#!/bin/bash

# Download Freetz packages from a randomly chosen mirror server. There are
# predefined servers in 'make menuconfig' which can be edited, but there is
# also an empty input field for a user-defined server. Additionally, another
# download source maybe specified on the command line as $2. $1 is the name
# of the file to be downloaded.
#
# This script is designed to be called by makefile includes (*.mk), but can
# also be called directly. It expects to find a file with necessary variables
# at a relative location '../.config' to this script. The variables are:
#   - FREETZ_MOD_DL_NUM_SITES  (numeric value, e.g. 3)
#   - FREETZ_MOD_DL_SITE_1     (URL, e.g. http://freetz.3dfxatwork.de)
#   - ...
#   - FREETZ_MOD_DL_SITE_n     (n = FREETZ_MOD_DL_NUM_SITES)

helpmsg()
{
cat << 'EOF'
freetz_download - download Freetz packages

Usage: freetz_download (-?|--help) | ( (<download-dir> | check) <dot-config> <filename> [<main-url>] [<md5>])
    check         - check download
    download-dir  - target directory for download file
    dot-config    - path to .config for Freetz
    filename      - download file name
    main-url      - url without filename for primary download
    md5           - md5 of file
    -?, --help    - print this help text

Examples:
    freetz_download dl .config package.tar.bz2
    freetz_download dl .config package.tar.bz2 http://myserver.com/freetz

Debugging: just set DEBUG=1, like this:
    DEBUG=1 freetz_download dl .config package.tar.bz2
EOF
}

do_download()
{
  # $1 = full download URL, $2 = target directory
  echo
  if [ "$DEBUG" == "1" ]; then echo "wget -nd -T 20 -t 3 --passive-ftp -P $1 $2"; fi
  wget -nd -t3 --timeout=20 --passive-ftp -P "$1" "$2"
  wget_result=$?
  if [ "$wget_result" != "0" ]; then
    echo "Download failed - $2  ->  error code $wget_result" >&2
    fname=$(basename $2)
    rm -f $1/$fname
    return $wget_result
  fi
  echo "Download succeeded - $2  ->  saved to folder $1"
}

do_check()
{
  wget --quiet -t3 --timeout=20 --passive-ftp --spider "$1"
  wget_result=$?
  return $wget_result
}


# Regular use: help parameter -> exit without error
if [ "$1" == "-?" -o "$1" == "--help" ]; then
  helpmsg
  exit 0
fi

# Wrong number of parameters -> exit with error
if [ $# -lt 3 -o $# -gt 5 ]; then
  helpmsg >&2
  exit 1
fi

DL_DIR="$1"
DOT_CONFIG="$2"
DL_FILE="$3"
MAIN_URL="$4"
MD5="$5"

# Import Freetz config variables
. $DOT_CONFIG

if [ "$DEBUG" == "1" ]; then
  echo "freetz_download parameters:"
  echo "  DL_DIR=$1"
  echo "  DOT_CONFIG=$2"
  echo "  DL_FILE=$3"
  echo "  MAIN_URL=$4"
  echo "  MD5=$5"
fi

num_sites=0
# Fill array 'sites' with download server URLs, first primary site (if specified)
if [ -n "$MAIN_URL" ]; then
  # give sourceforge a few more tries, because it redirects to different mirrors
  if [ ${MAIN_URL:0:3} == "@SF" ]; then
    MAIN_URL=${MAIN_URL/@SF\//}
    for (( n=0; n < 5; n++ )); do
      sites[$num_sites]=http://downloads.sourceforge.net/$MAIN_URL
      (( num_sites++ ))
    done
  elif [ ${MAIN_URL:0:4} == "@AVM" ]; then
    MAIN_URL=${MAIN_URL/@AVM\//}
    sites[0]=ftp://ftp.avm.de/$MAIN_URL
    sites[1]=http://download.avm.de/$MAIN_URL
    num_sites=2
  else
    sites[$num_sites]=$MAIN_URL
    (( num_sites++ ))
  fi
fi

# Get Freetz mirror sites in array
FREETZ_SITES=( $(
	for (( i=1; i <= FREETZ_MOD_DL_NUM_SITES ; i++ )); do
	  eval "echo \$FREETZ_MOD_DL_SITE_$i"
	done
	) )
# Fill array 'sites' with download server URLs, add Freetz Mirrors, in random order
for (( n=${#FREETZ_SITES[@]}; n > 0; n-- )); do
  p=$(( RANDOM % n ))
  sites[$num_sites]=${FREETZ_SITES[$p]}
  (( num_sites++ ))
  FREETZ_SITES[$p]=${FREETZ_SITES[$((n-1))]}
done

# Loop over servers until a download succeeds or all requests have failed.
for i in ${sites[@]}; do
  if [ ${DL_DIR:0:5} == "check" ]; then
    do_check "$i/$DL_FILE"
    if [ "$?" != "0" ]; then
      continue
    fi
  else
    do_download "$DL_DIR" "$i/$DL_FILE"
    if [ "$?" != "0" ]; then
      continue
    fi
    if [ -n "$MD5" ]; then
      FILE_MD5=( $(md5sum "$DL_DIR/$DL_FILE") )
      if [ "$MD5" != "$FILE_MD5" ]; then
        echo "MD5 mismatch for $DL_DIR/$DL_FILE: $MD5 $FILE_MD5" 1>&1
        rm -f "$DL_DIR/$DL_FILE"
        continue;
      else
        echo "MD5 verified for $DL_DIR/$DL_FILE: $FILE_MD5"
      fi
    fi
  fi
  exit 0
  done

exit 1