# 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

[ -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 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="$datafile.$RANDOM"
        while read line; do
            # only count directories
            [ -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 += $2
            }
            END {
                if( count > 6000 ) {
                    # aging
                    for( i in rank ) print i "|" 0.99*rank[i] "|" time[i]
                } else for( i in rank ) print i "|" rank[i] "|" time[i]
            }
        ' 2>/dev/null >| "$tempfile"
        if [ $? -ne 0 -a -f "$datafile" ]; then
            env rm -f "$tempfile"
        else
            env mv -f "$tempfile" "$datafile" || env rm -f "$tmpfile"
        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} [-chlrtx] args" >&2; return;;
                    x) sed -i "\:^${PWD}|.*:d" "$datafile";;
                    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) {
                # relate frequency and 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, common) {
                # list or return the desired directory
                if( list ) {
                    cmd = "sort -n >&2"
                    for( i in files ) {
                        if( files[i] ) printf "%-10s %s\n", files[i], i | cmd
                    }
                    if( common ) {
                        printf "%-10s %s\n", "common:", common > "/dev/stderr"
                    }
                } else {
                    if( common ) toopen = common
                    print toopen
                }
            }
            function common(matches) {
                # find the common root of a list of dirs, if it exists
                for( i in matches ) {
                    if( matches[i] && (!short || length(i) < length(short)) ) {
                        short = i
                    }
                }
                if( short == "/" ) return
                # use a copy to escape special characters, as we want to 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
    # zsh
    [ "$_Z_NO_PROMPT_COMMAND" ] || {
        # populate directory list, avoid clobbering any other precmds
        if [ "$_Z_NO_RESOLVE_SYMLINKS" ]; then
            _z_precmd() {
                _z --add "${PWD:a}"
            }
        else
            _z_precmd() {
                _z --add "${PWD:A}"
            }
        fi
        precmd_functions+=(_z_precmd)
    }
    _z_zsh_tab_completion() {
        # 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.
        grep -q "_z --add" <<< "$PROMPT_COMMAND" || {
            PROMPT_COMMAND="$PROMPT_COMMAND"$'\n''_z --add "$(pwd '$_Z_RESOLVE_SYMLINKS' 2>/dev/null)" 2>/dev/null;'
        }
    }
fi