#!/bin/sh
#---------------------------------------------
#   xdg-realpath
#
#   Utility script to canonicalize filepaths.
# 
#   Copyright 2023, Slatian <baschdel@disroot.org>
#
#   LICENSE:
#
#   Permission is hereby granted, free of charge, to any person obtaining a
#   copy of this software and associated documentation files (the "Software"),
#   to deal in the Software without restriction, including without limitation
#   the rights to use, copy, modify, merge, publish, distribute, sublicense,
#   and/or sell copies of the Software, and to permit persons to whom the
#   Software is furnished to do so, subject to the following conditions:
#
#   The above copyright notice and this permission notice shall be included
#   in all copies or substantial portions of the Software.
#
#   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
#   OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#   FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
#   THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
#   OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
#   ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
#   OTHER DEALINGS IN THE SOFTWARE.
#
#---------------------------------------------

manualpage()
{
cat << '_MANUALPAGE'
Name

xdg-realpath - Canonicalizes filepaths in a consistent way.

Synopsis

xdg-realpath [--] file ...

xdg-realpath --get-backend

xdg-realpath { --help | --manual | --version }

Description

xdg-realpath canonicalizes filepaths using the installed realpath or readlink
-f implementation, automatically choosing the right calling conventions so you
don't have to worry about it.

Canonicalization happens by resolving relative paths and symbolic links
resulting in an absolute path to a file. It fails if the path does not lead to
any kind file or directory.

It is strongly recommended to call xdg-realpath using the -- option.

When using xdg-realpath with multiple files and one of the given paths leads
directly or indirectly to a missing file a message will be printed to stdout
and xdg-realpath will continue resolving until it has finished with all given
paths. If at least one path does not resolve, it will return an exit code 2.

Unlike realpath or readlink -f xdg-realpath will error if one attempts to
resolve a non-existing file in an existing directory. If such behavior is added
in the future it will be behind a command line flag.

Options

--help
    Show command synopsis.
--manual
    Show this manual page.
--version
    Show the xdg-utils version information.

Exit Codes

An exit code of 0 indicates success while a non-zero exit code indicates
failure. The following failure codes can be returned:

1
    Error in command line syntax.
2
    One of the files passed on the command line did not exist.
3
    A required tool could not be found.
4
    The action failed.

Environment Variables

xdg-realpath honours the following environment variables:

XDG_UTILS_REALPATH_BACKEND

    When left empty (recommended) xdg-realpath automatically chooses an
    appropriate backend. Possible values are realpath, busybox-realpath and
    readlink. This is also used by other scripts from the xdg-utils family.

    Setting this variable has the possibility to break a lot of things. It is
    primarily intended for testing and quick-fixing. If you are not the local
    system administrator or a distribution maintainer leave it alone!

    The --get-backend option will print the used backend.

See Also

realpath(1), readlink(1), xdg-utils-common(7)

Examples

xdg-realpath -- /./bin

Canonicalizes the path to /./bin, on most systems the output will be /bin or /
usr/bin.

xdg-realpath -- foo.txt

Will print the absolute path of the file foo.txt or inform you that foo.txt
doesn't exist.

xdg-realpath -- .

Will print the present working directory path with symbolic links resolved.

_MANUALPAGE
}

usage()
{
cat << '_USAGE'
xdg-realpath - Canonicalizes filepaths in a consistent way.

