# Copyright (c) 2009 rupa deadwyler under the WTFPL license
  
  # maintains a jump-list of the directories you actually use
  #
  # INSTALL:
  #   * put something like this in your .bashrc/.zshrc:
  #     . /path/to/z.sh
  #   * cd around for a while to build up the db
  #   * PROFIT!!
  #   * optionally:
  #     set $_Z_CMD in .bashrc/.zshrc to change the command (default z).
  #     set $_Z_DATA in .bashrc/.zshrc to change the datafile (default ~/.z).
  #     set $_Z_NO_RESOLVE_SYMLINKS to prevent symlink resolution.
  #     set $_Z_NO_PROMPT_COMMAND if you're handling PROMPT_COMMAND yourself.
  #     set $_Z_EXCLUDE_DIRS to an array of directories to exclude.
  #
  # USE:
  #   * z foo     # cd to most frecent dir matching foo
  #   * z foo bar # cd to most frecent dir matching foo and bar
  #   * z -r foo  # cd to highest ranked dir matching foo
  #   * z -t foo  # cd to most recently accessed dir matching foo
  #   * z -l foo  # list matches instead of cd
  #   * z -c foo  # restrict matches to subdirs of $PWD
  
  case $- in
   *i*) ;;
     *) echo 'ERROR: z.sh is meant to be sourced, not directly executed.'
  esac
  
  [ -d "${_Z_DATA:-$HOME/.z}" ] && {
      echo "ERROR: z.sh's datafile (${_Z_DATA:-$HOME/.z}) is a directory."
  }
  
  _z() {
  
   local datafile="${_Z_DATA:-$HOME/.z}"
  
   # bail out if we don't own ~/.z (we're another user but our ENV is still set)
   [ -f "$datafile" -a ! -O "$datafile" ] && return
  
   # add entries
   if [ "$1" = "--add" ]; then
    shift
  
    # $HOME isn't worth matching
    [ "$*" = "$HOME" ] && return
  
    # don't track excluded dirs
    local exclude
    for exclude in "${_Z_EXCLUDE_DIRS[@]}"; do
     [ "$*" = "$exclude" ] && return
    done
  
    # maintain the file
    local tempfile
    tempfile="$(mktemp "$datafile.XXXXXX")" || return
    while read line; do
     [ -d "${line%%\|*}" ] && echo $line
    done < "$datafile" | awk -v path="$*" -v now="$(date +%s)" -F"|" '
     BEGIN {
      rank[path] = 1
      time[path] = now
     }
     $2 >= 1 {
      if( $1 == path ) {
       rank[$1] = $2 + 1
       time[$1] = now
      } else {
       rank[$1] = $2
       time[$1] = $3
      }
      count += $2
     }
     END {
      if( count > 6000 ) {
       for( i in rank ) print i "|" 0.99*rank[i] "|" time[i] # aging
      } else for( i in rank ) print i "|" rank[i] "|" time[i]
     }
    ' 2>/dev/null >| "$tempfile"
    if [ $? -ne 0 -a -f "$datafile" ]; then
     env rm -f "$tempfile"
    else
     env mv -f "$tempfile" "$datafile"
    fi
  
   # tab completion
   elif [ "$1" = "--complete" ]; then
    while read line; do
     [ -d "${line%%\|*}" ] && echo $line
    done < "$datafile" | awk -v q="$2" -F"|" '
     BEGIN {
      if( q == tolower(q) ) nocase = 1
      split(substr(q,3),fnd," ")
     }
     {
      if( nocase ) {
       for( i in fnd ) tolower($1) !~ tolower(fnd[i]) && $1 = ""
      } else {
       for( i in fnd ) $1 !~ fnd[i] && $1 = ""
      }
      if( $1 ) print $1
     }
    ' 2>/dev/null
  
   else
    # list/go
    while [ "$1" ]; do case "$1" in
     --) while [ "$1" ]; do shift; local fnd="$fnd $1";done;;
     -*) local opt=${1:1}; while [ "$opt" ]; do case ${opt:0:1} in
          c) local fnd="^$PWD $fnd";;
          h) echo "${_Z_CMD:-z} [-chlrt] args" >&2; return;;
          l) local list=1;;
          r) local typ="rank";;
          t) local typ="recent";;
         esac; opt=${opt:1}; done;;
      *) local fnd="$fnd $1";;
    esac; local last=$1; shift; done
    [ "$fnd" -a "$fnd" != "^$PWD " ] || local list=1
  
