# $1, $2, ... - elements of the list
  # $NLIST_NONSELECTABLE_ELEMENTS - array of indexes (1-based) that cannot be selected
  # $REPLY is the output variable - contains index (1-based) or -1 when no selection

  # $reply (array) is the second part of the output - use the index (REPLY) to get selected element

  #
  # Copy this file into /usr/share/zsh/site-functions/
  # and add 'autoload n-list` to .zshrc
  #
  # This function outputs a list of elements that can be
  # navigated with keyboard. Uses curses library
  
  emulate -LR zsh
  
  setopt typesetsilent extendedglob noshortloops
  
  _nlist_has_terminfo=0
  
  zmodload zsh/curses
  zmodload zsh/terminfo 2>/dev/null && _nlist_has_terminfo=1
  
  trap "REPLY=-2; reply=(); return" TERM INT QUIT
  trap "_nlist_exit" EXIT
  
  # Drawing and input
  autoload n-list-draw n-list-input
  
  # Cleanup before any exit
  _nlist_exit() {
      setopt localoptions
      setopt extendedglob
  
      [[ "$REPLY" = -(#c0,1)[0-9]## ]] || REPLY="-1"
      zcurses 2>/dev/null delwin inner
      zcurses 2>/dev/null delwin main
      zcurses 2>/dev/null refresh
      zcurses end
      _nlist_alternate_screen 0
      _nlist_cursor_visibility 1
      unset _nlist_has_terminfo
  }
  
  # Outputs a message in the bottom of the screen
  _nlist_status_msg() {
      # -1 for border, -1 for 0-based indexing
      zcurses move main $(( term_height - 1 - 1 )) 2
      zcurses clear main eol
      zcurses string main "$1"
      #status_msg_strlen is localized in caller
      status_msg_strlen=$#1
  }
  
  # Prefer tput, then module terminfo
  _nlist_cursor_visibility() {
      if type tput 2>/dev/null 1>&2; then
          [ "$1" = "1" ] && { tput cvvis; tput cnorm }
          [ "$1" = "0" ] && tput civis
      elif [ "$_nlist_has_terminfo" = "1" ]; then
          [ "$1" = "1" ] && { [ -n $terminfo[cvvis] ] && echo -n $terminfo[cvvis];
                             [ -n $terminfo[cnorm] ] && echo -n $terminfo[cnorm] }
          [ "$1" = "0" ] && [ -n $terminfo[civis] ] && echo -n $terminfo[civis]
      fi 
  }
  
  # Reason for this function is that on some systems
  # smcup and rmcup are not knowing why left empty
  _nlist_alternate_screen() {
      [ "$_nlist_has_terminfo" -ne "1" ] && return
      [[ "$1" = "1" && -n "$terminfo[smcup]" ]] && return
      [[ "$1" = "0" && -n "$terminfo[rmcup]" ]] && return
  
      case "$TERM" in
          *rxvt*)
              [ "$1" = "1" ] && echo -n $'\x1b7\x1b[?47h'
              [ "$1" = "0" ] && echo -n $'\x1b[2J\x1b[?47l\x1b8'
              ;;
          *)
              [ "$1" = "1" ] && echo -n $'\x1b[?1049h'
              [ "$1" = "0" ] && echo -n $'\x1b[?1049l'
              # just to remember two other that work: $'\x1b7\x1b[r\x1b[?47h', $'\x1b[?47l\x1b8'
              ;;
      esac
  }
  
  _nlist_compute_user_vars_difference() {
          if [[ "${(t)NLIST_NONSELECTABLE_ELEMENTS}" != "array" &&
                  "${(t)NLIST_NONSELECTABLE_ELEMENTS}" != "array-local" ]]
          then
              last_element_difference=0
              current_difference=0
          else
              last_element_difference=$#NLIST_NONSELECTABLE_ELEMENTS
              current_difference=0
              local idx
              for idx in "${(n)NLIST_NONSELECTABLE_ELEMENTS[@]}"; do
                  [ "$idx" -le "$NLIST_CURRENT_IDX" ] && current_difference+=1 || break
              done
          fi
  }
  
  # List was processed, check if variables aren't off range
  _nlist_verify_vars() {
      [ "$NLIST_CURRENT_IDX" -gt "$last_element" ] && NLIST_CURRENT_IDX="$last_element"
      [[ "$NLIST_CURRENT_IDX" -eq 0 && "$last_element" -ne 0 ]] && NLIST_CURRENT_IDX=1
      (( NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN=0+((NLIST_CURRENT_IDX-1)/page_height)*page_height+1 ))
  }
  
