#!/bin/bash
#
# Might want to drop this in ~/bin/ and chmod u+x it
#

#  Initial Author: Karanbir Singh <kbsingh@centos.org>
#         Updates:
#                  Mike McLean <mikem@redhat.com>
#                  Pat Riehecky <riehecky@fnal.gov>
#                  Tyler Parsons <tparsons@fnal.gov>
#                  Tuomo Soini <tis@foobar.fi>
set -eux


#####################################################################
usage() {
    echo ''                                               >&2
    echo "$0 [-hcq] [-b branch] [--surl url]"             >&2
    echo ''                                               >&2
    echo 'Script to parse the non-text sources metadata file'   >&2
    echo ' and download the required files from the lookaside'  >&2
    echo ' cache.'                                              >&2
    echo ''                                                     >&2
    echo 'PLEASE NOTE: this script is non-destructive, it wont' >&2
    echo ' replace files that already exist, regardless of'     >&2
    echo ' their state, allowing you to have work-in-progress'  >&2
    echo ' content that wont get overwritten.'                  >&2
    echo ''                                                     >&2
    echo 'You need to run this from inside a sources git repo'  >&2
    echo ''                                               >&2
    echo ' -h: This help message'                         >&2
    echo ''                                               >&2
    echo "  $0 -b c7"                                     >&2
    echo "  $0 -q -b c7"                                  >&2
    echo "  $0 -c -b remotes/origin/c7"                   >&2
    echo "  $0 -c -b c7 --surl '$SURL'"                   >&2
    echo "  $0"                                           >&2
    exit 1
}

#####################################################################

SURL="https://git.centos.org/sources"

QUIET=0
BRANCH=''
CHECK=0

# for setting any overrides, such as SURL, default BRANCH, or force CHECK
if [ -f /etc/centos-git-common ]; then
  . /etc/centos-git-common
fi

#####################################################################
# setup args in the right order for making getopt evaluation
# nice and easy.  You'll need to read the manpages for more info
# utilizing 'while' construct rather than 'for arg' to avoid unnecessary
# shifting of program args
args=$(getopt -o hcqb: -l surl: -- "$@")
eval set -- "$args"

while [[ 0 -eq 0 ]]; do
    case $1 in
        -- )
            # end of getopt args, shift off the -- and get out of the loop
            shift
            break
           ;;
         -c )
            # verify the sha1sum of the downloaded file
            CHECK=1
            shift
           ;;
         -q )
            # suppress warnings
            QUIET=1
            shift
           ;;
         -b )
            # Check this particular branch
            BRANCH=$2
            shift
            shift
           ;;
         --surl )
            # override sources url
            SURL=$2
            shift
            shift
           ;;
         -h )
            # get help
            usage
           ;;
    esac
done

# set curl options this way so defaults can be set in /etc/centos-git-common
# across multiple scripts
if [[ ${QUIET} -eq 1 ]]; then
    QUIET='--silent'
else
    QUIET=''
fi

command -v git >/dev/null 2>&1
if [[ $? -ne 0 ]]; then
    echo 'You need git in PATH' >&2
    exit 1
fi

command -v curl >/dev/null 2>&1
if [[ $? -ne 0 ]]; then
    echo 'You need curl in PATH' >&2
    exit 1
fi

if [ ! -d .git ] && ([ ! -d SPECS ] || [[ ! -s sources ]] ); then
      echo 'You need to run this from inside a sources git repo' >&2
      exit 1
    fi

# sort out our branch
if [ -n "$BRANCH" ]
then
  branches=("$BRANCH")
else
  # generate a list of all branches containing current HEAD
  branches=()
  while IFS='' read -r line
  do
    # input from: git branch --contains HEAD
    branch="${line:2}"
    if [[ "$branch" =~ "detached from" ]]
    then
      # ignore detached heads
      continue
    fi
    if [ ".${line:0:1}" = ".*" ]
    then
      # current branch, put it first
      branches=("${branch}" ${branches[@]+"${branches[@]}"})
    else
      branches=(${branches[@]+"${branches[@]}"} "${branch}")
    fi
  done <<< "$(git branch -r --contains HEAD | sed 's#origin/##g')"
fi

if [[ -f sources ]]; then
    if [[ ! -s sources ]]; then
      echo "Empty sources file -- nothing to check"
    else
      # This section is for the "flat" dist-git layout, where the spec file and
      # patches are all present at the top level directory and the sha of the tarball
      # present in a 'sources' file.
      # This code was re-used from the fedpkg-pkg minimal project which is licensed
      # under GPLv3 or any later version.

