE="holidays-jp.csv"
 
 # Run
 curl -sS -L -o $TMP_CSV_FILE $CSV_URL
 if ! diff -q $RAW_CSV_FILE $TMP_CSV_FILE >/dev/null 2>&1; then
   mv $TMP_CSV_FILE $RAW_CSV_FILE
-  nkf -w $RAW_CSV_FILE >$CSV_FILE
+  nkf -w $RAW_CSV_FILE >$ALL_CSV_FILE
+  current_year=$(date +'%Y')
+  tail -n +2 $ALL_CSV_FILE | awk -v cy="$current_year" -F'/' '{ if ($1 >= cy) print }' >$CSV_FILE
   log "Changed"
 else
   log "No Change"