Synopsis

xdg-realpath [--] file ...

xdg-realpath --get-backend

xdg-realpath { --help | --manual | --version }

_USAGE
}

XDG_UTILS_ENABLE_DOUBLE_HYPEN="y"

#@xdg-utils-common@
#----------------------------------------------------------------------------
#   Common utility functions included in all XDG wrapper scripts
#----------------------------------------------------------------------------

#shellcheck shell=sh

# (level, echo_args ...)
DEBUG()
{
  [ -z "${XDG_UTILS_DEBUG_LEVEL}" ] && return 0;
  [ "${XDG_UTILS_DEBUG_LEVEL}" -lt "$1" ] && return 0;
  shift
  echo "$@" >&2
}

# This handles backslashes but not quote marks.
# 
# (text)
# shellcheck disable=SC2317 # Not using this function is okay
first_word()
{
    # shellcheck disable=SC2162 # No -r is intended here
    read first rest
    echo "$first"
}

#-------------------------------------------------------------
# map a binary to a .desktop file
# 
# (command_or_path_to_binary)
# shellcheck disable=SC2317 # Not using this function is okay
binary_to_desktop_file()
{
    if [ -z "$1" ] ; then
        DEBUG 2 "binary_to_desktop_file argument is empty"
        return
    fi
    search="${XDG_DATA_HOME:-$HOME/.local/share}:${XDG_DATA_DIRS:-/usr/local/share:/usr/share}"
    binary="$(command -v "$1")"
    binary="$(xdg_realpath "$binary")"
    base="$(basename "$binary")"
    IFS=:
    for dir in $search; do
        unset IFS
        [ "$dir" ] || continue
        [ -d "$dir/applications" ] || [ -d "$dir/applnk" ] || continue
        for file in "$dir"/applications/*.desktop "$dir"/applications/*/*.desktop "$dir"/applnk/*.desktop "$dir"/applnk/*/*.desktop; do
            [ -r "$file" ] || continue
            # Check to make sure it's worth the processing.
            grep -q "^Exec.*$base" "$file" || continue
            # Make sure it's a visible desktop file (e.g. not "preferred-web-browser.desktop").
            grep -Eq "^(NoDisplay|Hidden)=true" "$file" && continue
            command="$(grep -E "^Exec(\[[^]=]*])?=" "$file" | cut -d= -f 2- | first_word)"
            command="$(command -v "$command")"
            if [ x"$(xdg_realpath "$command")" = x"$binary" ]; then
                # Fix any double slashes that got added path composition
                echo "$file" | tr -s /
                return
            fi
        done
    done
}

#-------------------------------------------------------------
# map a .desktop file name to its Exec binary
# Returns the realpath resolved path to the binary or noting.

# (desktop_file_name)
# shellcheck disable=SC2317 # Not using this function is okay
desktop_file_to_binary()
{
    DEBUG 1 "desktop_file_to_binary '$1'"
    if [ -z "$1" ] ; then
        DEBUG 2 "desktop_file_to_binary argument is empty"
        return
    fi
    search="${XDG_DATA_HOME:-$HOME/.local/share}:${XDG_DATA_DIRS:-/usr/local/share:/usr/share}"
    desktop="$(basename "$1")"
    IFS=:
    for dir in $search; do
        DEBUG 2 "Searching in '$dir/{applications,applnk}'"
        unset IFS
        [ -n "$dir" ] && [ -d "$dir/applications" ] || [ -d "$dir/applnk" ] || continue
        # Check if desktop file contains -
        if [ "${desktop#*-}" != "$desktop" ]; then
            vendor="${desktop%-*}"
            app="${desktop#*-}"
            if [ -r "$dir/applications/$vendor/$app" ]; then
                file_path="$dir/applications/$vendor/$app"
            elif [ -r "$dir/applnk/$vendor/$app" ]; then
                file_path="$dir/applnk/$vendor/$app"
            fi
        fi
        if test -z "$file_path" ; then
            for indir in "$dir"/applications/ "$dir"/applications/*/ "$dir"/applnk/ "$dir"/applnk/*/; do
		        DEBUG 4 "Does file exist? '$indir/$desktop'"
                file="$indir/$desktop"
                if [ -r "$file" ]; then
                    file_path="$file"
                    break
                fi
            done
        fi
        if [ -r "$file_path" ]; then
	        DEBUG 2 "Checking desktop file '$file_path'"
            # Get the command name from the correct Exec
            # Note: Ignoring quoting and escape sequences here, see #253
            binary="$(awk -F '=' '
            	/^\[/{ in_entry=0 }
            	$0 == "[Desktop Entry]"{ in_entry=1 }
            	in_entry && /^Exec\s*=/ {
					sub(/^\s+/,"",$2);
					match($2,/^[^ ]+/);
					print substr($2,RSTART,RLENGTH)
				}' \
            	< "$file_path" )"
            if [ -z "$binary" ] ; then
                DEBUG 2 "No or empty Exec key in .desktop file. Search failed."
                return
            fi
            DEBUG 2 "Found command: $binary"
            binary="$(xdg_which "$binary")"
            DEBUG 2 "Resolved to command to file: '$binary'"
            [ -z "$binary" ] || xdg_realpath "$binary"
            return
        fi
    done
}

