history-cleaner

#!/bin/sh

# shellcheck shell=dash

# POSIX-compliant shell script to clean up raw shell history files

USAGE="Usage: $0 [--mode <mode>] <command>
Available modes: remove (default), trash
Available commands: cleanup, list, delete, concat
- cleanup: removes all raw history files that have only one line
- list: lists all raw history files that have less than the specified number of lines
- delete: deletes all raw history files that have less than the specified number of lines
- concat: concatenates all raw history files that have less than the specified number of lines into a new file and opens it in the editor, then removes or moves the old files"

# Default value for the trash directory
TRASH_DIR=${TRASH_DIR:="$HOME/.local/share/Trash/files"}

# Error messages
ERROR_MISSING_VAR='Required environment variable is not set: HISTORY_DIR.'
ERROR_UNSUPPORTED_ACTION='Error: unsupported action'
ERROR_UNSUPPORTED_MODE='Error: unsupported mode'

# logging functions
log() {
  printf '%s\n' "$1" >&2
}

error() {
  printf '%s\n' "$1"
  exit 1
}

# Ask a question and expect a yes or no answer
# Usage: ask_question "Question" "y" && echo "Yes" || echo "No"
ask_question() {
  question="$1"
  printf "%s [y/N] " "$question"
  read -r response
  case $response in
    [yY] | [yY][eE][sS]) return 0 ;;
    *) return 1 ;;
  esac
}

# Get the maximum number of lines for a file to be considered 'short'
get_max_lines(){
  printf "Enter the maximum number of lines for a file to be considered 'short': " >&2
  read -r max_lines
  echo "$max_lines"
}

# Find all history files in the raw history directory
find_history_files() {
  find "${HISTORY_DIR}/raw" -type f -name '*.sh' -print
}

# Filter the files whose number of lines is lower of equal that the given threshold
having_max_lines() {
  max_lines="$1"
  while read -r file; do
    lines=$(wc -l < "$file" | awk '{print $1}')
    if [ "$lines" -le "$max_lines" ]; then
      printf '%s\n' "$file"
    fi
  done
}

# Remove or move files based on the remove_mode global variable
remove_or_move_files() {
  while read -r file; do
    if $remove_mode; then
      rm "$file"
    else
      mv "$file" "$TRASH_DIR"
    fi
  done
}

# List all history files that have less than max_lines lines
list_short_files() {
  max_lines="$1"
  find_history_files | (
    while read -r file; do
      lines=$(wc -l <"$file")
      if [ "$lines" -le "$max_lines" ]; then
        log "File: $file"
        cat "$file"
        echo ""
      fi
    done
  )
}

# Remove all history files that have less than max_lines lines
delete_short_files() {
  max_lines="$1"
  find_history_files | having_max_lines "$max_lines" | remove_or_move_files
}

# Remove all history files that have only one line
cleanup_empty_files() {
  delete_short_files 1
}

# Concatenate all history files that have less than max_lines lines into a new file
# and open it in the editor, then remove or move the old files.
concat_short_files() {
  max_lines="$1"
  new_file_name="${2:-history_short_files_$(date +"%Y%m%d_%H%M%S").sh}"
  new_file="${HISTORY_DIR}/raw/$new_file_name"

  # Collect the list of files to be concatenated
  files_to_concat=$(find_history_files | having_max_lines "$max_lines")

  # Concatenate the files
  printf '%s\n' "$files_to_concat" | while read -r file; do
    cat "$file" >>"$new_file"
    echo "" >>"$new_file"
  done

  # Open the new file in the editor
  "${EDITOR:-vi}" "$new_file"

  # Confirm before removing files
  if ! ask_question "Do you want to remove the old files?"; then
    exit 0
  fi

  # Remove or move the old files
  echo "$files_to_concat" | remove_or_move_files
}

# Argument parsing function
parse_arguments() {

  # parse command line options using getopt
  if ! options=$(getopt -o h --long help,mode: -n 'history-cleaner' -- "$@"); then
    error "$ERROR_PARSING"
  fi

  # set positional parameters
  eval set -- "$options"

  # Set default values for options
  mode='remove'
  remove_mode=true

  # process options
  while true; do
    case $1 in
    --mode)
      mode="$2"
      shift 2
      ;;
    -h | --help)
      log "$USAGE"
      exit 0
      ;;
    --)
      shift
      break
      ;;
    *)
      error "$ERROR_PARSING"
      ;;
    esac
  done

  case "$mode" in
  "remove") remove_mode=true ;;
  "trash") remove_mode=false ;;
  *) error "$ERROR_UNSUPPORTED_MODE" ;;
  esac

  # Get arguments
  if [ $# -lt 1 ]; then
    error 'Error: action is required'
  fi

  # set action
  action=$1

  # check if action is supported
  if [ "$action" != 'cleanup' ] && [ "$action" != 'list' ] && [ "$action" != 'delete' ] && [ "$action" != 'concat' ]; then
    error "$ERROR_UNSUPPORTED_ACTION"
  fi
}

# main function
main() {
  action="$1"
  remove_mode="$2"

  case $action in
  "cleanup") cleanup_empty_files;;
  "list") list_short_files "$(get_max_lines)";;
  "delete") delete_short_files "$(get_max_lines)";;
  "concat") concat_short_files "$(get_max_lines)";;
  *)
    echo "Usage: $0 <command> [-m remove|trash]" >&2
    echo "Available commands: cleanup, list, delete, concat" >&2
    exit 1
    ;;
  esac
}

# shellcheck disable=3028
if [ "$0" = "${BASH_SOURCE:-$0}" ]; then
  # Call the argument parsing function
  parse_arguments "$@"

  # Check if required environment variables are set
  if [ -z "$HISTORY_DIR" ]; then
    error "$ERROR_MISSING_VAR"
  fi

  # call main function
  main "$action" "$remove_mode"
fi