#!/bin/sh

# Settings
CSV_URL="https://www8.cao.go.jp/chosei/shukujitsu/syukujitsu.csv"
MAIL_TO="$USER"
MAIL_FROM="info@holiday.kareha.org"
MAIL_SUBJECT="Holiday CSV Updated"
MAIL_BODY="Holiday CSV file has been updated."

# Constants
EXIT_SUCCESS=0
EXIT_FAILURE=1

# Verify the required runtime environment
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"
verify_command "mailx"

# Logging
CURRENT_MONTH=$(date "+%Y-%m%z")
SCRIPT_NAME=$(basename $0)
LOG_DIR="log"
LOG_FILE="$LOG_DIR/$SCRIPT_NAME-$CURRENT_MONTH"

get_current_time() {
  date "+%Y-%m-%d %H:%M:%S%z"
}

log() {
  local timestamp=$(get_current_time)
  local message=$1
  echo "$timestamp $message" >>$LOG_FILE
}

send_mail() {
  echo "$MAIL_BODY" | mailx -r "$MAIL_FROM" -s "$MAIL_SUBJECT" "$MAIL_TO"
  if [ $? -ne 0 ]; then
    log "Failed to send email"
  fi
}

# Acquire the lock or exit
LOCK_DIR="$SCRIPT_NAME-lock"
if ! mkdir "$LOCK_DIR" 2>/dev/null; then
  echo "Another process is holding the lock. Exiting."
  exit $EXIT_FAILURE
fi

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 $TMP_CSV_FILE >/dev/null 2>&1; then
  CACHE_DIR="cache"
  mkdir -p "$CACHE_DIR"
  CURRENT_DATETIME=$(date "+%Y-%m-%d_%H:%M:%S%z")
  cp $TMP_CSV_FILE "$CACHE_DIR/holidays-jp-$CURRENT_DATETIME.csv"
  mv $TMP_CSV_FILE $RAW_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 ($1 >= cy) print }' | tr -d '\r' >$CSV_FILE
  log "Changed"
  send_mail
  ./merge
else
  log "No Change"
  rm $TMP_CSV_FILE
fi

# Release the lock
rmdir "$LOCK_DIR"

# Exit
exit $EXIT_SUCCESS