#-------------------------------------------------------------
# Exit script on successfully completing the desired operation

# (message (optional))
# shellcheck disable=SC2120 # It is okay to call this without arguments
# shellcheck disable=SC2317 # Not using this function is okay
exit_success()
{
    if [ $# -gt 0 ]; then
        echo "$*"
        echo
    fi

    exit 0
}


#-----------------------------------------
# Exit script on malformed arguments, not enough arguments
# or missing required option.
# prints usage information

# (message (optional))
# shellcheck disable=SC2317 # Not using this function is okay
exit_failure_syntax()
{
    if [ $# -gt 0 ]; then
        echo "xdg-realpath: $*" >&2
        echo "Try 'xdg-realpath --help' for more information." >&2
    else
        usage
        echo "Use 'man xdg-realpath' or 'xdg-realpath --manual' for additional info."
    fi

    exit 1
}

#-------------------------------------------------------------
# Exit script on missing file specified on command line

# (message (optional))
# shellcheck disable=SC2317 # Not using this function is okay
exit_failure_file_missing()
{
    if [ $# -gt 0 ]; then
        echo "xdg-realpath: $*" >&2
    fi

    exit 2
}

#-------------------------------------------------------------
# Exit script on failure to locate necessary tool applications

# (message (optional))
# shellcheck disable=SC2317 # Not using this function is okay
exit_failure_operation_impossible()
{
    if [ $# -gt 0 ]; then
        echo "xdg-realpath: $*" >&2
    fi

    exit 3
}

#-------------------------------------------------------------
# Exit script on failure returned by a tool application

# (message (optional))
# shellcheck disable=SC2317 # Not using this function is okay
exit_failure_operation_failed()
{
    if [ $# -gt 0 ]; then
        echo "xdg-realpath: $*" >&2
    fi

    exit 4
}

#------------------------------------------------------------
# Exit script on insufficient permission to read a specified file

# (message (optional))
# shellcheck disable=SC2317 # Not using this function is okay
exit_failure_file_permission_read()
{
    if [ $# -gt 0 ]; then
        echo "xdg-realpath: $*" >&2
    fi

    exit 5
}

#------------------------------------------------------------
# Exit script on insufficient permission to write a specified file

# (message (optional))
# shellcheck disable=SC2317 # Not using this function is okay
exit_failure_file_permission_write()
{
    if [ $# -gt 0 ]; then
        echo "xdg-realpath: $*" >&2
    fi

    exit 6
}

# (path)
# shellcheck disable=SC2317 # Not using this function is okay
check_input_file()
{
    if [ ! -e "$1" ]; then
        exit_failure_file_missing "file '$1' does not exist"
    fi
    if [ ! -r "$1" ]; then
        exit_failure_file_permission_read "no permission to read file '$1'"
    fi
}

# (label_for_error_message, path_to_check)
# shellcheck disable=SC2317 # Not using this function is okay
check_vendor_prefix()
{
    file_label="$2"
    [ -n "$file_label" ] || file_label="filename"
    file="$(basename "$1")"
    case "$file" in
       [[:alpha:]]*-*)
         return
         ;;
    esac

    echo "xdg-realpath: $file_label '$file' does not have a proper vendor prefix" >&2
    echo 'A vendor prefix consists of alpha characters ([a-zA-Z]) and is terminated' >&2
    echo 'with a dash ("-"). An example '"$file_label"' is '"'example-$file'" >&2
    echo "Use --novendor to override or 'xdg-realpath --manual' for additional info." >&2
    exit 1
}

