#!/usr/bin/env bash

# set_alias_with_backup - A Bash function to alias a command while preserving the original.
#
# Usage:
#   set_alias_with_backup <alias_name> <new_command>
#
# Parameters:
#   alias_name: The alias name to override (e.g., "cat").
#   new_command: The command to alias to (e.g., "bat").
#
# Behavior:
#   - Checks if the new command exists.
#   - If it exists and the backup alias (alias_name with an underscore appended) isn't set,
#     it creates a backup alias pointing to the original command.
#   - Sets the alias (alias_name) to use the new command.
#
# Example:
#   To alias "bat" as "cat" and preserve the original "cat" as "cat_", run:
#       set_alias_with_backup cat bat
set_alias_with_backup() {
  local alias_name="$1"
  local new_cmd="$2"

  # Allow for extra parameters to be passed to the new command.
  shift 2
  local extra_params="$*"

  # Check that both arguments are provided.
  if [ -z "$alias_name" ] || [ -z "$new_cmd" ]; then
    echo "Usage: set_alias_with_backup <alias_name> <new_command> [extra_params]"
    return 1
  fi

  # Check that the new command exists.
  if type "$new_cmd" >/dev/null 2>&1; then
    # Define a backup alias by appending an underscore
    # (e.g., "cat_" for "cat")
    local backup_alias="${alias_name}_"

    # If the backup alias isn't already set, create it pointing
    # to the original command.
    if ! type "$backup_alias" >/dev/null 2>&1; then
      alias "$backup_alias"="$(which "$alias_name")"
    fi

    # Create the alias: e.g., alias "cat" to "bat" and pass any extra params.
    alias "$alias_name"="$new_cmd $extra_params"
  fi
}