#!/usr/bin/env bash
#
#	debinfo - Show metadata information on Debian package files
#
#	Version 1.1 (with 20/27 fields on -a instead of previous 18/25)
#
Prg="$(basename "$0")"

# We use bash arrays
#   Our short headers for file-only info
Hdrx=(Path File Size Links Inod MD5 SHA1 SHA256)
#   Our full headers for file-only info, mimicking dpkg-query fields (for FmtHelp only)
Hlpx=(Filepath Filename FileSize Hardlinks Inode MD5sum SHA1sum SHA256sum)
nHx=${#Hdrx[*]}

#   Our short headers for all installed packages
Hdrs=([$nHx]=Name Vers Arch Sect Prio Orig Summ Desc Maint Home Source Stat LastMod Instsz Confl Break Prov Predeps Deps Recom Essen)
#   Corresponding dpkg-deb & dpkg-query fields (man dpkg-query)
Fmts=([$nHx]=Package Version Architecture Section Priority Origin binary:Summary Description Maintainer Homepage Source db:Status-Abbrev db-fsys:Last-Modified Installed-Size Conflicts Breaks Provides Pre-Depends Depends Recommends Essential)
# (non-internal) omitted: Bugs Enhances Replaces Suggests

#   Format characters for all file-only + installed fields
Abrs=(F f z h i m 1 2 n v a s p o k c M H S t T Z C B P D d r e)

#   Format translation from our file-abrs to stat -c %x
declare -A StFs
StFs=([z]=s [h]=h [i]=i)

#   Field Abr RE (extract abrs from Format)
faRE='s/[^%]*%(.)[^%]*/\1 /pg'

#   Show usage and exit
#	Usage [<exit-code>]
Usage()
{
    echo "debinfo - Display debian package(s) control fields - Version 1.1" >&2
    echo -e "Usage:\t$Prg [-c] [-f format-string | -a [-d]] [-r] [-s separator] [package-file ...]" >&2
    echo -e "\t-c compatible with version 1.0 (with 18/25 fields on -a)" >&2
    echo -e "\t-a sets format-string to display all existing fields (except Path)" >&2
    echo -e "\t-d full Description with -a, instead of Summary" >&2
    echo -e "\t-r suppresses the header" >&2
    echo -e "\t$Prg -H will list %<x> format specifiers" >&2
    echo "If no package-file is specified, installed packages will be displayed"
#   shellcheck disable=SC2086	# Double quote to prevent globbing
    exit $1
}

#   Return number of repeats in a string
nbRep()
{
    local str="$1"
    local -i len=${#str}
    local -i hc=$(((len / 2) + (len % 2))) i=1 nb
    local rpt tst flt

    while [ "$i" -le "$hc" ]; do
	if [ $((len % i)) -eq 0 ]; then
	    nb=$((len / i))	# Potential number of repeats
	    #	We rotate str $i chars
	    eval "$(echo "$str" | sed -nr "s/^(.{$i})(.*)$/rpt=\"\1\" tst=\"\2\1\"/p")"
	    #	If str is unchanged, we found our repeat string !
	    test "$str" = "$tst" && break
	else
	    nb=1
	    rpt="$str"
	fi
	i=$((++i))
    done
    #	IF "$3", convert TABs to escape code OR leave as is
    test "$3" && flt="sed 's/\t/\\\\t/g'" || flt='cat'
    #	IF "$2", echo number & repeat-string OR just number
    test "$2" && echo "nb=$nb rpt=\"$rpt\"" | eval "$flt" || echo $nb
}

#   Assemble -a Format
#	allFmt <with-files>
allFmt()
{
    #global Hdrx Abrs Hdrs Sep fDesc Compat
    local s idx fmt

    s=
    if [ "$1" ]; then
	for idx in "${!Hdrx[@]}"
	do
	    test "${Abrs[$idx]}" = 'F' && continue	# Path
	    fmt="$fmt$s%${Abrs[$idx]}"
	    s="$Sep"
	done
    fi
    for idx in "${!Hdrs[@]}"
    do
	test "${Abrs[$idx]}" = 'c' -a -z "$fDesc" && continue	# Description
	test "${Abrs[$idx]}" = 'k' -a "$fDesc" && continue	# Summary
	fmt="$fmt$s%${Abrs[$idx]}"
	s="$Sep"
	test "$Compat" -a "${Hdrs[$idx]}" = 'Deps' && break
    done
    printf '%s\\n\n' "$fmt"
}

#   Show all full and short fields, with index in Format
FmtHelp()
{
    #global Format faRE Hdrx Abrs Hlpx Hdrs Fmts
    local fAbr fmt xHdr xFmt fix afi v
    local -i nAbr nRep idx afo aio

    fAbr=($(echo "$Format" | sed -nr "$faRE"))
    nAbr=${#fAbr[*]}
    nRep=$(nbRep "$(echo -e "$Format" | sed 's/%.//g')")
    #echo "nAbr=${#fAbr[*]} fAbr=\"${fAbr[*]}\" nRep=$nRep" >&2