      pkgname=$(basename "$PWD")
      # Read first word of first line. For old MD5 format it's the 32 character
      # hash. Otherwise let's assume the sources have the BSD format where lines
      # start with hash type.
      hashtype="$(head -n1 sources | cut -d' ' -f1 | tr '[:upper:]' '[:lower:]')"
      # The format is
      #   SHA512 (filename) = ABCDEF
      # We don't care about the equals sign. We also assume all hashes are
      # the same type, so we don't need to read it again for each line.
      while read -r _ filename _ hash || [[ -n "$filename" && -n "$hash" ]]; do
          if [ -z "$filename" ] || [ -z "$hash" ]; then
              continue
          fi
          # Remove parenthesis around tarball name
          filename=${filename#(}
          tarball=${filename%)}
          if [ ! -e "$tarball" ]; then
            for br in "${branches[@]}"
            do
              br=$(echo ${br}| sed -e s'|remotes/origin/||')
              # Try the branch-specific lookaside structure
              url="${SURL}/$pkgname/${br}/$hash"
              echo "Retrieving ${url}"
              HTTP_CODE=$(curl -L ${QUIET} -H Pragma: -o "./$tarball" -R -S --fail --retry 5 "${url}" --write-out "%{http_code}" || true)
              echo "Returned ${HTTP_CODE}"
              if [[ ${HTTP_CODE} -gt 199 && ${HTTP_CODE} -lt 300 ]] ; then
                 echo "bailing"
                 break
              fi
              # Try the hash-specific lookaside structure
              url="${SURL}/$pkgname/$tarball/$hashtype/$hash/$tarball"
              echo "Retrieving ${url}"
              curl -L ${QUIET} -H Pragma: -o "./$tarball" -R -S --fail --retry 5 "${url}" && break
            done
          else
            echo "$filename exists. skipping"
          fi
      done < sources
      "${hashtype}sum" -c sources
    fi
else
    # This section is for the "non-flat" dist-git layout, where the spec file
    # is stored in a SPECS folder, the patches in a SOURCES folder and the sha
    # of the tarball of the project is present in a '.<pkg_name>.metadata' file.

    mkdir -p SOURCES
    # should go into a function section at some point
    weakHashDetection () {
      strHash=${1};
      case $((`echo ${strHash}|wc -m` - 1 )) in
        128)
          hashBin='sha512sum'
          ;;
        64)
          hashBin='sha256sum'
          ;;
        40)
          hashBin='sha1sum'
          ;;
        32)
          hashBin='md5sum'
          ;;
        *)
          hashBin='unknown'
          ;;
      esac
      echo ${hashBin};
    }

    # check metadata file and extract package name
    shopt -s nullglob
    set -- .*.metadata
    if (( $# == 0 ))
    then
        echo 'Missing metadata. Please run from inside a sources git repo' >&2
        exit 1
    elif (( $# > 1 ))
    then
        echo "Warning: multiple metadata files found. Using $1"
    fi
    meta=$1
    pn=${meta%.metadata}
    pn=${pn#.}

    while read -r fsha fname ; do
      if [ ".${fsha}" = ".da39a3ee5e6b4b0d3255bfef95601890afd80709" ]; then
        # zero byte file
        touch ${fname}
      else
        hashType=$(weakHashDetection ${fsha})
        if [ "${hashType}" == "unknown" ]; then
          echo 'Failure: Hash type unknown.' >&2
          exit 1;
        fi
        hashName=$(echo ${hashType}| sed -e s'|sum||')

        if [ ${CHECK} -eq 1 ]; then
          which ${hashType} >/dev/null 2>&1
          if [[ $? -ne 0 ]]; then
            echo "Failure: You need ${hashType} in PATH." >&2
            exit 1;
          fi
        fi
        if [ -e ${fname} -a ${CHECK} -eq 1 ]; then
            # check hash sum and force download if wrong
            downsum=$(${hashType} ${fname} | awk '{print $1}')
            if [ "${fsha}" != "${downsum}" ]; then
                rm -f ${fname}
            fi
        fi
        if [ ! -e "${fname}" ]; then
          for br in "${branches[@]}"
          do
            br=$(echo ${br}| sed -e s'|remotes/origin/||')
            # Try the branch-specific lookaside structure
            url="${SURL}/${pn}/${br}/${fsha}"
            echo "Retrieving ${url}"
            HTTP_CODE=$(curl -L ${QUIET} -H Pragma: -o "${fname}" -R -S --fail --retry 5 "${url}" --write-out "%{http_code}" || true)
            echo "Returned ${HTTP_CODE}"
            if [[ ${HTTP_CODE} -gt 199 && ${HTTP_CODE} -lt 300 ]] ; then
               echo "bailing"
               break
            fi
            # Try the hash-specific lookaside structure
            url="${SURL}/$pn/$fname/${hashName}/$fsha/$fname"
            echo "Retrieving ${url}"
            curl -L ${QUIET} -H Pragma: -o "${fname}" -R -S --fail --retry 5 "${url}" && break
          done
        else
          echo "${fname} exists. skipping"
        fi
        if [ ${CHECK} -eq 1 ]; then
            downsum=$(${hashType} ${fname} | awk '{print $1}')
            if [ "${fsha}" != "${downsum}" ]; then
                rm -f ${fname}
                echo "Failure: ${fname} hash does not match hash from the .metadata file" >&2
                exit 1;
            fi
        fi
      fi
    done < "${meta}"

fi