#! /bin/sh

# downloader.sh -- call N fetchers to download M files, in parallel 
# $Id$
# Carlos Duarte <cgd@teleweb.pt>, 000408

FETCHER='curl -Osc'
NR=10
DO=sh
USAGE='
	eval cat<<EOF
usage: $0 [-h] [-m #] [-n] [[-f files] ...] urls...

  -h      this help
  -n      no op
  -f files
	  files that contains on URL per line 
  -m      number of simultaneous downloads to launch (def: $NR)
  -F 	  fetcher program to use (default: $FETCHER)
EOF
	exit 1
'

while : ; do
	case x"$1" in 
	x-h)	eval "$USAGE" ;;
	x-n)	DO=cat ;;
	x-f)	FILES="$FILES $2" ; shift ;;
	x-m)	NR="$2" ; shift ;;
	x-F)	FETCHER="$2"; shift ;;
	x--)	shift; break ;;
	x-*)	echo "invalid option -- `echo $1|cut -c2-`"
		eval "$USAGE" ;;
	*)	break ;;
	esac
	shift
done

echo "$@" | tr ' ' \\n | awk '
/^#/ {next}
/^ *$/ {next}
{ gsub(/'\''/,"'\'\\\'\''"); x[n++] = "'\''" $0 "'\''" }
END {
	r=n/'"$NR"'
	k=int(r)
	if (r!=int(r))
		k++
	nn=0
	for (i=0;i<n;) {
		for (j=k; j--; ) {
			if (j == k-1) printf "("; 
			if (i>=n) break
			printf "'"$FETCHER"' %s %s\n", 
			  x[i++], 
			  j ? ";\\" : ") >/dev/null 2>&1 &\n"
		}
		nn++
		k=int(r)
		if (i/nn < r)
			k++
	}
}' - $FILES | ${DO}