starship/src/init/starship.zsh

# ZSH has a quirk where `preexec` is only run if a command is actually run (i.e
# pressing ENTER at an empty command line will not cause preexec to fire). This
# can cause timing issues, as a user who presses "ENTER" without running a command
# will see the time to the start of the last command, which may be very large.

# To fix this, we create STARSHIP_START_TIME upon preexec() firing, and destroy it
# after drawing the prompt. This ensures that the timing for one command is only
# ever drawn once (for the prompt immediately after it is run).

zmodload zsh/parameter  # Needed to access jobstates variable for NUM_JOBS

# Will be run before every prompt draw
starship_precmd() {
    # Save the status, because commands in this pipeline will change $?
    STATUS=$?

    # Use length of jobstates array as number of jobs. Expansion fails inside
    # quotes so we set it here and then use the value later on.
    NUM_JOBS=$#jobstates  
    # Compute cmd_duration, if we have a time to consume
    if [[ ! -z "${STARSHIP_START_TIME+1}" ]]; then
        STARSHIP_END_TIME="$(date +%s)"
        STARSHIP_DURATION=$((STARSHIP_END_TIME - STARSHIP_START_TIME))
        PROMPT="$(::STARSHIP:: prompt --status=$STATUS --cmd-duration=$STARSHIP_DURATION --jobs="$NUM_JOBS")"
        unset STARSHIP_START_TIME
    else
        PROMPT="$(::STARSHIP:: prompt --status=$STATUS --jobs="$NUM_JOBS")"
    fi
}
starship_preexec(){
    STARSHIP_START_TIME="$(date +%s)"
}

# If precmd/preexec arrays are not already set, set them. If we don't do this,
# the code to detect whether starship_precmd is already in precmd_functions will
# fail because the array doesn't exist (and same for starship_preexec)
[[ -z "${precmd_functions+1}" ]] && precmd_functions=()
[[ -z "${preexec_functions+1}" ]] && preexec_functions=()

# If starship precmd/preexec functions are already hooked, don't double-hook them
# to avoid unnecessary performance degradation in nested shells
if [[ ${precmd_functions[(ie)starship_precmd]} -gt ${#precmd_functions} ]]; then
    precmd_functions+=(starship_precmd)
fi
if [[ ${preexec_functions[(ie)starship_preexec]} -gt ${#preexec_functions} ]]; then
    preexec_functions+=(starship_preexec)
fi

# Set up a function to redraw the prompt if the user switches vi modes
function zle-keymap-select
{
    PROMPT=$(::STARSHIP:: prompt --keymap=$KEYMAP --jobs="$(jobs | wc -l)")
    zle reset-prompt
}

STARSHIP_START_TIME="$(date +%s)"
zle -N zle-keymap-select
export STARSHIP_SHELL="zsh"