#!/bin/bash

# --- Script Configuration ---
LOG_FILE="/var/log/my_script.log"
SCRIPT_NAME=$(basename "$0")
DATE_FORMAT="+%Y-%m-%d %H:%M:%S"

# --- Error Handling ---
# Exit immediately if a command exits with a non-zero status.
set -e
# Treat unset variables as an error.
set -u
# If any command in a pipeline fails, that return code will be used.
set -o pipefail

# Function to log messages with timestamp and script name
log() {
  local type="$1"
  local message="$2"
  echo "$(date "${DATE_FORMAT}") [${SCRIPT_NAME}] [${type}] ${message}" | tee -a "${LOG_FILE}"
}

# Function to handle errors before exiting
error_handler() {
  local last_command="${BASH_COMMAND}"
  local last_line="${BASH_LINENO[0]}"
  log "ERROR" "Script failed at line ${last_line}: '${last_command}'"
  # You might want to send an alert here
  exit 1
}

# Trap errors and call error_handler
trap 'error_handler' ERR

# --- Main Script Logic ---
log "INFO" "Script started."

# Example: Check if a required command exists
if ! command -v "jq" &> /dev/null; then
  log "WARN" "jq command not found. Some functionality might be limited."
  # Or, make it a critical error:
  # log "FATAL" "jq command is required but not found. Exiting."
  # exit 1
fi

# Example: Perform a task that might fail
log "INFO" "Attempting a critical operation..."
# Simulate a failing command:
# ls /nonexistent-directory 
# If 'ls /nonexistent-directory' was uncommented, it would trigger the error_handler due to 'set -e'

# Simulate a successful command
log "DEBUG" "Listing current directory contents."
ls -la | head -n 3
log "INFO" "Operation completed successfully."

# Example: Access an unset variable (will trigger error due to 'set -u')
# echo "This will fail: ${UNSET_VARIABLE}"

log "INFO" "Script finished successfully."