website_watch

#!/bin/bash

CONFIG_FILE="$XDG_CONFIG_HOME/website_watch.json"
STATE_FILE="$XDG_STATE_HOME/website_watch_state.json"
LOCK_FILE="/tmp/website_watch.lock"
TMP_FILE=$(mktemp)
SCRIPT_PATH="$(readlink -f "${BASH_SOURCE[0]}")"
CRON_CMD="@daily bash $SCRIPT_PATH"

# Exit if another instance of the script is running
if [ -e "$LOCK_FILE" ]; then
  echo "Script is already running. Exiting."
  exit 1
fi

# Create a lock file and clean it up on exit
trap "rm -f $LOCK_FILE $TMP_FILE" EXIT
touch "$LOCK_FILE"

# Ensure configuration file exists
if [ ! -f "$CONFIG_FILE" ]; then
  echo "Configuration file not found at $CONFIG_FILE"
  exit 1
fi

# Ensure state file exists
if [ ! -f "$STATE_FILE" ]; then
  echo "{}" > "$STATE_FILE"
fi

# Add script to cron if not already present
if ! crontab -l | grep -q "$CRON_CMD"; then
  (crontab -l; echo "$CRON_CMD") | crontab -
fi

# Function to send notifications
send_notification() {
  local message="$1"
  local title="$2"
  if command -v osascript &>/dev/null; then
    osascript -e "display notification \"$message\" with title \"$title\""
  elif command -v notify-send &>/dev/null; then
    notify-send "$title" "$message"
  else
    echo "Notification: $title - $message"
  fi
}

# Process each entry in the config file
jq -c '.[]' "$CONFIG_FILE" | while read -r entry; do
  url=$(echo "$entry" | jq -r '.url')
  regex=$(echo "$entry" | jq -r '.regex')
  message=$(echo "$entry" | jq -r '.message // "Website change detected at $url"')
  title=$(echo "$entry" | jq -r '.title // "Website Change Detected"')

  # Fetch webpage
  if ! curl -s "$url" -o "$TMP_FILE"; then
    echo "Failed to fetch URL: $url"
    continue
  fi

  # Check for regex match
  if grep -qE "$regex" "$TMP_FILE"; then
    prev_state=$(jq -r --arg url "$url" '.[$url] // "not_found"' "$STATE_FILE")
    if [ "$prev_state" != "found" ]; then
      send_notification "$message" "$title"
      jq --arg url "$url" '.[$url] = "found"' "$STATE_FILE" > "${STATE_FILE}.tmp" && mv "${STATE_FILE}.tmp" "$STATE_FILE"
    fi
  else
    jq --arg url "$url" '.[$url] = "not_found"' "$STATE_FILE" > "${STATE_FILE}.tmp" && mv "${STATE_FILE}.tmp" "$STATE_FILE"
  fi
done

website_watch.json

[
  {
    "url": "https://locations.dollartree.com/il/chicago",
    "regex": "Some St",
    "message": "Dollar Tree on Some Street in now open",
    "title": "Dollar Tree Open"
  }
]