starship/src/init/starship.bash

# We use PROMPT_COMMAND and the DEBUG trap to generate timing information. We try
# to avoid clobbering what we can, and try to give the user ways around our
# clobbers, if it's unavoidable. For example, PROMPT_COMMAND is appended to,
# and the DEBUG trap is layered with other traps, if it exists.

# A bash quirk is that the DEBUG trap is fired every time a command runs, even
# if it's later on in the pipeline. If uncorrected, this could cause bad timing
# data for commands like `slow | slow | fast`, since the timer starts at the start
# of the "fast" command.

# To solve this, we set a flag `STARSHIP_PREEXEC_READY` when the prompt is
# drawn, and only start the timer if this flag is present. That way, timing is
# for the entire command, and not just a portion of it.

# A way to set '$?', since bash does not allow assigning to '$?' directly
function _starship_set_return() { return "${1:-0}"; }

# Will be run before *every* command (even ones in pipes!)
starship_preexec() {
    # Save previous command's last argument, otherwise it will be set to "starship_preexec"
    local PREV_LAST_ARG=$1

    # Avoid restarting the timer for commands in the same pipeline
    if [ "${STARSHIP_PREEXEC_READY:-}" = "true" ]; then
        STARSHIP_PREEXEC_READY=false
        STARSHIP_START_TIME=$(::STARSHIP:: time)
    fi

    : "$PREV_LAST_ARG"
}

# Will be run before the prompt is drawn
starship_precmd() {
    # Save the status, because commands in this pipeline will change $?
    STARSHIP_CMD_STATUS=$? STARSHIP_PIPE_STATUS=(${PIPESTATUS[@]})
    if [[ "${#BP_PIPESTATUS[@]}" -gt "${#STARSHIP_PIPE_STATUS[@]}" ]]; then
        STARSHIP_PIPE_STATUS=(${BP_PIPESTATUS[@]})
    fi

    # Due to a bug in certain Bash versions, any external process launched
    # inside $PROMPT_COMMAND will be reported by `jobs` as a background job:
    #
    #   [1]  42135 Done                    /bin/echo
    #
    # This is a workaround - we run `jobs` once to clear out any completed jobs
    # first, and then we run it again and count the number of jobs.
    #
    # More context: https://github.com/starship/starship/issues/5159
    # Original bug: https://lists.gnu.org/archive/html/bug-bash/2022-07/msg00117.html
    jobs &>/dev/null

    local NUM_JOBS=0
    # Evaluate the number of jobs before running the preserved prompt command, so that tools
    # like z/autojump, which background certain jobs, do not cause spurious background jobs
    # to be displayed by starship. Also avoids forking to run `wc`, slightly improving perf.
    for job in $(jobs -p); do [[ $job ]] && ((NUM_JOBS++)); done

    # Run the bash precmd function, if it's set. If not set, evaluates to no-op
    "${starship_precmd_user_func-:}"

    # Set $? to the preserved value before running additional parts of the prompt
    # command pipeline, which may rely on it.
    _starship_set_return "$STARSHIP_CMD_STATUS"

    eval "$_PRESERVED_PROMPT_COMMAND"

    # Prepare the timer data, if needed.
    if [[ $STARSHIP_START_TIME ]]; then
        STARSHIP_END_TIME=$(::STARSHIP:: time)
        STARSHIP_DURATION=$((STARSHIP_END_TIME - STARSHIP_START_TIME))
        PS1="$(::STARSHIP:: prompt --terminal-width="$COLUMNS" --status=$STARSHIP_CMD_STATUS --pipestatus="${STARSHIP_PIPE_STATUS[*]}" --jobs="$NUM_JOBS" --cmd-duration=$STARSHIP_DURATION)"
        unset STARSHIP_START_TIME
    else
        PS1="$(::STARSHIP:: prompt --terminal-width="$COLUMNS" --status=$STARSHIP_CMD_STATUS --pipestatus="${STARSHIP_PIPE_STATUS[*]}" --jobs="$NUM_JOBS")"
    fi
    STARSHIP_PREEXEC_READY=true  # Signal that we can safely restart the timer
}

# If the user appears to be using https://github.com/rcaloras/bash-preexec,
# then hook our functions into their framework.
if [[ "${__bp_imported:-}" == "defined" || $preexec_functions || $precmd_functions ]]; then
    # bash-preexec needs a single function--wrap the args into a closure and pass
    starship_preexec_all(){ starship_preexec "$_"; }
    preexec_functions+=(starship_preexec_all)
    precmd_functions+=(starship_precmd)
else
    # We want to avoid destroying an existing DEBUG hook. If we detect one, create
    # a new function that runs both the existing function AND our function, then
    # re-trap DEBUG to use this new function. This prevents a trap clobber.
    dbg_trap="$(trap -p DEBUG | cut -d' ' -f3 | tr -d \')"
    if [[ -z "$dbg_trap" ]]; then
        trap 'starship_preexec "$_"' DEBUG
    elif [[ "$dbg_trap" != 'starship_preexec "$_"' && "$dbg_trap" != 'starship_preexec_all "$_"' ]]; then
        starship_preexec_all() {
            local PREV_LAST_ARG=$1 ; $dbg_trap; starship_preexec; : "$PREV_LAST_ARG";
        }
        trap 'starship_preexec_all "$_"' DEBUG
    fi

    # Finally, prepare the precmd function and set up the start time. We will avoid to
    # add multiple instances of the starship function and keep other user functions if any.
    if [[ -z "$PROMPT_COMMAND" ]]; then
        PROMPT_COMMAND="starship_precmd"
    elif [[ "$PROMPT_COMMAND" != *"starship_precmd"* ]]; then
        # Appending to PROMPT_COMMAND breaks exit status ($?) checking.
        # Prepending to PROMPT_COMMAND breaks "command duration" module.
        # So, we are preserving the existing PROMPT_COMMAND
        # which will be executed later in the starship_precmd function
        _PRESERVED_PROMPT_COMMAND="$PROMPT_COMMAND"
        PROMPT_COMMAND="starship_precmd"
    fi
fi

# Ensure that $COLUMNS gets set
shopt -s checkwinsize

# Set up the start time and STARSHIP_SHELL, which controls shell-specific sequences
STARSHIP_START_TIME=$(::STARSHIP:: time)
export STARSHIP_SHELL="bash"

# Set up the session key that will be used to store logs
STARSHIP_SESSION_KEY="$RANDOM$RANDOM$RANDOM$RANDOM$RANDOM"; # Random generates a number b/w 0 - 32767
STARSHIP_SESSION_KEY="${STARSHIP_SESSION_KEY}0000000000000000" # Pad it to 16+ chars.
export STARSHIP_SESSION_KEY=${STARSHIP_SESSION_KEY:0:16}; # Trim to 16-digits if excess.

# Set the continuation prompt
PS2="$(::STARSHIP:: prompt --continuation)"