  # Compute the variables which are shown to the user
  _nlist_setup_user_vars() {
      if [ "$1" = "1" ]; then
          # Basic values when there are no non-selectables
          NLIST_USER_CURRENT_IDX="$NLIST_CURRENT_IDX"
          NLIST_USER_LAST_ELEMENT="$last_element"
      else
          _nlist_compute_user_vars_difference
          NLIST_USER_CURRENT_IDX=$(( NLIST_CURRENT_IDX - current_difference ))
          NLIST_USER_LAST_ELEMENT=$(( last_element - last_element_difference ))
      fi
  }

  _nlist_colorify_disp_list() {

      local col=$'\x1b[00;34m' reset=$'\x1b[0m'
      [ -n "$NLIST_COLORING_COLOR" ] && col="$NLIST_COLORING_COLOR"
      [ -n "$NLIST_COLORING_END_COLOR" ] && reset="$NLIST_COLORING_END_COLOR"
  
      if [ "$NLIST_COLORING_MATCH_MULTIPLE" -eq 1 ]; then

          disp_list=( "${(@)disp_list//(#mi)$~NLIST_COLORING_PATTERN/$col${MATCH}$reset}" )

      else

          disp_list=( "${(@)disp_list/(#mi)$~NLIST_COLORING_PATTERN/$col${MATCH}$reset}" )

      fi
  }
  
  #
  # Main code
  #
  
  # Check if there is proper input
  if [ "$#" -lt 1 ]; then
      echo "Usage: n-list element_1 ..."
      return 1
  fi
  
  REPLY="-1"
  typeset -ga reply
  reply=()
  
  integer term_height="$LINES"
  integer term_width="$COLUMNS"
  if [[ "$term_height" -lt 1 || "$term_width" -lt 1 ]]; then
      local stty_out=$( stty size )
      term_height="${stty_out% *}"
      term_width="${stty_out#* }"
  fi
  integer inner_height=term_height-3
  integer inner_width=term_width-3
  integer page_height=inner_height
  integer page_width=inner_width

  typeset -a list disp_list

  integer last_element=$#
  local action
  local final_key
  integer selection
  integer last_element_difference=0
  integer current_difference=0
  local prev_search_buffer=""
  integer prev_uniq_mode=0
  integer prev_start_idx=-1

  local MBEGIN MEND MATCH mbegin mend match

  
  # Ability to remember the list between calls
  if [[ -z "$NLIST_REMEMBER_STATE" || "$NLIST_REMEMBER_STATE" -eq 0 || "$NLIST_REMEMBER_STATE" -eq 2 ]]; then
      NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN=1
      NLIST_CURRENT_IDX=1
      NLIST_IS_SEARCH_MODE=0
      NLIST_SEARCH_BUFFER=""
      NLIST_TEXT_OFFSET=0
      NLIST_IS_UNIQ_MODE=0
  
      # Zero - because it isn't known, unless we
      # confirm that first element is selectable
      NLIST_USER_CURRENT_IDX=0
      [[ ${NLIST_NONSELECTABLE_ELEMENTS[(r)1]} != 1 ]] && NLIST_USER_CURRENT_IDX=1
      NLIST_USER_LAST_ELEMENT=$(( last_element - $#NLIST_NONSELECTABLE_ELEMENTS ))
  
      # 2 is init once, then remember
      [ "$NLIST_REMEMBER_STATE" -eq 2 ] && NLIST_REMEMBER_STATE=1
  fi
  
  if [ "$NLIST_START_IN_SEARCH_MODE" -eq 1 ]; then
      NLIST_START_IN_SEARCH_MODE=0
      NLIST_IS_SEARCH_MODE=1
  fi
  
  if [ -n "$NLIST_SET_SEARCH_TO" ]; then
      NLIST_SEARCH_BUFFER="$NLIST_SET_SEARCH_TO"
      NLIST_SET_SEARCH_TO=""
  fi
  
  if [ "$NLIST_START_IN_UNIQ_MODE" -eq 1 ]; then
      NLIST_START_IN_UNIQ_MODE=0
      NLIST_IS_UNIQ_MODE=1
  fi
  
  _nlist_alternate_screen 1
  zcurses init
  zcurses delwin main 2>/dev/null
  zcurses delwin inner 2>/dev/null
  zcurses addwin main "$term_height" "$term_width" 0 0
  zcurses addwin inner "$inner_height" "$inner_width" 1 2
  zcurses bg main white/black
  zcurses bg inner white/black
  if [ "$NLIST_IS_SEARCH_MODE" -ne 1 ]; then
      _nlist_cursor_visibility 0
  fi
  