    #	If at leat 2 Abr and one more than nRep, format is of a xSV file
    test "$nAbr" -gt 1 -a "$nAbr" -eq $((++nRep)) && fmt=y

    echo "Format specifiers, tags and indexes:"
    echo "  Package files only:"
    #	If format for xSV, add extra column
    if [ "$fmt" ]; then
	xHdr=' Fmt'
	xFmt='   %2s'
    fi
    echo "    Abr Full            Short   File Inst$xHdr"
    for idx in "${!Hdrx[@]}"
    do
	fix=	# Format IndeX
	if [ "$fmt" ]; then
	    fix=$(Index fAbr "${Abrs[$idx]}")
	    test "$fix" -ge 0 && fix=$((++fix)) || fix=-
	fi
	test "$idx" -eq 0 && afi=- || afi=$idx	# all-files-index
	printf "    %%%s  %-14s  %-7s  %2s    -$xFmt\n" "${Abrs[$idx]}" "${Hlpx[$idx]}" "${Hdrx[$idx]}" "$afi" $fix
    done
    echo "  Files and installed packages:"
    afo=0	# all file offset
    aio=-$idx	# all inst offset
    for idx in "${!Hdrs[@]}"
    do
	v="$(expr "${Fmts[$idx]}" : '.*:\(.*\)')"
	test "$v" || v="${Fmts[$idx]}"

	test "${Hdrs[$idx]}" = 'Desc' && { afo=$((--afo)); aio=$((--aio)); }

	fix=	# Format IndeX
	if [ "$fmt" ]; then
	    fix=$(Index fAbr "${Abrs[$idx]}")
	    test "$fix" -ge 0 && fix=$((++fix)) || fix=-
	fi
	printf "    %%%s  %-14s  %-7s  %2s   %2s$xFmt\n" "${Abrs[$idx]}" "$v" "${Hdrs[$idx]}" $((idx+afo)) $((idx+aio)) $fix
    done
    echo "Current format is:"
    echo "   \"$Format\"" | sed -e 's/\t/\\t/g' -e 's/\n/\\n/g'
}

#   Index <array> <value>
Index()
{
    local idx
    local -n a=$1

    for idx in "${!a[@]}"
    do
	test "${a[$idx]}" = "$2" && { echo "$idx"; return; }
    done
    echo -1
}

#   sums file fs...
#
#   shellcheck disable=SC2046	# Quote this to prevent word splitting
sums()
{
    local file fmt fs

    file="$1"
    shift
    fmt=
    for fs in "$@"
    do
	case $fs in
	    m)	set $(md5sum "$file");;
	    1)	set $(sha1sum "$file");;
	    2)	set $(sha256sum "$file");;
	esac
	fmt="$fmt -e 's/%$fs/$1/g'"
    done
    echo "$fmt"
}

#
# Main
#
#   Parse args
Sep='	'	# Tab
while getopts 'acf:s:rdHh' opt
do
    case $opt in
	a)  fmtAll=y;;
	c)  Compat=y;;
	f)  Format="$OPTARG"	;;
	s)  Sep="$OPTARG"	;;
	r)  noHdr=y;;
	d)  fDesc=y;;
	H)  doHelp=y;;
	h)  Usage 0;;	# help
	\?) Usage 1;;	# error
    esac
done
if [ "$Format" ]; then
    test "$fmtAll" && { echo "$Prg: cannot specify -a with -f <string>" >&2; Usage 1; }
else
    Format="%n$Sep%v$Sep%a$Sep%k\n"
fi
if [ "$fDesc" -a -z "$fmtAll" ]; then
    echo "$Prg: discarding -d option not used with -a" >&2
    fDesc=
fi
shift $((OPTIND - 1))
test $# -gt 0 && onFiles=y

test "$fmtAll" && Format="$(allFmt $onFiles)"

# Check format specifiers
sedHdrs=" -e 's/\\\\n/\n/g' -e 's/\\\\t/\t/g'"
sedFmts=" -e 's/\\\\n/\f/g'"
for fs in $(echo "$Format" | sed -nr "$faRE")
do
    idx=$(Index Abrs "$fs")
    if [ "$idx" -ge 0 ]; then
	if [ "$idx" -lt "$nHx" ]; then
	    if [ "$onFiles" ]; then
		sedHdrs=" $sedHdrs -e 's/%$fs/${Hdrx[$idx]}/g'"
		test "$idx" -eq 0 && doPath=y
		test "$idx" -eq 1 && doFile=y
		test "$idx" -ge 2 -a "$idx" -le 4 && statFmt="$statFmt -e 's/%%$fs/%${StFs[$fs]}/g'"
		test "$idx" -ge 5 -a "$idx" -lt "$nHx" && sumsOpt="$sumsOpt$fs "
	    else
		echo "$Prg: ignoring %$fs file specifier" >&2
	    fi
	else
	    sedHdrs=" $sedHdrs -e 's/%$fs/${Hdrs[$idx]}/g'"
	    sedFmts=" $sedFmts -e 's/%$fs/\${${Fmts[$idx]}}/g'"
	fi
    else
	echo "$Prg: ignoring unknown %$fs specifier" >&2
    fi
done

#   Show Format Help and exit
test "$doHelp" && { FmtHelp; exit 0; }

#   All set: display them !
test "$noHdr" || echo -n "$Format" | eval "sed$sedHdrs"
if [ "$onFiles" ]; then	# Some .deb args, display info on them
    for path in "$@"
    do
	test -f "$path" || { echo "File '$path' not found" >&2; continue; }
	file=$(basename "$path")
	sedFmtx=
	test "$doPath" && sedFmtx="$sedFmtx -e 's;%${Abrs[0]};$path;g'"
	test "$doFile" && sedFmtx="$sedFmtx -e 's;%${Abrs[1]};$file;g'"
	test "$statFmt" && sedFmtx="$sedFmtx$(stat -c "$statFmt" "$path")"
#	shellcheck disable=SC2086   # Double quote to prevent globbing sumsOpt
	test "$sumsOpt" && sedFmtx="$sedFmtx$(sums "$path" $sumsOpt)"
	Fmt=$(echo "$Format" | eval "sed$sedFmtx$sedFmts")
	dpkg-deb -W --showformat "$Fmt" "$path" | tr '\n\f' '\v\n'
    done
else			# else display info on installed packages
    Fmt=$(echo "$Format" | eval "sed$sedFmts")
    dpkg-query -W -f "$Fmt" | tr '\n\f' '\v\n'
fi