#!/bin/bash
# fileMenu - Generic file menu based on dates, using dialog
# (C) 2024-2025 Felix Hauri - felix@f-hauri.ch
# Version: 0.0.3 -- Last update: Fri May  2 13:47:25 2025
# Sort list of *backup* paths (files or dirs), render date
# based on `locale date_fmt`, then run dialog menu selector,
# defaulting to most recent path.
# Intented to be used in a script, this function populate a variable
# instead of produce any output.
# Support format dates like: /path/to/name?YYYY?MM?DD[?HH[?MM]][.suffix]
# or /path/to/name?YYYYMMDD[HH[MM]][.suffix]
#
# Note this don't use bash's RE, only two forks to `locale` and `date`
# and use limited number of loop (max 4) not regarding length of list.
#
# Syntaxe:
#   fileMenu <resultVar> <title of dialog boxe> <entry> [entry] [entry]...
# Sample:
#    if filemenu myVar 'Choose backup' /path/to/backups_*; then ...; fi
#    DIALOG=dialog fileMenu myVar 'DB to restore` /path/to/file-????????.sql
#    DIALOG=gdialog fileMenu myVar 'Count files in' /path/to/backups_????-??-??
#    DIALOG=dialog _fM_date_fmt='%a %d %b %y, %Hh.' fileMenu myVar 'Choose...

fileMenu() {
    local -n _fM_result=$1
    local _fM_title=$2  _fM_tmpStr _fM_date_fmt _fM_argDialog _fM_sel _fM_dates
    shift 2
    # $_fM_date_fmt is date format for menu, may be defined before running func
    : ${_fM_date_fmt:=$(locale date_fmt||echo '%c')}
    # _fM_files is arguments, _fM_sep separators for date: 'YYYYY/MM/DD HH:MM'
    local -a _fM_files=("$@") _fM_sep=('/' '/' ' ' ':')
    _fM_dates=("${_fM_files[@]##*[a-z][^a-zA-Z0-9]}") # Drop begin: /path/bknam_
    _fM_dates=(${_fM_dates[@]%.*})                    # Drop any suffix 
    case ${_fM_dates[0]} in    # case format in 'YYYYMMDD[HH[MM]]':
	[12][0-9][0-9][0-9][01][0-9]* )               # Add separators
	    _fM_sel=3
	    for _fM_tmpStr in \
		[12][0-9][0-9][0-9]{[01][0-9]{[0-3][0-9]{[0-2][0-9],},},}; do
		_fM_dates=("${_fM_dates[@]/$_fM_tmpStr/&${_fM_sep[_fM_sel--]}}")
	    done
	    ;;
	* )                # case format in, for sample: ' YYYY-MM-DD_HHhMM'
	    for _fM_tmpStr in "${_fM_sep[@]}"; do          # Replace separators
		_fM_dates=("${_fM_dates[@]/[^0-9\/: ]/$_fM_tmpStr}")
	    done
	    ;;
    esac
    # Convert normalized dates "YYYY/MM/DD HH:MM" to UNIXEPOCH
    mapfile -t _fM_dates < <( date -f - +'%s' < <(
				  printf '%s\n' "${_fM_dates[@]}" ))
    # Prepare dialog command's  arguments as an array containing both:
    # id (in files's array) and rendered date: (0 'mon 1 apr' 1 'thu 2 apr' ..)
    printf -v _fM_tmpStr "%d\n%%40(${_fM_date_fmt//%/%%})T\\n" ${!_fM_files[@]}
    mapfile -t _fM_argDialog < <(printf "$_fM_tmpStr" "${_fM_dates[@]}")
    # Run $DIALOG comnmad and store result (id in files's array)
    _fM_sel=$( ${DIALOG:-whiptail} --default-item $(( ${#_fM_files[@]} - 1 )) \
	--menu "$_fM_title" $((${LINES:-24}-3)) $((${COLUMNS:-80}-3)) \
	$((${LINES:-24}-11)) "${_fM_argDialog[@]}" 2>&1 > /dev/tty )
    if [[ -n $_fM_sel ]]; then
	_fM_result=${_fM_files[$_fM_sel]}
    else
	_fM_result= ; return 1
    fi
}