# Make Bash more like Zsh


## Hooks
# https://zsh.sourceforge.io/Doc/Release/Functions.html#Hook-Functions

# TODO: support precmd_functions and chpwd_functions arrays

### Defaults: NOOPs

function preexec { :; }

function precmd  { :; }

function chpwd   { :; }

### Implementations

# Alternative cd function that calls chpwd afterwards builtin cd
#
# zsh: Executed whenever the current working directory is changed.
__cd_invoke_chpwd() {
    builtin cd "$@"

    chpwd

    # TODO: chpwd_functions array
}

# zsh: Executed before each prompt. Note that precommand functions are not
#      re-executed simply because the command line is redrawn, as happens, for
#      example, when a notification about an exiting job is displayed.
__prompt_command_invoke_precmd() {
    precmd

    # TODO: precmd_functions array
}

# to properly trigger only before command exec this must be the last prompt command
__prompt_command_hook_preexec() {
    trap '__debug_invoke_preexec' DEBUG
}

__prompt_command_unhook_preexec() {
    # Unfortunately there's no way to remove just one trap from a signal
    trap - DEBUG
}

# zsh: Executed just after a command has been read and is about to be executed. If
#      the history mechanism is active (regardless of whether the line was discarded
#      from the history buffer), the string that the user typed is passed as the
#      first argument, otherwise it is an empty string. The actual command that will
#      be executed (including expanded aliases) is passed in two different forms:
#      the second argument is a single-line, size-limited version of the command
#      (with things like function bodies elided); the third argument contains the
#      full text that is being executed.
__debug_invoke_preexec () {
    # somehow PROMPT_COMMAND contents seems to be still affected by the
    # just-removed trap. Ignore ours.
    [[ "$BASH_COMMAND" == "__prompt_command_unhook_preexec" ]] && return
    [[ "$BASH_COMMAND" == "__prompt_command_invoke_precmd" ]] && return
    [[ "$BASH_COMMAND" == "__prompt_command_hook_preexec" ]] && return

    # TODO: not sure this is still necessary
    [[ -n "$COMP_LINE" ]] && return  # completion

    local this_command;

    # TODO: hack: doesn't work when command is not added to history
    this_command=`history 1 | sed -e "s/^[ ]*[0-9]*[ ]*//g"`;
    preexec "$this_command"
}

### Set up the hooks

# Define a function to override the cd builtin
#
# - does not apply to `bash -c 'cd foo`
# - does apply to shubshells: `(cd foo)` will call so side effects beware (env
#   vars are conveniently scoped to subshell)
cd() { __cd_invoke_chpwd "$@"; }

# Call on each prompt. This transitively sets preexec to work for each prompt
#
# PROMPT_COMMAND is evaluated right before PS1 is displayed. This matches zsh
# semantics for precmd.
#
# We forcefully set it instead of taking whatever was set:
# - to control order (precmd eval + preexec hooking must be last)
# - because of the trap issue
PROMPT_COMMAND=(
    # this also conveniently clears DEBUG traps
    __prompt_command_unhook_preexec

    # precmd hook processing
    __prompt_command_invoke_precmd

    # must be last to properly have DEBUG trigger only before command exec
    __prompt_command_hook_preexec
)


## Other bits

# clears a line that was not terminated by a LF fixing the dangling prompt
# issue by marking it with a reversed %, like zsh
clear_incomplete_line() {
    local row
    local col

    # ask for cursor position then read answer
    # TODO: fix read: mashing keyboard makes syntax errors
    stty -echo
    echo -en "\033[6n"
    IFS=';' read -r -d R -a pos
    stty echo

    # extract tput-compatible answer
    row=$(( ${pos[0]:2} - 1 ))
    col=$(( ${pos[1]} - 1 ))

    # not on first column? do clean up: fill with spaces and rag left
    if [[ $col != 0 ]]; then
        printf "\e[7m%%\e[m"
        printf "%*s\r" $(( COLUMNS - $col ))
    fi
}

function sub_prompt_colors_unsized() {
    sed \
        -e 's#%F{black}#\\033[30m#g' \
        -e 's#%F{red}#\\033[31m#g' \
        -e 's#%F{green}#\\033[32m#g' \
        -e 's#%F{yellow}#\\033[33m#g' \
        -e 's#%F{blue}#\\033[34m#g' \
        -e 's#%F{magenta}#\\033[35m#g' \
        -e 's#%F{cyan}#\\033[36m#g' \
        -e 's#%F{white}#\\033[37m#g' \
        -e 's#%f#\\033[00m#g'
}

function sub_prompt_colors_sized() {
    sed \
        -e 's#%F{black}#\\[\\033[30m\\]#g' \
        -e 's#%F{red}#\\[\\033[31m\\]#g' \
        -e 's#%F{green}#\\[\\033[32m\\]#g' \
        -e 's#%F{yellow}#\\[\\033[33m\\]#g' \
        -e 's#%F{blue}#\\[\\033[34m\\]#g' \
        -e 's#%F{magenta}#\\[\\033[35m\\]#g' \
        -e 's#%F{cyan}#\\[\\033[36m\\]#g' \
        -e 's#%F{white}#\\[\\033[37m\\]#g' \
        -e 's#%f#\\[\\033[00m\\]#g'
}

function strip_prompt_colors() {
    sed \
        -e 's#%F{black}##g' \
        -e 's#%F{red}##g' \
        -e 's#%F{green}##g' \
        -e 's#%F{yellow}##g' \
        -e 's#%F{blue}##g' \
        -e 's#%F{magenta}##g' \
        -e 's#%F{cyan}##g' \
        -e 's#%F{white}##g' \
        -e 's#%f##g'
}

# right prompt support and PROMPT/RPROMPT vars
function apply_prompt_rprompt() {
    local rprompt=$(echo "${RPROMPT}" | sub_prompt_colors_unsized)
    local prompt=$(echo "${PROMPT}" | sub_prompt_colors_sized)
    #local rprompt=$(echo "${RPROMPT}" | strip_prompt_colors)
    #local prompt=$(echo "${PROMPT}" | strip_prompt_colors)
    if [[ -n "${RPROMPT}" ]]; then
        PS1="$(printf "\[%*s\r\]%s" "${COLUMNS}" "${rprompt:-}" "${prompt:-}")"
    else
        PS1="${prompt:-}"
    fi
}

# vim: ft=bash