  #
  # Listening for input
  #
  
  local key keypad
  
  # Clear input buffer
  zcurses timeout main 0
  zcurses input main key keypad
  zcurses timeout main -1
  key=""
  keypad=""

  # This loop makes script faster on some Zsh's (e.g. 5.0.8)
  repeat 1; do
      list=( "$@" )
  done

  last_element="$#list"

  
  while (( 1 )); do
      # Do searching (filtering with string)
      if [ -n "$NLIST_SEARCH_BUFFER" ]; then

          # Compute new list?

          if [[ "$NLIST_SEARCH_BUFFER" != "$prev_search_buffer" || "$NLIST_IS_UNIQ_MODE" -ne "$prev_uniq_mode" ]]; then
              prev_search_buffer="$NLIST_SEARCH_BUFFER"
              prev_uniq_mode="$NLIST_IS_UNIQ_MODE"
              # regenerating list -> regenerating disp_list
              prev_start_idx=-1
  
              # Take all elements, including duplicates and non-selectables
              typeset +U list

              repeat 1; do
                  list=( "$@" )
              done

  
              # Remove non-selectable elements
              [ "$#NLIST_NONSELECTABLE_ELEMENTS" -gt 0 ] && for i in "${(nO)NLIST_NONSELECTABLE_ELEMENTS[@]}"; do
                  list[$i]=()
              done
  
              # Remove duplicates
              [ "$NLIST_IS_UNIQ_MODE" -eq 1 ] && typeset -U list
  
              last_element="$#list"
  
              # Next do the filtering
              local search_buffer="${NLIST_SEARCH_BUFFER%% ##}"
              search_buffer="${search_buffer## ##}"
              search_buffer="${search_buffer//(#m)[][*?|#~^()><\\]/\\$MATCH}"

              local search_pattern=""
              local colsearch_pattern=""

              if [ -n "$search_buffer" ]; then

                  # Patterns will be *foo*~^*bar* and (foo|bar)

                  search_pattern="${search_buffer// ##/*~^*}"
                  colsearch_pattern="${search_buffer// ##/|}"

                  # The repeat will make the matching work on a fresh heap
                  repeat 1; do
                      list=( "${(@M)list:#(#i)*$~search_pattern*}" )
                  done

                  last_element="$#list"

              fi
  
              # Called after processing list
              _nlist_verify_vars
          fi
  
          _nlist_setup_user_vars 1
  
          integer end_idx=$(( NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN + page_height - 1 ))
          [ "$end_idx" -gt "$last_element" ] && end_idx=last_element
  
          if [ "$prev_start_idx" -ne "$NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN" ]; then
              prev_start_idx="$NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN"

              disp_list=( "${(@)list[NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN, end_idx]}" )
  
              if [ -n "$colsearch_pattern" ]; then
                  local red=$'\x1b[00;31m' reset=$'\x1b[00;00m'

                  # The repeat will make the matching work on a fresh heap
                  repeat 1; do
                      disp_list=( "${(@)disp_list//(#mi)($~colsearch_pattern)/$red${MATCH}$reset}" )
                  done

              fi

              # We have display list, lets replace newlines with "
  " when needed (1/2)

              [ "$NLIST_REPLACE_NEWLINES" -eq 1 ] && disp_list=( "${(@)disp_list//$'
  '/\
  }" )
          fi
  
          # Output colored list
          n-list-draw "$(( (NLIST_CURRENT_IDX-1) % page_height + 1 ))" \
              "$page_height" "$page_width" 0 0 "$NLIST_TEXT_OFFSET" inner \
              "$disp_list[@]"
      else
          # There is no search, but there was in previous loop
          # OR
          # Uniq mode was entered or left out

          # -> compute new list

          if [[ -n "$prev_search_buffer" || "$NLIST_IS_UNIQ_MODE" -ne "$prev_uniq_mode" ]]; then
              prev_search_buffer=""
              prev_uniq_mode="$NLIST_IS_UNIQ_MODE"
              # regenerating list -> regenerating disp_list
              prev_start_idx=-1
  
              # Take all elements, including duplicates and non-selectables
              typeset +U list

              repeat 1; do
                  list=( "$@" )
              done

  
              # Remove non-selectable elements only when in uniq mode
              [ "$NLIST_IS_UNIQ_MODE" -eq 1 ] && [ "$#NLIST_NONSELECTABLE_ELEMENTS" -gt 0 ] &&
              for i in "${(nO)NLIST_NONSELECTABLE_ELEMENTS[@]}"; do
                  list[$i]=()
              done
  