    # if we hit enter on a completion just go there
    case "$last" in
     # completions will always start with /
     /*) [ -z "$list" -a -d "$last" ] && cd "$last" && return;;
    esac
  
    # no file yet
    [ -f "$datafile" ] || return
  
    local cd
    cd="$(while read line; do
     [ -d "${line%%\|*}" ] && echo $line
    done < "$datafile" | awk -v t="$(date +%s)" -v list="$list" -v typ="$typ" -v q="$fnd" -F"|" '
     function frecent(rank, time) {
      dx = t-time
      if( dx < 3600 ) return rank*4
      if( dx < 86400 ) return rank*2
      if( dx < 604800 ) return rank/2
      return rank/4
     }
     function output(files, toopen, override) {
      if( list ) {
       cmd = "sort -n >&2"
       for( i in files ) if( files[i] ) printf "%-10s %s
  ", files[i], i | cmd
       if( override ) printf "%-10s %s
  ", "common:", override > "/dev/stderr"
      } else {
       if( override ) toopen = override
       print toopen
      }
     }
     function common(matches) {
      # shortest match
      for( i in matches ) {
       if( matches[i] && (!short || length(i) < length(short)) ) short = i
      }
      if( short == "/" ) return
      # shortest match must be common to each match. escape special characters in
      # a copy when testing, so we can return the original.
      clean_short = short
      gsub(/[\(\)\[\]\|]/, "\\\\&", clean_short)
      for( i in matches ) if( matches[i] && i !~ clean_short ) return
      return short
     }
     BEGIN { split(q, a, " "); oldf = noldf = -9999999999 }
     {
      if( typ == "rank" ) {
       f = $2
      } else if( typ == "recent" ) {
       f = $3-t
      } else f = frecent($2, $3)
      wcase[$1] = nocase[$1] = f
      for( i in a ) {
       if( $1 !~ a[i] ) delete wcase[$1]
       if( tolower($1) !~ tolower(a[i]) ) delete nocase[$1]
      }
      if( wcase[$1] && wcase[$1] > oldf ) {
       cx = $1
       oldf = wcase[$1]
      } else if( nocase[$1] && nocase[$1] > noldf ) {
       ncx = $1
       noldf = nocase[$1]
      }
     }
     END {
      if( cx ) {
       output(wcase, cx, common(wcase))
      } else if( ncx ) output(nocase, ncx, common(nocase))
     }
    ')"
    [ $? -gt 0 ] && return
    [ "$cd" ] && cd "$cd"
   fi
  }
  
  alias ${_Z_CMD:-z}='_z 2>&1'
  
  [ "$_Z_NO_RESOLVE_SYMLINKS" ] || _Z_RESOLVE_SYMLINKS="-P"
  
  if compctl &> /dev/null; then
   [ "$_Z_NO_PROMPT_COMMAND" ] || {
    # zsh populate directory list, avoid clobbering any other precmds
    if [ "$_Z_NO_RESOLVE_SYMLINKS" ]; then
      _z_precmd() {
        _z --add "${PWD:a}"
      }
    else
      _z_precmd() {
        _z --add "${PWD:A}"
      }
    fi
    precmd_functions+=(_z_precmd)
   }
   # zsh tab completion
   _z_zsh_tab_completion() {
    local compl
    read -l compl
    reply=(${(f)"$(_z --complete "$compl")"})
   }
   compctl -U -K _z_zsh_tab_completion _z
  elif complete &> /dev/null; then
   # bash tab completion
   complete -o filenames -C '_z --complete "$COMP_LINE"' ${_Z_CMD:-z}
   [ "$_Z_NO_PROMPT_COMMAND" ] || {
    # bash populate directory list. avoid clobbering other PROMPT_COMMANDs.
    echo $PROMPT_COMMAND | grep -q "_z --add" || {
     PROMPT_COMMAND='_z --add "$(pwd '$_Z_RESOLVE_SYMLINKS' 2>/dev/null)" 2>/dev/null;'"$PROMPT_COMMAND"
    }
   }
  fi