: ${AUTOENV_AUTH_FILE:=~/.env_auth}
: ${AUTOENV_FILE_ENTER:=.autoenv.zsh}
: ${AUTOENV_FILE_LEAVE:=.autoenv_leave.zsh}
: ${AUTOENV_LOOK_UPWARDS:=1}
: ${AUTOENV_HANDLE_LEAVE:=1}
: ${AUTOENV_DISABLED:=0}

typeset -a _autoenv_stack_entered
typeset -A _autoenv_stack_entered_ctime
typeset -a _autoenv_ctime

zmodload -F zsh/stat b:zstat
_autoenv_get_file_ctime() {
    zstat -a _autoenv_ctime +ctime $1 2>/dev/null || _autoenv_ctime=(0)
}

_autoenv_stack_entered_remove() {
    local env_file=$1
    _autoenv_stack_entered[$_autoenv_stack_entered[(i)$env_file]]=()
    _autoenv_stack_entered_ctime[$env_file]=
}

_autoenv_stack_entered_add() {
    local env_file=$1
    _autoenv_stack_entered_remove $env_file
    _autoenv_stack_entered+=($env_file)
    _autoenv_get_file_ctime $env_file
    _autoenv_stack_entered_ctime[$env_file]=${_autoenv_ctime[1]}
}

_autoenv_stack_entered_contains() {
    local env_file=$1
    local f i
    if (( ${+_autoenv_stack_entered[(r)${env_file}]} )); then
        f=$env_file
    else
        local env_file_abs=${env_file:A}
        for i ($_autoenv_stack_entered) {
            [[ ${i:A} == ${env_file_abs} ]] && {
                f=$i
                break
            }
        }
    fi
    [[ -n $f ]] || return 1
    _autoenv_get_file_ctime $f
    [[ ${_autoenv_stack_entered_ctime[$f]} == ${_autoenv_ctime[1]} ]] || return 1
}

_autoenv_hash_pair() {
    local env_file=${1:A}
    env_cksum=${${:-$(cksum "$env_file")}[1]}
    ret_pair=":${env_file}:${env_cksum}"
}

_autoenv_authorized_env_file() {
    local env_file=$1
    local env_file_abs=${env_file:A}
    local ret_pair
    local -a lines
    [[ -s $AUTOENV_AUTH_FILE ]] &&
        lines=( ${(M)"${(f@)"$(< $AUTOENV_AUTH_FILE)"}":#:$env_file_abs:*} )
    [[ -z $lines ]] && return 1
    line=${lines[-1]}
    _autoenv_hash_pair $env_file
    [[ $line == $ret_pair ]] || return 1
}

_autoenv_authorize() {
    local env_file=${1:A}
    _autoenv_deauthorize $env_file
    [[ -d ${AUTOENV_AUTH_FILE:h} ]] || mkdir -p ${AUTOENV_AUTH_FILE:h}
    local ret_pair
    _autoenv_hash_pair $env_file && print "$ret_pair" >>| $AUTOENV_AUTH_FILE
}

_autoenv_deauthorize() {
    local env_file=${1:A}
    [[ -s $AUTOENV_AUTH_FILE ]] || return
    perl -i -ne "print unless m[:${env_file}:]" $AUTOENV_AUTH_FILE
}

_autoenv_check_authorized_env_file() {
    local env_file=$1
    [[ -f $env_file ]] || return 1
    _autoenv_authorized_env_file $1 && return
    command ls -l $1 >&2
    local answer
    setopt localtraps
    trap "return 1" INT
    read -q answer\?"Authorize? "
    print
    [[ $answer == "y" ]] || return 1
    _autoenv_authorize $1
}

_autoenv_source() {
    local autoenv_env_file=$1
    local autoenv_event=$2
    print "autoenv: $autoenv_env_file" >&2
    (( $+functions[autostash] )) || source ${${funcsourcetrace[1]%:*}:h}/lib/varstash
    varstash_dir=${autoenv_env_file:h} source $autoenv_env_file
    [[ $autoenv_event == enter ]] && _autoenv_stack_entered_add $autoenv_env_file
}

_autoenv_get_file_upwards() {
    setopt EXTENDED_GLOB NO_NOMATCH
    found=( (../)#$AUTOENV_FILE_ENTER(Y1:A) )
    env_file=${found[1]}
}

_autoenv_chpwd_handler() {
    emulate -L zsh
    (( $AUTOENV_DISABLED )) && return
    local env_file="$PWD/$AUTOENV_FILE_ENTER"
    if [[ $AUTOENV_HANDLE_LEAVE == 1 ]] && (( $#_autoenv_stack_entered )); then
        local prev_file prev_dir
        for prev_file in ${_autoenv_stack_entered}; do
            prev_dir=${prev_file:h}
            if ! [[ ${PWD}/ == ${prev_dir}/* ]]; then
                local env_file_leave=$prev_dir/$AUTOENV_FILE_LEAVE
                if _autoenv_check_authorized_env_file $env_file_leave; then
                    varstash_dir=$prev_dir _autoenv_source $env_file_leave leave $prev_dir
                fi
                (( $+functions[autostash] )) && varstash_dir=$prev_dir autounstash
                _autoenv_stack_entered_remove $prev_file
            fi
        done
    fi
    if ! [[ -f $env_file ]] && [[ $AUTOENV_LOOK_UPWARDS == 1 ]]; then
        _autoenv_get_file_upwards $PWD
        [[ -f $env_file ]] || return
    fi
    _autoenv_stack_entered_contains $env_file && return
    _autoenv_check_authorized_env_file $env_file || return
    _autoenv_source $env_file enter
}

autoload -U add-zsh-hook
add-zsh-hook chpwd _autoenv_chpwd_handler
_autoenv_chpwd_handler