              # Remove duplicates when in uniq mode
              [ "$NLIST_IS_UNIQ_MODE" -eq 1 ] && typeset -U list

              last_element="$#list"
              # Called after processing list
              _nlist_verify_vars
          fi
  
          # "1" - shouldn't bother with non-selectables
          _nlist_setup_user_vars "$NLIST_IS_UNIQ_MODE"
  
          integer end_idx=$(( NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN + page_height - 1 ))
          [ "$end_idx" -gt "$last_element" ] && end_idx=last_element

          if [ "$prev_start_idx" -ne "$NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN" ]; then
              prev_start_idx="$NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN"
              disp_list=( "${(@)list[NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN, end_idx]}" )

              [ -n "$NLIST_COLORING_PATTERN" ] && _nlist_colorify_disp_list

              # We have display list, lets replace newlines with "
  " when needed (2/2)
              [ "$NLIST_REPLACE_NEWLINES" -eq 1 ] && disp_list=( "${(@)disp_list//$'
  '/\
  }" )

          fi
  
          # Output the list
          n-list-draw "$(( (NLIST_CURRENT_IDX-1) % page_height + 1 ))" \
              "$page_height" "$page_width" 0 0 "$NLIST_TEXT_OFFSET" inner \
              "$disp_list[@]"
      fi
  
      local status_msg_strlen
      if [ "$NLIST_IS_SEARCH_MODE" = "1" ]; then
          local _txt2=""
          [ "$NLIST_IS_UNIQ_MODE" -eq 1 ] && _txt2="[-UNIQ-] "
          _nlist_status_msg "${_txt2}Filtering with: ${NLIST_SEARCH_BUFFER// /+}"
      elif [[ ${NLIST_NONSELECTABLE_ELEMENTS[(r)$NLIST_CURRENT_IDX]} != $NLIST_CURRENT_IDX ||
              -n "$NLIST_SEARCH_BUFFER" || "$NLIST_IS_UNIQ_MODE" -eq 1 ]]; then
          local _txt="" _txt2=""
          [ -n "$NLIST_GREP_STRING" ] && _txt=" [$NLIST_GREP_STRING]"
          [ "$NLIST_IS_UNIQ_MODE" -eq 1 ] && _txt2="[-UNIQ-] "
          _nlist_status_msg "${_txt2}Current #$NLIST_USER_CURRENT_IDX (of #$NLIST_USER_LAST_ELEMENT entries)$_txt"
      else
          _nlist_status_msg ""
      fi
  
      zcurses border main

  
      local top_msg="${(C)ZSH_NAME} $ZSH_VERSION, shell level $SHLVL, $USER"
      zcurses move main 0 $(( term_width / 2 - $#top_msg / 2 ))
      zcurses string main $top_msg

      zcurses refresh main inner
      zcurses move main $(( term_height - 1 - 1 )) $(( status_msg_strlen + 2 ))
  
      # Wait for input
      zcurses input main key keypad
  
      # Get the special (i.e. "keypad") key or regular key
      if [ -n "$key" ]; then

          final_key="$key"

      elif [ -n "$keypad" ]; then
          final_key="$keypad"
      else
          _nlist_status_msg "Inproper input detected"
          zcurses refresh main inner
      fi
  
      n-list-input "$NLIST_CURRENT_IDX" "$NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN" \
                      "$page_height" "$page_width" "$last_element" "$NLIST_TEXT_OFFSET" \
                      "$final_key" "$NLIST_IS_SEARCH_MODE" "$NLIST_SEARCH_BUFFER" \
                      "$NLIST_IS_UNIQ_MODE"
  
      selection="$reply[1]"
      action="$reply[2]"
      NLIST_CURRENT_IDX="$reply[3]"
      NLIST_FROM_WHAT_IDX_LIST_IS_SHOWN="$reply[4]"
      NLIST_TEXT_OFFSET="$reply[5]"
      NLIST_IS_SEARCH_MODE="$reply[6]"
      NLIST_SEARCH_BUFFER="$reply[7]"
      NLIST_IS_UNIQ_MODE="$reply[8]"
  
      if [ "$action" = "SELECT" ]; then
          REPLY="$selection"
          reply=( "$list[@]" )
          break
      elif [ "$action" = "QUIT" ]; then
          REPLY=-1
          reply=( "$list[@]" )
          break
      elif [ "$action" = "REDRAW" ]; then
          zcurses clear main redraw
          zcurses clear inner redraw
      fi
  done
  
  # vim: set filetype=zsh: