#!/bin/sh

# Settings
SITE_URL="https://www8.cao.go.jp/chosei/shukujitsu/gaiyou.html"
MAIL_TO="$USER"
MAIL_FROM="info@holiday.kareha.org"
MAIL_SUBJECT="Holiday Site Updated"
MAIL_BODY="Holiday web site 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 "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_HTML_FILE="summary-jp-tmp.html"
HTML_FILE="summary-jp.html"

# Run
curl -sS -L -o $TMP_HTML_FILE $SITE_URL
if ! diff -q $HTML_FILE $TMP_HTML_FILE >/dev/null 2>&1; then
  CACHE_DIR="cache"
  mkdir -p "$CACHE_DIR"
  CURRENT_DATETIME=$(date "+%Y-%m-%d_%H:%M:%S%z")
  cp $TMP_HTML_FILE "$CACHE_DIR/summary-jp-$CURRENT_DATETIME.html"
  mv $TMP_HTML_FILE $HTML_FILE
  log "Changed"
  send_mail
  ./extract
  ./merge 2>/dev/null
else
  log "No Change"
  rm $TMP_HTML_FILE
fi

# Release the lock
rmdir "$LOCK_DIR"

# Exit
exit $EXIT_SUCCESS