# (path)
# shellcheck disable=SC2317 # Not using this function is okay
check_output_file()
{
    # if the file exists, check if it is writeable
    # if it does not exists, check if we are allowed to write on the directory
    if [ -e "$1" ]; then
        if [ ! -w "$1" ]; then
            exit_failure_file_permission_write "no permission to write to file '$1'"
        fi
    else
        DIR="$(dirname "$1")"
        if [ ! -w "$DIR" ] || [ ! -x "$DIR" ]; then
            exit_failure_file_permission_write "no permission to create file '$1'"
        fi
    fi
}

#----------------------------------------
# Checks for shared commands, e.g. --help

# (args ...)
check_common_commands()
{
    while [ $# -gt 0 ] ; do
        parm="$1"
        shift

        case "$parm" in
            --help)
            usage
            echo "Use 'man xdg-realpath' or 'xdg-realpath --manual' for additional info."
            exit_success
            ;;

            --manual)
            manualpage
            exit_success
            ;;

            --version)
            echo "xdg-realpath 1.2.99"
            exit_success
            ;;

            --)
	        [ -z "$XDG_UTILS_ENABLE_DOUBLE_HYPEN" ] || break
	        ;;
        esac
    done
}

check_common_commands "$@"

[ -z "${XDG_UTILS_DEBUG_LEVEL}" ] && unset XDG_UTILS_DEBUG_LEVEL;
# shellcheck disable=SC2034
if [ "${XDG_UTILS_DEBUG_LEVEL-0}" -lt 1 ]; then
    # Be silent
    xdg_redirect_output=" > /dev/null 2> /dev/null"
else
    # All output to stderr
    xdg_redirect_output=" >&2"
fi

#--------------------------------------
# Checks for known desktop environments
# set variable DE to the desktop environments name, lowercase
# Don't forget to update the manpage!
#
# ()
detectDE()
{
    # see https://bugs.freedesktop.org/show_bug.cgi?id=34164
    unset GREP_OPTIONS

    # Tool specific desktop override
    xdg_util="$(basename -- "$0" | sed 's/^xdg-//' | tr '[:lower:]' '[:upper:]')"
    # printenv isn't posix, but implemented by almost all coreutils packages
    DE="$(printenv -- "XDG_UTILS_${xdg_util}_OVERRIDE_DE")"
    unset xdg_util
    [ -z "$DE" ] || return

    # General desktop override
    if [ -n "${XDG_UTILS_OVERRIDE_DE}" ]; then
        DE="${XDG_UTILS_OVERRIDE_DE}"
        return
    fi

    # Check for toolbx first; as this runs "inside" an existing
    # environment.
    if [ -f /run/.toolboxenv ]; then
       DE="toolbx"
       return
    fi

    IFS=:
    for desktop in $XDG_CURRENT_DESKTOP ; do
      unset IFS
      case "$desktop" in
         # only recently added to menu-spec, pre-spec X- still in use
         Cinnamon|X-Cinnamon)
           DE=cinnamon;
           ;;
         ENLIGHTENMENT)
           DE=enlightenment;
           ;;
         # GNOME, GNOME-Classic:GNOME, or GNOME-Flashback:GNOME
         GNOME)
           DE=gnome;
           ;;
         KDE)
           DE=kde;
           ;;
         DEEPIN|Deepin|deepin|DDE)
           DE=deepin;
           ;;
         LXDE)
           DE=lxde;
           ;;
         LXQt)
           DE=lxqt;
           ;;
         MATE)
           DE=mate;
           ;;
         XFCE)
           DE=xfce
           ;;
         X-Generic)
           DE=generic
           ;;
      esac
      [ -n "$DE" ] && break
    done

