# SPDX-License-Identifier: LGPL-2.1-or-later
# shellcheck shell=bash
# shellcheck disable=SC2016
# shellcheck disable=SC1003

#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

# This implements the UAPI.15 "OSC 3008: Hierarchical Context Signalling"
# specification for the shell prompt. For details see:
# https://uapi-group.org/specifications/specs/osc_context/

# This file is "activated" through systemd-tmpfiles which links it into
# /etc/profile.d/. To disable this, remove the
# /etc/profile.d/80-systemd-osc-context.sh symlink and mask the
# 20-systemd-osc-context.conf snippet (as root):
#
#   test -h /etc/profile.d/80-systemd-osc-context.sh && \
#     rm -v /etc/profile.d/80-systemd-osc-context.sh && \
#     ln -s /dev/null /etc/tmpfiles.d/20-systemd-osc-context.conf

# Not bash?
[ -n "${BASH_VERSION:-}" ] || return 0

# If we're on a "dumb" terminal, do not install the prompt.
# Treat missing $TERM same as "dumb".
[ "${TERM:-dumb}" = "dumb" ] && return 0

# We need promptvars, otherwise the prompt strings won't undergo parameter expansion
# and we'd print them literally
shopt -q promptvars || return 0

__systemd_osc_context_escape() {
    # Escape according to the OSC 3008 spec. We'll skip it when processing
    # strings we are pretty sure we won't need it for, such as uuids
    # (originating from /proc/sys/kernel/ or /etc/machine-id) and special shell
    # variables such as $$ and $? that always expand to decimal numbers.
    local systemd_format="$1"
    local systemd_value="$2"
    systemd_value="${systemd_value//\\/\\x5c}"
    systemd_value="${systemd_value//;/\\x3b}"
    systemd_value="${systemd_value//[[:cntrl:]]/⍰}"
    # shellcheck disable=SC2059 # always called with fixed format strings with a single string specifier
    printf "$systemd_format" "$systemd_value"
}

__systemd_osc_context_common() {
    if [ -f /etc/machine-id ]; then
        printf ";machineid=%.36s" "$(</etc/machine-id)"
    fi
    __systemd_osc_context_escape ";user=%.255s" "$USER"
    __systemd_osc_context_escape ";hostname=%.255s" "$HOSTNAME"
    printf ";bootid=%.36s;pid=%.20s" "$(</proc/sys/kernel/random/boot_id)" "$$"
    __systemd_osc_context_escape ";cwd=%.255s" "$PWD"
}

__systemd_osc_context_precmdline() {
    local systemd_exitstatus="$?" systemd_signal

    # Close previous command
    if [ -n "${systemd_osc_context_cmd_id:-}" ]; then
        if [ "$systemd_exitstatus" -gt 128 ] && systemd_signal=$(kill -l "$systemd_exitstatus" 2>&-); then
            printf "\033]3008;end=%.64s;exit=failure;status=%d;signal=SIG%s\033\\" "$systemd_osc_context_cmd_id" "$systemd_exitstatus" "$systemd_signal"
        elif [ "$systemd_exitstatus" -ne 0 ]; then
            printf "\033]3008;end=%.64s;exit=failure;status=%d\033\\" "$systemd_osc_context_cmd_id" "$systemd_exitstatus"
        else
            printf "\033]3008;end=%.64s;exit=success\033\\" "$systemd_osc_context_cmd_id"
        fi
    fi

    # Prepare a context ID for this shell if we have none
    if [ -z "${systemd_osc_context_shell_id:-}" ]; then
        read -r systemd_osc_context_shell_id </proc/sys/kernel/random/uuid
    fi

    # Create or update the shell session
    printf "\033]3008;start=%.64s;type=shell%s\033\\" "$systemd_osc_context_shell_id" "$(__systemd_osc_context_common)"

    # Prepare cmd id for next command
    read -r systemd_osc_context_cmd_id </proc/sys/kernel/random/uuid
}

__systemd_osc_context_ps0() {
    # Skip if PROMPT_COMMAND= is cleared manually or by other profiles.
    [ -n "${systemd_osc_context_cmd_id:-}" ] || return

    printf "\033]3008;start=%.64s;type=command%s\033\\" "$systemd_osc_context_cmd_id" "$(__systemd_osc_context_common)"
}

if [ -n "${BASH_VERSION:-}" ]; then
    # Legacy bashrc will assign PROMPT_COMMAND=, which is equivalent to assigning
    # index 0 in the array. Leave an empty spot to handle this gracefully.
    [ -n "$(declare -p PROMPT_COMMAND 2>/dev/null)" ] || PROMPT_COMMAND+=('')

    # Whenever a new prompt is shown, close the previous command, and prepare new command
    PROMPT_COMMAND+=(__systemd_osc_context_precmdline)

    # PS0 is shown right after a prompt completed, but before the command is executed
    PS0='$(__systemd_osc_context_ps0)'"${PS0:-}"
fi