#!/bin/sh -u
# Test #2 sample answer - Script Part II - 88 marks - 13 of 25%
#------------------------------------------------------------
# One line summary: look for a program in a tar file fetched from web
#------------------------------------------------------------
# Syntax:   $0  URL  [ program_name ]
#------------------------------------------------------------
# Purpose: not required for test
# Assignment Label: not required for test
#-------------------------------------------------------------

# Step 1 - 6 marks
PATH=/bin:/usr/bin ; export PATH
umask 022
LC_COLLATE=C ; export LC_COLLATE

# Step 2 - 9 marks
if [ "$#" -lt 1 -o "$#" -gt 2 ]; then
        echo 1>&2 "$0: expecting URL and optional program name,"
        echo 1>&2 "    found $# ($*)"
        exit 1
fi

# Step 3 - 1 mark
url="$1"

# Step 4 - 12 marks
if echo "$url" | grep '^http://' >/dev/null ; then
        echo "Fetching $url from web..."
else
        echo 1>&2 "$0: URL '$url' is not an http:// URL"
        exit 2
fi

# Step 5 - 2 marks
tmp=/tmp/url$$

# Step 6 - 10 marks
if ! wget -O "$tmp" "$url" ; then
        echo 1>&2 "$0: wget of '$url' failed"
        rm "$tmp"
        exit 3
fi

# Step 7 - 9 marks
if [ ! -s "$tmp" ] ;  then
        echo 1>&2 "$0: fetched URL '$url' is empty"
        rm "$tmp"
        exit 4
fi

# Step 8 - 3 marks
chmod ugo-w "$tmp" || exit 5

# Step 9 - 10 marks
if file "$tmp" | grep 'tar archive' >/dev/null ; then
        echo "Looking in tar archive..."
else
        echo 1>&2 "$0: fetched URL '$url' is not a tar archive"
        exit 6
fi

# Step 10 - 7 marks
if [ $# -eq 2 ]; then
        prog="$2"
else
        echo 1>&2 "Enter a program file name:" 
        read prog || exit 7
fi

# Step 11 - 10 marks
if tar tf "$tmp" | grep "$prog" >/dev/null ; then
        echo "Program $prog is contained in $url"
else
        echo 1>&2 "$0: Cannot find program '$prog' in URL '$url'"
        exit 8
fi

# Step 12 - 7 marks
tar=foo.tar
if [ -e "$tar" -a -w .. ] ; then
        mv "$tar" .. || exit 9
fi

# Step 13 - 2 marks
mv "$tmp" "$tar" || exit 10