    # shellcheck disable=SC2153
    if [ -z "$DE" ]; then
      # classic fallbacks
      if [ -n "$KDE_FULL_SESSION" ]; then DE=kde;
      elif [ -n "$GNOME_DESKTOP_SESSION_ID" ]; then DE=gnome;
      elif [ -n "$MATE_DESKTOP_SESSION_ID" ]; then DE=mate;
      elif dbus-send --print-reply --dest=org.freedesktop.DBus /org/freedesktop/DBus org.freedesktop.DBus.GetNameOwner string:org.gnome.SessionManager > /dev/null 2>&1 ; then DE=gnome;
      elif echo "$DESKTOP" | grep -q '^Enlightenment'; then DE=enlightenment;
      elif [ -n "$LXQT_SESSION_CONFIG" ]; then DE=lxqt;
      fi
    fi

    if [ -z "$DE" ]; then
      # fallback to checking $DESKTOP_SESSION
      case "$DESKTOP_SESSION" in
         gnome)
           DE=gnome;
           ;;
         LXDE|Lubuntu)
           DE=lxde;
           ;;
         MATE)
           DE=mate;
           ;;
         xfce|xfce4|'Xfce Session')
           DE=xfce;
           ;;
      esac
    fi

    if [ -z "$DE" ]; then
      # fallback to uname output for other platforms
      case "$(uname 2>/dev/null)" in
        CYGWIN*)
          DE=cygwin;
          ;;
        Darwin)
          DE=darwin;
          ;;
        Linux)
          grep -q microsoft /proc/version > /dev/null 2>&1 && \
          command -v explorer.exe > /dev/null 2>&1 && \
          DE=wsl;
          ;;
      esac
    fi

    if [ x"$DE" = x"gnome" ]; then
      # gnome-default-applications-properties is only available in GNOME 2.x
      # but not in GNOME 3.x
      command -v gnome-default-applications-properties > /dev/null || DE="gnome3"
    fi

    if [ -f "/.flatpak-info" ]; then
      DE="flatpak"
    fi
}

#----------------------------------------------------------------------------
# kfmclient exec/openURL can give bogus exit value in KDE <= 3.5.4
# It also always returns 1 in KDE 3.4 and earlier
# Simply return 0 in such case
# 
# (exit_code)
# shellcheck disable=SC2317 # Not using this function is okay
kfmclient_fix_exit_code()
{
    version="$(LC_ALL=C.UTF-8 kde-config --version 2>/dev/null | grep '^KDE')"
    major="$(echo "$version" | sed 's/KDE.*: \([0-9]\).*/\1/')"
    minor="$(echo "$version" | sed 's/KDE.*: [0-9]*\.\([0-9]\).*/\1/')"
    release="$(echo "$version" | sed 's/KDE.*: [0-9]*\.[0-9]*\.\([0-9]\).*/\1/')"
    test "$major" -gt 3 && return "$1"
    test "$minor" -gt 5 && return "$1"
    test "$release" -gt 4 && return "$1"
    return 0
}

#----------------------------------------------------------------------------
# Returns true if there is a graphical display attached.
#
# ()
# shellcheck disable=SC2317 # Not using this function is okay
has_display()
{
    if [ -n "$DISPLAY" ] || [ -n "$WAYLAND_DISPLAY" ]; then
        return 0
    else
        return 1
    fi
}

#----------------------------------------------------------------------------
# Prefixes a path with a "./" if it starts with a "-".
# This is useful for programs to not confuse paths with options.
#
# ()
# shellcheck disable=SC2317 # Not using this function is okay
unoption_path()
{
	case "$1" in
		-*)
			printf "./%s" "$1" ;;
		*)
			printf "%s" "$1" ;;
	esac
}

