#!/bin/bash
#
# diffzips - diff two ZIP files
#
# $Id$

me=`basename "$0"`

TMPDIR=${TMPDIR:=/tmp}

Die() { echo $me: fatal error: $@ 1>&2; exit 1; }
DieIfMissing() { command -v "$1" >/dev/null || Die missing executable $1; }

DieIfMissing unzip
DieIfMissing realpath

[ -d "$TMPDIR" ] || Die not a directory: $TMPDIR

zip1="${@:$#-1:1}"
zip2="${@:$#}"

IsZipFile()
{
  [ -f "$1" ] || Die not a file: $1
  case `file -b "$1"` in 'Zip archive data'*);; *) Die no ZIP file: $1;; esac
}

IsZipFile "$zip1"
IsZipFile "$zip2"

Havedir()
{
  [ -d "$1" ] || mkdir -p "$1" || Die no directory and cannot create it: $1
}

Unhavedir()
{
  [ -d "$1" ] || return
  rm -rf "$1"

  d=`dirname "$1"`

  while rmdir "$d" 2>/dev/null
  do
    d=`dirname "$d"`
  done
}

zip1=`realpath "$zip1"`
zip2=`realpath "$zip2"`

wd="$TMPDIR/$me-$$"

Havedir "$wd" || Die cannot create working directory: $wd
cd "$wd" || Die cannot cd to $wd

td1=`echo "$zip1" | sed 's#^/##'`
td2=`echo "$zip2" | sed 's#^/##'`

Havedir "$td1" || Die cannot create directory "$TMPDIR$zip1"
Havedir "$td2" || Die cannot create directory "$TMPDIR$zip2"

unzip -qd "$td1" "$zip1"
unzip -qd  "$td2" "$zip2"

diff "${@:1:$#-2}" "$td1" "$td2"

cd -

Unhavedir "$wd"