#----------------------------------------------------------------------------
# Performs a symlink and relative path resolving for a single argument.
# This will always fail if the given file does not exist!
#
# (path)
# shellcheck disable=SC2317 # Not using this function is okay
xdg_realpath()
{
	# allow caching and external configuration
	if [ -z "$XDG_UTILS_REALPATH_BACKEND" ] ; then
		if command -v realpath >/dev/null 2>/dev/null ; then
			lines="$(realpath -- / 2>&1)"
			if [ $? = 0 ] && [ "$lines" = "/" ] ; then
				XDG_UTILS_REALPATH_BACKEND="realpath"
			else
				# The realpath took the -- literally, probably the busybox implementation
				XDG_UTILS_REALPATH_BACKEND="busybox-realpath"
			fi
			unset lines
		elif command -v readlink >/dev/null 2>/dev/null ; then
			XDG_UTILS_REALPATH_BACKEND="readlink"
		else
			exit_failure_operation_failed "No usable realpath backend found. Have a realpath binary or a readlink -f that canonicalizes paths."
		fi
	fi
	# Always fail if the file doesn't exist (busybox realpath does that for example)
	[ -e "$1" ] || return 1
	case "$XDG_UTILS_REALPATH_BACKEND" in
		realpath)
			realpath -- "$1"
			;;
		busybox-realpath)
			# busybox style realpath implementations have options too
			realpath "$(unoption_path "$1")"
			;;
		readlink)
			readlink -f "$(unoption_path "$1")"
			;;
		*)
			exit_failure_operation_impossible "Realpath backend '$XDG_UTILS_REALPATH_BACKEND' not recognized."
			;;
	esac
}

#----------------------------------------------------------------------------
# The `which` command but as a shell implementation.
# Returns either the path of the resolved binary or nothing
# because command -v does not always return the path of a command
# (builtins, aliases, functions, etc.)
#
# (command)
# shellcheck disable=SC2317 # Not using this function is okay
xdg_which()
{
	case "$1" in
		'') return 1 ;;
		*/*)
			# We got a path containing slashes, test if it is executable
			# and return its absolute path with symlinks resolved.
			if [ -x "$1" ] ; then
				xdg_realpath "$1"
				return 0
			fi
			return 1
			;;
	esac
	# search PATH for command
	old_ifs="$IFS"
	IFS=:
	for p in $PATH ; do
		IFS="$old_ifs"
		if [ -x "$p/$1" ] ; then
			printf "%s\n" "$p/$1"
			return
		fi
	done
	return 1
}

#----------------------------------------------------------------------------
# Helper function that returns the value for `$XDG_CONFIG_HOME`,
# independent of it being explicitly set or simply a fallback.
#
# ()
# shellcheck disable=SC2317 # Not using this function is okay
get_xdg_config_home()
{
	# Only use XDG_CONFIG_HOME if it is an absolute path
	# shellcheck disable=SC2153 # not misspelled
	case "$XDG_CONFIG_HOME" in
		/*) printf "%s\n" "$XDG_CONFIG_HOME" ;;
		*) printf "%s\n" "$HOME/.config" ;;
	esac
}

set -e

[ -n "$1" ] || exit_failure_syntax

past_double_hyphen=""
exit_with_missing_status=""

run_realpath() {
	if [ -e "$1" ] ; then
		xdg_realpath "$1"
	else
		echo "xdg-realpath: $1: No such file or directory" >&2
		exit_with_missing_status=y
	fi
}

while [ $# -gt 0 ] ; do
	if [ -n "$past_double_hyphen" ] ; then
		run_realpath "$1"
	else
		case "$1" in
			--)
				past_double_hyphen="y"
				;;
			--get-backend)
				xdg_realpath || true
				echo "$XDG_UTILS_REALPATH_BACKEND"
				;;
			-*)
				exit_failure_syntax "Unknown option: '$1'"
				;;
			*)
				run_realpath "$1"
				;;
		esac
	fi
	shift
done

[ -z "$exit_with_missing_status" ] || exit_failure_file_missing
